Patent Publication Number: US-9839548-B2

Title: Orthopedic device

Description:
TECHNICAL FIELD 
     The disclosure relates to an orthopedic device for protecting and/or immobilizing one or more affected areas on a user&#39;s lower leg, ankle, and/or foot. 
     BACKGROUND 
     It is common that people, especially frail elderly people and diabetics, experience a variety of lower leg, ankle, and foot injuries. Physicians traditionally have treated, and still currently treat, injuries such as pressure ulcers affecting the foot by fitting the injured patient with the well-known, molded plaster or resin cast. The placement of this type of cast is time consuming, heavy, and costly. Further, this type of cast must not come into contact with water, which makes patient bathing difficult and time consuming. Additionally, if the cast needs to be removed for any reason, for example, inspection, a whole new cast must be prepared and applied. 
     Alternatively, walking boots or walkers have been used for protecting and immobilizing injured or affected areas of the lower leg, ankle, and/or foot, such that at least partial mobility may be maintained while the affected areas are in the process of healing. Further, in contrast to the molded plaster or resin cast, a walker can be easily removed in order to bathe or for inspection of the injured limb by a physician or practitioner. 
     Existing wrap-around or circumferential walkers however can be bulky and uncomfortable for users. Particularly, hard edges and/or surfaces of existing walkers can cause pressure points on the user&#39;s toes, feet, ankle, and/or lower leg that can cause users pain and discomfort, and may also cause injury to a user, such as pressure ulcers. Pressure ulcers can become infected, contain scar tissue, and may result in secondary problems up to and including amputation. 
     Alternatively, existing walkers may include inflatable supports for improving the comfort of the walker, but these inflatable supports can be more harmful than helpful. Particularly, existing walkers require the user to regulate or control the pressure level in the inflatable supports. This is problematic because patients, especially those with diabetes, often experience reduced sensation in their extremities, which can result in them inadvertently overinflating the inflatable supports. Over-inflation of the inflatable supports can cause pressure on the skin which can reduce both capillary blood flow to the skin and arterial flow to the affected limb. It can also lead to the formation of pressure ulcers on the foot of the patient and longer healing times for existing ulcers. Further, existing walkers with inflatable supports often require patients to monitor pressure levels in the inflatable supports with a pressure gauge. However, many patients do not see well enough to read the pressure gauges and such pressure gauges are also known to malfunction. 
     Additionally, features associated with the inflatable supports in existing walkers are known to create pressure points within the walker and/or to be unreliable. For instance, tubing associated with the inflatable supports is typically routed along the inside surface of the walker, creating pressure points on the inside of the walker, which can be uncomfortable and can cause additional pressure ulcers. Moreover, such tubing can become kinked and/or pinched between the walker and the patient&#39;s lower leg, ankle, and/or foot, rendering the inflatable supports effectively inoperable. Pump features associated with the inflatable supports are also commonly arranged on the walker such that they are prone to being bumped, misaligned, and/or damaged during use, increasing the likelihood that the inflatable supports will be inadvertently inflated, deflated, and/or rendered inoperable. 
     SUMMARY 
     The orthopedic device described herein may be, in exemplary embodiments, a lightweight walker. It is also contemplated that other orthopedic devices may utilize similar configurations as described below. 
     The orthopedic device described herein typically takes the form of a semi-rigid or substantially rigid shell walker, which provides protection and immobilization to an affected area on the lower leg, ankle, and/or foot by surrounding the lower leg, ankle, and/or foot with an appropriate structure. It will be recognized that the features described herein may have applicability to other walker configurations or other types of orthopedic devices. 
     In the exemplary embodiments, various configurations of flexible edge arrangements, inflation system arrangements, and shell arrangements are utilized to limit pressure points and/or excessive pressure on a user&#39;s lower leg, ankle, and/or foot in order to provide a more comfortable fit and more effective treatment of affected areas on the user&#39;s lower leg, ankle, and/or foot. 
     For example, an orthopedic device may include a base shell having ankle and foot receiving portions and forming an opening over a dorsal aspect of the base shell. A dorsal shell can be contoured to generally correspond to the opening in the base shell. The dorsal shell can include a proximal member connected to a distal member via a flexible or resilient connecting portion arranged to accommodate a portion of the user&#39;s lower leg or ankle. 
     A first flexible edge portion can be attached to a distal terminal end of the distal member. During use, the distal member of the dorsal shell can become pitched or angled relative to the user&#39;s toes due to a variety of different circumstances, including, but not limited to, user anatomy, use of heel lifts and/or wedges, or as the user walks. The first flexible edge portion can be arranged to flex or bend relative to the distal member when the distal member pitches or angles relative to the toes. This has the effect of reducing the transfer of force from the distal member to the toes and/or distributing the force from the distal member over a greater surface area, which, in turn, reduces the likelihood of a potentially harmful pressure point on the user&#39;s toes from the distal member. 
     The first flexible edge portion can also help accommodate bandaging of the user&#39;s toes or the forefoot because the first flexible edge portion can be flexed upward or removed from the distal member. The first flexible edge portion can also include a toe relief portion radially extending away from the user&#39;s toes, substantially reducing the likelihood of the distal member diving down into the toes, which could cause discomfort or even injury. 
     The proximal member of the dorsal shell may also include a second flexible edge portion attached to a proximal terminal end of the proximal member. The second flexible edge portion on the proximal member can be arranged to bend or flex when the user&#39;s leg exerts a force on the second flexible edge portion. This has the effect of reducing the likelihood of creating a pressure point on the user&#39;s lower leg from the dorsal shell and can provide pressure relief to the user&#39;s tibia, improving the comfort and effectiveness of the orthopedic device. 
     At least one observation hole may be formed in the base shell posterior of the user&#39;s malleoli to allow for tactile confirmation of the position of the user&#39;s foot within the orthopedic device, which can reduce the likelihood of one or more pressure points within the orthopedic device from the user&#39;s heel being too far back within the base shell. 
     By way of another example, an orthopedic device may include a base shell and a dorsal shell contoured to generally correspond to an opening in the base shell. At least one tightening member can be connectable to the base shell and extendable over the dorsal shell to secure the base shell and dorsal shell together about a user&#39;s lower leg and foot. At least one inflatable bladder may be provided in the base shell and a pump assembly may be arranged to inflate the at least one inflatable bladder. 
     The pump assembly can be situated on the at least one tightening member such that the position of the pump assembly is substantially fixed relative to the base shell as the user walks in the orthopedic device. This advantageously limits unwanted movement of the pump assembly, reducing the likelihood of the pump assembly inadvertently inflating or deflating the at least one inflatable bladder as in the prior art. The pump assembly may also be situated on an anterior aspect of the at least one tightening member, increasing the usability of the pump assembly. 
     The base shell can include at least one tube hole formed therein that allows at least one inflation tube to pass from the pump assembly to an exterior surface of the base shell such that the at least one inflation tube can run along the exterior surface of the base shell rather than the interior of the base shell as in the prior art. This has the effect of reducing the likelihood of a pressure point from the at least one inflation tube as the user walks in the orthopedic device and the likelihood of the at least one inflation tube being pinched or kinked inside of the orthopedic device. 
     A pressure relief valve assembly can be fluidly connected to the at least one inflatable bladder and arranged to automatically release air from the at least one inflatable bladder to atmosphere when pressure within the at least one inflatable bladder exceeds a cracking pressure of the pressure relief valve assembly. This allows the pressure relief valve to automatically regulate or limit the pressure level within the at least one inflatable bladder rather than requiring the user to regulate the pressure level, as in the prior art, eliminating or substantially decreasing the likelihood that a user will over-inflate the at least one inflatable bladder. This is advantageous because users of walkers and other orthopedic devices, especially diabetic patients, often experience reduced sensation in their extremities, which can result in them inadvertently over-inflating the at least one inflatable bladder. Such over-inflation can cause pressure on the skin, which can reduce both capillary blood flow to the skin and arterial flow to the anatomical member. It can also lead to the formation of pressure ulcers on the foot of the patient and longer healing times for existing ulcers. 
     Further, because the pressure relief valve automatically regulates pressure within the at least one inflatable bladder, users can inflate the at least one inflatable bladder without the need of reading a pressure gauge as in the prior art, making the orthopedic device easier and safer to use. The pressure relief valve assembly also overcomes issues with changes in ambient pressure creating excessive pressure within the at least one inflatable bladder, such as a change in altitude, as the pressure relief valve assembly automatically reduces excess pressure in the at least one inflatable bladder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present disclosure will become better understood regarding the following description, appended claims, and accompanying drawings. 
         FIG. 1  is a front side isometric view of an orthopedic device comprising a walker according to an embodiment. 
         FIG. 2  is a back side isometric view of the walker shown in  FIG. 1 . 
         FIG. 3  is a detail view of an eyelet shown in  FIG. 2  according to an embodiment. 
         FIG. 4  is a front isometric view of a hook tab component according to an embodiment. 
         FIG. 5  is a back isometric view of the hook tab component shown in  FIG. 4 . 
         FIG. 6  is a back isometric view of the hook tab component and a tightening tool according to another embodiment. 
         FIG. 7  is a front side isometric view of the base shell shown in  FIG. 1 . 
         FIG. 8A  is a front side isometric view of the dorsal shell shown in  FIG. 1 . 
         FIG. 8B  is a partial front side isometric view of the dorsal shell shown in  FIG. 8A . 
         FIG. 9  is a back side isometric view of the dorsal shell shown in  FIG. 1 . 
         FIG. 10  is a front isometric view of a walker according to another embodiment. 
         FIG. 11  is a front isometric view of a compliance clasp assembly in a closed position according to another embodiment. 
         FIG. 12  is a partial front isometric view of a compliance clasp in an open position according to an embodiment. 
         FIG. 13  is a sectional view of the compliance clasp shown in  FIG. 12  taken along section line  12 - 12 . 
         FIG. 14  is a front isometric view of a compliance clasp in an open position according to another embodiment. 
         FIG. 15  is a front isometric view of a walker according to another embodiment. 
         FIG. 16  is a back isometric view of the walker shown in  FIG. 15 . 
         FIG. 17  is a schematic view of an air inflation system for use with the walker shown in  FIG. 15  according to an embodiment. 
         FIG. 18  is an exploded view of a pump assembly according to an embodiment. 
         FIG. 19  is an exploded view of a pump assembly according to another embodiment. 
         FIG. 20  is a partial side view of the walker shown in  FIG. 15 . 
         FIG. 21  is a partial exploded back view of the walker shown in  FIG. 15 . 
         FIG. 22  is a side isometric view of the pressure relief valve assembly shown in  FIG. 21 . 
         FIG. 23  is a cross sectional view of the pressure relief valve assembly shown in  FIG. 22 . 
         FIG. 24  is a side isometric view of a pressure relief valve assembly according to another embodiment. 
         FIG. 25  is a cross sectional view of the pressure relief valve assembly shown in  FIG. 24 . 
         FIG. 26  is an isometric view of a pressure relief valve assembly and cover member according to another embodiment. 
         FIG. 27  is a front view of the base shell shown in  FIG. 15  with the liner removed, showing the bladder. 
         FIG. 28  is a schematic diagram of an inflation system according to another embodiment. 
         FIG. 29  is a front isometric view of an orthopedic system according to another embodiment. 
         FIG. 30  is a schematic diagram of the orthopedic device in  FIG. 29  positioned on a knee scooter. 
         FIG. 31  is a back isometric view of the protective part in  FIG. 29  removed from the orthopedic device for ease of reference. 
         FIG. 32  is a front isometric view of an orthopedic system according to another embodiment. 
         FIG. 33  is a front isometric view of an orthopedic system according to another embodiment. 
         FIG. 34  is a front isometric view of an orthopedic system according to another embodiment. 
         FIG. 35  is a back isometric view of the protective part in  FIG. 34  removed from the dorsal shell for ease of reference. 
         FIG. 36  is a back isometric view of the dorsal shell in  FIG. 34 . 
         FIG. 37  is a side isometric view of an orthopedic system according to another embodiment. 
         FIG. 38  is a partial exploded view of the orthopedic device and stabilizing part in  FIG. 37 . 
         FIG. 39  is a top view of the stabilizing part in  FIG. 37 . 
         FIG. 40  is a back view of the stabilizing part in  FIG. 37 . 
         FIG. 41  is a side view of the stabilizing part in  FIG. 37 . 
         FIG. 42  is a top view of a stabilizing part according to another embodiment. 
         FIG. 43  is a back isometric view of an orthopedic system according to another embodiment. 
         FIG. 44  is a front view of the inside of the orthopedic device in  FIG. 43 . 
         FIG. 45  is a front view of the cover member and activity tracking device in  FIG. 43  removed from the orthopedic device for ease of reference. 
         FIG. 46  is an architectural schematic diagram of a monitoring system according to an embodiment. 
         FIG. 47  is a back view of an orthopedic system according to another embodiment. 
         FIG. 48  is a front view of an orthopedic system according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     A better understanding of different embodiments of the disclosure may be had from the following description read with the accompanying drawings in which like reference characters refer to like elements. 
     While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments are in the drawings and described below. It should be understood, however, there is no intention to limit the disclosure to the embodiments disclosed, but on the contrary, that the intention covers all modifications, alternative constructions, combinations, and equivalents falling with the spirit and scope of the disclosure. 
     For further ease of understanding the embodiments of an orthopedic device as disclosed herein, a description of a few terms is necessary. As used herein, the term “dorsal” has its ordinary meaning and refers to the top surfaces of the foot, ankle and foreleg or shin. As used herein, the term “plantar” has its ordinary meaning and refers to a bottom surface, such as the bottom of a foot. As used herein, the term “proximal” has its ordinary meaning and refers to a location that is closer to the heart than another location. Likewise, the term “distal” has its ordinary meaning and refers to a location that is further from the heart than another location. The term “posterior” also has its ordinary meaning and refers to a location that is behind or to the rear of another location. Lastly, the term “anterior” has its ordinary meaning and refers to a location that is ahead of or to the front of another location. 
     The terms “rigid,” “flexible,” and “resilient” may be used herein to distinguish characteristics of portions of certain features of the orthopedic device. The term “rigid” is intended to denote that an element of the device is generally devoid of flexibility. Within the context of support members or shells that are “rigid,” it is intended to indicate that they do not lose their overall shape when force is applied, and in fact they may break if bent with sufficient force. On the other hand, the term “flexible” is intended to denote that features are capable of repeated bending such that the features may be bent into retained shapes or the features do not retain a general shape, but continuously deform when force is applied. The term “resilient” is used to qualify such flexible features as generally returning to an initial general shape without permanent deformation. As for the term “semi-rigid,” this term is used to connote properties of support members or shells that provide support and are free-standing; however such support members or shells may have some degree of flexibility or resiliency. 
     An exemplary embodiment of a walker  100  is shown in  FIGS. 1-9 . As can be seen from the figures this embodiment includes complementary base  102  and dorsal  104  shells that are selectively engageable with each other in order to provide easy access to the interior of the device for ease of donning and doffing the device, in particular for donning and doffing the device unto an injured limb. The base shell  102  has ankle and foot receiving portions  101 ,  103  (best shown in  FIG. 7 ) and forms an opening  105  (best shown in  FIG. 7 ) over a dorsal aspect thereof. The dorsal shell  104  is contoured to generally correspond to the opening  105  of the base shell  102 . 
     The walker  100  can include a semi-rigid or substantially rigid shell configuration that is formed to support and support the lower leg, foot, and ankle of the user or patient. The shell configuration can extend from the foot and ankle up along the shin and tibia of the lower leg to a desired point below the knee joint. Exemplary suitable materials for forming the shells can include metals, such as aluminum, carbon, composites, glass fiber/epoxy composites, or suitable plastic materials, such as thermoplastic or thermosetting polymers, fiber reinforced plastic, molded chopped fibers, or any other suitable material. Other exemplary materials include, but are not limited to, nylons, glass filled nylon, polypropylenes, vinyls, polyvinyl chlorides, high density polyethylene, epoxies, urethanes, and polyesters. While the walker is described having a rigid shell configuration, it will be appreciated that the walker  100  may be any type of walker or other suitable orthopedic device. 
