Patent Publication Number: US-2021161686-A1

Title: Adjustable socket system

Description:
TECHNICAL FIELD 
     The disclosure relates to an adjustable socket system for a residual limb. 
     BACKGROUND 
     A typical prosthetic leg and foot includes a socket, pylon, and foot. A socket is commonly referred to as the portion of a prosthesis that fits around and envelops a residual limb or stump, and to which prosthetic components, such as a foot, are attached. When providing a socket to an amputee, it is essential to properly fit the socket and align various parts of the prosthesis to the amputee. Fitting and alignment of the socket and the parts are difficult tasks to perform, and require extensive knowledge, training and skill for the prosthetist. 
     Typically, sockets for definitive prostheses are customized for a residual limb of a user. According to one method, the sockets are formed over a model of the stump, such as one formed by plaster-of-Paris, to be used to distribute forces between the socket and the stump in a comfortable way to the amputee. In another method, the socket may be obtained from computer aided design by modeling the shape of the stump, and subsequently forming a model. Once the model is obtained in either of these methods, a socket is formed over the model by using fabric and liquid plastic resin to obtain a definitive rigid socket customized to a limb. 
     Proper fitting of a socket to the stump is critical to the success of the prosthesis. The socket must fit closely to the stump to provide a firm connection and support, but must also be sufficiently loose to allow for circulation. In combination with proper fitting, the socket must transfer loads from the residual limb to the ground in a comfortable manner. 
     Most prosthetic sockets are permanently formed to a customized shape that is static, meaning the socket does not account for shape and volume fluctuations of the residual limb. When there are shape and volume fluctuations, the fitting of the socket is impeded, with these sockets causing discomfort, pain and soft tissue breakdown of the stump. Conventional sockets tend to be bulky and cumbersome to wear, and may be difficult to don making the residual limb uncomfortable when worn. 
     As to methods of attaching the socket to the residual limb, conventional sockets rely on different mechanisms such as negative pressure or a friction or tension based interface. Conventional sockets may have poor force distribution on the residual limb causing a concentration of pressure on a certain area of the stump. This poor distribution of pressure causes pain, discomfort, and tissue breakdown. Conventional sockets generally are not breathable which results in undesirable temperature and humidity within the socket. 
     For certain types of amputations such as disarticulation amputations where the limb is separated at a joint, it is difficult to create sockets which are not bulky and provide use of the natural anatomy. Conventional sockets for disarticulation amputations use a rigid socket which requires that the opening for the socket be larger than the joint to allow for donning and doffing. The rigid sockets generally have a general uniform shape which receives a large portion of the residual limb and the space between the residual limb and the interior of the rigid socket wall is filled in with a soft or cushioning material. 
     There is a need for an adjustable prosthetic socket that accommodates shape and volume fluctuations of the residual limb and comfortably transfers loads from the residual limb to the ground. 
     SUMMARY 
     The disclosure describes various embodiments of an adjustable socket system that is adapted to receive and fit a range of sizes of a residual limb, and accommodate volume and shape fluctuations of the residual limb. From its versatility in fitting and adjustment, the adjustable socket system can decrease pain, discomfort and soft tissue breakdown over known sockets static in size and shape. 
     Embodiments described can include an adjustable socket system having a distal portion and proximal portion. An axis extends between the distal and proximal portions. A plurality of struts are connected to the distal portion and distributed circumferentially about the axis. The struts at least in part define a receiving volume adapted to receive a residual limb and are movable between an expanded configuration in which at least some of the struts are moved radially outward relative to the axis to loosen the fit of the adjustable system, and a closed configuration in which at least some of the struts are moved radially inward relative to the axis to tighten the fit of the adjustable socket system. A tightening system is operatively connected to the struts and arranged to tighten and loosen the fit of the adjustable socket system on one or more areas of the residual limb. The tightening system can be manually or automatically operable. 
     According to a variation, the tightening system is arranged to automatically loosen and tighten the fit of the adjustable socket system when it is loaded and unloaded by a user. For instance, when the adjustable socket system is not in use, the struts can assume the expanded configuration, allowing a residual limb to be easily inserted into and removed from the receiving volume. When the residual limb is inserted into the receiving volume a distal end of the residual limb applies a load or pressure to a distal support of the tightening system, the tightening system automatically moves the struts toward the closed configuration, tightening the fit of the adjustable socket system on the residual limb in proportion to the load or pressure applied to the distal support. 
     The tightening system can thus advantageously permit the adjustable socket system to “relax” and be looser when the user is inactive (e.g., sitting or lying down) and become tighter when walking, and become very tight during sports. It also permits the adjustable socket system to tighten or clamp onto the residual limb during stance and loosen during swing, thus optimally using cyclic loading to best load or compress on the residual limb. 
     According to a variation, the tightening system is arranged to control the proportion of load or compression imparted by the struts to different areas of the residual limb, helping to create an improved fit between the adjustable socket system and the residual limb. For instance, insufficient compression or loading distally can create pistoning (e.g., excessive movement of the adjustable socket system up and down vertically relative to the residual limb). If there is too much loading distally, then it can be painful for the user of the system. If the proximal aspect of the system is too tight, then the residual limb can be forced in an upward direction out of the receiving volume, effectively stretching the residual limb, which can be uncomfortable and dangerous for the user. If the proximal aspect of the system is too loose, the distal aspect of the system can take too much load. By controlling or fine-tuning the proportion of the distal compression and proximal compression, the tightening system can improve control and suspension. 
     Additional features and advantages of embodiments of the present disclosure will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary embodiments. These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of such exemplary embodiments as set forth hereinafter. 
    
    
     
       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 an isometric view of an adjustable socket system according to an embodiment. 
         FIG. 2  is an isometric view of an adjustable socket system according to another embodiment. 
         FIG. 3  is an isometric view of an adjustable socket system according to another embodiment. 
         FIG. 4  is a top view of the adjustable socket system in  FIG. 3 . 
         FIG. 5  is a top view of the adjustable socket system in  FIG. 3  in another position. 
         FIG. 6  is an isometric view of an adjustable socket system including a tightening system according to an embodiment. 
         FIG. 7  is a cross-sectional view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 8  is a partial cross-sectional view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 9  is a side view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 10  is a side view of the adjustable socket system in  FIG. 9  in another position. 
         FIG. 11  is a side view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 12  is a side view of the adjustable socket system in  FIG. 11  in another position. 
         FIG. 13  is a side view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 14  is a side view of the adjustable socket system in  FIG. 13  in another position. 
         FIG. 15  is an isometric view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 16  is an isometric view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 17  is a top view of the adjustable socket system in  FIG. 16 . 
         FIG. 18  is a top view of the adjustable socket system in  FIG. 16  in another position. 
         FIG. 19  is a cross-sectional view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 20  is another cross-sectional view of the adjustable socket system in  FIG. 19  in another position. 
         FIG. 21  is an isometric view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 22  is a detailed view of the adjustable socket system in  FIG. 21 . 
         FIG. 23  is an isometric view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 24  is another isometric view of the adjustable socket system in  FIG. 23  in another position. 
         FIG. 25  is an isometric view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 26  is an isometric view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 27  is a schematic view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 28  is a schematic view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 29  is a schematic view of a tightening system according to another embodiment. 
         FIG. 30  is a schematic view of a tightening system according to another embodiment. 
         FIG. 31  is a schematic view of a tightening system according to another embodiment. 
         FIG. 32  is a schematic view of a tightening system according to another embodiment. 
         FIG. 33  is a cross section view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 34  is the tightening system in  FIG. 33 . 
         FIG. 35  is a cross section view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 36  is a schematic view of the tightening system in  FIG. 35 . 
         FIG. 37  is a side view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 38  is another side view of the adjustable socket system in  FIG. 37 . 
         FIG. 39  is a side perspective view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 40  is a partial side view of the adjustable socket system in  FIG. 39 . 
         FIG. 41  is a side perspective view of an adjustable socket system including a tightening system according to another embodiment. 
         FIG. 42  is a bottom perspective of the distal support in  FIG. 41 . 
         FIG. 43  is a partial cross section view of the adjustable socket system in  FIG. 41 . 
     
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     A better understanding of different embodiments of the disclosure may be had from the following description read in conjunction 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 shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific embodiments disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, combinations, and equivalents falling within the spirit and scope of the disclosure and defined by the appended claims. 
     For further ease of understanding the embodiments of a prosthetic system as disclosed herein, a description of a few terms is necessary. 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 prosthetic system. The term “rigid” is intended to denote that an element of the device is generally devoid of flexibility. 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 members that provide support and are free-standing; however, such members may have some degree of flexibility or resiliency. 
     Some of the components described herein share similarities to components in U.S. Pat. Nos. 9,050,202; 8,795,385; 7,867,286; and 7,488,349 and pending U.S. application Ser. No. 14/704,572, incorporated herein by reference and belonging to the assignee of this disclosure. 
       FIG. 1  shows an embodiment of a prosthetic system comprising an adjustable socket system  100  that is adapted to receive and fit a range of sizes of a residual limb, as well as to accommodate volume and shape fluctuations of a residual limb. From its versatility in fitting and adjustment, the adjustable socket system can decrease pain, discomfort and soft tissue breakdown over known sockets that are static in size and shape. Moreover, the adjustability of the socket provides an off-the-shelf socket system that takes much of the guesswork out of making a socket and provides an instant solution when urgency may be required to provide an amputee with a socket. It will be appreciated that the system  100  may be adapted to a variety of different types of amputations, whether configured for the leg or arm. 
     The system  100  includes a distal portion  102 , a proximal portion  104 , and an axis  106  extending between the distal portion  102  and the proximal portion  104 . The distal portion  102  is shown having a cup-like configuration but can have any suitable configuration. For instance, the distal portion can include a base connector adapted to connect to prosthetic components, such as an artificial foot or pylon. 
     A plurality of struts  108  having an elongated configuration are distributed circumferentially about the axis  106 . Each of the struts  108  can include a distal end  110  connected to the distal portion  102  and a proximal free end  112 . The struts  108  generally extend between the distal portion  102  and the proximal portion  104 . The struts  108  can exhibit any suitable shape and/or size. For instance, at least one of the struts  108  can include parts extending in different directions along the outer surface of the residual limb, helping to distribute pressure from the struts  108  on the residual limb over a greater area. In other embodiments, the struts  108  can be adjustable or extendible in length. For instance, one or more of the struts  108  can include a telescoping mechanism that can adjust strut length or width. In other embodiments, the struts  108  can be available in different lengths and/or sizes that can be selectively attached to the distal portion  102  to adjust the length or size of the struts  108 . 