     In use, a user can move the walker  100  from a closed configuration to an open configuration by moving the dorsal shell  104  away from the base shell  102 , allowing insertion of the lower leg, ankle, and foot into the walker  100 . Once the user has inserted their lower leg into the walker  100 , the dorsal shell  104  can be returned to the closed configuration to enclose the lower leg within the walker  100 . The user can then utilize one or more tightening mechanisms described below to apply pressure and support and to maintain the walker  100  in the closed configuration. 
     The walker  100  can be oversized to accommodate a number of different accessory components and/or sized feet. A width of the walker  100  can be defined between the lateral and medial sides of the walker  100 . The width of the walker  100  can be between about 1.02 and about 1.5, between about 1.05 and about 1.3 (e.g., about 1.08), or between about 1.1 and about 1.2 times greater than the width of a conventional walker. For instance, if a conventional walker has a width of about 140 mm, the walker  100  can have a width between about 145 mm and about 160 mm (e.g., about 152 mm). This has the effect of providing a larger foot bed within the walker  100  for insertion of accessory components, such as, but not limited to, heel wedges, inflatable bladders, padding, or other suitable components. This also allows the walker  100  to accommodate larger feet and/or to be a multi-purpose walker. For instance, the oversized foot bed can provide sufficient space to add and/or remove components from the walker  100 , allowing the walker  100  to be customized for a specific purpose. More particularly, by adding and/or removing components from the foot bed of the walker  100 , the walker  100  can be converted from one type of walker to another type of walker (e.g., from a diabetic walker to an Achilles walker, or a fracture walker, or vice versa). 
     The shell configuration includes a base shell  102  and a dorsal shell  104 . At least one of the base shell  102  or the dorsal shell  104  can have generally smooth rounded edges, helping to increase the comfort and safety of the walker  100 . The base shell  102  has a posterior portion  106  (best shown in  FIG. 2 ) and a plantar portion  108  that is arranged to extend along the plantar surface of the foot. Lateral and medial (first and second) wing portions  110  extend from the posterior portion  106  and the plantar portion  108 . The wing portions  110  can be arranged to at least partially enclose and support a user&#39;s leg. A soft good liner  112  can be situated inside the base shell  102 . An insole  114  can be provided on the proximal surface of the liner  112  and/or the base shell  102 . An outsole  116  is formed on the base shell  102 , either integrally, or separately. The outsole  116  can define a toe protector portion  118  and can have any suitable configuration, such as a rubber sole having a roll over shape. 
     In order to reduce the weight of the walker  100  and/or to provide ventilation, material can be removed from areas of the shell portions to provide apertures  120 . The apertures  120  can be formed in any of the shells  102 ,  104 . The apertures  120  can have different sizes and/or shapes. The apertures  120  can extend at an angle. For instance, some of all of the apertures  120  can have a generally oblong shape and can extend at an angle. The apertures  120  in the ankle region of the base shell  102  can be longer than the apertures  120  in a toe region of the base shell  102 . 
     Some or all of the apertures  120  can be arranged in one or more gradients. Arranging the apertures  120  in gradients can improve the biomechanical properties of the shells with respect to an anatomical limb positioned in the walker  100  by influencing the flexibility or stiffness of the shells with the apertures. For instance, the apertures  120  in the foot receiving portion  103  of the base shell  102  can be arranged in a gradient with larger apertures  120  in the ankle region and smaller apertures in the toe region. The apertures  120  in an upper region of the base shell  102  can be arranged with larger apertures  120  toward the middle of the lower leg and smaller apertures  120  toward the ankle and the knee. 
     In other embodiments, the apertures  120  in the upper region of the base shell  102  can have different sizes and shapes and can be extending at an angle. Some or all of the apertures  120  can also be arranged in a plurality of rows. Some or all of the apertures  120  in the foot receiving portion  103  of the base shell  120  can comprise a series of slots extending at an angle and a singular larger, irregularly shaped non-through hole in the toe region. 
     The apertures  120  can comprise through holes and/or non-through holes. Some or all of the apertures  120  in the foot receiving portion  103  of the base shell  102  can be non-through holes. This can prevent ingress of external objects through the apertures  120  that may potentially injure the foot, which, in turn, enhances user safety. This also has the effect of protecting the user&#39;s foot from sharp edges that can injure the foot. The non-through holes in the foot receiving portion  103  are especially important for users of the walker  100  who suffer from neuropathy having nerve damage in the foot. Non-through holes in either shell can also reinforce or strength the walker  100  in the region of the apertures  120 . 
     Some or all of the apertures  120  can comprise through holes. Some or all of the through holes can be positioned, shaped, sized, and/or patterned to enhance heat and/or fluid transfer from the interior of the walker  100  to the exterior of the walker  100 . This can allow the walker  100  to vent heat and/or perspiration from the interior of the walker  100 , which, in turn, increases user comfort. The through-holes can also provide some level of resiliency to the shells. This can allow the walker  100  to better accommodate swelling of a limb or different sizes of lower legs, ankles, and/or feet. 
     Some or all of the apertures  120  can include a through-hole portion and a non-through hole portion. For instance, some or all of the apertures  120  can include a periphery and upstanding sidewall portions extending about the periphery. A non-through hole portion can include a bottom surface formed by a portion of the shell and a through-hole portion can be open ended, extending completely through the shell. 
     Some or all of the apertures  120  can include radiused or rounded-off edges, reducing the likelihood of a user inadvertently scrapping or injuring a non-affected limb on the edges of the apertures  120  as the non-affected limb moves back and forth across the apertures. 
     The walker  100  can have structures designed to selectively strengthen the base shell  102  and the dorsal shell  104  in a specific direction. The base shell  102  can include reinforcing ridges  121  that extend at an angle along both lateral and medial sides thereof. 
     As can be seen in  FIGS. 1 and 2 , eyelets  122  can be formed in the wing portions  110  of the base shell  102  for providing one or more anchoring points for different components and/or accessories.  FIG. 3  is a detailed view of an eyelet  122  according to an embodiment. 
     The eyelet  122  can include an annular rim portion  124 , a sloping inner sidewall portion  126 , a through-hole portion  128 , and a seat  130  formed in the inner sidewall portion  126  for receiving and securing a portion of an attachment system (e.g., a hook portion) therein. The eyelets  122  can be at least partially debossed below an exterior surface of the base shell  102  such that each eyelet  122  is at substantially the same depth below the exterior surface. 
     Some or all of the eyelets  122  can provide an anchoring a point for a hook tab component, such as the hook tab component  132  shown in  FIGS. 4 and 5 . As seen, the hook tab component  132  can comprise a larger generally elliptical main body  134 , a smaller portion  136 , a generally planar bottom side  138 , and an upper side  140 . The hook tab component  132  can be formed from any suitable material such a plastic, rubber, or metal material. 
     The bottom side  138  of the hook tab component  132  can arranged to provide an attachment surface for a portion of a hook-and-loop type system (e.g., Velcro®), the liner  112 , a pad, an inflatable bladder described below, or any other suitable component. The attachment surface can be used to place an adhesive dot or two sided tape on the hook tab component  132 . For instance, a pad could be adhered to the bottom side  138  of the hook tab component  132  via the adhesive dot or two sided tape and then secured in a fixed position on the walker  100  as desired. 
     A hook member  142  can be formed on the upper side  140  for interfacing with an eyelet  122 . The hook member  142  can exhibit any suitable configuration. The hook member  142  can include a generally rectangular base portion attached to the upper side  140  and a generally oblong head portion attached to the rectangular base portion. 
     The hook member  142  can anchor the hook tab component  132  to the base shell  102 . The hook tab component  132  can be situated inside the walker (shown in  FIG. 7 ) and the head portion of the hook member  142  can be generally aligned with the through-hole portion  128  in the eyelet  122 . The head portion of the hook member  142  can then be inserted through the through-hole portion  128  and rotated until the head portion of the hook member  142  rests in the seat  130  of the eyelet  122 , which secures the hook tab component  132  within the eyelet  122 . While secured in the eyelet  122 , the upper side  140  of the hook tab component  132  can be facing and/or secured against the interior surface of the base shell  102 . This allows the location of components inside of the walker  100  to be customized by installing hook tab components  132  attached or attachable to the components in different eyelets  122  formed in the base shell  102 . 
     Optionally, the hook tab component  132  can include installation features to aid in the installation of the hook tab component in the eyelet  122 .  FIG. 6  illustrates a hook tab component  232  according to another embodiment including a recessed portion  244  formed in the bottom side  238  of the smaller portion  236 . 
     A user can insert a tightening tool  246  or key within the recessed portion  244  to rotate the hook tab component  232  within the eyelet  122  relative to the base shell  102 . A first portion of the tightening tool  246  can be positioned on the bottom side  238  at or near a center of the hook tab component  232 . A protrusion  247  on the tightening tool  246  can be positioned in the recessed portion  244 . The tightening tool  246  can then be rotated about the first portion on the center of the hook tab component  232 , which, in turn, causes the protrusion to engage a shoulder formed by the recessed portion  244 , rotating the hook tab component  232 . This can facilitate installation of the hook tab component  232  in the eyelet  122 . Requiring the use of the tightening tool  246  can help deter a patient or user from removing or moving the hook tab components  232 , and thereby components attached thereto, from the walker  100  without the consent of a clinician or medical professional. The tightening tool  246  can also be provided to the clinician or medical professional but not the user or patient, helping to prevent tampering. 
     Referring again to  FIG. 2 , a flexible or resilient edge portion  148  and expansion joints  150  can be formed on the posterior portion  106  of the base shell  102  along the edges of and between the posterior of the wing portions  110 . The expansion joints  150  can be arranged in discrete groupings and formed having a larger dimension at the proximal end and tapering down to a smaller dimension at the distal end. The expansion joints  150  can include any number of expansion holes  151  passing therethrough. The expansion holes  151  can be arranged in any suitable manner and can have any desired shape or size. 
     Some or all of the expansion joints  150  and/or the flexible edge portion  148  can be formed via overmolding a different material onto end portions of the base shell  102 . For instance, the flexible edge portion  148  can be formed via a flexible plastic or elastomer, such as, for example, thermoplastic elastomer (TPE), rubber, or ethylene vinyl acetate (EVA) foam. In other embodiments, any other suitable material may be utilized, including silicone or natural or synthetic fibers. Overmolds and overmolding techniques are described in more detail in U.S. Pat. No. 5,951,504, granted Sep. 14, 1999, U.S. Pat. No. 7,018,351, granted Mar. 28, 2006, U.S. Pat. No. 7,288,076, granted Oct. 30, 2007, U.S. Pat. No. 7,311,686, granted Dec. 25, 2007, and U.S. Pat. No. 8,002,724, granted Aug. 23, 2011, all of which are incorporated herein, in their entirety, by this reference. 
     One or more observation holes  152  are formed in the wing portions  110  of the base shell  102  in the ankle receiving portion  101 , allowing for easy observation of the position of the user&#39;s foot within the walker  100  and/or observation of the operation of one or more inflatable bladders within the walker  100 . The observation holes  152  can exhibit any suitable configuration. The observation holes  152  can comprise generally rounded triangular through-holes positioned posterior to the malleoli in the base shell  102 . The position, size and shape of the observation holes  152  can be arranged for tactile confirmation of the position of the foot within the walker  100 . Using the observation holes  152  a clinician, medical professional, or user can confirm that the heel of the user is properly positioned within the walker  100 , which, in turn, reduces the likelihood of pressure points within the walker  100  from the heel being too far back. 
     Wounds in the ankle region of the user&#39;s foot can be observed via the observation holes  152  without the need of removing the walker  100  from the foot, increasing the convenience of the walker  100 . The observation holes  152  can also allow for tactile and/or visual confirmation that inflatable bladders positionable inside the base shell  102  are properly inflating or inflated, decreasing the likelihood of improper inflation. 
     While the observation holes  152  are described as generally triangular, it will be appreciated that the observation holes  152  can be generally circular, generally oval, generally diamond, or any other suitable shape. Further, while two observation holes are shown, in other embodiments, the walker  100  can include one, three, four, or any other suitable number of observation holes. The observation holes  152  can also be formed in any portion of the walker  100 . 
     As best seen in  FIGS. 1, 2 and 7 , a plurality of tightening mechanisms  154  can be arranged to bring the base shell  102  and the dorsal shell  104  closer together for tightening the walker  100  around the lower leg, ankle, and the foot. The plurality of tightening mechanisms  154  can include an ankle strap  154 A, an upper strap  154 B, and a foot strap  154 C. 
     The ankle strap  154 A can be arranged to cross over the ankle and to substantially fix the position of the ankle relative to the walker  100 . The upper strap  154 B can be arranged to cross over the lower leg below the knee. The upper strap  154 B in concert with the ankle strap  154 A can substantially fix the position of the lower leg relative to the base shell  102  by forming at least two anchoring points, one over the ankle and the other below the knee. The foot strap  154 C can be arranged to cross over the dorsal aspect of the foot. The foot strap  154 C in concert with the ankle strap  154 A can substantially fix the position of the foot relative to the base shell  102  by forming at least two anchoring points, one over the ankle and one over the distal aspect of the foot. The arrangement of the straps  154  help to keep the foot and/or ankle from moving around in the foot bed of the walker  100  reduces the likelihood of sores forming on the plantar surface of the foot, ankle, and/or lower leg from unwanted movement of the same within the walker  100 . 
     The straps  154  can comprise any suitable material. The straps  154  can include woven materials, cotton, foam, rubber, nylon, polyesters, neoprene, vinyl, webbing, or any other suitable material. The straps  154  can include any suitable type of fastening system. The straps  154  can include corresponding hook-and-loop fasteners so that at least an end portion of the straps  154  can connect a strap  154  to itself. A loop or D-ring can be attached to one end portion of the strap  154 , allowing the strap  154  to be looped through the loop or D-ring and attaching to itself via any suitable fastener. 
     A plurality of strap slots  156  can be formed in the wing portions  110  and the posterior portion  106  of the base shell  102  for receiving and positioning the straps. Strap connecting portions  158  can be provided on the wing portions  110  for anchoring the straps  154  on the base shell  102 . The strap connecting portions  158  can comprise reduced thickness portions, holes for rivet connections, or other suitable structure. If holes or rivet connections are used, connections points for the straps  154  can be pivotable. For instance, an end portion of some or all of the straps  154  can include one or more grommets arranged to receive one or more rivets, forming a riveted connection between the strap and the base shell  102 , allowing the strap to rotate at least some degree relative to the base shell  102 . 
     A loop or D-ring  160  can be attached to one end of the upper strap  154 B. The upper strap  154 B can be threaded through the strap slots  156  on the wing portions  110  of the base shell  102  and the strap slots  156  on the posterior portion  106  of the base shell  102 . The upper strap  154 B can then be looped through the loop or D-ring  160  and attached to itself, securing the upper strap  154 B over the dorsal shell  104 . 
     Loops or D-rings  160  are attached via loops of fabric that are attached to the strap connecting portions  158  on one of the wing portions  110  in the foot receiving portion  103  via loops of fabric. Each of the ankle strap  154 A and the foot strap  154 C can be connected at one end to the strap connecting portions  158  on the opposite wing portion  110 . To fasten the ankle strap  154 A and the foot strap  154 C over the dorsal shell  104 , the straps  154 A,  154 C can be extended across the dorsal shell  104  and free ends thereof can be looped through the loops or b-rings  160  on the opposite wing portion  110 . Each of the ankle strap  154 A and the foot strap  154 C can then be connected to itself via any suitable fastener, such as hook-and-loop fasteners. Alternatively, the loops or D-rings in the foot and/or ankle region can be omitted. For instance, the ankle strap  154 A and the foot strap  154 C can be attached to the wing portions  110  via strap slots formed in the wing portions  110 . 
     Strap slots  156  can be formed medial and lateral of the foot receiving portion  103  in the base shell  102 . The foot strap  154 C and the connection of the loop or D-ring  160  in this region pass from the strap connecting portions  158  on the interior of the base shell  102  through these strap slots  156  to the exterior of the base shell  102 , situating the foot strap  154 C on the outside of the base shell  102 . The foot strap  154 C can thus be accessible on the exterior of the base shell  102  rather than the interior of the base shell  102 , as in the prior art. This allows a user to more easily locate and/or thread the foot strap  154 C through the loop or D-ring  160  and reduces the likelihood of the foot strap  154 C failing inside of the walker  100 , making the walker  100  easier to don and doff. Further because the foot strap  154 C is on the outside of the base shell  102 , the likelihood of pressure points forming along the dorsal surface of the user&#39;s foot from the foot strap  154 C is significantly reduced, making the walker  100  safer and more comfortable to wear. 
     The number and configuration of the straps  154  is to be regarded as exemplary only, as any suitable number and/or configuration of tightening mechanisms is possible. For instance, the walker  100  can include two, four, or any other suitable number of straps. In place of straps, other suitable tightening mechanisms, such as buckles or quick connecting strap mechanisms can be utilized. 
     Referring to  FIGS. 8A-9 , the dorsal shell  104  can be formed either in a single piece or in multiple portions. The dorsal shell  104  can include a proximal member  162  and a distal member  164  connected to the proximal member  162  via a flexible or resilient connecting portion  166 . A plurality of apertures  120  are formed in the distal member  164  of the dorsal shell  104 . The apertures  120  can be slanted and can include a generally oblong periphery. The apertures  120  can be arranged in a first column on one side of a longitudinal axis of the distal member  164  and a second column on the opposite side of the longitudinal axis. Some or all of the apertures  120  can have rounded or curved edges, protecting an unaffected limb from being scratched or cut by the edges of the apertures  120 . 
     Some or all of the apertures  120  in the distal member  164  can be non-through holes, preventing ingress of external objects (e.g., debris, gravel, sand) through the apertures  120  that could injure the foot of the user. The non-through holes can further help protect the foot from sharp edges and/or objects. It will be appreciated that some or all of the apertures  120  in the distal member  164  can be through-holes or omitted. 
     A flexible edge or flexible toe portion  168  can be attached to a distal terminal end of the distal member  164  for reducing the likelihood of pressure points from the dorsal shell  104  in the toe region of the user&#39;s foot. The flexible toe portion  168  extends between the medial and lateral sides of the distal member  164 . The flexible toe portion  168  can include a periphery, an upper surface area, a distal sidewall portion, and a proximal sidewall portion extending from the upper surface area. The flexible toe portion  168  can be formed of any suitable material. The flexible toe portion  168  can be formed of a flexible plastic or elastomer, such as for example, rubber or EVA foam. Other suitable materials may include silicone or natural or synthetic fibers. 
     During use, the dorsal shell  104  can become pitched or angled relative to the user&#39;s toes, forcing the distal member  164  and the flexible toe portion  168  onto the toes. The distal member  164  can become pitched or angled relative to the toes due to a variety of different circumstances. For instance, the distal member  164  can become pitched or angled relative to the toes by user anatomy (e.g., high instep) or with the use of heel lifts and/or wedges. By way of another example, the distal member  164  can become pitched or angled relative to the toes as the user walks. 
     As the distal member  164  pitches or angles relative to the user&#39;s toes, the flexible toe portion  168  can bend or flex relative to the distal member  164 . This has the effect of reducing the transfer of force from the distal member  164  to the toes and/or distributing the force from the distal member  164  over a greater surface area, which, in turn, reduces the likelihood of pressure points forming on the toes from the distal member  164 . The flexible toe portion  168  can also help accommodate bandaging of the toes or the forefoot because the flexible edge portion can be flexed upwards, cut, and/or removed from the distal member  164 . The arrangement of the flexible toe portion  168  also provides a barrier over the toes, protecting the toes from external objects and/or sharp edges. 
     Optionally, a toe relief portion  170  of the flexible toe portion  168  can angle, curve upward, and/or radially extend away from the user&#39;s toes, spacing the toe relief portion  170  a distance away from the toes and/or creating an axis other than the toe relief portion  170  about which the flexible toe portion  168  can flex. This has the effect of reducing the likelihood of pressure points on the user&#39;s toes from the flexible toe portion  168 . In addition, if the flexible toe portion  168  is forced downward onto the toe protector portion  118  (shown in  FIG. 1 ) of the outsole  116 , the upward angle of the toe relief portion  170  can allow the flexible toe portion  168  to move up and away from the user&#39;s toes rather than diving down into the toes, which could cause discomfort or even injury. The toe relief portion  170  can bend back away from the toes and toward an upper surface of the distal member  164 . The upward angle of the edge portion  168  also can help create additional space to accommodate the user&#39;s toes. 
     The flexible toe portion  168  can be attached to the distal member  164  of the dorsal shell  104  in any suitable manner. The flexible toe portion  168  can be overmolded on a distal edge of the distal member  164  with alternating and/or intermeshing portions of the flexible toe portion  168  and distal member  164  mechanically fastening the flexible toe portion  168  and the distal member  164 . 
     As best seen in  FIG. 8B , a ridge portion  172  can be formed on an upper surface of the distal member  164  for increasing the attachment strength between the flexible toe portion  168  and the distal member  164 . The ridge portion  172  can extend at least in part between the lateral and medial sides of the distal member  164  adjacent the flexible toe portion  168 . The ridge portion  172  can be elongated, having a proximal sidewall portion, a distal sidewall portion, and an upper surface area extending between the proximal and distal sidewall portions. The ridge portion  172  can increase the attachment surface area between distal member  164  and the flexible toe portion  168 . 
     The flexible toe portion  168  can be attached to both the distal sidewall portion and the upper surface area of the ridge portion  172 , increasing the connection surface area between the distal member  164  and the flexible toe portion  168 , which, in turn, increases the connection strength between the flexible toe portion  168  and the distal member  164 . 
     The distal sidewall portion of the ridge portion  172  can physically block the foot strap  154 C (shown in  FIG. 1 ) from sliding onto the flexible toe portion  168 , increasing the protection of the user&#39;s toes. The ridge portion  172  preventing or limiting movement of the foot strap  154 C can also reduce the likelihood of the dorsal shell  104  being prematurely worn down by a migrating foot strap  154 C. The ridge portion  172  further can reinforce the flexible toe portion  168 . For instance, if the flexible toe portion  168  is forced into the toe protector portion  118  (shown in  FIG. 1 ) of the outsole  116 , the distal sidewall portion of the ridge portion  172  can support the proximal sidewall portion of the flexible toe portion  168  against shear or other forces that could potentially cause the flexible toe portion  168  to tear away from the distal member  164  of the dorsal shell  104 . In other embodiments, the flexible toe portion  168  can be omitted. 
     Similar to the flexible edge portion, the connecting portion  166  between the distal member  164  and the proximal member  162  can be arranged to flex or bend. The connecting portion  166  can flex or bend between the proximal member  162  and the distal member  164  as the proximal member  162  and/or the distal member  164  move toward and/or away from one another. The proximal member  162  and the distal member  164  can be forced toward one another as the user walks or due to user anatomy or with the user of heel lifts and/or wedges in the foot bed of the walker  100 , or under other conditions. 
     By flexing between the proximal member  162  and the distal member  164 , the connecting portion  166  can help reduce or eliminate the formation of pressure points along the dorsal surface of a user&#39;s lower leg, ankle, or foot from the dorsal shell  104 . Further, due to the flexible nature or resiliency of the connection portion  166 , when the dorsal shell  104  is closed around the user&#39;s lower leg, ankle or foot, different sized anatomies can be accommodated using the same sized walker  100 . In addition, the connecting portion  166  can help the dorsal shell  104  automatically expand or contract due to swelling or reduction of swelling in the lower leg, ankle, and foot of a user. 
     The connecting portion  166  can include a periphery, an upper generally continuous surface area and a pair of laterally upstanding, sidewall portions extending along two opposed sides of the upper surface area. The connecting portion  166  can further include a distal sidewall portion extending along an edge of the upper surface area and a proximal sidewall portion extending along an edge of the upper surface area. The proximal sidewall portion can extend along an imaginary curved line that defines a peak near a center of the connecting portion  166 . 
     As best seen in  FIG. 9 , the connecting portion  166  further includes a lower generally continuous surface area opposed the upper surface area. At least a portion of the lower surface area can have a concave curvature to help the connecting portion  166  fit over the ridge of the foot and/or the ankle. The concave curvature of the connecting portion  166  can allow the connecting portion  166  to be more comfortably arranged along the dorsal surface of the ankle and/or the foot of a user. A thickness defined between the upper and lower surface areas of the connecting portion  166  can be arranged to provide cushioning and/or protection to the ankle and/or foot. 
     The connecting portion  166  can be attached between the proximal member  162  and the distal member  164  in any suitable manner. The connecting portion  166  may be formed via overmolding as discussed above. The connecting portion  166  can overlap a portion of the upper surface areas of the proximal member  162  and the distal member  164 , increasing the connection surface area between the connecting portion  166 , the proximal member  162 , and the distal member  164 . 
     Referring again to  FIG. 8B , a ridge  174  is formed on the upper surface area of the proximal member  162  near a distal edge of the proximal member  162 . A ridge  176  is formed on the upper surface of the distal member  164  near a proximal edge of the distal member  164 . The connecting portion  166  extends between the ridge  174  and the ridge  176 . 
     The ridge portion  174  can include an upper surface area, a distal sidewall surface attached to the connecting portion  166  and a general shape that corresponds to the proximal sidewall portion of the connecting portion  166 . The ridge portion  176  can include an upper surface area, a distal sidewall portion, and proximal sidewall portion attached to the connecting portion  166 . As shown, the proximal sidewall portion of the ridge portion  176  can be curved such that the width of the ridge portion  176  between the proximal and distal sidewall portions varies. 
     The ridge portions  174 ,  176  can help maintain the position of the ankle strap  154 A on the dorsal shell  104 . When the strap  154 A is tightened over the connecting portion  166  across the ankle of the user (best shown in  FIG. 1 ), the strap  154 A can compress the connecting portion  166  to a degree such that the lower surface area of the strap  154 A descends below the upper surface areas of the ridge portions  174 ,  176 . This can allow the distal sidewall portion of the ridge  174  and the proximal sidewall portion of the ridge  176  to limit proximal and distal movement of the strap  154 A. 
     The ridge portions  174 ,  176  can help prevent the strap  154 A from digging into the ankle of the user. The connecting portion  166  can be arranged such that compressive pressure or forces exerted on the connecting portion  166  by the strap  154 A are substantially transferred from the connecting portion  166  to the ridge portions  174 ,  176 , and the upper surfaces of the distal member  164  and the proximal portion  166  rather than the ankle and/or the foot. 
     While the connecting portion  166  is described forming a hinge mechanism between the proximal member  162  and the distal member  164 , alternative hinge mechanisms can be used, such as pivot pins and sleeves, piano or butterfly hinges, or other suitable hinge mechanisms can be used in place of the connecting portion  166 . For instance, one or more malleable bars or bars (not shown) can connect the proximal member  162  and the distal member  164 . The bars can be arranged as a metal stay such that a clinician or medical professional can selectively bend the bars to change or set the aspect ratio of the proximal and distal members  162 ,  164  relative to one another. This can help accommodate treatment of Achilles tendon injuries, for example, where heel wedges are selectively positioned within the foot bed of the walker  100  by a medical professional to adjust the angle of the user&#39;s foot within the foot bed. Optionally, the bars can be enclosed within a protective member such as an overmold portion to provide a comfort fit. 
     Referring now to the proximal member  162  best shown in  FIG. 8A , a plurality of apertures  120  can be formed in the proximal member  162 . The apertures  120  can exhibit any suitable configuration. The apertures  120  can have a periphery having opposed parallel longitudinal sidewall portion and curved or rounded end wall portions. The apertures  120  can be arranged in two columns extending at least a portion of the distance between the proximal edge of the proximal member  162  and the distal edge of the proximal member  162 . The columns can be located on opposite sides of the longitudinal axis of the dorsal shell  104 . 
     Some or all of the apertures  120  can be slanted with a through-hole portion and a non-through hole portion. For example, one or more of the apertures  120  can include two through-holes separated by a non-through hole. Similar to the apertures in the base shell  102 , the apertures  120  can help venting by allowing air to flow into and out of the through-hole portion. The apertures  120  can help reduce the weight of the walker  100  by reducing the amount of material in the dorsal shell  104 . The apertures  120  also may help strengthen the dorsal shell  104  by reinforcing the proximal member  162  with the material remaining in the non-through hole portion of the aperture  120 . 
     A flexible or resilient edge portion  178  can be formed on the proximal terminal end of the proximal member  162 . The flexible edge portion  178  can exhibit any suitable configuration and can be formed via any suitable technique as discussed above. The flexible edge portion  178  can include a periphery, a generally convex upper surface area, a distal sidewall portion attached to the proximal member  162 , a proximal sidewall portion, and a generally concave lower surface area. The distal sidewall portion of the flexible edge portion  178  can extend along a generally wavy line defining a valley in the tibial crest area of the user. 
     The flexible edge portion  178  can bend or flex when the leg of the user pushes on the flexible edge portion  178 . The flexible edge portion  178  can bend or flex when the proximal member  162  becomes angled or pitched toward the user&#39;s lower leg. This can allow the flexible edge portion  178  to act as an expansion mechanism to accommodate different sized lower legs of different users, providing a comfortable fit for different users having different sized anatomies. The bending or flexing of the flexible edge portion  178  can also reduce and/or eliminate the likelihood of pressure points on the tibia, increasing the comfort of the walker  100  and providing tibia relief. 
     Optionally, a tibia relief portion  180  of the flexible edge portion  178  can angle, curve, or radially extend away from the other portions of the upper surface area of the flexible edge portion  178  or the user&#39;s leg, spacing the tibia relief portion  180  of the flexible edge portion  178  a distance away from the user&#39;s leg. This can provide additional space for the tibial crest, allowing the flexible edge portion  178  to better accommodate the tibial crest as the user walks. This can also help reduce the likelihood of pressure points or edge pressures on the leg or tibia from the dorsal shell  104 . For instance, because the tibia relief portion  180  extends away from the lower leg, as the user&#39;s lower leg pushes against the flexible edge portion  178 , the user&#39;s leg can bend or flex the flexible edge portion  178  further away from proximal member  162 , reducing pressure points or edge pressures on the leg from the dorsal shell  108 . The tibia relief portion  180  can be arranged to bend away from the leg and toward an outer surface of the proximal member  162 . In other embodiments, the flexible edge portion  178  can be omitted. 
     A compliance strap guide  182  can be formed on the dorsal shell for accommodating a compliance strap. A compliance strap is a strap that can be used to deter a user or patient from prematurely or frequently removing a walker, which can disrupt the healing process of the foot. 
     Another exemplary embodiment of a walker  300  is shown in  FIG. 10 . This embodiment includes a base shell  302 , a dorsal shell  304 , and a compliance strap guide  382  can be positioned on an anterior aspect of a proximal member  362  of the dorsal shell  304 . A compliance strap assembly  384  can comprise a compliance strap  386  arranged through the compliance strap guide  382  and irreversibly attached to itself via an adhesive. When the compliance strap  386  is used with the walker  300 , the dorsal shell  304  cannot be moved away from the base shell  302 , preventing removal of the walker  300  from the user&#39;s foot. 
     Locating the guide  382  on the anterior aspect can help increase the usability of the guide  382 . For instance, when the walker  300  is placed on a user by a medical professional, the medical professional is typically situated in front of the walker  300 . The position of the compliance strap guide  382  on the anterior aspect of the proximal member  362  allows the medical professional to more easily install a compliance strap on the walker through the guide  382 . This also allows the compliance strap guide  382  to be positioned such that it will not rub against and/or damage an unaffected limb of the user during use of the walker  300 . 