     The struts  108  at least in part define a receiving volume  114  adapted to receive a residual limb. It will be appreciated that the configuration and distribution of the struts  108  about the axis  106  can be adjusted or selected based on the needs of the user for structural stability and/or to accommodate the underlying anatomy and physiology of the residual limb. At least some of the struts  108  are radially adjustable relative to the axis  106  to vary the receiving volume  114 . The struts  108  or the system  100  is movable between an expanded configuration and a closed configuration. In the expanded configuration, at least some of the struts are moved or forced radially outward relative to the axis  106 , increasing the receiving volume  114  or increasing a circumference of the system  100 . This loosens the fit of the system  100  on a residual limb inserted in the receiving volume  114  or decreases the loading on the residual limb from the system  100 . In the closed configuration, at least some of the struts  108  are moved or forced radially inward relative to the expanded configuration, decreasing the receiving volume  114  or decreasing a circumference of the system  100 . This tightens the fit of the system  100  on the residual limb or increases the loading on the residual limb from the system  100 . It will be appreciated that movement of one or more portions of a strut can move the struts  108  between the expanded and closed configurations. 
     According to a variation, at least one of the struts  108  can have a non-articulating configuration. For instance, the distal end  110  of one of the struts  108  can be rigidly connected to the distal portion  102  and the strut  108  can be adapted to bend or flex between the distal end  110  and the proximal end  112  to adjust or vary the receiving volume  114 . This arrangement advantageously allows the system  100  to better accommodate the underlying anatomy and physiology of the residual limb, providing an improved fit between the system  100  and a residual limb in the receiving volume  114 . In other embodiments, at least one of the struts  108  is adapted to pivot or articulate about a connection point relative to the axis  106 . 
     One or more portions of the struts  108  can be at least in part rigid or semi-rigid, helping to provide support to the residual limb and/or stabilization of the system  100 . The struts  108  can be of multi-durometer construction. For instance, the distal portion of the struts  108  can be semi-rigid and the proximal portion of the struts  108  can be rigid. This can allow the struts  108  to more easily expand or flex in response to volume fluctuations of the distal end of the residual limb. In an embodiment, the struts  108  can be contoured to generally correspond to an outer surface of the user&#39;s residual limb, which, in turn, creates a more comfortable fit. This can also improve cosmesis. For instance, a contour of one or more of the struts  108  can be adapted to make the system  100  less visible under trousers or other articles of clothing. 
     The system  100  can define pressure release regions adapted to allow for tissue displacement if the struts apply significant force to the tissues of the residual limb. The release regions may be in openings, recesses, soft elastically deformable material, or stiff material having regions that are elastically deformable. For instance, pressure release regions can include gaps  116  are defined between the struts  108 . The gaps  116  can allow soft issue of the residual limb to bulge out between the struts  108 , relieving pressure if needed and increasing user comfort. The gaps  116  can also provide ventilation to the system  100 . Further, the gaps  116  can allow the struts  108  to be radially positioned closer to bone of the residual limb and may improve control of the system  100 . 
     According to a variation, the distal portion  102  of the system  100  can include a distal support  118  as shown in  FIG. 2 . The distal support  118  is adapted to receive and support a distal end of the residual limb inserted in the receiving volume  114 . The distal support  118  axially supports the residual limb to help prevent the distal end of the residual limb from “bottoming out” or displacing vertically to a base or other component below the distal support  118 , which could negatively impact the distal end of the residual limb and potentially injure the user. The distal support  118  can be flexible such that it substantially conforms to the shape of the distal end of the residual limb. 
     The distal support  118  can have any shape but is shown having a cup-like configuration. The distal support  118  has a bottom portion and one or more side portions  120  arranged to extend up and around the distal end of the residual limb, providing protection and support to the distal end of the residual limb. The distal support  118  can be formed from an elastomeric material such as silicone or rubber. The distal support  118  can be a knitted, woven, or netted structure. The distal support  118  can be generally non-elastic in the axial direction such that when tension is applied to it, the distal support  118  can transfer load to the residual limb. The distal support  118  can provide a cushion and/or distribution of pressure at the distal end of the residual limb. As discussed in more detail below, the amount of pressure exerted on the residual limb by the distal support  118  can be adjustable and/or tensioned differently or independently of the struts  108 . 
     According to a variation, the system  100  includes a plurality of petal members  124  operatively connected to the struts  108 . One or more portions of the petal members  124  are arranged to move radially inward and/or outward relative to the axis  106 , which, in turn, varies the receiving volume  114 . The petal members  124  are situated radially inside of the struts  108  and extend along a length of the struts  108 . In an embodiment, the petal members  124  define an inner surface  122  of the system  100  such that the petal members  124  form the interface between a residual limb and the system  100 . This can help reduce the need of a separate liner and distribute pressure from the struts  108  to the residual limb, which, in turn, helps reduce the likelihood of the user feeling the struts  108  as points of pressure, improving user comfort. It also forms a larger contact surface between the residual limb and the system  100 , providing a more secure coupling between the residual limb and the system  100 . 
     As seen in  FIG. 4 , the petal members  124  are arranged in an overlapping configuration. For instance, each petal member  124  can include a leading edge  126  adapted to extend beyond a trailing edge  128  of an adjacent ones of the petal members  124 . As such, there are none or almost no gaps or spaces present between adjacent ones of the petal members  124 . This allows the petal members  124  to substantially enclose the residual limb within the system  100 , which, in turn, prevents or limits soft tissue of the residual limb from bulging out between the struts  108 . The leading and/or trailing edges  126 ,  128  are shown generally linear but can be arcuate, curvilinear, combinations thereof, or any other suitable configuration. The leading edge  126  and the trailing edge  128  can be the same or different. 
     As discussed above, one or more of the struts  108  are radially adjustable relative to the axis  106  to vary the receiving volume  114 . When the struts  108  are moved radially inward, as seen in  FIG. 5 , the struts  108  move the petal members  124  radially inward toward the axis  106 , decreasing the receiving volume  114 . As the petal members  124  come together, the leading edges  126  slide or move a greater distance beyond the trailing edges  128  of the adjacent petal members  124 . In an embodiment, the petal members  124  can come together to effectively become a single body forming a generally continuous inner surface area to interface with the residual limb. When the struts  108  are moved radially outward, the struts  108  move the petal members  124  radially outward from the axis  106 , increasing the receiving volume  114 . This allows the residual limb to be more easily inserted into and or removed from the system  100 , facilitating donning and doffing the system  100 . In an embodiment, the system  100  can include at least two struts  108  and at least two petal embers  124 . 
     In an embodiment, the leading edges  126  and/or the trailing edges  128  can be adapted to form a seal with adjacent petal members  124  so that when the user places weight upon the system  100 , the overlapping petal members  124  can in part create a substantially air-tight seal, allowing vacuum suspension of the system  100  on the residual limb. 
     One or more of the leading edges  126  can be rounded or rolled, helping it to more easily slide or move over the adjacent petal member  124 . The distance the leading edge  126  overlaps the adjacent petal member  124  can vary between proximal and distal ends of the petal members  124 . Optionally, at least one of the leading edges  126  or the trailing edges  128  can be chamfered or feathered. This can help prevent pressure points from the edges  126 ,  128  on the residual limb, providing a more comfortable fit. The leading edges  126  or the trailing edges  128  can be made of a softer durometer material than other portions of the petal members  124 . For instance, one or more of the edges  126 ,  128  can comprise a flexible portion overmolded onto a body of the petal members  124 . A distal portion of the petal members  124  can be thinner with a lower coefficient of friction than a proximal portion of the petal members  124 , helping the petal members  124  to more easily slide or move over one another. 
     The petal members  124  can exhibit any suitable shape and/or configuration. The petal members  124  can be generally rectangular or trapezoidal. The petal members  124  can be generally leaf-shaped. The petal members  124  can have a shape that is preformed or customizable to an individual user. The petal members  124  can be shaped or contoured to generally correspond to the shape of a portion of the residual limb. An inner surface of one or more of the petal members  124  can have a resilient configuration, helping the petal members  124  to better fit the residual limb. 
     In an embodiment, the petal members  124  can be separate from and attached to the struts  108  via adhesives, mechanical fasteners, or any other suitable attachment method. In other embodiments, the petal members  124  and the struts  108  can be integrally formed in one piece. For example, one or more of the petal members  124  can be overmolded on the struts  108 . The petal members  124  may or may not be attached to the struts  108 . 
     The petal members  124  can have a multi-durometer configuration. In an embodiment, the proximal portion of the petal members  124  can be formed of a soft, compliant, conforming material arranged to follow the contour of the residual limb. The petal members  124  can include regions of softer durometer materials contained within larger areas of firmed durometer materials. The proximal portion of the petal members  124  can have a greater stiffness than a stiffness of the distal portion of the petal members  124 . The petal members  124  can be formed of a flexible material, such as a polymeric material. The petal members  124  can be formed of a breathable material and situated directly next to the user&#39;s skin. 
     At least one of the petal members  124  can define one or more slots or cuts. For example, the petal members  124  can define a plurality of slots in a targeted region to increase flexibility or conformity of the petal member  124  within the targeted region. The slots or cuts can extend axially, circumferentially, and/or can exhibit any suitable size, shape, or length. 
     Embodiments of the adjustable socket system include a tightening system for tightening and loosening the fit of the adjustable socket system onto the user&#39;s residual limb. Embodiments of the tightening system can stabilize the struts or other structural components, contributing to the overall structural integrity of the adjustable socket system. The tightening system can provide adjustability to the adjustable socket system. Adjustments provided by the tightening system may include adjustments to the circumference of the adjustable socket system, or more particularly to the receiving volume defined by the struts. According to a variation, the tightening system can adjust tension or compression imparted to the struts even in the absence of noticeable change in the receiving volume. The tightening system can be manually or automatically operable. 