     The compliance strap  386  can comprise a strap including high-density polyethylene fibers (e.g., a Tyvek® strap) arranged through the compliance strap guide  382  and irreversibly attached to itself via an adhesive such that the compliance strap cannot be removed from the walker  300  by sliding the compliance strap up and over the walker  300 . The compliance strap  386  can only be removed by cutting or damaging the strap  386 , preventing removal of the walker without a clinician or medical professional knowing. It will be appreciated that that the compliance strap guide  382  and the compliance strap  386  are exemplary only, and other suitable configurations are possible. For instance, the base shell  302  can include a recess or other feature suitable to receive a compliance strap. 
     Another exemplary embodiment of a compliance strap assembly  484  is shown in  FIG. 11-13 . The compliance strap assembly  484  can include a compliance strap  486  and a compliance clasp  488 . The compliance strap  486  can be formed of any suitable material such as, but not limited to, nylon and/or high-density polyethylene fibers. 
     The compliance clasp  488  can include a base member  490  and a door member  492  pivotally attached to one another. A living hinge  494  can be formed between the base member  490  and the door member  492 . The living hinge  494  can be arranged to allow a clinician or medical professional to close the compliance clasp  488  with one hand applying tension to the compliance strap  486  and the other hand bringing the door member  492  and the base member  490  together. Alternatively, the base member  490  can be formed as a separate piece from the door member  492  and pivotally attached thereto in any suitable manner. 
     The base member  490  and the door member  492  can exhibit any suitable configuration. For instance, each of the base member  490  and the door member  492  can exhibit a generally rounded rectangular shape having a periphery, an upper surface area, and a lower surface area. In other embodiments, the base member  490  and the door member  492  can exhibit a generally triangular shape, a generally diamond shape, a generally oval shape, combinations thereof, or any other suitable shape. 
     A pair of strap guides  496  can be formed on the upper surface of the base member  490  for receiving an end portion of the compliance strap  486 . The strap guides  496  can be arranged to maintain alignment of the compliance strap  486  with the compliance clasp  488 , reducing the likelihood that the compliance strap  486  will interfere with the door member  492  in a closed position described below. 
     A receiving loop  498  can also be formed on the base member  490  for providing an attachment point for one end of the compliance strap  486 . This advantageously allows the one end to be attached to the receiving loop  498  and the other end of the compliance strap  486  to be looped through a compliance strap guide (e.g., guide  382 ), around the walker (e.g., walker  300 ), through the strap guides  496 , and attached to itself. 
     Referring to  FIGS. 12 and 13 , a plurality of recesses  401  can be formed in the upper surface of the base member  490 . A plurality of spike-like protrusions  403  can be formed on the lower surface area of the door member  492  that correspond to the plurality of recesses  401 . The spike-like protrusions  403  can include a wider base portion  403 A, providing additional strength to the spike-like protrusions  403 . 
     The compliance clasp  488  can be moveable between an open position (shown in  FIG. 12 ) in which the door member  492  is rotated away from the base member  490 , and a closed position in which the lower surface area of the door member  492  is rotated onto the upper surface area of the base member  490 . When the compliance clasp  488  is in the closed position, the spike-like protrusions  403  penetrate the recesses  401  to lock or grasp the portion of the compliance strap  486  extending between the base member  490  and the door member  492  within the compliance clasp  488 . 
     The spike-like protrusions  403  and the recesses  401  can be arranged in any suitable manner. The spike-like protrusions  403  and the recesses  401  can be generally upright. The spike-like protrusions  403  and the recesses  401  can extend at one or more angles. For instance, the spike-like protrusions  403  and the recesses  401  can extend at one or more angles configured to allow for limited one-way movement of the compliance strap  486  with the compliance clasp  488  in the closed position. This can allow a clinician or medical professional to tighten the compliance strap  486  with the compliance clasp  488  in the closed or position. 
     The spike-like protrusions  403  can be arranged to at least partially pierce the compliance strap  486 . Applying tension to the compliance strap  486  when the compliance clasp  488  is in the closed position can tear the strap  486  or break one or more of the spike-like protrusions  403 . Thus, if a non-compliant patient removes the compliance clasp  488  from the strap  486  to remove the walker  300 , the clinician or medical professional will know upon examination of the compliance assembly  484 . 
     One or more detents  405  may be formed on and extend from the lower surface of the door member  492 . One or more locking grooves  407  corresponding to the detents  405  can be formed in the upper surface of the base member  490 . The locking detents  405  can engage the locking grooves  407  when the compliance clasp  488  is in the closed position, creating an irreversible closure. 
     This allows the compliance clasp  488  to be irreversibly locked in the locking position, preventing a user from removing the compliance clasp  488  from the strap  486  without breaking or damaging the strap  486  and/or the compliance clasp  488 . As seen, the detents  405  and the locking grooves  407  can be concealed within the compliance clasp  488  when the compliance clasp  488  is in the closed position, preventing the user from over-riding or tampering with the locking mechanism of the compliance clasp  488 . 
     The compliance clasp  488  can be formed from any suitable material. The compliance clasp  488  can include metals, such as aluminum, carbon, composite materials, such as carbon fiber/epoxy composites, glass fiber/epoxy composites, or suitable plastic materials, such as thermoplastic or thermosetting polymers, fiber reinforced plastic, molded chopped fibers, or any other suitable material. Different portions of the compliance clasp  488  can be formed from different materials. For instance, one portion of the compliance clasp  488  can be formed form polypropylene (e.g., the living hinge) and another portion can be formed by a metal insert (e.g., the spike-like protrusions). 
     While the door member  492  is described including the spike-like protrusions  403  and the base member  490  is described including the recesses  401 , it will be appreciated that the door member  492  may include the recesses and the base member  490  may include the spike-like protrusions. Moreover, it will be appreciated that the door member and/or the base member may include any suitable numbers of spike-like protrusions and/or recesses. Further, the compliance clasp  488  can include any suitable feature to lock or grasp the compliance strap  486  between the base and door members. 
     Another exemplary embodiment of a compliance clasp  588  is illustrated in  FIG. 14 . The compliance clasp  588  can be similar to the compliance clasp  488 , except that base member  590  includes a first plurality of teeth  501  formed in the upper surface of the base member  590  and the door member  592  includes a second plurality of teeth  503  of complementary shape in the lower surface of the door member  592  for interlocking with the first plurality of teeth  501  of the base member  590 . 
     When the compliance clasp  588  is in the receiving position, the compliance strap can easily slide through the strap guides  596  on the base member  590  to adjust the location and/or tension in the strap. When the compliance clasp  588  is moved into the closed position, the teeth  501  of the base member  590  engage the teeth  503  of the door member  592  to lock or grasp the compliance strap within the compliance clasp  588 . Similar to the compliance clasp  488 , the compliance clasp  588  can include detents  505  and locking grooves  507  arranged to irreversibly lock the compliance clasp  588  in the closed position. 
     Another exemplary embodiment of a walker  600  is shown in  FIGS. 15-28 . The walker  600  can be similar to the walker  100  except that the walker  600  includes an inflation system  601  arranged to reduce pressure points within the walker  600 , accommodate different sized anatomies, and/or to accommodate swelling. 
     As can be seen from  FIGS. 15 and 16 , the walker  600  includes complementary base shell  602  and dorsal shell  604  and a plurality of straps  654  arranged to bring the base shell  602  and the dorsal shell  604  closer together. The plurality of straps  654  can include an ankle strap  654 A, an upper strap  654 B, and a foot strap  654 C. A soft good liner  612  can be provided inside the base shell  602  and the inflation system  601  can be integrated on the interior and/or the exterior of the walker  600 . 
     For simplicity,  FIG. 17  shows the inflation system  601  removed from the walker  600  according to an embodiment. The inflation system  601  can include a pump assembly  603 , one or more inflation tubes  605 , and an inflatable bladder  607 . The inflatable bladder  607  can be arranged in an ankle receiving portion of the walker  600  (best shown in  FIG. 27 ) and inflated and/or deflated via the one or more inflation tubes  605 , which are in fluid communication with the pump assembly  603 . Optionally, the inflation system  601  can include a pressure relief valve assembly  609  that can automatically expel excess air from the inflation system  601 , reducing the likelihood of over-inflation that can harm the user. 
     As best shown in  FIGS. 15 and 20 , the pump assembly  603  can be connected to the inflation tube  605  and can be attached to and/or carried by the upper strap  654 B. Arranging the pump assembly  603  on the upper strap  654 B can allow the pump assembly  603  to be in a relatively fixed position with respect to the base shell  602 . As the location of the dorsal shell  604  moves up and down as a user moves or to accommodate variations in user anatomy, the position of the pump assembly  603  relative to the base shell  602  can remain substantially fixed on the upper strap  654 B. This has the effect of preventing kinking of the inflation tubes  605  and/or unwanted movement of the pump assembly  603  that could inadvertently inflate or deflate the inflatable bladder  607 . Arranging the pump assembly  603  on the upper strap  654 B on the anterior of the walker  600  can also make the pump assembly  603  more usable and accessible to a user. 
     Optionally, the pump assembly  603  can be permanently attached to the strap  654 B so that the pump assembly  603  is not easily misplaced. The upper strap  654 B may be generally flexible, allowing the pump assembly  603  to generally conform to the shape of the dorsal shell  604  below the strap  654 B, regardless of the anterior and/or posterior position of the dorsal shell  604  relative to the strap  654 B. 
     It will be appreciated that the location of the pump assembly  603  on the anterior region of the upper strap  654 B is exemplary only, as other suitable locations of the pump assembly  603  are possible. For example, the pump assembly  603  can be located on the ankle strap  654 A. The pump assembly  603  can be arranged on the lateral region of the upper strap  654 B or the exterior of the base shell  602  in the lower leg region of the walker  600 . 
     As seen in  FIG. 18 , the pump assembly  603  can include a cover  611 , a pump  613 , a fill valve  615 , and a release valve  617 . The cover  611  can be arranged to house the pump  613 , the fill valve  615 , and the release valve  617 . The cover  611  can exhibit any suitable configuration. The cover  611  can be made from any suitable flexible, resilient, or compliant material. The cover  611  can include one or more vent openings to allow air vented from the inflatable bladder  607  to pass through the cover  611  to the atmosphere. 
     Optionally, the cover  611  can include one or more enhancement features  619 , such as raised or recessed portions, which can be configured in any suitable design. For example, the enhancement features  619  may be configured as a cross “+” indicating inflation and an elongated recess “−” indicating deflation. The enhancement features  619  can also help enhance function and/or gripping so that a user can more easily actuate the pump  613  and/or the release valve  617 . The enhancement features  619  can also provide visual and/or tactile indicators for the user. The cover  611  can further include one or more features to wrap around the strap  654 B for better securement of the pump assembly  603  to the strap  654 B. As noted above, the cover  611  can exhibit any suitable configuration. 
     The pump  613  is housed within the pump cover  611  and can comprise any suitable pump type. For example, the pump  613  can be a diaphragm or positive displacement pump including a diaphragm or body  621 , an inlet  623 , and an outlet  625 . The inlet  623  can be formed in one end of the body  621  and can allow air to flow into the body  621 . The inlet  623  can also be selectively closed when the pump  613  is actuated so that air does not flow out of the pump  613  through the inlet  623 . Optionally, the inlet  623  can be arranged as a release valve or the pressure relief valve described below. The outlet  625  can be opposed to the inlet  623  on the other side of the body  621 . A one-way valve assembly  627  can be provided within the outlet  625  for allowing air to pass from the pump  613  into the inflatable bladder  607 , but not from the inflatable bladder  607  to the pump  613 . 
     In operation, when the diaphragm or body  621  of the pump  613  moves up (e.g., volume increases), pressure within the pump  613  decreases, causing air to be drawn into the pump through the inlet  623 . When the body  621  of the pump  613  moves down (e.g., volume decreases), the pressure in the pump  613  increases, forcing the air that was previously drawn in out of the pump  613  through the outlet  625 . Finally, the body  621  moving up once again draws air into the pump  613 . 
     The pump  613  can have any suitable shape and size. For instance, the pump can include a generally box-like shape with a convex anterior side and/or a convex posterior side. The shape of the pump can be arranged to maximize the useable stroke volume of the pump  613 . 
     The release valve  617  can be arranged to selectively release pressure within the inflatable bladder  607  and/or the inflation system  601 . The release valve  617  can be incorporated with the pump  613 . The release valve  617  can be incorporated with the pump assembly  603 . The one-way outlet valve assembly  627  can communicate with the inflatable bladder  607  via the release valve  617 . The release valve  617  can be activated manually by a user. The release valve  617  can be separate from the pump assembly  603 . The release valve  617  can be located at any suitable location on the walker  600 . 
     Alternatively, the pump  613  and/or release valve  617  can be electrically powered by a portable power source associated with the walker  600 . The pump  613  can be configured to be usable with fluid or liquid. For example, the pump  613  can be usable with liquid to provide hot and/or cold therapy. 
       FIG. 19  illustrates a pump assembly  703  according to another embodiment. The pump assembly  703  can include a pump  713  having an elongated ovoid-like shape including a maximum dimension between the anterior and posterior sides at a center of the pump  713  that tapers toward each end of the pump  713 . A larger, more elongate cover  711  can cover the pump  713  and a release valve  717 . The shape of the pump  713  can be arranged to maximize the useable stroke volume of the pump  713 . 
     As seen in  FIG. 20 , a tube hole  662  can be formed in the proximal wing portion  610  of the base shell  602  for receiving the inflation tube  605  exiting the pump assembly  603 . The tube hole  662  can exhibit any suitable configuration. The tube hole  662  can comprise a semi-elliptical relieved portion or cutout on a strap slot  656  in the proximal portion of the wing portion  610 . The tube hole  662  can be separate from the strap slot  656 . The tube hole  662  can be elongated, circular, or can exhibit any other suitable shape. While one tube hole  662  is shown in the wing portion  610 , in other embodiments, two, three, four, or any other number of tube holes  662  are possible. 
     The inflation tube  605  exiting the pump assembly  603  can be threaded from the interior of the base shell  602  through the tube hole  662 . From the tube hole  662 , the inflation tube  605  is guided or routed along the exterior of the base shell  602  to the posterior aspect of the base shell  602  where it is connected to the pressure relief valve assembly  609  (shown in  FIG. 21 ), positioned under a cover member  664  attached to the posterior aspect of the base shell  602 . 
     The inflation tube  605  can be flexible so that the inflation tube  605  can generally conform to the contour of the base shell  602 . The inflation tube  605  can include one or more segments sized and shaped to generally contour the exterior of the base shell  602 . For example, at least one of the segments of the inflation tube  605  can include one or more bends that generally contours the bends or curves in the exterior of the base shell  602 . In other embodiments, the inflation tube  605  can be routed in grooves formed on the interior surfaces of the base shell  602 . 
     A fabric sleeve  628  can be located on the upper strap  654 B for guiding the inflation tube  605  along the outside of the base shell  602  from the pump assembly  603  to the pressure relief valve assembly  609  within the cover member  664 . The fabric sleeve  628  can comprise a unitary sleeve or a plurality of discrete portions of the sleeve  628 . The fabric sleeve  628  can comprise an integrated portion of the upper strap  654 B. For instance, the fabric sleeve  628  can comprise vertical cutouts in the upper strap  654 B into which the inflation tube  605  can be interwoven. 
     Routing the inflation tube  605  on the outside of the base shell  602  can help reduce or eliminate pressure points on the interior or inside of the walker  600 , which can be both uncomfortable as well as a risk for resulting in pressure ulcers. Further, routing the inflation tube  605  on the outside of the base shell  602  protects the inflation tube  605  from being pinched or compressed between the interior of the walker  600  and the leg of the user. 
     It will be appreciated that the inflation tube  605  can exit the pump assembly  603  in any suitable manner. For example, the inflation tube  605  can be routed in one or more indentations or grooves formed in the exterior or interior surface of the base shell  602 . The inflation tube  605  can be routed through guides (e.g., rings or clips) attached to the exterior of the base shell  602 , between the upper strap  654 B and the exterior of the base shell  602 , or in any other suitable arrangement. 
     For simplicity,  FIG. 21  is a partial view of the posterior of the base shell  602  with the cover member  664  removed. As shown, the inflation tube  605  connects to the pressure relief valve assembly  609 , which is housed within a cavity or cutout  631  formed in the base shell  602 . The cutout  631  can have any suitable configuration. The cutout  631  can extend completely between the interior and exterior surface of the base shell  602 . The cutout  631  can have a generally rectangular shape, a generally trapezoidal shape, a shape that generally corresponds to the shape of the pressure relief valve assembly, or any other suitable shape. 
     A pair of strap slots  656  can be formed on opposing sides of the cutout  631 . The upper strap  654 B can pass from the exterior of the base shell  602  and through a strap slot  656 , situating the upper strap  654 B behind the pressure relief valve assembly  609 . The strap  654 B can then extend through the other strap slot  656  back to the exterior of the base shell  602 . This allows the strap  654 B to form a protective barrier between the pressure relief valve assembly  609  and the user&#39;s leg. 
     The cover member  664  can be attached the base shell  602  over the cutout  631  and the pressure relief valve assembly  609 . The cover member  664  can include a base portion  633  and a peripheral sidewall  635  arranged to extend from the base portion  633  toward the base shell  602  of the walker  600 . 
     A recess  639  in the cover member  664  is bounded the sidewall  635  and the base portion  633  so that the bottom of the recess  639  is above (recessed within) the rim  637  of the sidewall  635  to provide a space for the pressure relief valve assembly  648 . This can allow the base portion  633  and the sidewall  535  to substantially enclose the pressure relief valve assembly  609  within the recess  639 , protecting the pressure relief valve assembly  609  within the cutout  631  and helping to deter tampering. 
     The sidewall  635  defines a rim  637  extending around the base portion  633 . At least a portion of the rim  637  can be contoured to generally correspond to the contour of the posterior of the base shell  602 . This can allow the cover member  664  to form a better fit between the cover member  664  and the base shell  602 . The rim  637  can also provide a support area for the cover member  664  when the cover member  664  is attached to the base shell  602 . Optionally, one or more ribs  643  can be formed on the rim  637  arranged to crush during attachment of the cover member  664  to the base shell  602  to accommodate variations in the geometry of the base shell  602 . 
     One or more side openings  641  can be formed along the rim  637  of the sidewall  635  for accommodating a portion of the inflation tubes  605 . One side opening  641  can be arranged to accommodate a portion of the inflation tube  605  extending between the pump assembly  603  and the pressure relief valve assembly  609 . Another side opening  641  can be arranged to accommodate a portion of the inflation tube  605  extending between the pressure relief valve assembly  609  and the inflatable bladder  607 . 
     The cover member  664  can be attached to the base shell  602  in any suitable manner. The cover member  664  can be secured to the base shell  602  via a snap-type connection. The cover member  664  can include a plurality of snaps or hook members  629  integrally formed in the sidewall  635  and configured to snap into the cutout  631  formed in the base shell  602 , facilitating assembly. The cover member  664  can be attached to the base shell  602  via gluing or plastic welding. Alternatively, the cover member  664  can be removably attached to the base shell  602  via fasteners, hook-and-loop type systems, clips, magnets, or any other suitable attachment system. 
     By arranging the pressure relief valve assembly  609  within the cutout  631  and cover member  664 , the pressure relief valve assembly  609  can be protected from damage due to accidental contact with external objects. Moreover, the cover member  664  can help limit or eliminate pressure points from components of the inflation system  601  (e.g., the pressure relief valve assembly). The cover member  664  can be used with other components of the inflation system  601 . The cover member  664  can also be interchangeable based on needs for various indications such as an adjustable relief valve or housing an activity monitor. 
     The location of the pressure relief valve assembly  609  on the posterior of the base shell  602 , helping to deter tampering. In other embodiments, the pressure relief valve assembly  609  can be incorporated in the inflatable bladder  607 , on the lateral side of the base shell  602 , or in any other suitable position. 
     The pressure relief valve assembly  609  can exhibit any suitable configuration. Referring now to  FIGS. 22 and 23 , the pressure relief valve assembly  609  can comprise a pressure relief valve  643  including a valve body  645  having a first port  647 , a second port  649 , and a third port  651 . A first fluid pathway  653  connects the second port  649  and the third port  651 . A second fluid pathway  655  connects the first fluid pathway  653  and the first port  647 . The first port  647  of the valve body  645  is connected to the inflation tube  605  extending between the pump assembly  603  and the pressure relief valve  643 . The second port  649  is connected to the inflation tube  605  extending between the pressure relief valve  643  and the inflatable bladder  607 . As seen, the first port  647  can be at about a 90 degree angle relative to the second port  649 . 
     The first port  647  and the second port  649  can be connected to the inflation tubes  605  in any suitable manner. For example, in the illustrated embodiment, the first port  647  and the second port  649  can be connected to the inflation tubes  605  via a barb-type connection. The inflation tubes  605  can be attached to the pressure relief valve  643  via solvent bonding, friction or spin welding, adhesives such as a UV cure adhesive, or any other suitable attachment means. 
     The valve body  645  further includes an upper portion  657  that can have any suitable configuration. The upper portion  657  comprises a generally cylindrical member including a bottom opening that is in fluid communication with the third port  651  and one or more vent openings  659  in the side thereof for venting air to the atmosphere. The bottom of the upper portion  657  can include a surface surrounding a bottom opening that forms a valve seat  661  for a sealing member  663 . 
     The upper portion  657  is generally hollow, providing a space for the sealing member  663 . The sealing member  663  can comprise an elastomeric disk having a diaphragm shape or an umbrella shape positioned within the upper portion  657 . The sealing member  663  can comprise a disk having a generally Belleville spring washer shape that includes stem portion  665 . An upstream side of the sealing member  663  can be situated within the first fluid pathway  653  and a downstream side can be situated between the sealing member  663  and a retainer member  667 . The sealing member  663  can be formed from any suitable material such as silicone and/or other elastomeric materials. 
     The retainer member  667  is arranged to retain the sealing member  663  within the upper portion  657  of the valve body  645 . The retainer member  667  can comprise a generally cylindrical member including a stem having a recessed or hollow portion configured to receive and hold the stem portion  665  of the sealing member  663  in place. 
     The retainer member  667  may be a separate component from the valve body  645 . The upper portion  657  can include a plurality of detents or catches  671  and the retainer member  667  can include a plurality of corresponding locking apertures  673  extending between the top and bottom surface of the retainer member  667 . The locking apertures  673  can engage the detents  671  of the upper portion  657  when the retainer member  667  is positioned on the upper portion  657  so that the retainer member  667  snaps over the upper portion  657  of the valve body  645  and is locked thereon. 
     Raised portions  675  can be situated between the detents  671 , providing a support surface for the retainer member  667  when the retainer member  667  is snapped over the upper portion  657 . This arrangement can help ensure that the distance from the valve sealing surface to the retainer member  667  is controlled, which acts to control compression of the sealing member  663  and thereby the valve cracking pressure. Alternatively, the retainer member  667  may be integral to the valve body  645 . For example, the retainer member  667  could be integrated into the valve body  645  via a hinged snap. 
     The pressure relief valve  643  is movable between the closed position, wherein the third port  651  is sealed by sealing member  663 , and the open position, wherein the third port  651  is unsealed, such that air or other fluids may flow, from the inflatable bladder  607  and/or pump  613  through the first and second fluid pathway  653 ,  655  to atmosphere. 
     When the sealing member  663  is mounted in the valve seat  661 , the sealing member  663  can have a generally convex shape that flattens out against the valve seat  661  to create a certain sealing force that maintains the pressure relief valve  643  in the closed position. The sealing member  663  can use at least in part its elastic material properties and its preloaded convex shape to create the sealing force against the valve seat  661 . 
     When the internal pressure within the inflation system  601  or head pressure creates enough force to lift or pop the sealing member  663  from the valve seat  661  of the upper portion  657 , the third port  651  is unsealed and air can be vented from the inflatable bladder  607  and/or inflation system  601  to atmosphere. The stem  665  of the sealing member  663  positioned within the retainer member  667  can form a hinge about which disc portion of the sealing member  663  pops between its convex shape and a more flattened or concave shape in which the disc portion of the sealing member  663  lifts away from the valve seat  661  of the upper portion  657 . 
     The pressure at which the sealing member  663  lifts off of the valve seat  661  is called the cracking pressure. When the head pressure is less than the cracking pressure, the sealing member  663  can automatically pop back closed. The cracking pressure of the pressure relief valve  643  can be greater than about 40 mmHg, about 50 mmHg, about 55 mmHg, about 60 mmHg, or about 65 mmHg. In other embodiments, the cracking pressure of the pressure relief valve  643  can be between about 40 mmHg and about 70 mmHg, about 45 mmHg and about 65 mmHg, or about 50 mmHg and about 60 mmHg. In other embodiments, the cracking pressure may be greater or lower. The cracking pressure of the pressure relief valve  643  can be set or varied by varying the shape and/or elastomeric properties of the sealing member  663 . 
     The cracking pressure of the pressure relief valve  643  can be selected, set, or adjusted to generally correspond to a selected pressure limit within the inflatable bladder  607 . The selected pressure limit can comprise a safe operating pressure, a therapeutic pressure, an activity specific pressure, a treatment pressure, or any other suitable pressure limit. 
     Alternatively, the retainer member  667  can be threadedly attached to the upper portion  657  of the valve body  645  such that the height of the retainer member  667  relative to the sealing member  663  can be adjusted, which, in turn, can influence the cracking pressure of the sealing member  663  by adjusting the force exerted on the sealing member  663  by the retainer member  667 . Thus, the cracking pressure can be adjusted by adjusting the position of the retainer member  667  relative to the sealing member  663 . The cracking pressure adjustment can be made by the user based on their activity level. For instance, a higher pressure setting could be used for periods of high activity like walking, while a lower pressure setting could be used for periods of rest. 
     In use, when the inflatable bladder  607  is inflated to point where the internal pressure within the inflation system  601  or head pressure on the sealing member exceeds the cracking pressure of the pressure relief valve  643 , the pressure relief valve  643  can automatically move to the open position, thereby expelling or releasing air from the inflation system  601  and/or inflatable bladder  607  to atmosphere through the third port  651  of the pressure relief valve  643 . As air is released from the inflation system  601 , the internal pressure within the inflation system  601  can drop below the cracking pressure of the pressure relief valve  643  such that the pressure relief valve  643  automatically returns to the closed position, thereby resealing the inflation system  601 . 
     Because the pressure relief valve  643  automatically limits or regulates the level of pressure within the inflation system  601 , the pressure relief valve  643  can reduce the likelihood that a user will over-inflate the inflatable bladder  607 . This is advantageous because users of walkers and other orthopedic devices, especially diabetic patients, often experience reduced sensation in their extremities, which can result in them inadvertently over-inflating the inflatable bladder  607 . Such over-inflation can cause pressure on the skin, which can reduce both capillary blood flow to the skin and arterial flow to the anatomical member. Thus, by limiting or automatically regulating the level of pressure within the inflatable bladder  607  and/or inflation system  601 , the pressure relief valve  643  eliminates or reduces the likelihood of over-inflation that can harm the user. 
     In addition, the pressure relief valve  643  can automatically release excess pressure within the inflation system  601  resulting from other factors, such as, for example, changes in ambient pressure due to a change in altitude. The pressure relief valve  643  also reduces the need for users themselves to set or monitor safe pressure levels within the inflation system  601 . For example, conventional inflation systems often require patients to monitor pressure in the system using a pressure gauge attached to a pump. However, many patients, especially diabetic patients, do not see well enough to read the pressure gauge and pressure gauges are known to malfunction. Consequently, such patients tend to over-inflate the inflatable bladder causing injury to the patient. By including the pressure relief valve  643  in the inflation system  601 , the patient/user can inflate the inflatable bladder  607  without the need of reading a pressure gauge or the risk of over-inflation. 
     The configuration of the pressure relief valve assembly  609  described herein is to be regarded as exemplary only, as any suitable configuration of the pressure relief valve assembly is possible. For example, the pressure relief valve  643  can be a spring-loaded over-pressure relief valve, a check valve, a swing-check valve, a diaphragm valve, a ball valve, luer check valves, miniature check valves, or any other suitable valve. In other embodiments, the pressure relief valve  643  can include, but is not limited to the Series 500 Miniature Check Valves, commercially available from Smart Products, Inc., Morgan Hill, Calif., which are incorporated herein, in their entirety, by this reference. Of course, other pressure relief valves may be employed. 
     Another exemplary embodiment of a pressure relief valve assembly  709  is illustrated in  FIGS. 24 and 25 . The pressure relief valve assembly  709  can comprise a pressure relief valve  743  similar to the pressure relief valve  643 , except that retainer member  767 , upper portion  757 , and second port  749  exhibit a different configuration. As seen, the upper portion  757  can comprise a hollow substantially cylindrical member having a generally solid sidewall. The upper portion  757  can include vent openings  759  formed in the sidewall for venting air the atmosphere. The inner surface of the upper portion  757  can include a plurality of catches  771  formed thereon, each including a generally planar bottom surface area and an angled upper surface area. The retainer member  767  can comprise a disc-like member sized and configured to snap inside of the upper portion  757 . When the retainer member  767  is inserted or snapped into the upper portion  757  of the valve body  745 , the planar bottom surface areas of the catches  771  can form a stop by engaging the top surface of the retainer member  767  to lock the retainer member  767  within the upper portion  757 . 
     The valve body  745  includes a first port  747 , a second port  749 , and a third port  751 . A first fluid pathway  753  connects the first port  747  and the second port  749 . A second fluid pathway  755  connects the first fluid pathway  753  and the third port  751 . 
     Another exemplary embodiment of a pressure relief valve assembly  809  and cover member  864  is illustrated in  FIG. 26 . The pressure relief valve assembly  809  includes a pressure relief valve  843 , a fitting  877 , a relief tube  879  connected to the pressure relief valve  843 , and the inflation tube  605 . The fitting  877  may have any suitable configuration. For example, the fitting  877  may be a tee-type fitting having a first port, a second port, and a third port. The fitting  877  can include a first fluid pathway may extend between the second port and the third port and a second fluid pathway extending between the first port and the first fluid pathway. In an embodiment, the first port of the fitting  877  is connected to the inflation tube  605  extending between to the pump assembly  603  and the fitting  877 . The second port of the fitting  877  is connected to the inflation tube  605  extending through a tube hole  662  (shown in  FIG. 27 ) and between the fitting  877  and the inflatable bladder  607 . As shown, the inflation tube  605  can be routed such that it at least partially loops around the pressure relief valve assembly  609 . The third port can be connected to the relief tube  879  extending between the fitting  877  and the pressure relief valve  843 . 
     The pressure relief valve  843  can exhibit any suitable configuration. For example, the pressure relief valve  843  can include a valve body having a valve seat, a first port  847 , a second port  849 , and a fluid pathway extending between the first port  847  and the second port  849 . 
     The pressure relief valve  843  can include a sealing member configured to cooperate with the valve seat in order to seal the second port  849 . The pressure relief valve  843  is movable between a closed position, wherein the second port  849  is sealed by the sealing member, and an open position, wherein the second port  849  is unsealed, such that air may flow, for example, from the inflatable bladder  607  and/or pump assembly  603  to the atmosphere. The pressure at which the pressure relief valve  843  moves to the open position is the cracking pressure. In an embodiment, the sealing member can be biased against the valve seat to seal the second port  849  with the aid of a resilient retainer member. In other embodiments, the sealing member can be held within the valve body by a retainer member and the sealing member can be configured to seal the second port  849  based on the material properties and/or shape of the sealing member. 
     The pressure relief valve  843  can include means to adjust the resilient force applied to the sealing member, such as a dial on the posterior of the base shell  602 . The dial may be positioned on the base shell  602 , integrated with the cover member  664 , or in any other suitable location. By adjusting the resilient force, the cracking pressure of the pressure relief valve  843  adjusts. Thus, the dial may have different settings such as high pressure, medium pressure, and low pressure. A user, clinician, or medical professional can select, set, or adjust the cracking pressure to customize the inflation system  601  for different users and/or user needs. 