     Some embodiments of the tightening system can control a proportion compression imparted by the struts to different areas of the residual limb, helping to create an improved fit between the adjustable socket system and the residual limb. For instance, insufficient loading distally can create pistoning (e.g., excessive movement of the adjustable socket system up and down vertically relative to the residual limb). If there is too much loading distally, then it can be painful for the user of the system. If the proximal aspect of the system is too tight, then the residual limb can be forced in an upward direction out of the receiving volume, effectively stretching the residual limb, which can be uncomfortable and dangerous for the user. If the proximal aspect of the system is too loose, the distal aspect of the system can take too much load. By controlling or fine-tuning the proportion of the distal compression and proximal compression, the tightening system can improve control and suspension. 
     Some embodiments of the tightening system can control the fit of the adjustable socket system in different parts. Some embodiments of the tightening system can tighten and loosen the overall fit of the adjustable socket system but with a local control system so that the one part of the system can be tightened and loosened proportionally with respect to another portion of the system. In other embodiments, the tightening system can differentially control the fit of the adjustable socket system in different parts. In other embodiments, the tightening system can automatically tighten or loosen the adjustable socket system in response to loading and unloading of the system. 
     Different embodiments of the tightening system are shown in  FIGS. 6-22 . It will be appreciated that the tightening system embodiments described herein can be used alone or in combination with one or more features included in other embodiments of the present disclosure. 
     As shown in the example in  FIG. 6 , a tightening system  130  can include a tubular member  132  selectively positionable along a length of the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  132  can define a continuous circumference. The tubular member  132  can be a sleeve  132  having a body portion  134  with open upper and lower ends  136 ,  138 , and a central opening  137 . The central opening  137  of the sleeve  132  defines an inner surface  139  for securing over an outer surface of the struts  108 . The body portion  134  can have a circular or elliptical configuration. 
     The inner surface  139  can engage and frictionally secure against the outer surface of the struts  108 . The body portion  134  may be formed from a fabric material and/or elastomer material. The body portion  134  can be radially stiff. The body portion  134  can be radially stretchable. The body portion  134  can generally resist elongation in the axial direction. 
     In use, the sleeve  132  is positioned on the distal portion  102  of the system  100  such that the struts  108  extend through the central opening  137  of the sleeve  132 . The diameter of the central opening  137  is sized such that when the sleeve  132  is moved in a proximal direction along the outer surface of the struts  108 , the inner surface  139  of the sleeve  132  imparts a compressive force on the struts  108 , moving the struts  108  radially inward and tightening the fit of the system  100  on a residual limb. 
     The struts  108  can form a generally conical structure. As such, the amount of compression imparted to the struts  108  by the sleeve  132  can increase as the sleeve  132  is moved in a proximal direction along the length of the struts  108 . The tightness of the system  100  on the residual limb can thus be controlled or varied by adjusting the axial position of the sleeve  132  along the struts  108 . This advantageously allows a user to tighten the system  100  by positioning the sleeve  132  more closer to the proximal ends  112  of the struts  108  when the user is more active, and to loosen the system  100  by positioning the sleeve closer to the distal ends  100  of the struts  108  when the user is less active. 
     The sleeve  132  can also provide greater stability to the system  100 . For instance, when the sleeve  132  is positioned near the proximal ends  112  of the struts  108 , it can interconnect and stabilize the proximal ends  112  against undesired bending or expansion while allowing a length of the struts  108  below the sleeve  132  to bend or flex. This advantageously helps accommodate volume fluctuations of the distal end of the residual limb in the receiving volume  114 . It will be appreciated that the sleeve  132  can form a large contact surface between the sleeve  132  and the struts  108 , which, in turn, improves the connection between the system  100  and the residual limb. 
     According to a variation, the sleeve  132  can include a handle system including opposing handles  131  that a user can grasp to pull the sleeve  132  onto the struts  108 . This can be done against resistance of the struts  108  or other components and the inner surface  139  of the sleeve  132 . The handles  131  can be permanently attached to the sleeve  132  and storable thereon. 
     The handles  131  can be an add-on module and/or removable from the sleeve  132 , allowing the handles  131  to be attached for donning and removed after donning the sleeve  132 . In use, a user can grasp the handles  131  to pull the sleeve  132  onto the system  100  positioned on a residual limb. When the sleeve  132  is in a desired position, the user can remove the handles  131  from the sleeve  132 . This advantageously facilitates placement of the tightening system  130  on the adjustable socket system  100 . 
       FIG. 7  illustrates another embodiment of a tightening system  140  for tightening and loosening the adjustable socket system  100 . The tightening system  140  includes a tubular member  144  selectively positionable on an outer surface of the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  144  can define a continuous circumference. The tubular member  144  can comprise a ring member  144  defining a central opening  146 . The ring member  144  can be formed of a rigid or substantially rigid material. The ring member  144  can be generally circular, generally elliptical, or any other suitable shape. 
     The struts  108  can extend through the central opening  146  of the ring member  144 . The diameter of the central opening  146  is sized such that as the ring member  144  is forced in a proximal direction along the outer surface of the struts  108 , the ring member  144  generally forces the struts  108  radially inward, reducing the receiving volume  114  and tightening the fit of the system  100  onto a residual limb. The amount of compression exerted on the residual limb can be increased as the ring member  144  is moved in the proximal direction along the struts. While one ring member is shown, in other embodiments, the tightening system  140  can include a plurality of ring members. For instance, the tightening system  140  may include a distal ring member arranged to be used and adjusted on an initial fitting of the system  100  and a proximal ring member arranged to be used and adjusted regularly by a user. 
     According to a variation, the ring member  144  may be spring loaded. For instance, a pair of spring members  148  may extend on opposite sides of the ring member  144  between the ring member  144  and a part of the distal portion  102 . Each spring member  148  may exhibit a force constant or K-value. The spring members  148  can have the same or different K-values. If the K-value of each spring member  148  is generally the same, then the ring member  144  can generally center the struts  108  about the residual limb in the receiving space  114 , which, in turn, causes the struts  108  to apply substantially the same pressure to a residual limb positioned in the receiving space  114 . If the K-value of the spring members  148  is different, the ring member  144  applies uneven forces to the struts  108 , which, in turn, causes the struts  108  to apply uneven pressure to the residual limb. For instance, the ring member  144  can generate more compression anteriorly on the residual limb as to posteriorly on the residual limb. This can also allow the ring member  144  to be tilted or oriented in a non-parallel position relative to the ground. It will be appreciated that in other embodiments, the tightening system  140  may include one, three, four, or any other suitable number of spring members. 
     According to a variation, the tightening system  140  may include a locking mechanism for selectively securing the ring member  144  in place on the struts  108  as seen in  FIG. 8 . For instance, one or more of the struts  108  can define one or more notches  141  for receiving one or more locking members  143  protruding radially inward from the inner diameter of the ring member  144 . The notches  141  may exhibit any suitable shape. In an embodiment, the locking members  143  can comprise spring-loaded pegs that are selectively receivable in the notches  141  for holding the ring member  144  in place on the struts  108 . 
       FIGS. 9 and 10  show a tightening system  150  for tightening and loosening the adjustable socket system  100  according to another embodiment. The tightening system  150  comprises a tubular member  152  selectively positionable on an outer surface of the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  152  can define a continuous circumference. The tubular member  152  can comprise a sleeve  152  having a body portion  154  extending between a closed distal end  156  and an open proximal end  158 . The sleeve  152  can be formed of an elastomeric material, a fabric material, combinations thereof, or any other suitable material. The sleeve  152  can be formed of a breathable material. The body portion  154  can be generally cylindrical or conical. The body portion  154  can define a substantially continuous inner surface. The body portion  154  can define an inner volume for receiving the system  100 . 
     At least a portion of the body portion  154  is configured to roll onto itself and unroll to adjust compression applied to the struts  108  by the sleeve  152 , which, in turn adjusts loading of the residual limb in the area of the sleeve  152  by the struts  108 . The body portion  154  may include a constant thickness. The body portion  154  may include a tapered thickness from the distal end  156  toward the proximal end  158 . The thickness of the body portion  154  can provide additional cushioning at the distal end of the system  100 , and easier roll-on/off at the proximal end when the sleeve  152  is donned and doffed. The body portion  154  may exhibit different stiffness in different areas or zones. The body portion  154  may be elastically resilient. The body portion  154  can be radially stretchable. 
     In use, with the residual limb in the receiving space  114 , the sleeve  152  is rolled up from the proximal end  158  toward the distal end  156 , and placed over the distal portion  102  of the system  100  with the distal end  156  of the sleeve  152  positioned on the struts  108  as shown in  FIG. 9 . This allows the sleeve  152  to impart a first compressive force on the struts  108  toward the distal portion  102  of the system  100 , tightening the fit of the system  100  on a distal part of the user&#39;s residual limb. 
     The sleeve  152  is then rolled back up or out over the struts  108  as shown in  FIG. 10 . With the sleeve  152  rolled out over the proximal ends  112  of the struts  108 , the sleeve  152  imparts a second compressive force on the struts  108  in the proximal portion  104 . This forces the proximal ends  112  of the struts  108  radially inward, which, in turn, tightens the fit of the system  100  onto a proximal part of the user&#39;s residual limb. The sleeve  152  rolled out over the proximal ends  112  of the struts  108  also helps stabilize the struts  108 . The tightening system  150  can thus adjust the fit of the system  100  on different areas of the residual limb. In an embodiment, the sleeve  152  can be configured to exert a greater compressive force on the proximal portion  104  of the system  100  than the distal portion  102  or vice versa, proportionally tightening or loosening the system  100 . 
     In addition, because the sleeve  152  is separate from the struts  108 , the struts  108  can be moved or forced radially outward from the axis  106  before the sleeve  152  is positioned on the system  100 , facilitating donning. The closed distal end  156  of the sleeve  152  creates a connection between the sleeve  152  and the distal portion  102  of the system  100  after the system  100  is donned on a residual limb and the sleeve  152  is secured on the system  100 . This advantageously can assist a user with placement of the tightening system  150 , improving ease of use. In an embodiment, properties of the body portion  154  can resiliently compress the sleeve  152  against the struts  108  in a radially inward direction. 
     According to a variation, the tightening system  150  includes a plurality of sleeves, each arranged to apply a different compression to the struts  108 . For instance, a first sleeve can be configured to apply a lower compression for a first fit of the system  100  and a second sleeve can be configured to apply a higher compression for a second fit of the system  100 , allowing the fit of the system  100  to be adjusted or customized based on user characteristics, activity levels, and/or other factors. 