     The cover member  864  can be similar to the cover member  664  except that the cover member  864  is larger and includes a u-shaped inner wall  881  formed on the bottom of the recess  839 . The u-shaped inner wall  881  can be arranged to provide additional support and/or protection to the pressure relief valve assembly  809 . The u-shaped inner wall  881  may include side openings  841  formed along the rim thereof arranged to accommodate and/or receive the inflation tubes  605 . The inner wall  881  can also help align the cover member  864  with the base shell  602 . For instance, the inner wall  881  can fit into a corresponding groove or recess formed on the base shell  602 . This arrangement can eliminate the need of hook members or snaps to withstand transverse loading. 
     A plurality of hook members  829  can be formed on and extending from the bottom of the recess  839 . The hook members  829  can be arranged to selectively snap into the cutout  631 . As shown, at least one of the hook members  829  can provide a support or guide for the inflation tube  605  extending between the fitting  877  and the inflatable bladder  607 . It will be appreciated that the cover member  864  can exhibit any suitable configuration. 
       FIG. 27  illustrates the base shell  602  with the liner removed for simplicity. As seen, the posterior of the base shell  602  can include another tube hole  662  formed in a bottom wall of the cutout  631  that is in communication with the interior of the walker  600 . The tube hole  662  can exhibit any suitable configuration. 
     The inflation tube  605  connecting the pressure relief valve assembly  609  and the inflatable bladder  607  can be inserted through the tube hole  662  to the interior of the base shell  602  where an indentation or groove  883  can be formed for guiding the inflation tube  605  to the inflatable bladder  607 . The groove  883  can have any suitable configuration. For example, the groove  883  can extend from the tube hole  662  to a point below the terminal edge of the inflatable bladder  607 . 
     Routing the inflation tube  605  through the groove  883  on the interior of the base shell  602  can help reduce or eliminate pressure points on the interior of the walker  600 , which can be both uncomfortable as well as a risk for resulting in pressure ulcers. Guiding the inflation tube  605  in the groove  883  can also protect the inflation tube  605  from being inadvertently crushed or pinched. In other embodiments, the inflation tube  605  can be covered or secured into the groove  883  using adhesive tape, a separate cover component, or any other suitable means. As seen, the inflatable bladder  607  can be arranged within the posterior of the base shell  602  such that when the inflatable bladder  607  is inflated, the inflatable bladder  607  can support the lower leg, ankle, and/or foot. 
     The inflatable bladder  607  can be arranged in the ankle receiving portion of the base shell  602  and generally shaped to correspond to the posterior, medial, and lateral side of the base shell  602 . As noted above, observation holes  652  can be formed in the wing portions  610  of the base shell  602 , allowing for tactile and/or visual confirmation that the inflatable bladder  607  is properly inflating or inflated. 
     The inflatable bladder  607  can include a posterior portion  685  and wing portions  687 . The inflatable bladder  607  can be formed of two sheets of air impervious plastic material that is welded around the edges to create air chambers therebetween. Optionally, perspiration wicking material can be applied to the surfaces of the inflatable bladder  607  that are configured to contact the wearer&#39;s anatomy. 
     The inflatable bladder  607  can be attached to the base shell  602  and/or liner  612  by a hook-and-loop type system, a snap-fit system, combinations thereof, or any other suitable attachment system. For example, a portion of the inflatable bladder  607  can be covered with a loop material (e.g., UBL loop) to make it easily attachable to a corresponding hook material on the base shell  602 . In other embodiments, the inflatable bladder  607  can snap into or onto the base shell  602 . Welds and/or holes  689  can be arranged in the inflatable bladder  607  to serve a number of functions. For example, the welds  689  in the inflatable bladder  607  can be configured to direct airflow within the inflatable bladder and also to provide heat and perspiration wicking channels along the surfaces of the inflatable bladder  607 . 
     The inflatable bladder  607  can include a central opening  691  having an hour-glass like shape. The central opening  691  can be configured to receive and support the Achilles tendon so that the lower leg fits snugly within the walker  600 , and the ankle is securely positioned within the walker  600 . In other embodiments, the inflatable bladder  607  may include longitudinally extending openings (not shown) that provide venting for heat and perspiration. Moreover, the posterior of the inflatable bladder  607  can include a bridge portion that includes an inlet for the inflation tube  605  and this is in fluid communication with the lateral and medial sides of the inflatable bladder  607 . Such a configuration can help the inflatable bladder  607  inflate more equally, reducing the likelihood that one side inflates faster than the other side. 
     The shape of the inflatable bladder  607  can further be configured to focus compression where it is needed and uniform compression is provided to areas of the anatomy where the inflatable bladder  607  provides compression. In other embodiments, the shape of the inflatable bladder  607  can be configured to create specific areas of pressure off-loading. The inflatable bladder  607  can be encased within a fabric covering, providing increased comfort to a user. 
     It will be appreciated that while a single inflatable bladder is described, the walker  600  can include any suitable number of inflatable bladders. For example, in an embodiment, the walker  600  can include separate medial, lateral, and dorsal bladders. Moreover, while the inflatable bladder is described being inflated with air, it will be appreciated that the inflatable bladder can be filled with any suitable material or fluid. For example, the inflatable bladder  607  can be selectively filled with gel, foam, water, silicone, combinations thereof of the like. Moreover, in other embodiments, the inflatable bladder  607  can be included as part of a liner within the walker  600 . In other embodiments, the inflatable bladder  607  is separate from a liner within the walker  600 . Such a configuration may facilitate removal the liner for washing or replacement. 
     While the inflation system  601  is shown with the walker  600 , it will be appreciated that the exemplary embodiments of the inflation system can be incorporated and/or used with a number of different orthopedic devices. For instance, exemplary embodiments of the inflation system can be used with a short leg walker, an ankle walker, a strut walker, a fracture walker, an Achilles walker, or any other suitable orthopedic device. In other embodiments, the inflation system  601  can be integrated with a system providing Deep Vein Thrombosis (“DVT”) therapy. 
     In other embodiments, the inflation system  601  can be arranged to control the amount of pressure within the inflation system  601  based on sensed conditions. As seen in  FIG. 28 , an inflation system  601 A according to another embodiment can include a pressure regulation system  693  having a control unit  695  and one or more sensors  697  arranged to sense pressure within the inflatable bladder  607  and/or inflation system  601  and to send one or more sensing signals  699  to the control unit  695 . The sensing signals  699  can include information about pressure levels within the inflatable bladder  607  and/or inflation system  601 . The control unit  695  can be operably connected to the pump  613  and the release valve  617  and/or the pressure relief valve assembly  609  such that the control unit  695  can direct the pump the  613  to inflate the inflatable bladder  607  and the release valve  617  and/or the pressure relief valve assembly  609  to deflate the inflatable bladder  607  in response to the pressure information received from the one or more pressure sensors  697 . 
     For instance, the one or more sensors  697  can detect strain (or deflection) due to pressure over an area in the inflatable bladder  607  and/or the inflation system  601 . The one or more sensors  697  can convert this pressure energy to the one or more sensing signals  699  in the form of electrical energy. One or more analog-to-digital converters (ADC) convert the electrical energy to digital data that is provided to the control unit  695 . The ADC can be a separate component, can be integrated into the control unit  695 , or can be integrated into the one or more sensors  697 . The control unit  695  can include processing hardware (e.g., processing electrical circuitry) and an operating system configured to run one or more application software programs. The control unit  695  can use one or more processing techniques to analyze the digital data in order to determine pressure levels within the inflatable bladder  607  and/or inflation system  601 . Responsive to the one or more sensing signals  699  output by the one or more sensors  697 , the control unit  695  (including control electrical circuitry) can direct the pump  613  to inflate the inflatable bladder  607  or the release valve  617  to deflate the inflatable bladder  607 , automatically controlling safe pressure levels within the inflation system  601 . In other embodiments, the control unit  695  can direct the pressure relief valve assembly  609  to deflate the inflatable bladder  607  responsive to the one or more sensing signals  699 . 
     Another exemplary embodiment of an orthopedic device comprising a walker  900  is shown in  FIGS. 29-31 . Similar to the other embodiments, the walker  900  includes complementary base and dorsal shells  902 ,  904  and at least one strap  906  arranged to bring the base shell  902  and the dorsal shell  904  closer together. The at least one strap  906  can comprise an upper strap arranged to extend over a patient&#39;s lower leg. A pump assembly  908  is attached to and/or carried by the at least one strap  906  along the anterior aspect of the walker  900  and an inflatable bladder can be arranged in an ankle receiving portion of the walker  900  and inflated and/or deflated via one or more inflation tubes  910 , which are in fluid communication with the pump assembly  908 . The pump assembly  908  can include a pump to increase pressure within the inflatable bladder and a release valve arranged to selectively release pressure within the inflatable bladder. 
     As can be seen from the figures, this embodiment includes a protective part  914  securable over the pump assembly  908  of the walker  900 . The protective part  914  is arranged to protect the pump assembly  908  from damage and/or inadvertent operation due to contact with external objects. For instance, walkers are commonly used in combination with a knee scooter  901  (or knee walker or a platform walker) as shown in  FIG. 30 . A knee scooter  901  allows a patient to propel oneself with one leg, while the patient&#39;s affected leg rests on a support platform  903  of the knee scooter  901 . 
     As seen in  FIG. 30 , when riding a knee scooter  901 , the patient typically positions the anterior aspect of the walker  900  on the support platform  903  to support the weight of the patient on the knee scooter  901 . With the pump assembly  908  positioned on the anterior aspect of the walker  900 , the weight of the patient on the walker can force or compress the pump assembly  908  against the support platform  903  of the knee scooter, which, in turn, can damage or inadvertently operate the pump assembly. This can be problematic because it can damage the pump assembly and/or over inflate the inflatable bladder inside the walker, which can cause pressure on the skin and reduce both capillary blood flow to the skin and arterial flow to the affected limb. This can also be problematic because it can under inflate the inflatable bladder in the walker, which can result in a poor fit and/or inadequate support for the affected limb. Also problematic is that leaning on the anterior aspect of the walker  900  can deflate the inflatable bladder by depressing the release valve. 
     The protective part  914  advantageously protects the pump assembly  908  from damage and/or inadvertent operation by providing a physical barrier between the pump assembly  908  and an external object (e.g., the support platform  903 ). For instance, when the anterior aspect of the walker  900  is positioned on the support platform  903 , the rigidity of the protective part  914  distributes the user&#39;s weight on the walker  900  away from the pump assembly  908  and directly to the support platform  903 , eliminating or substantially reducing any load on the pump assembly  908  from the patient&#39;s weight. This advantageously protects the pump assembly  908  from being inadvertently compressed between the walker  900  and the support platform  903 , reducing the likelihood of the pump assembly  908  being damaged or undesirably operated, which in turn, increases patient safety, convenience, and freedom to use the walker  900  with a knee scooter. 
     The protective part  914  protects the pump assembly  908  without substantially affecting the functionality of the walker  900 . It also does so without the use of complicated and bulky components. Furthermore, the protective part  914  can be a separate add-on component to the walker and can be adapted to fit a number of different orthopedic devices, providing versatility. 
     As shown in  FIG. 31 , the protective part  914  can include a semi-rigid or rigid body  912  defining an inner surface  918  arranged to engage and/or face the dorsal shell  904 , an outer surface  920  opposite the inner surface  918 , and side surfaces  922  extending between the inner and outer surfaces  918 ,  920 . The body  912  is formed of at least one material having a rigidity or strength selected to resist impact loads and/or sustained loads when it is secured on the walker  900 . The body  912  can be formed of plastic, foam, carbon fiber, metal, combinations thereof, or any other material which would provide sufficient strength to resist undesirable deformation during use. In an embodiment, the body  912  can be formed of a high density foam so that it can provide some cushioning and/or shock absorption. For instance, the body  912  can include high density foam having a Shore A hardness between about 30 and about 50. In other embodiments, the body  912  can include a high density foam having a higher or lower Shore A hardness. 
     The body  912  extends proximally and distally of the pump assembly  908 . The body  912  can be secured over the pump assembly  908  in any suitable manner. For instance, the body  912  can be removably secured over the pump assembly  908  via an interference fit between the body  912  and the pump assembly  908 . This allows the body  912  to be easily secured over the pump assembly  908  as needed and easily removed. In other embodiments, the body  912  can be secured over the pump assembly  908  via fasteners, hook-and-loop type systems, clips, magnets, adhesives or any other suitable securing system. The body  912  can be attached to the at least one strap  906 . The body  912  can be directly attached to the dorsal shell  904 . 
     The outer surface  920  of the body  912  can be continuous or interrupted. The outer surface  920  can provide a support area for the body  912  when it is engaged with a support platform or other external object. It will be appreciated that the body  912  can be oversized relative to the pump assembly  908 , helping to distribute forces through the body  912  away from the pump assembly  908 . 
     The inner surface  918  of the body  912  can be contoured to generally correspond to the contour of the anterior of the dorsal shell  904 . This can allow the body  912  to form a better fit between the protective part  914  and the dorsal shell  904 . The inner surface  918  can also provide a support area for the body  912  against the dorsal shell  904  when the protective part  914  is engaged with the dorsal shell  904 . 
     As seen in  FIG. 31 , a cutout portion  924  is formed in the inner surface  918  that extends between the side surfaces  922 . The cutout portion  924  can have a rectangular shape or any other shape arranged to accommodate a portion of the at least one strap  906 , facilitating the securement of the body  912  over the pump assembly  908 . The cutout portion  924  can terminate at upper and lower abutments  928 . The cutout portion  924  can taper in a direction toward the dorsal shell  904 , allowing the upper and lower abutments  928  to engage with the inner surface of the upper and lower edges of the pump assembly  908  to secure to the body  912  over the pump assembly  908 . 
     A receiving space or cavity  926  is defined in the cutout portion  924 . The cavity  926  is arranged to accommodate at least part of the pump assembly  908 , allowing the control features of the pump assembly  908  to be recessed within the body  912 . Optionally, the cavity  926  can include a side opening for accommodating an inflation tube in fluid communication with the pump assembly. 
     The cutout portion  924  and/or the cavity  926  also facilitates alignment of the body  912  with the pump assembly  908 . For instance, the pump assembly  908  and the inflation tube  910  can fit into the cavity  926  to ensure the body  912  is properly positioned. When the body  912  is secured over the pump assembly  908 , the pump assembly  908  is positioned within the cavity  926  and the body  912  keeps compressive forces exerted on the body  912  away from the control features of the pump assembly  908 . 
     In use, when a patient positions the anterior aspect of the dorsal shell  904  on the support platform  903  of the knee scooter  901 , the rigidity of the body  912  generally resists deformation and distributes the weight of the patient from the dorsal shell  904  through the body  912  away from the pump assembly  908  and to the support platform  903 . The body  912  thus beneficially protects the pump assembly  908  from damage and/or inadvertent operation when the walker  900  is used with a knee scooter, making the walker  900  safer and more versatile. 
       FIG. 32  shows another embodiment of a protective part  1012  for protecting the pump assembly  908  from damage or inadvertent operation. The protective part  1012  comprises a wire structure  1014  extending over the pump assembly  912 . The wire structure  1014  includes a base frame  1016  and a plurality of intersecting wire members  1020  defining openings  1022  and extending over and across the pump assembly  908 . The wire members  1020  collectively define a receiving space or cavity  1026  for receiving or accommodating at least part of the pump assembly  908  when the wire structure  1014  is secured on the walker  900 . The wire structure  1014  can be made of metal, plastic, rubber, carbon, combinations thereof, or any other suitable materials. 
     The wire structure  1014  has a rigidity arranged to distribute pressure from the patient or another external object away from the pump assembly  908 . The wire structure  1014  extends proximally and distally of the pump assembly  908 . The wire structure  1014  can be secured over the pump assembly  908  in any suitable manner but is shown being secured over the pump assembly  908  by feeding or threading the at least one strap  906  and the pump assembly  908  through at least two of the openings  1022  so that the base frame  1016  of the wire structure  1014  is secured between the at least one strap  906  and the dorsal shell  904 . 
     One or more access openings  1022 A in the wire structure  1014  can be sized and arranged so that a patient can manipulate the control features of the pump assembly  908  through the wire structure  1014  while it is secured over the pump assembly  908 . This allows the wire structure  1014  to both protect the pump assembly  908  from inadvertent operation and provide operational access to the patient and/or clinician. While the protective parts  914 ,  1012  are shown for use with the walker  900 , it will be appreciated that the exemplary embodiments of the protective part can be incorporated and/or used with a number of different orthopedic devices. 
       FIG. 33  shows another embodiment of a protective part protective part  814  for protecting the pump assembly  908  from damage or inadvertent operation. The protective part  814  comprises a body  812  defining an inner surface arranged to engage and/or face the dorsal shell  904 , an outer surface  820  opposite the inner surface, and side surfaces  822  extending between the inner surface and the outer surface  820 . The body  812  can be formed of any of the materials previously described. For instance, the body  812  can be formed of a high density foam. The inner surface of the body  812  can be contoured to generally correspond to the contour of the anterior of the dorsal shell  904 . The inner surface of the body  812  can be permanently attached or integral to the anterior of the dorsal shell  904 . The inner surface of the body  812  can be removably secured to the anterior of the dorsal shell  904  under the at least one strap  906 . 
     The outer surface  820  of the body  812  can provide a support area for the body  812  when it is engaged with a support platform or other external object. As seen, the body  812  can be oversized relative to the pump assembly  908 , helping to distribute forces through the body  812  away from the pump assembly  908 . A receiving space or cavity  826  is defined in the outer surface  820  for accommodating at least part of the pump assembly  908 . The cavity  826  is sized and configured such that the pump assembly  908  can be generally recessed within the cavity  826  relative to the outer surface  820  of the body  812 . As such, the body  812  can both provide protection to the pump assembly  908  and allow a patient or clinician to manipulate the control features of the pump assembly  908  while the protective part  814  is secured under the at least one strap  906 . 
     In an embodiment, the cavity  826  can extend completely through the side surfaces  822  of the body and can terminate at upper and lower abutments  828 , helping to facilitate alignment of the protective part  814  and the pump assembly  908 . The cavity  826  can have any suitable shape but is shown to have a generally rectangular shape. 
       FIGS. 34-36  illustrate another embodiment of a protective part  1112  for protecting a pump assembly on a walker  1100  from damage or inadvertent operation.  FIGS. 34-36  show a partial dorsal shell  1102  of the walker  1100 , which is removed from the base shell for ease of reference. The dorsal shell  1102  can be formed either in a single piece or in multiple shell portions. In the exemplary embodiment, the dorsal shell  1102  includes a proximal shell portion  1104  that is connected to a distal shell portion via a flexible or resilient portion or hinge connection  1108 . 
     The dorsal shell  1102  can include a reinforcing portion  1110  that extends generally longitudinally along the dorsal shell  1102  to selectively strengthen the dorsal shell  1102 . The reinforcing portion  1110  can be formed in a single piece and from the same material as the dorsal shell  1102 . In addition to adding structural support, the reinforcing portion  1110  can also enhance the low profile form of the walker  1100 . The reinforcing portion  1110  can further provide additional support for engaging straps extending across the dorsal shell  1102 . 
     The dorsal shell  1102  also includes a pump receiving opening  1116 . The pump receiving opening  1116  is shown formed in the reinforcing portion but can be formed in any portion of the dorsal shell  1102 . A pump assembly comprising a flexible bulb type pump and push button release valve can be inserted through the pump receiving opening  1116 . 
     The dorsal shell  1102  can include clearance holes  1114  defined therein. The clearance holes  1114  can be arranged in any suitable pattern. For instance, the clearance holes  1114  may be arranged at an oblique angle relative to the reinforcing portion  1110  and may exhibit different sizes. The clearance holes  1114  can reduce the weight of the walker  1100 . Further, the clearance holes  1114  can act as vents to allow heat and perspiration to pass from inside the walker  1100  to the exterior thereof. Additionally, the clearance holes  1114  may also allow the dorsal shell  1102  to have some additional resiliency to accommodate swelling of a limb or users having different sizes of lower legs, ankles, and feet. 
     The protective part  1112  can be similar to the protective part  914  except that the protective part  1112  is arranged to be selectively secured over a pump assembly extending through the pump receiving opening  1116  on the dorsal shell  1102 . The protective part  1112  comprises a semi-rigid or rigid body  1118  defining an inner surface  1120  arranged to face the dorsal shell  1102 , an outer surface  1122  opposite the inner surface  1120 , and side surfaces  1124  extending between the inner and outer surfaces  1120 ,  1122 . The body  1118  can have an elongate configuration extending in a longitudinal direction along the dorsal shell  1102 . The body  1118  can extend proximally and distally of the pump assembly. 
     The outer surface  1122  can be continuous or interrupted. The inner surface  1120  can be contoured to generally correspond to the anterior of the dorsal shell  1102 . This can allow the body  1118  to form a better fit between the body  1118  and the dorsal shell  1102 . The inner surface  1120  can also provide a support area for the body  1118  against the dorsal shell  1102  when the body  1118  is secured over a pump assembly extending through the pump receiving opening  1116 . The inner surface  1120  of the body  1118  can engage the dorsal shell  1102  on opposing sides of the reinforcing portion  1110  which, in turn, helps the body  1118  to distribute forces away from a pump assembly. 
     The inner surface  1120  defines a cutout portion  1128  arranged to receive the reinforcing portion  1110  of the dorsal shell  1102 . This can help align the body  1118  with the pump assembly. For instance, the reinforcing portion  1110  can fit into the cutout portion  1128  to help ensure the pump assembly is properly positioned in the body  1118 . The cutout portion  1128  can also help lower the profile of the body  1118  on the dorsal shell  1102 . 
     A receiving space or cavity  1126  is defined in the cutout portion  1128 . The cavity  1126  is arranged to receive or accommodate at least part of the pump assembly, allowing the pump assembly to be generally recessed within the body  1118 . 
     Similar to the other embodiments, the body  1118  is securable over the pump assembly in any suitable manner and has a rigidity arranged to distribute pressure from the patient, walker, or another external object away from the pump assembly. The body  1118  can be removably secured directly to the dorsal shell  1102 . For instance, the body  1118  can be removably secured to the dorsal shell  1102  via hook-and-loop type systems, magnets, adhesives, or fasteners. According to a variation, the body  1118  can be secured to the dorsal shell  1102  via a snap-type connection. The body  1118  can include a plurality of snaps or hook members integrally formed on the inner surface  1120  and configured to snap, lock or clip into one or more clearance holes  1114  formed in the dorsal shell  1102 , facilitating assembly. 
     In other embodiments, the protective part can be permanently attached to the dorsal shell. For instance, the protective part can be a structure or body that is permanently and pivotally attached to the dorsal shell. The body can be arranged to pivot away from the dorsal shell to provide access to the pump assembly and to pivot toward the dorsal shell to conceal and protect the pump assembly. 
     Another exemplary embodiment of an orthopedic device comprising a walker  1200  is shown in  FIGS. 37-41 . Similar to the other embodiments, the walker  1200  includes complementary base and dorsal shells  1202 ,  1204  and a plurality of straps  1206  arranged to bring the base shell  1202  and the dorsal shell  1204  closer together. This embodiment includes a stabilizing part  1208  positioned on a posterior aspect of the base shell  1202  that is arranged to support the walker  1200  against rotation (e.g., external and/or internal rotation) when a patient has their foot elevated or is resting the foot with the posterior aspect of the walker  1200  on a resting surface  1201  such as a bed, the ground, an examination table, a couch, or any other applicable surface. 
     Conventional walkers typically have rounded posterior heel profiles (when viewed from the proximal aspect of the calf) based on the internal features of the walker to accommodate the patient&#39;s rounded heel anatomy. This rounded posterior heel profile of the walker causes the walker to be relatively unstable when the patient is elevating their foot and resting the walker on the posterior aspect of the walker. In addition, the walker tends to be fairly heavy as compared to the typical weight of the patient&#39;s foot, which, in turn, tends to cause the walker to roll or externally rotate when the walker is elevated. Furthermore, patients tend to rest with their feet externally rotated (e.g., toed-out to the lateral side) further exacerbating the instability of the walker. 
     The stabilizing part  1208  supports the walker  1200  against rotation when a patient is resting the foot without substantially affecting the functionality of the walker  1200  during gait. It also does so without the use of complicated and bulky components. Furthermore, the stabilizing part  1208  can be a separate add-on component to the walker and can be adapted to fit a number of different orthopedic devices, providing versatility. 
     The stabilizing part  1208  can be formed in a single piece and of the same material as the base shell  1202 . The stabilizing part  1208  can be formed of a semi-rigid or rigid material such as, for example, rigid plastic like polypropylene and/or a softer material such as foam. According to a variation, an elastomer can be overmolded or adhered to the stabilizing part  1208  to provide a softer contact surface in the event the stabilizing part  1208  contacts external objects. The stabilizing part  1208  can be separate from or integral to the posterior heel portion  1214  of the walker. 
     In an embodiment, the stabilizing part  1208  comprises an elongate body  1210  arranged to be secured across the posterior heel portion  1214  of the base shell  1202 . The body  1210  can wrap or extend around a portion of the lateral and/or medial side of the walker  1200 . 
     The body  1210  defines an inner surface  1216 , an outer surface  1218  opposite the inner surface  1216 , and side surfaces  1220  extending between the outer and inner surfaces  1218 ,  1216 . The inner surface  1216  is arranged to engage the posterior heel portion  1214  and is contoured to generally correspond to the shape or curvature of the posterior heel portion  1214  of the walker  1200 . This can allow the stabilizing part  1208  to form a better fit between the body  1210  and the posterior heel portion  1214 . The inner surface  1216  can also provide a support area for the body  1210  against the base shell  1202  when a patient is resting the foot with the posterior aspect of the walker  1200  on a resting surface. 
     As noted above, the stabilizing part  1208  has a low-profile configuration such that it generally does not disrupt a patient&#39;s gait while it is secured to the posterior heel portion  1214 . The body  1210  can have a width that is between about 0.5 times and about 1 times (e.g., about 0.9 times), about 0.6 times and about 0.9 times, or about 0.7 times and about 0.8 times a maximum width of the walker  1200 . In other embodiments, the body  1210  can have a greater or lesser width. 
     In an embodiment, the outer surface  1218  of the body  1210  can have a width generally corresponding to the width of the posterior aspect of the walker  1200 . The outer surface  1218  can have width between about 3 inches and about 7 inches, about 3.5 inches and about 6.5 inches, or about 4 inches and 6 inches. In other embodiments, the outer surface  1218  can have a greater or lesser width. 
     As seen in  FIGS. 39 and 40 , the body  1210  extends along an axis X between the side surfaces  1220 . An axis Y extends along a height of the body  1210  between the upper and lower edges so that the axis Y intersects the axis X. The body  1210  can define upper and lower cutouts  1234 ,  1236 . The cutouts  1234 ,  1236  reduce the weight of the stabilizing part  1208  and improve the fit of the stabilizing part  1208  on the posterior heel portion  1214  of the walker  1200 . 
     The stabilizing part  1208  includes at least one counter-rotation feature  1240  arranged to support the walker  1200  against external and/or internal rotation when a patient is resting the posterior aspect of the walker  1200  on the resting surface. In the illustrated embodiment, the at least one counter-rotation feature defines a first point of rotation  1242  about which the walker  1200  will have to overturn to externally rotate and a second point of rotation  1246  about which the walker  1200  will have to overturn to internally rotate. The first and second points of rotation  1242 ,  1246  are each offset a distance from a center of mass  1248  of the walker  1200  along the axis X. The distances between the first and second rotation points  1242 ,  1246  and the center of mass  1248  can be the same or different. At least one of the first point of rotation  1242  and the second point of rotation  1246  can be offset a distance from the center of mass  1248  of greater than about 0.3 times, 0.4 times 0.5 times, or about 0.6 times the width of the posterior aspect of the walker  1200 . 
     If the posterior heel portion  1214  of the walker  1200  is resting on a resting surface and leans toward one side or the other, a driving moment is created that tends to rotate the walker  1200  about the first or second points of rotation  1242 ,  1246 . Because the points of rotation are spaced a distance from the center of mass  1248  along the axis X, the weight of the walker  1200  can provide a counterforce that creates a resisting moment in the opposite direction about the first or second points of rotation  1242 ,  1246 . This resisting moment can resist rotation of the walker  1200  about the points of rotation  1242 ,  1246 , stabilizing the walker  1200  on the resting surface. 
     When the posterior heel portion  1214  of the walker  1200  is resting on a resting surface and the walker  1200  tends to externally rotate about the first point of rotation  1242  of the counter-rotation feature  1240  on the resting surface, the weight of the walker  1200  can provide a counter force that creates a resisting moment in the opposite direction about the first point of rotation  1242 , supporting the walker  1200  against such external rotation. 
     When the posterior heel portion  1214  of the walker  1200  is resting on a resting surface and the walker  1200  tends to internally rotate about the second point of rotation  1246  of the counter-rotation feature  1240  on the resting surface, the weight of the walker  1200  can provide counter force that creates a resisting moment in the opposite direction about the second point of rotation  1246 , supporting the walker  1200  against such internal rotation. 
     The stabilizing part  1208  can thus stabilize the walker  1200  against both internal and external rotation when the patient is resting the foot with the posterior aspect of the walker  1200  on a resting surface. It will be appreciated that when the walker  1200  with the stabilizing part  1208  is placed on a softer resting surface, the stabilizing part  1208  can partially sink or be absorbed into the softer resting surface to allow or accommodate some degree of external rotation of the walker  1200 . For instance, the stabilizing part  1208  can sink and partially rotate on the resting surface to accommodate between about 5 and about 7 degrees external rotation of the walker  1200 . 
     As seen  FIG. 39 , the at least one counter-rotation feature  1240  is a portion of the outer surface  1218  being generally flat or level in a transverse direction along the axis X. The flat or level of the outer portion  1218  can extend between the side surfaces  1220 A,  1220 B. 
     It will be appreciated that other counter-rotation features are possible. For instance, the at least one counter-rotation feature can include the outer surface  1218  being concave across the width of the outer surface  1218 . In other embodiments, the at least one counter-rotation feature can include posteriorly extending lateral and medial support arms on the outer surface  1218  defining first and second rotation points, each offset a distance from a center of mass  1248  of the walker  1200  along the axis X. 
     While two points of rotation are described, it will be appreciated three, four, or any other suitable number of points of rotation are possible. For instance, the at least one counter-rotation feature can define a lateral point of rotation spaced from the center of mass  1248  but not a medial point of rotation so that the stabilizing part  1208  only substantially supports the walker  1200  against external rotation. 
     In other embodiments, one of the points of rotation can be closer to the center of mass than the other so that the stabilizing part  1208  provides more support against rotation along the axis X in one direction than another direction. In addition, while the stabilizing part is described for use on a walker, in other embodiments, the stabilizing part can be arranged for use with a cast, a therapeutic boot, or any other suitable orthopedic device. 
     According to a variation, the side surface  1220 A can define a generally flat surface extending substantially normal to the outer surface  1218 . Opposite the side surface  1220 A, the side surface  1220 B can define an inclined surface  1224  extending between the inner and outer surfaces and arranged to extend along the medial side of the walker  1200 . The inclined surface  1224  advantageously lowers the profile of the stabilizing part  1208  along the medial side, helping to reduce the likelihood of the stabilizing part  1208  catching or bumping against the unaffected leg during gait. The inclined surface  1224  also can enhance the flexibility of the body  1210  at or near the side surface  1220 B, facilitating attachment of the stabilizing part  1208  to the walker  1200 . 