     In an embodiment, the body portion  154  can have a length dimensioned so that when the sleeve  152  is rolled out over the struts  108 , the body portion  154  extends axially beyond the proximal ends  112  of the struts  108 . Optionally, the body portion  154  can have a length dimensioned so that when the sleeve  152  is rolled out over the struts  108  it extends axially beyond the proximal ends  112  of the struts  108  to form a brim part. The brim part can allow for proximal loading and more proximal stability of the system  100  on the residual limb. The brim part can also enable more even distribution of loading and consistent stability around the proximal end of the system  100 . 
     In another embodiment of the tightening system of the disclosure of  FIGS. 11 and 12 , a tightening system  160  comprises a tubular member  162  positionable on the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  162  can define a continuous circumference. The tubular member  162  may comprise a sleeve  162  having a body portion  164  with open upper and lower ends  166 ,  168 , and an inner surface  169  for securing over an outer surface of the system  100  and/or the residual limb. For instance, the inner surface  169  can engage and frictionally secure against the outer surface of the struts  108  and residual limb. The body portion  164  can be formed of any of the materials previously described. 
     As shown, the body portion  164  can have an elongate configuration extending between the upper and lower ends  166 ,  168 . The body portion  164  can form a circle or ellipse. At least a portion of the body portion  164  is arranged to be rolled onto itself. The body portion  164  can have a constant or variable thickness. The body portion  164  may be elastically resilient. 
     In use, the sleeve  162  is at least in part rolled up from the distal end  166  to the proximal end  168  on the residual limb proximal of the system  100  as shown in  FIG. 11 . The residual limb is then placed in the receiving space  114 . The sleeve  162  is then rolled back down or out over the struts  108  as shown in  FIG. 12 . With the sleeve  162  rolled out over the outer surface of the struts  108 , the sleeve  162  imparts a compressive force on the struts  108 , which, in turn, forces the struts  108  radially inward. This increases loading of the residual limb in the area of the sleeve  162  by the struts  108  and tightens the fit of the system  100  on the residual limb. In an embodiment, the distance the sleeve  162  is rolled out over the struts  108  can be varied to adjust the compressive force imparted to the struts  108 , which, in turn, adjusts the location and/or magnitude of loading on the residual limb by the system  100 . The sleeve  162  also stabilizes the struts  108  on the residual limb. 
     Because the sleeve  162  is open ended, the position of the sleeve  162  relative to the struts  108  is freely adjustable. As such, the position of the sleeve  162  along the axis  106  can be varied to increase or decrease the contact surface area between the sleeve  162  and the system  100  and the sleeve  162  and the residual limb. It will be appreciated that the steps described above can be performed in different orders. For instance, the sleeve  162  can be positioned on the distal portion  102  of the system  100  before the residual limb is inserted in the receiving space  114 . 
     In an embodiment, the sleeve  162  can be arranged to extend more than about 0.3 times, about 0.4, about 0.5 times, or about 0.6 times the length of the struts. As seen in  FIG. 12 , the sleeve  162  can be positioned on the residual limb to form a brim part extending in axial direction beyond the proximal ends  112  of the struts  108 . The brim part can form a greater contact surface area between the sleeve  162  and the residual limb. The brim part can allow for proximal loading and more proximal stability of the system  100  on the residual limb. In an embodiment, the sleeve  162  can define an adjustable circumference. This allows a clinician or user to adjust the sleeve  162 , decreasing the number of sizes and/or optimizing stability and comfort. 
       FIGS. 13 and 14  show another embodiment of a tightening system  170  including a tubular member  172  selectively positionable on the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  172  can define a continuous circumference. 
     The tubular member  172  can be a sleeve  172  having a body portion  174  extending between a closed distal end  176  and an open proximal end  178 . The sleeve  172  can be formed of any of the materials previously described. The body portion  174  can be generally cylindrical or conical. The body portion  174  can define an inner volume for receiving the system  100 . 
     The sleeve  172  can include a brim part  179  attached to the body portion  174  and defining the proximal end  178  of the sleeve  172 . The brim part  179  is arranged to move relative to the body portion  174  to adjust compression imparted to the struts  108  by the sleeve  172 . For instance, the proximal end  178  of brim part  179  is arranged to be folded back onto the sleeve  172  from an original position and to be resiliently flipped or rolled back to the original position. The brim part  179  can be made from a same or different material than the body portion  174 . The brim part  179  can be a soft member arranged to conform to the shape of the residual limb. The brim part  179  can have a symmetrical shape such as a cylindrical shape. The brim part  179  can have an asymmetrical shape. For instance, the brim part  179  can be arranged to extend a length along the posterior of the sleeve  172 , increasing seated comfort for a user of the system  100 . 
     In use, with the residual limb positioned in the receiving space  114 , the sleeve  172  can be positioned on the distal portion  102  of the system  100  with the proximal end  178  of the brim part  179  folded back onto itself, imparting a first compression to the struts  108  in the distal portion  102 . With the sleeve  172  positioned on the distal portion  102 , the sleeve  172  forces the struts  108  in the distal portion  102  radially inward, increasing the load and tightening the fit of the system  100  in at least the distal portion  102  onto the residual limb. 
     The proximal end  178  of the brim part  179  can then be flipped or folded up over the proximal ends  112  of the struts  108  as shown in  FIG. 14 , imparting a second compression to the proximal ends  112  of the struts  108 . With the sleeve  172  positioned on the struts  108  and the brim part  179  flipped up, the sleeve  172  forces the struts  108  in the proximal portion  104  radially inward, increasing the load and tightening the fit of the system  100  in the proximal portion  104  onto the residual limb. The tightening system  170  can thus adjust the fit of the system  100  on different areas of the residual limb. The tightening system  170  also interconnects and stabilizes the struts  108 . 
     It will be appreciated that the steps described above can be performed in one or more different sequences. For instance, the sleeve  172  can be positioned on the distal portion  102  of the system  100  before the residual limb is inserted in the receiving space  114 . 
       FIG. 15  shows another embodiment of a tightening system  180  including a tubular member  182  positioned on the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  182  can define a continuous circumference. The tubular member  182  can include a sleeve  182  forming a brim part  184 . The brim part  184  can be connected to the proximal end  112  of two or more of the struts  108 . The brim part  184  can have open upper and lower ends  186 ,  188 , an outer surface arranged to engage the struts, and an inner surface  181  arranged to provide an interface between the proximal portion  104  of the system  100  and the residual limb. The brim part  184  can be formed as a molded member, such as by injection molding. The brim part  184  can be formed of an elastomeric material or another suitable material. 
     The sleeve  182  is configured to apply tension and compression to the struts  108  to adjust the fit of the system  100 . For instance, the brim part  184  can be manually expanded radially outward, forcing the proximal ends  112  of the struts  108  radially outward and loosening the fit of the system  100 , and the properties or elasticity of the brim part  184  can force the struts  108  radially inward, tightening the fit of the system  100  onto the residual limb. 
     In an embodiment, a user can grip and stretch the brim part  184  radially outward to move the system  100  to the expanded configuration. With the system  100  in the expanded configuration, a user can position the residual limb in the receiving space  114 , facilitating donning. To move the struts  108  to the closed configuration, the user can release the brim part  184  so that the properties or elasticity of the brim part  164  pull the struts  108  radially inward, increasing the load and tightening the fit of the system  100  onto the residual limb. 
     Because the brim part  184  is positioned between the struts  108  and the residual limb, the brim part  184  can distribute pressure from the struts  108  to the residual limb, providing a more even distribution of pressure from the system  100  on the residual limb. This helps improve the fit and feel of the system  100 . Similar to other embodiments, the brim part  184  can also stabilize the proximal ends  112  of the struts  108  against undesired bending while allowing a length of the struts  108  below the brim part  184  to bend or flex. 
     The brim part  184  can be weight bearing (e.g., arranged to transfer load from the pelvis) or non-weight bearing. In other embodiments, the inner surface  181  of the brim part  184  can engage the outer surface of the struts  108 . The number of struts  108  the brim part  184  is attached to can be varied, varying the fit and stability of the system  100 . The brim part  184  can be ischial bearing or sub-ischial bearing. As noted above, embodiments of the tightening system can be used alone or in combination with other embodiments of the tightening system. For instance, the tightening system  180  can be used in combination with any of the previously described tightening systems. 
       FIGS. 16-18  show another embodiment of a tightening system  190  including a tubular member  192  positioned on the struts  108  and arranged to adjust the fit of the system  100  on a residual limb. The tubular member  192  can define a continuous circumference. The tubular member  192  can be a sleeve  192  integrated with the struts  108 . The sleeve  192  has a body portion  194  extending between a distal end  196  and an open proximal end  198 . The distal end  196  may be open or closed. The sleeve  192  can be formed of any of the materials previously described. The body portion  194  can be generally cylindrical or conical. The body portion  194  can have an inner surface  199  that at least in part defines the receiving volume  114  of the system  100 . The body portion  194  can conform to the specific shape of the residual limb. The body portion  194  can rely on deformation to stretch and compress. At least a part of the body portion  194  can be formed of a polymeric material and/or an elastomeric material to allow for such deformation. 
     The struts  108  can be embedded within the body portion  194 . The struts  108  can extend along an outer surface of the struts  108 . In an embodiment, the body portion  194  can be separate from and attached to one or more of the struts  108  via adhesives, mechanical fasteners, or any other suitable attachment means. In other embodiments, the body portion  194  and the struts  108  can be integrally formed in one piece. For example, the body portion  194  can be overmolded to the struts  108 . 
     As noted above, the inner surface  199  at least in part defines the receiving volume  114  such that the sleeve  192  forms an interface between the residual limb and the system  100 . This advantageously reduces the likelihood of the user feeling the struts  108  as pressure points, increasing comfort. This also increases the contact surface area between the system  100  and the residual limb, creating a more secure fit between the residual limb and the system  100 . 
     In an embodiment, the sleeve  192  is arranged to form an air-tight coupling or connection between the residual limb and the system  100 , permitting vacuum and elevated suspension. The sleeve  192  can also help prevent tissue from bulging out of the system  100 . 
     The sleeve  192  can include an outer textile layer and inner silicone layer or a reinforcement material embedded within a polymeric material. In an embodiment, the sleeve  192  may include a soft or low density polyethylene. In other embodiments, the sleeve  192  can include rigid sections and flexible sections positioned in strategic locations, allowing the sleeve  192  to provide targeted support and/or pressure relief. The sleeve can include a single layer or multiple layers. For instance, the sleeve  192  can include an inner layer arranged to be next to the user&#39;s skin and an outer layer. 
     Similar to the previous embodiment, the sleeve  192  is configured to apply tension and compression to the struts  108  to adjust the fit of the system  100 . In use, a user can grip and stretch a proximal part of the body portion  194  radially outward to move the struts  108  to the expanded configuration as shown in  FIG. 17 , facilitating donning. To move the struts  108  to the closed configuration as shown in  FIG. 18 , the user can release the body portion  194  so that the properties or elasticity of the body portion  194  forces the struts  108  radially inward, increasing the load and tightening the fit of the system  100  on the residual limb  100 . Forces applied by the body portion  194  on the struts  108  can be symmetrical or asymmetrical. For instance, the body portion  194  can apply a greater force along one side of the system  100  as compared to another. 
     Similar to the previous embodiment, the sleeve  192  helps distribute pressure from the struts  108  to the residual limb, improving the fit and feel of the system. Because the struts  108  are embedded or located within a thickness of the body portion  194 , the sleeve  192  also stabilizes the struts  108  against undesired bending. Furthermore, the tightening system  190  can be used alone or in combination with previously described tightening systems. For instance, the tightening system  190  can be used in combination with the tightening system  160  to secure the system  100  on a residual limb. 
     Referring to  FIGS. 19 and 20 , the tightening system  190  can include at least one tensioning element arranged to help move the struts  108  between the expanded and closed configurations. For instance, a tensioning element  202  can be routed through or attached to the body portion  194 . In an embodiment, the tensioning element  202  can include a first end  204  anchored to the sleeve  192  and a second free end  206  extending in a proximal direction beyond the sleeve  192 . The tensioning element  202  can be arranged in a zig-zagging pattern.  FIG. 19  shows the system  100  with the struts  108  in the expanded configuration. To move the struts  108  toward the closed configuration, a user can tension or pull the tensioning element  202  to shorten the length of the tensioning element  202  within or attached to the body portion  194 , which, in turn, pulls the struts  108  closer together as seen in  FIG. 20 . The tensioning element  202  may be formed from any type of line, cord, strap, rope, string, wire, cable, or other suitable element. 
     According to a variation, the tightening system  190  can include a sleeve  192 A having a plurality of sections  214  extending between the proximal and distal ends of the sleeve  192 A as seen in  FIGS. 21 and 22 . The sections  214  can be circumferentially distributed about the sleeve  192 A. For instance, the sections  214  can include a first section  214 A opposite a second section  214 B, and a third section  214 V opposite a fourth section  214 D. The sections  214  can have a corrugated or accordion-like configuration. The sections  214  are arranged to facilitate movement of the struts  108  between the expanded and closed configurations. In an embodiment, areas  216  of the sleeve  192 A between the sections  214  can be rigid or semi-rigid. This allows the areas  216  to provide support to the residual limb and stabilization to the system  100  while the sections  214  provide stretchiness and flexibility to the sleeve  192 A. 
       FIGS. 23-43  show embodiments of the adjustable socket system including tightening systems arranged to mechanically control or adjust the fit of the system on a residual limb. It will be appreciated that these systems can include many of the same or similar features as the embodiments in  FIGS. 1-22 . In addition, it will be appreciated that the mechanical tightening system embodiments can be used alone or in combination with the tightening systems previously described. 
     As shown in the example in  FIGS. 23 and 24 , an adjustable socket system  300  includes a distal portion  302 , a proximal portion  304 , and an axis  306  extending between the distal portion  302  and the proximal portion  304 . The distal portion  302  can include a base  320  and a distal support  322 . The distal support  322  is adapted to receive and support a distal end of the residual limb inserted in the receiving volume  314 . 
     A plurality of struts  308  are connected to the distal portion  302  and generally extend between the distal portion  302  and the proximal portion  304 . The struts  308  at least in part define a receiving volume  314  adapted to receive a residual limb. It will be appreciated that the struts  308  can be adjustable in length. For instance, one or more of the struts  308  can have a telescoping mechanism that can adjust strut length or width. In other embodiments, the struts  308  can be available in different lengths and/or sizes that can be selectively attached to the distal portion  302  to adjust the length or size of the struts  308 . 
     At least some of the struts  308  are radially adjustable relative to the axis  306  to vary the receiving volume  314 . The struts  308  can be movable between an expanded configuration in which at least some of the struts are moved radially outward relative to the axis  306  to loosen the fit (or decrease the load) of the system  300  on a residual limb, and a closed configuration in which at least some of the struts  308  are moved radially inward relative to the expanded configuration to tighten the fit (or increase the load) of the system  300  on the residual limb. 
     In an embodiment, each of the struts  308  are arranged to rotate relative to the base  320  via a pivot point  324  to vary the receiving volume  314 . The pivot point  324  can comprise a hinge mechanism, a pinned connection, and/or any other suitable type of pivot connection. Each pivot point  324  can comprise a pin member pivotally connecting the strut  308  to the base  320 . The pivot points  324  can be located at or near the base  320 . 
     A tightening system  330  is arranged to move the struts  308  between the expanded and closed configurations. Optionally, the system  300  can include a biasing mechanism arranged to bias the struts  308  toward the expanded configuration. The tightening system  330  can comprise a threaded portion  332  defined on an outer surface of the base  320  and an actuating part  334  comprising a collar member  334  defining an internal threaded portion  335  attached to the threaded portion  332  of the base  320 . When the collar member  334  is rotated relative to the base  320 , the threaded connection between the collar member  334  and the base  320  moves the collar member  334  proximally or distally along the axis  306 . The collar member  334  can include a rigid or semi-rigid material. 
     To move the struts  308  toward the closed configuration, a user or clinician can rotate the collar member  334  in a first direction relative to the base  320 , which, in turn, moves the collar member  334  proximally or upward along the axis  306 . As the collar member  334  moves proximally, an inner surface  336  of the collar member  334  can move upwardly along the outer surface of the struts  308 , which, in turn, moves or rotates the struts  308  about the pivot points  324  toward the closed configuration, tightening the fit (or increasing the load) of the system  300  on a user&#39;s residual limb. 
     To move the struts  308  toward the expanded configuration, the user or clinician can rotate the collar member  334  in a second direction opposite the first direction, which, in turn, moves the collar member  334  distally or downward along the axis  306 . As the collar member  334  moves distally, the inner surface  336  of the collar member  334  can move downwardly along the outer surface of the struts  308 , which, in turn, allows the struts to move or rotate about the pivot points  324  back toward the expanded configuration, loosening the fit (or decreasing the load) of the system  300  on the user&#39;s residual limb. This advantageously allows a user or clinician to selectively rotate the collar member  334  relative to the base  320  to tighten and loosen the system  300 . It will be appreciated that the range adjustment of the system  300  can be defined or varied at least in part by the thread angle, pitch, and/or lead of the threaded portions on the collar member  334  and base  320 . 
       FIG. 25  illustrates another adjustable socket system  400  including a tightening system for controlling or adjusting the fit of the system  400 . It will be appreciated that the system  400  can be similar to and can include many of the same or similar features as any of the other embodiments described herein. The system  400  includes a distal portion  402 , a proximal portion  404 , and an axis  406  extending between the distal and proximal portions  402 ,  404 . The distal portion  402  can exhibit any suitable configuration. The distal portion  402  includes a base  420  forming a limb receiving portion or seat adapted to receive a distal end portion of a residual limb. A base connector  422  is secured to a bottom portion of the base  420 , and is adapted to connect to prosthetic components. 
     A plurality of struts  408  are connected to the distal portion  402  and generally extend between the distal portion  402  and the proximal portion  404 . At least some of the struts  408  are radially adjustable relative to the axis  406  to vary the receiving volume  414 . The struts  408  can be movable between an expanded configuration in which at least some of the struts are moved radially outward to loosen the fit of the system  400  on a residual limb, and a closed configuration in which at least some of the struts  408  are moved radially inward to tighten the fit of the system  400  on the residual limb. 
     The struts  408  can be generally linear or curved. The struts  408  can be contoured to correspond to the contour of the residual limb. The struts  408  can include one or more rod members  428 . Each strut  408  can include a pair of rod members  428 . Optionally, one or more of the rod members  428  can have a telescoping mechanism, allowing the length of the strut  408  to adapt to residual limbs of different lengths. The struts  408  can include multiple parts. 
     The struts  408  can include one or more support members  430  at or near a proximal portion of the struts  408 . In an embodiment, the support members  430  can extend along a length of the rod members  428 . The support members  430  can have any suitable shape but are shown shaped to generally correspond to a portion of a residual limb of a user. The support members  430  can be overmolded on the rod members  428 . The support members  430  can be formed of a plastic material, a rubber material, or any other suitable material. Optionally, an inner surface of the support members  430  can have a resilient configuration such that the inner surface generally conforms to the residual limb. 
     The support members  430  define an interface between the residual limb and the system  400 . The support members  430  can have a width arranged to form a larger contact surface between the residual limb and the system  400 , providing a more secure fit. This also helps distribute pressure or loads from the struts  408  to the residual limb. This has the effect of reducing the likelihood of the user feeling the struts  408  as pressure points, improving comfort. The width of the support members  430  can vary. The width of the support members  430  can generally taper in a distal direction to help provide a better fit. 
     A tightening system  432  is arranged to move the one or more portions of the struts  408  between the closed and expanded configurations and/or to stabilize the struts  408 . The tightening system  432  includes a plurality of tensioning elements  436  rotatably linked to a plurality of tensioning control mechanisms  434  and operatively connected to the struts  408 . The tensioning elements  436  may be formed from any type of line, cord, strap, rope, string, wire, cable, or other suitable element. At least one of tensioning control mechanisms  434  can have rotational increments, allowing the tension in the at least one tensioning element  436  to be incrementally increased or decreased. It is advantageously simple for the user to quickly adjust the tension in the system  400 . Other exemplary tensioning control systems can be found in U.S. patent application Ser. No. 13/930,053 and U.S. Pat. No. 8,795,385, each of which is incorporated by reference in its entirety. 
     When at least one of the tensioning control mechanisms  434  is rotated in a first direction, a corresponding tensioning element  436  is drawn into the tensioning control mechanism  434 , increasing tension in the tensioning element  436 . This causes the struts  408  in one or more areas of the system  400  to move toward the closed configuration, tightening the fit of the system  400 . When at least one of the tensioning control mechanisms  434  is rotated in a second direction opposite the first direction, a corresponding tensioning element  436  exits the tensioning control mechanism  434 , decreasing tension in the tensioning element  436 . This allows the struts in one or more areas of the system  400  to move toward the expanded configuration, loosening the fit of the system  400 . 