     The stabilizing part  1208  can also be configured so that it can be used on the left foot or the right foot. For instance,  FIG. 40  illustrates the body  1210  being substantially symmetric about the axis X. This advantageously allows the same stabilizing part  1208  to be used on the left or right foot by simply turning the body  1210  over and attaching it to the walker  1200 . Such a configuration can allow a patient to position the inclined surface  1224  along the medial side of the walker  1200  on either the right or left foot as needed. Optionally, the stabilizing part  1208  includes visual indicators  1226  to clarify which orientation of the body  1210  is to be used for which foot. The visual indicators  1226  may include an “R” for right and an “L” for left. 
     The stabilizing part  1208  can be secured to the posterior heel portion  1214  of the walker  1200  in any suitable manner. For instance, the body  1210  can include an attachment system  1230  for securing the stabilizing part  1208  on the posterior heel portion  1214 . The attachment system  1230  can include hook members  1232  defined by the body  1210  arranged to selectively clip or lock in one or more attachment holes  1238  (shown in  FIG. 38 ) defined on the base shell  1202 . The hook members  1232  can be configured to engage an interior surface of the base shell  1202  when the body  1210  is secured on the posterior heel portion  1214 . In other embodiments, the attachment system  1230  can comprise hook-and-loop systems, snaps, fasteners, or any other suitable system. 
     As seen in  FIG. 41 , the outer surface  1218  can also be contoured in a vertical direction (e.g., about the axis X or generally between the upper and lower edges). For instance, the outer surface  1218  of the body  1210  can curve in the vertical direction along the axis Y upward (e.g., away from the inner surface) from the lower edge through an apex  1228 , and then downward to the upper edge. The radius of the curvature of the outer surface  1218  along the axis Y can be constant or can vary. Thus, the outer surface  1218  along the axis Y can be convexly curved. This advantageously reduces the likelihood of the stabilizing part  1208  from catching during use, or more specifically when descending stairs. This also advantageously allows the walker  1200  to be titled or slightly pivoted with respect to the resting surface, such that the body  1210  still supports the position of the patient&#39;s foot even when the posterior of the walker  1200  is not completely parallel to the resting surface. In other embodiments, the outer surface  1218  can be contoured in the vertical direction such that the body  1210  has a faceted, trapezoidal, or other cross-section shape. 
     Another exemplary embodiment of a stabilizing part  1308  is shown in  FIG. 42 . The stabilizing part  1308  comprises an outer member  1314  having a rigid or semi-rigid configuration and an inner member  1316 . The outer member  1314  can include a pair of side members  1318  arranged to extend along a portion of the lateral and medial sides of a walker and a center portion  1320  extending between the side members  1318 . The center portion  1320  can include at least one counter-rotation feature comprising a central channel  1322  in the outer surface and supports  1340  on opposite sides of the central channel  1322 . 
     The supports  1340  define a first point of rotation  1342  about which a walker will have to overturn to externally rotate and a second point of rotation  1344  about which the walker will have to overturn to internally rotate. The first and second points of rotation  1342 ,  1344  are each offset a distance from a center of mass  1348  of a walker along an axis X 1 . As such, if the posterior aspect of the walker is resting on a resting surface and leans toward one side or the other, a driving moment is created that tends to rotate the walker about the first or second points of rotation  1342 ,  1344 . Because the points of rotation  1342 ,  1344  are spaced a distance from the center of mass  1348  along the axis X 1 , the weight of the walker on the stabilizing part  1308  can create a resisting moment in the opposite direction about the first or second points of rotation  1342 ,  1344  that tends to resist rotation of the walker about the points of rotation  1342 ,  1344 , stabilizing the walker on the resting surface. 
     The inner member  1316  can be attached to the outer member  1314  and define an inner surface  1324  arranged to engage the posterior heel portion of the walker. The inner surface  1324  extends across the posterior of the walker and along a portion of the lateral and medial sides of the walker. According to a variation, the inner member  1316  can be formed of a softer material arranged to conform to the shape of the walker, allowing the stabilizing part  1308  to fit walkers of different shapes. 
     The stabilizing part  1308  can be attached to the walker in any suitable manner but is shown being removably attachable to a walker via a hook-and-loop type system  1326 . In other embodiments, the stabilizing part  1308  can be attached to the walker via clips, fasteners, magnets, adhesives, or any other suitable attachment system. 
     As noted above, embodiments of the orthopedic system can be adapted for use with other components.  FIGS. 43-45  illustrate another embodiment including an activity tracking device integrated into an orthopedic device comprising a walker. This beneficially allows a clinician to monitor a patient&#39;s activity levels and/or compliance by identifying both patients who may be too active as well as those who may be inactive (potentially indicating a lack of compliance with clinician instructions). 
     Conventional walkers do not integrate a means of remotely monitoring patient activity level or compliance with physician instructions. This can lead to negative patient outcomes with unknown or difficult to diagnose causes. For instance, a very active patient may be running or jogging with sprains or fractures of the lower leg, increasing stress on an injury and delaying healing. Alternatively, a patient may be removing a walker which is required for a specific treatment, such as in the case of diabetic ulcer healing, where lack of compliance is believed to be a common cause of increased diabetic ulcer healing time. 
     In the illustrated embodiment, an activity tracking device  1402  is added to or integrated with a walker  1400  and linked or registered within a software application or remote patient monitoring system. The activity tracking device  1402  can generate information associated with the patient&#39;s level of activity or compliance during treatment. A clinician can then access and use the data or information collected by the activity tracking device  1402 . The clinician can have continuous or intermittent access to the data or information collected by the activity tracking device  1402 . For instance, the clinician may only be able to access the data or information from the activity tracking device  1402  during an office visit or during a specific period of time. In other embodiments, the clinician may be able to access the information or data on demand or at any time. 
     The clinician can use the data or information for determining compliance and/or monitoring the patient&#39;s activity level. A clinician can also use such information for troubleshooting potential treatment issues and/or to identify other treatment options for the patient. This advantageously offers an improvement over prior art walkers, which are unable to track and report on a patient&#39;s activity during therapy. While the orthopedic device is described as a walker, it will be appreciated that in other embodiments the orthopedic device can be a therapeutic shoe, a total contact cast, or any other suitable orthopedic device. 
     The activity tracking device  1402  can be any suitable device. The activity tracking device  1402  can include one or more sensors such as a three-dimensional accelerometer to sense patient movement. The activity tracking device  1402  can measure steps taken and combine this data with individual patient characteristics to calculate distance walked, calories burned, floors climbed, activity duration, and/or activity intensity. The activity tracking device  1402  can measure periods of inactivity. In other embodiments, the one or more sensors may include pressure sensors, force sensors, and/or temperature sensors. 
     The activity tracking device  1402  can include a control system to receive and/or process information from the one or more sensors and/or connect, and transmit information to a computer device or system as described below. The activity tracking device  1402  can be a sealed or waterproof unit and/or have a long battery life (e.g., greater than about 3 months), enhancing the usability of the system, as walkers tend to get wet during use and some patients visit their clinicians infrequently, creating a lengthy time between opportunities for charging. 
     The activity tracking device  1402  can be integrated in the walker  1400  in a variety of different ways. For example, the activity tracking device  1402  is positioned under a cover member  1404  attached to the posterior aspect of a base shell  1406  of the walker  1400 . Placement of the activity tracking device  1402  on the posterior aspect of the walker  1400  reduces the likelihood of patient tampering or interference as the activity tracking device  1402  is out of the patient&#39;s sight and is more difficult to access during use. 
     In an embodiment, the cover member  1404  can be a removable and replaceable component of the walker  1400 . For instance, the cover member  1404  can be sized and configured to be interchangeable with embodiments of the air system cover previously described. As such, the cover member  1404  and activity tracking device  1402  can be an add-on module or accessory sold separately from the walker  1400 . 
     As seen in  FIGS. 43 and 44 , the cover member  1404  can be attached to the base shell  1406  over a cutout  1408  formed in the walker  1400 . The cover member  1404  includes a base portion  1410  and a peripheral sidewall  1412  extending from the base portion  1410  toward the base shell  1406  of the walker  1400 . 
     As shown in  FIG. 45 , a receiving space  1414  in the cover member  1404  is bounded by the sidewall  1412  and the base portion  1410  so that the bottom of the receiving space  1414  is recessed within the sidewall  1412  to provide a space for the activity tracking device  1402 . This can allow the base portion  1410  and the sidewall  1412  to substantially enclose the activity tracking device  1402  within the receiving space  1414 , protecting the activity tracking device  1402  and helping to deter tampering. The cover member  1404  also helps reduce the likelihood of the activity tracking device  1402  being accidentally dislodged during use. The activity tracking device  1402  can be secured in the receiving space  1414  via a hook member  1422  defined on the inner surface of the cover member  1404 . The activity tracking device  1402  can be secured in the receiving space  1414  via an interference fit between the cover member  1404  and the activity tracking device  1402 . The activity tracking device  1402  can be secured in the receiving space  1414  via adhesives, a snap fit, or any other suitable manner. 
     The sidewall  1412  defines a rim  1416  extending around the base portion  1410 . At least a portion of the rim  1416  can be contoured to generally correspond to the contour or shape of the posterior of the base shell  1406 . This can allow the cover member  1404  to form a better fit between the cover member  1404  and the base shell  1406 . The rim  1416  can also provide a support area for the cover member  1404  when the cover member  1404  is attached to the base shell  1406 . 
     The cover member  1404  can be attached to the base shell  1406  in any suitable manner. The cover member  1404  can be secured to the base shell  1406  via a snap-type connection. The cover member  1404  includes a plurality of snaps or hook members  1420  integrally formed on the sidewall  1412  and configured to snap into the cutout  1408  formed in the base shell  1406 , facilitating attachment. Alternatively, the cover member  1404  can be removably attached to the base shell  1406  via fasteners, hook-and-loop type systems, clips, magnets, or any other suitable attachment system. 
     According to another embodiment, the cover member  1404  can be irreversibly attachable to the walker  1400 . To protect the activity tracking device  1402  and prevent tampering, the cover member  1404  can be securely attached to the walker  1400  via gluing, plastic welding, or any other suitable manner such that it cannot be removed by the patient without breaking the cover member  1404 , which would provide a visible indication of unauthorized tampering with the activity tracking device  1402 . 
     As noted above, the activity tracking device  1402  can be linked with a software application or patient monitoring system. For instance, the activity tracking device  1402  can be operatively coupled to a monitoring system  1500  including a computer device  1505  as seen in  FIG. 46 . The computer device  1505  can display information to a patient or clinician and receive input, respectively. For instance, a clinician or patient can input patient characteristics data via the computer device  1505 , which, in turn can be processed by the activity tracking device  1402  and/or the computer device  1505  with the step information from the activity tracking device  1402  to calculate activity information such as, but not limited to, distance walked, activity duration, and/or activity intensity. As seen, the computer device  1505  can be a mobile device. A mobile device is a processing device routinely carried by a user. It typically has a display screen with touch input and/or a keyboard, and its own power source. As such, the computer device  1505  can provide a patient or clinician the freedom to use it almost anywhere. The computer device  1505  can be a hand-held device. The computer device  1505  can be a tablet computer, a smartphone, a laptop, a mobile telephone, a PDA, or other appropriate device. 
     The computer device  1505  can be communicatively coupled to the activity tracking device  1402 . The computer device  1505  can be communicatively coupled to the activity tracking device  1402  via a secure or unsecure wireless connection. 
     The computer device  1505  can be communicatively coupled to a server or computer system  1501  over a network  1503 , such as for example, a Local Area Network (“LAN”), a Wide Area Network (“WAN”), or the internet. The computer system  1501  can be used for controlling/monitoring the computer device  1505  and/or the activity tracking device  1402 . In an embodiment, the computer system  1501  can provide a patient feedback by directing the activity tracking device  1402  to vibrate a vibrator of the activity tracking device  1402  if step or activity information generated by the activity tracking device  1402  and/or the computer device  1505  exceeds a value limit. 
     The computer system  1501  can be used for exchanging data/files with the computer device  1505  and/or the activity tracking device  1402 . For instance, the activity tracking device  1402  can send one or more files including step information and/or activity information to the computer device  1505  and/or the computer system  1501 . It will be appreciated that the computer device  1505  can be separate from or integral to the computer system  1501 . 
     This allows a clinician to ascertain the patient&#39;s level of activity or compliance during treatment by accessing the information generated by the activity tracking device  1402  remotely via the computer device  1505  and/or the computer system  1501 . For instance, the computer device  1505  can provide a clinician feedback if step or activity information generated by the activity tracking device  1402  exceeds or fails to exceed a value limit stored in the computer device  1505  or computer system  1501 . The value limit can be based on patient characteristics, treatment protocols, and/or physician instructions. The value limit can be time dependent. In an embodiment, the computer device  1505  can provide a clinician feedback if step information generated by the activity tracking device  1402  indicates that the patient has not taken a step within a specified time period (e.g., a 24-hour period). The clinician can then use such feedback to make a determination of non-compliance. 
     According to a variation, the clinician may setup the activity tracking device  1402  within the system  1500  via a registration link or program that limits connection to the activity tracking device  1402  to a single user, reducing the likelihood of unauthorized access to the activity tracking device  1402  and helping to maintain patient confidentiality. 
     The system  1500  thus gives a clinician freedom to monitor the patient&#39;s activity level and/or compliance from almost anywhere and at any time without having to have physical access to the activity tracking device  1402 . For instance, the clinician can access the activity tracking device  1402  wirelessly via the computer device  1505  or the computer system  1501  during office visits or routine check-ups. Information generated by the system  1500  can then be used by the clinician for troubleshooting potential treatment issues or to identify other courses of treatment for the patient. According to a variation, the activity tracking device  1402  can be accessed physically by a clinician. 
     The exact division of labor between the computer system  1501 , the activity tracking device  1402 , and the computer device  1505  may vary. For instance, the computer device  1505  can receive and store data/files from the activity tracking device  1402 , and the activity tracking device  1402  can perform all other operations. In other embodiments, the activity tracking device  1402  can transmit data to the computer device  1505  and/or computer system  1501  and the computer device  1505  and/or computer system  1501  processes, stores, and displays information to the clinician. Any division of labor between the activity tracking device  1402 , the computer device  1505 , and the computer system  1501  is also within the scope of the present disclosure. 
     In other embodiments, the walker can be modified, providing a receptacle to receive and secure embodiments of the activity tracking device.  FIG. 47  illustrates another embodiment of a walker  1600  defining a receptacle  1602  having a receiving space arranged to receive and secure an activity tracking device  1604  in the receptacle  1602 . This can allow for the activity tracking device  1604  to be sold as a stand-alone accessory or with the walker  1600  as a package. As seen, the receptacle  1602  can be positioned on a side of a base shell  1606  of the walker  1600 . This permits the activity tracking device  1604  to be located on the lateral side of the walker  1600 , which, in turn, helps prevent the activity tracking device  1604  from interfering with the patient&#39;s gait. 
     According to a variation, the activity tracking device can be integrated with the dorsal shell. For instance,  FIG. 48  shows another embodiment of a walker  1700  including a dorsal shell  1702  defining a receptacle  1704  having a receiving space arranged to receive an activity tracking device  1706 . It will be appreciated that the receptacle  1704  can be formed on the inner or outer surfaces of the dorsal shell  1702  and/or in the proximal shell section or the distal shell section. Integrating the activity tracking device  1706  on the dorsal shell may enhance the accuracy of data generated by the activity tracking device  1706  because the movement of the activity tracking device on the dorsal shell may more closely track the actual movement of the patient&#39;s foot and/or lower leg. 
     In yet other embodiments, the activity tracking device can be secured to a strap member of the walker, making the activity tracking device easy to attach and access for a clinician. In other embodiments, the activity tracking device can be integrated into an insole, outsole, or any other suitable portion of an orthopedic device. 
     While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting. Additionally, the words “including,” “having,” and variants thereof (e.g., “includes” and “has”) as used herein, including the claims, shall be open-ended and have the same meaning as the word “comprising” and variants thereof (e.g., “comprise” and “comprises”).