     In an embodiment, the tightening system  432  tensions the struts  408  to apply equal or substantially equal pressure to the residual limb, helping to limit pressure points from forming on different areas of the residual limb. Pressure points on the residual limb can be problematic in that the pressure points cause irritation, pain, and discomfort to the user. For instance, each tensioning control mechanism  434  can be operatively connected to all or substantially all of the tensioning elements  436  such that operation of one of the tensioning control mechanisms  434  tensions all of the tensioning elements  436  at a same or substantially same level. 
     The tensioning control mechanisms  434  can be located anywhere on the system  400  but are shown located on the base  420  of the distal portion  402 . In an embodiment, at least one of the tensioning elements  436  can be fed or passed through an interior space of the rod members  428 . From the rod members  428 , the tensioning element  436  can extend to the support members  430  where it passes through guides  438  formed on the support members  430  and between the support members  430 . The tightening system  432  can tension the struts  408  more toward the proximal portion  404  than the distal portion  402 , controlling the fit of the system  400 . 
     According to a variation, the tightening system  432  can proportionally control the fit of the system  400  on a residual limb. For instance, the tensioning control mechanisms  434  include a first tensioning element  436 A rotatably linked to a first tensioning control mechanism  434 A operatively connected to a first area of the system  400  and a second tensioning element  436 B rotatably linked to a second control mechanism  434 B operatively connected to a second area of the system  400 . As such, the position and/or force applied to the struts  408  in the first area of the system  400  can be controlled by tensioning the first tensioning element  436 A. The position and/or force applied to the struts  408  in the second area of the system  400  can be controlled by tensioning the second tensioning element  436 B. 
     This advantageously allows the fit of the system  400  in the first area to be adjusted and/or controlled independently of the second area of the system  400 . The first area can be an anterior side and the second area can be a posterior side or vice versa. The first area can be a medial side and the second area can be a lateral side or vice versa. 
       FIG. 26  illustrates another adjustable socket system  500  including a tightening system for controlling or adjusting the fit of the system  500 . The system  500  can be similar to and can include many of the same or similar features as any of the other embodiments described herein. The system  500  includes a distal portion  502 , a proximal portion  504 , and a plurality of struts  508  connected to the distal portion  502  and generally extending between the distal portion  502  and the proximal portion  504 . The distal portion  502  includes a base  520  forming a limb receiving portion. A base connector  522  is secured to a bottom portion of the base  420 , and is adapted to connect to prosthetic components. 
     One or more portions of the struts  508  can move radially inward and/or outward to vary a receiving volume  514  adapted to receive a residual limb. For instance, the struts  508  can be movable between an expanded configuration in which at least some of the struts  508  are moved radially outward to loosen the fit of the system  500  on a residual limb inserted in the receiving volume  514 , and a closed configuration in which at least some of the struts  508  are moved radially inward to tighten the fit of the system  500  on the residual limb. 
     A tightening system  530  is operatively coupled to the struts  508  and arranged to move the struts  508  between the expanded configuration and the closed configuration. The tightening system  530  can include at least one tensioning control mechanism  532  and at least one tensioning element  534 . The at least one tensioning element  534  is rotatably linked to the at least one tensioning control mechanism  532  and connecting two or more of the struts  508 . When the at least one tensioning element  534  rotates in a first direction, tension in the at least one tensioning element  534  increases, which, in turn, moves the struts  508  toward the closed configuration and tightens the system  500 . When the at least one tensioning element  534  rotates in a second direction opposite the first direction, tension in the at least one tension element  534  decreases, allowing the struts  508  to move toward the expanded configuration and loosening the fit of the system  500 . 
     The tightening system  530  can be operatively coupled to a distal support  516  adapted to receive and support a distal end of the residual limb inserted in the receiving volume  514 . The distal support  516  can be positioned proximal of the base  520  such that it can be tensioned by the tightening system  530 . In an embodiment, tension applied to the distal support  516  by the tightening system  530  can create axial pressure on the residual limb, helping to support a user&#39;s weight. The applied tension can also create radial pressure on the distal end of the residual limb, helping to stabilize the residual limb. Thus, through adjustment of the tightening system  530  the fit of the system  500  and the level of load or pressure applied by the distal support  516  can be controlled and/or adjusted. 
     This is advantageous because if the axial pressure applied to the residual limb by the distal support  516  is insufficient, the residual limb can painfully bottom out. Further, radial pressure applied to the residual limb by the struts  508  must be sufficient to secure the residual limb within the system  500  and limit pistoning but if it is too high the struts  508  may strangle the residual limb, causing discomfort and/or cutting off circulation to the residual limb. By adjusting and/or controlling the load or pressure applied to the distal end of the residual limb, the tightening system  530  can provide both a secure and comfortable fit. 
     Optionally, the distal support  516  can be tensioned differently or independently of the tensioning of the struts  508 . For instance, the tightening system  530  can include a tensioning control mechanism as described below including a first control part operatively connected to the distal support  516  and a second control part operatively connected to the struts  508 . This is beneficial as in some situations it is desirable for the distal end of the residual limb to bear no or little weight, and in other situations partial or full end bearing of the residual limb is desired. 
     The distal support  516  can be substantially non-elastic so that when tension is applied to it, the distal support  516  can transfer a lead to the residual limb. The distal support  516  can provide a cushion and distribution of pressure at the distal end of the residual limb. The distal support  516  can be any suitable member but is shown as a knitted, woven, or netted structure. The distal support  516  can include one or more segments  524  forming the netted structure and connected to one or more coupling parts  526  linking the netted structure to the tensioning elements  534 . The tightening system  530  can thus proportionally adjust the fit of the system  500  in different areas of the system  500 . 
       FIG. 27  is a schematic illustration of an adjustable socket system  600  including a tightening system  630 . The system  600  includes a distal portion  602 , a proximal portion  604 , and a plurality struts  608  connected to the distal portion  602  and generally extending between the distal portion  602  and the proximal portion  604 . 
     Similar to the other embodiments, the struts  608  can move radially inward and/or outward to vary a receiving volume  614  adapted to receive a residual limb. For instance, the struts  608  can be movable between an expanded configuration in which one or more portions of the struts  608  move radially outward to loosen the fit of the system  600  on a residual limb inserted in the receiving volume  614 , and a closed configuration in which one or more portions of the struts  608  move radially inward to tighten the fit of the system  600  on the residual limb. 
     Similar to the other embodiments, the tightening system  630  is operatively coupled to the struts  608  and can vary tension applied to the struts  608  to adjust or control the fit of the system  600  and loading of the residual limb. The tightening system  630  includes a tensioning control mechanism  632  that is operable to proportionally or differentially adjust the loading or fit of the system  600  in two or more different areas. The tensioning control mechanism  632  includes a first control part  634  operatively connected to a first area  614 A of the receiving volume  614 , and a second control part  635  operatively connected to a second area  614 B of the receiving volume  614 . The first control part  634  and the second control part  635  can be operatively connected. The first control part  634  can be operably independent from the second control part  635  such that the first area  614 A can be controlled or adjusted independent of the second area  614 B. 
     In an embodiment, the tensioning control mechanism  632  can control or fine-tune the fit or loading of the system  600  in the first area  614 A and in the second area  614 B. For instance, the first and second control parts  634 ,  635  of the tensioning control mechanism  632  can be operated to load the residual limb more in the first area  614 A than the second area  614 B. The first control part  634  can be operated to increase the tension applied to the struts  608  in the first area  614 A (tightening the system  600  in the first area  614 A) and/or the second control part  635  can be operated to decrease the tension applied to the struts  608  in the second area  614 B (loosening the system  600  in the second area  614 B). This advantageously gives a user or clinician greater control over the fit of the system  600  on a residual limb by allowing them to control the proportion of loading by the tightening system  630  in the different areas. 
     According to a variation, the tightening system  630  can include a feedback feature for communicating fitting or other information to a user or clinician. For example, the dial indicator  638  can display numbers corresponding with displacement and/or tension applied to the struts  608 . The dial indicator  638  can display overall displacement and/or tension applied to the struts  608 . The dial indicator  638  can display displacement and/or tension of the struts  608  in the first area  614 A or the second area  614 B. For instance, the dial indicator  638  can include a switch mechanism to change output readings of the dial indicator between the first area  614 A and the second area  614 B. In other embodiments, the dial indicator  638  can display tension levels in tensioning elements associated with the tightening system  630 . This provides a user or clinician a simple and convenient indicator of how secure a fit between the system  600  and a residual limb may be at any given time. 
       FIG. 28  is another schematic of an adjustable socket system  700  including a tightening system  730  arranged to control or adjust the fit of the system  700  in three different areas. The system  700  is similar to the system  600  except that the tightening system  730  includes a tensioning control mechanism  732  having a first control part  734 , a second control part  736 , and a third control part  738 . The first control part  734  is operatively connected to a first area  714 A of a receiving volume  714  defined by struts  708  and arranged to receive residual limb. The second control part  736  is operatively connected to a second area  714 B of the receiving volume  714 . The third control part  738  is operatively connected to a third area  714 C of the receiving volume  714 . The control parts  734 ,  736 ,  738  can be operatively connected. 
     The control parts  734 ,  736 ,  738  can be independently operable, permitting the tightening system  730  to control or adjust the proportion of load applied to the residual limb in the different areas  714 A,  714 B,  714 C of the receiving volume  714 . For instance, the tensioning control mechanism  732  can be operated to tighten the fit of the system  700  in the first area  714 A, loosen the fit of the system  700  in the second area  714 B, and tighten the fit of the system  700  in the third area  714 C. In other embodiments, the tensioning control mechanism  732  can be operated to loosen the fit of the system  700  n the first area  714 A, tighten the fit of the system  700  in the second area  714 B, and tighten the fit of the system  700  in the third area  714 C. It will be appreciated that the control parts  734  can be operated in different combinations. In other embodiments, the tensioning control mechanism  732  can differentially control the fit of the system  700  in the different areas. The tightening system  730  thus gives a user or clinician greater control over the fit and/or tightness of the system  700  on a residual limb. 
     According to a variation, a feedback feature for communicating information to a user or clinician comprises a set of light emitting diodes  740 . If pressure and/or displacement of the system  700  in one or more of the areas  714 A,  714 B,  714 C is good, the feedback feature can illuminate a green LED  740 A, communicating that the fit is good. If pressure and/or displacement in one or more of the areas  714 A,  714 B,  714 C is okay, the feedback feature can illuminate a yellow LED  740 B, communicating that the fit is okay. If pressure or displacement in one or more of the areas  714 A,  714 B,  714 C is bad, the feedback feature can illuminate a red LED  740 C, communicating that the fit is bad. In other embodiments, the feedback feature can communicate information related to the entire receiving volume  714 . In other embodiments, the feedback feature can communicate information related to a single or selected ones of the areas  714 A,  714 B, and  714 C. In other embodiments, each LED  740  can be associated with one of the areas  714 A,  714 B,  714 C and arranged to illuminate when the fit in the respective area is good. In other embodiments, the feedback feature can comprise the tensioning control mechanism clicking or tapping when tension or displacement in struts exceeds a target value, providing audio and/or tactile feedback to a user. 
       FIGS. 29-31  show different embodiments of the tensioning control mechanism for varying and controlling the load imparted to a residual limb in different areas of the adjustable socket system. It will be appreciated that the tensioning control mechanism embodiments described herein can be used alone or in combination with one or more features included in other embodiments of the present disclosure. 
     As shown in the example in  FIG. 29 , a tensioning control mechanism  750  includes a first tensioning element  752 , a second tensioning element  754 , a base  756 , a first spool  758 , and a second spool  760 . The first and second spools  758 ,  760  can be situated within the base  756  such that the spools  758 ,  760  are rotatable about an axis  764  relative to the base  756 . The first tensioning element  752  can be rotatably linked to the first spool  758  and operatively connected to a first area (e.g., first area  614 A) of an adjustable socket system. The second tensioning element  754  can be rotatably linked to the second spool  760  and operatively connected to a second area (e.g., second area  614 B) of the adjustable socket system. 
     When the first spool  758  rotates in a first direction, the first tensioning element  752  is drawn into the base  756  and wound around the spool  758 . As the first tensioning element  752  is wound around the first spool  758 , tension in the first tensioning element  752  increases, tightening the fit of the adjustable socket system in the first area. When the first spool  758  rotates in a second direction opposite the first direction, the first tensioning element  752  unwinds from the first spool  758  and at least a portion of the first tensioning element  752  exits the base  756 . As the first tensioning element  752  unwinds from the first spool  758 , tension in the first tensioning element  752  decreases, loosening the fit of the adjustable socket system in the first area. 
     When the second spool  760  rotates in a first direction, the second tensioning element  754  is drawn into the base  756  and wound around the second spool  760 . As the second tensioning element  754  is wound around the second spool  760 , tension in the second tensioning element  754  increases, tightening the fit of the adjustable socket system in the second area. When the second spool  760  rotates in a second direction opposite the first direction, the second tensioning element  754  unwinds from the second spool  760  and at least a portion of the second tensioning element  754  exits the base  756 . As the second tensioning element  754  unwinds from the second spool  760 , tension in the second tensioning element  754  decreases, loosening the fit of the adjustable socket system in the first area. 
     Optionally, the first and second spools  758 ,  760  can be rotated via a controller  762 . The controller  762  can be attached to the base  756  such that the controller  762  can rotate about the axis  764  relative to the base  756 . In an embodiment, the controller  762  can be arranged to rotate the first and second spools  756 ,  758  together. For instance, an input force (e.g., torque) applied to the controller  762  can be transferred to the first spool  758 , which, in turn, can be transferred to the second spool  760 . As such, a single input force applied to the controller  762  can adjust the fit in the first and second areas of the adjustable socket system. 
     In other embodiments, the controller  762  is arranged to rotate the first and second spools  756 ,  758  independently. For instance, the controller  762  can be rotated by a user in a first setting to adjust the tension in the first tensioning element  752  or can be rotated by the user in a second setting to adjust the tension in the second tensioning element  754 . This advantageously can allow a user to vary loading of a residual limb in different areas of the system using a single tensioning control mechanism. The controller  762  is shown as a dial but can be a pull cord, a lever, a handle, or any other suitable mechanism. 
       FIG. 30  shows another embodiment of a tensioning control mechanism  770  configured to differentially or proportionally vary loading of a residual limb in different areas of an adjustable socket system. The tensioning control mechanism  770  can be similar to the tensioning control mechanism  750  including a first tensioning element  772 , a second tensioning element  774 , a base  776 , a first control part or first spool  778 , and a second control part or second spool  780 . The first and second spools  778 ,  780  can be situated within the base  776  such that the spools  778 ,  780  are rotatable about an axis  784  relative to the base  776 . The first tensioning element  772  can be rotatably linked to the first spool  778  and operatively connected to a first area (e.g.,  614 B). The second tensioning element  774  can be rotatably linked to the second spool  780  and operatively connected to a second area (e.g.,  614 A). 
     The tensioning control mechanism  770  includes a gear assembly  786  is arranged to vary the speed, torque, and/or rotational direction of the second spool  780  relative to the first spool  778 . The gear assembly  786  comprises a gear member  788  positioned between the first and second spools  778 ,  780 . The gear member  788  includes a first set of teeth  790  arranged to mesh with a corresponding set of teeth  792  on the first spool  778  and a second set of teeth  794  arranged to mesh with a second set of teeth  796  on the second spool  780 . The gear member  788  is shown as a bevel gear member but can be any suitable gear member. 
     To adjust the tension in the first and second tensioning elements  772 ,  774 , a controller  782  is rotated at a first speed relative to the base  776 . This rotation of the controller  782  rotates the first spool  778  at the first speed with the controller  782 , which, in turn, generates a first tension in the first tensioning element  772 . Rotation of the first spool  778  drives rotation of the gear member  788  at a second speed, which, in turn, drives rotation of the second spool  780  at a third speed, generating a second tension in the second tensioning element  774 . When the first rotation speed of the first spool  778  is different than the third rotation speed of the second spool  780 , the output torque from the first spool  778  is different than the output torque from the second spool  780 , making the first and second tensions different. This allows the tensioning control mechanism  770  to differentially tension struts in the first and second areas of the adjustable socket system, which, in turn, loads a residual limb in the first and second areas differently. As such, the tightening system can better control or customize the fit of the adjustable socket system. 
     The difference between the first and second tensions can be at least in part defined by the size of the gear member  788  and/or spools  778 ,  780 , and/or interaction between the gear member  788  and the spools  778 ,  780 . The length, angle, depth, thickness, curvature, pressure, angle, and/or pitch of the teeth  794  can at least in part define a change in speed, torque, and/or direction in the second spool  780 , resulting in a different tension in the second tensioning element. This advantageously can allow a user to differentially or proportionally control the fit of the adjustable socket system in different areas via a single action or twist of the controller  782 . For instance, the gear assembly  786  can be arranged so that one complete turn of the controller  782  tightens a first area (e.g., proximal area) about two times, about three times, or about four times more than a second area (e.g., distal area). 
     According to a variation, the gear assembly  786  can be arranged to convert a smaller input force applied to the controller  782  into a larger output force transferred to the second tensioning element  774  by the second spool  780 . This allows a user to load or tighten the adjustable socket system with less strength or dexterity, making the adjustable socket system easier to use and adjust. The controller  782  can be a dial, a pull cord, a lever, a cable, or any other suitable mechanism. 
       FIG. 31  shows a tensioning control mechanism  830  according to another embodiment. The tensioning control mechanism  830  can be similar to the tensioning control mechanism  770  except that it includes another gear assembly  832  interposed between the controller  782  and the first spool  778 . This advantageously allows a user or clinician to differentially tension or tighten different parts of a socket. The gear assembly  832  can be similar to the gear assembly  786  and arranged to vary the speed and/or torque of the first spool  778  relative to the controller  782 . For example, when the controller  782  is smaller than the gear assembly  832 , the output torque transferred from the second gear assembly  832  to the first spool  778  is greater than the input torque applied to the controller  782  by a user or clinician, providing a mechanical advantage. 
     According to variation, the gear assembly  786  and/or gear assembly  832  can include at least one end stop  834  arranged to limit relative rotation between the first and second spools  778 ,  780  and the controller  782 , which, in turn, can limit tension applied to the different areas of the adjustable socket system. The at least one end stop  834  can be adjustable. 
     In an embodiment, the gear assemblies  786 ,  832  can be adjustable or customizable to vary the load or fit in one or more different areas of the adjustable socket system. For instance, a clinician may interchange, reposition, or change the sizes of the gear assemblies  786 ,  832  to adjust the speed ratio or gear ratio between the first and second spools  778 ,  780 , which, in turn, varies the tensions applied to the first and second areas by the first and second tensioning elements  772 ,  774 . It will be appreciated that while the tensioning control mechanism is shown including two spools, in other embodiments, the embodiments of the tensioning control mechanism can include one, three, four, or any other suitable number of spools. 
       FIG. 32  shows a tensioning control mechanism  835  according to another embodiment. The tensioning control mechanism  835  includes a first tensioning element  836 , a second tensioning element  838 , a base  840 , a first control part comprising a first spool  842 , a second control part comprising a second spool  844 , and a controller  846 . The first tensioning element  836  can be rotatably linked to the first spool  842  and operatively connected to a first area (e.g., a proximal area) of the receiving space. The second tensioning element  838  can be rotatably linked to the second spool  844  and operatively connected to a second area (e.g., a distal area) of the receiving space. 
     The controller  836  is arranged so that it can switch between rotating the first spool  842  and the second spool  844 . The controller  836  is shown as a collar member but can be any suitable member. The controller  836  defines a first plurality of teeth  846  that can selectively mesh with a second plurality of teeth  848  defined on the outer surface of the first spool  842  and with a third plurality of teeth  849  defined on the outer surface of the second spool  844 . The controller  836  is arranged to translate on the base  840  between the first spool  842  and the second spool  844 . To drive rotation of the first spool  842 , the controller  836  can be translated in a first direction into engagement with the first spool  842  and rotated relative to the base  840 . To drive rotation of the second spool  844 , the controller  836  can be translated in a second direction opposite the first direction into engagement with the second spool  844  and rotated. 
       FIGS. 33 and 34  show an adjustable socket system  850  including a tightening system  852  according to another embodiment. The system  850  includes a distal portion  802 , a proximal portion  804 , and a plurality of struts  808  connected to the distal portion  802  and generally extending between the distal portion  802  and the proximal portion  804 . At least some of the struts  808  are radially adjustable to vary a receiving volume  814  adapted to receive a user&#39;s residual limb. The struts  808  can be movable between an expanded configuration in which at least some of the struts  808  are moved radially outward to loosen the fit of the system  800  on a residual limb inserted in the receiving volume  814 , and a closed configuration in which at least some of the struts  808  are moved radially inward to tighten the fit of the system  800  on the residual limb. 
     The tightening system is arranged to move the struts  808  of the system  850  between the expanded and closed configurations. The tightening system  852  includes a tensioning control mechanism  856  disposed in a base  866  of the distal portion  802  and a controller  854  arranged to control the tensioning control mechanism  856 . The controller  854  can be any suitable mechanism but is shown as a crank handle  854  attached to the base  866 . 
     The crank handle  854  can be rotatably attached to the base  866  via a pivot point  862 . The pivot point  862  can comprise a hinged connection or pivot connection. The crank handle  854  can be removably attached to the base  866 . For instance, the crank handle  854  can be arranged to snap in and out of a receiving space defined in the base  866  and provide access to the tensioning control mechanism  856 . This can allow the crank handle  854  to be attached for fitting and removed after fitting. 
     The tensioning control mechanism  856  can be similar to other tensioning control mechanism embodiments previously described including a tensioning element  858  rotatably linked to a spool  860  and operatively connected to the struts  808 . When the spool  860  rotates in a first direction, the tensioning element  858  is wound around the spool  860 , which, in turn, increases tension in the tensioning element  858 . This applies tension to the struts  808 , moving the struts  808  toward the closed configuration and tightening the fit of the system  850  on the residual limb. When the spool rotates in a second direction opposite the first direction, the tensioning element  858  unwinds from the spool  860 . This decreases tension in the tensioning element  858 , allowing the struts  808  to move toward the expanded configuration and loosening the fit of the system  850  on the residual limb. 
     As seen in  FIG. 34 , the crank handle  854  is arranged to drive rotation of the spool  860  in the first and second directions. A distal end portion of the crank handle  854  can define a gear portion  864  arranged to mesh or engage with a plurality of teeth  865  defined on the outer surface of the spool  860 . The gear portion  864  can be any suitable gear portion but is shown as a worm gear or screw gear, creating a significant mechanical advantage. This advantageously allows a user to adjust the tightness of the system  800  with less strength and/or dexterity because a smaller input force on the crank handle  854  from a user can generate a larger output force from the spool  860  and therefore tension in the struts  808 . 
     When the crank handle  854  is rotated in a clockwise direction, the gear portion  864  of the handle feature  854  drives the spool  860  to rotate in the first direction, moving the struts  808  toward the closed configuration. When the crank handle  854  is rotated in a counter-clockwise direction, the gear portion  864  drives the spool  860  to rotate in the second direction, moving the struts  808  toward the expanded configuration. In other embodiments, rotation of the crank handle  854  in the counter-clockwise direction drives the spool  860  to rotate in the first direction and rotation in the clockwise direction drives the spool  860  to rotate in the second direction. 
     Because of the shear friction and/or mechanical advantage in the interaction between the gear portion  864  and the spool  860 , the tightening system  852  can be self-locking. In other words, an input force or torque applied to the spool  860  will not move the crank handle  854 . Thus, whatever tension is set by the crank handle  854  remains substantially fixed until the crank handle  854  is readjusted. 
       FIGS. 35 and 36  show another embodiment of an adjustable socket system  900  including a tightening system  950 . The system  900  includes a distal portion  902 , a proximal portion  904 , and a plurality of struts  908  connected to the distal portion  902  and generally extending between the distal portion  902  and the proximal portion  904 . At least some of the struts  908  are radially adjustable to vary a receiving volume  914  adapted to receive a residual limb. The struts  908  are movable between an expanded configuration in which at least some of the struts  908  are moved radially outward to loosen the fit of the system  950 , and a closed configuration in which at least some of the struts  908  are moved radially inward to tighten the fit of the system  950  on the residual limb. 
     The tightening system  950  is arranged to move the struts  908  of the system  950  between the closed and expanded configurations. The tightening system  950  includes a tensioning control mechanism  952  and a controller  954  operatively connected to the tensioning control mechanism  952 . The tensioning control mechanism  952  can be similar to other tension control mechanism embodiments previously described including a tensioning element  956 , a base  958 , a spool  960 , a disc  962 , and a spring  964  attached to the disc  962 . The tensioning element  956  is rotatably linked to the spool  960  and operatively connected to the struts  908 . The spool  960  and the disc  962  can be situated within the base  958  such that they are rotatable about an axis  966  relative to the base  958 . 
     The tensioning control mechanism  952  includes a ratcheting mechanism  967  comprising a plurality of teeth  968  defined on an outer surface of the spool  960  and a pawl  970  pivotally attached to the base  958  or the disc  962 . The ratcheting mechanism  967  allows the spool  960  and the disc  962  to rotate together in the first direction but prevents the spool  960  from rotating a second direction opposite the first direction such that the disc  962  rotates in the second direction relative to the spool  960 . 
     The controller  954  can comprise an elongate element  972  including a distal end attached to the spring  964  and a proximal free end including a soft grip  974 . The elongate element  972  can comprise a cord, wire, line, or other suitable element. The controller  954  can be arranged such that it can be attached to the struts  908  or the distal portion  902  for storage during use of the system  900 . In other embodiments, the controller  954  can be arranged to be tucked inside of the struts  908  for storage during use of the system  900 . While a single tensioning control mechanism  952  and controller  954  are shown, it will be appreciated that the system  900  can include two, three, or four or any other suitable number of tensioning control mechanisms. For instance, each strut  908  can include a tensioning control mechanism operatively connected to the controller  954 . 
     When the controller  954  is tensioned, the spring  964  is tensioned, which, in turn, causes the spring  962  to coil around the disc  962  and then stretch or elongate, storing energy. The tension in the spring  962  in turn rotates the disc  962  in the first direction. This beneficially can assist a user in tensioning the controller  954 , making the system  950  easier to use for users who may have limited strength or dexterity. 
     As the disc  962  rotates in the first direction, the pawl  970  is arranged to slide up and over the teeth  968  of the spool  960  so that the spool  960  rotates with the disc  962  in the first direction. Rotation of the spool  960  in the first direction causes the tensioning element  956  to wind around the spool  960 , tensioning the tensioning element  956  and struts  908  toward the closed configuration, tightening the fit of the system  950  on a residual limb. 
     When the controller  954  is released, stored energy in the spring  964  causes the spring  964  to reverse its direction, which, in turn, rotates the disc  962  in the second direction and recoils the spring  962 . When the disc  962  rotates in the second direction, the pawl  970  is arranged to lock against the teeth  968  so that the spool  960  is prevented from rotating with the disc  962  in the second direction. As such, the tensioning element  956  remains wound around the spool  960  as the spring  964  recoils on the disc  962 . The pawl  970  can be manually disengaged from the teeth  968  so that the tensioning element  956  can be unwound from the spool  960 , permitting the struts  908  to return toward the expanded configuration and loosening the fit of the system  950  on the residual limb. 
       FIGS. 37-43  show other embodiments the adjustable socket system including tightening systems arranged to automatically tighten and loosen the fit of the adjustable socket system when the system is loaded and unloaded by a user. It will be appreciated that these systems can be similar to and can include many of the same or similar features of the other adjustable socket systems described herein. 
     As shown in the example of  FIGS. 37 and 38 , an adjustable socket system  1000  can comprise a distal portion  1002 , a proximal portion  1004 , and an axis  1006  extending between the distal and proximal portions  1002 ,  1004 . A plurality of elongated struts  1008  are connected to the distal portion  1002  and extend between the distal portion  1002  and the proximal portion  1004 . The distal portion  1002  can include a base  1020  and a distal support  1022  proximal to the base  1020 . The distal support  1022  is adapted to receive and support a distal end of the residual limb inserted in the receiving volume  1014 . The distal support  1022  can have a cup-like configuration. The distal support  1022  is arranged to move along the axis  1006  relative to the base  1020 . A base connector  1025  is secured to a bottom portion of the base  1020 , and is adapted to connect to prosthetic components. 
     The struts  1008  at least in part define a receiving volume  1014  adapted to receive a residual limb. Similar to the other embodiments, one or more portions of the struts  1008  can move radially inward and/or outward to vary the receiving volume  1014 . In an embodiment, the struts  1008  are movable between a relaxed or expanded configuration (shown in  FIG. 37 ) in which portions of the struts  1008  are moved away from the axis  1006  to loosen the fit of the system  1000  on the residual limb, and a closed configuration (shown in  FIG. 38 ) in which portions of the struts  1008  are moved toward the axis  1006  from the expanded configuration to tighten the fit of the system  1000  on the residual limb. Each strut  1008  includes a distal end and a proximal free end  1012 . 
     A tightening system  1050  includes an actuating part  1022  arranged to move the struts  1008  of the system  1000  between the expanded configuration and the closed configuration in response to loading and unloading of the system  1000 . The actuating part  1022  can include the distal support  1022 . 
     When the system  1000  is not in use, the struts  1008  can assume the expanded configuration, allowing a residual limb to be easily inserted into and removed from the receiving volume  1014 . 
     When the residual limb inserted in the receiving volume and a distal end portion of the residual limb applies a load or pressure to the distal support  1022 , the tightening system  1050  automatically moves the struts  1008  toward the closed configuration. This tightens the fit of the system  1000  on the residual limb in proportion to the load or pressure applied to the distal support  1022 . 
     The tightening system  1050  thus advantageously permits the system  1000  to “relax” and be looser when the user is inactive (e.g., sitting or lying down) and become tighter when walking, and become very tight during sports. It also permits the system  1000  to tighten or clamp onto the residual limb during stance and loosen during swing, thus optimally using cyclic loading to best load the residual limb. The tightening system  1050  can be an alternative to or used in combination with other tightening systems described herein. For instance, the system  1000  can include the tightening system  1050  for providing a primary tightening of the system  1000  and the tightening system  180  or the tightening system  130  for providing a secondary tightening of the system  1000 . 
     It will be appreciated that the load applied by the user&#39;s residual limb, the position of the struts  1008  in the closed configuration, and/or the fit of the system  1000  can be selected or adjusted based on one or more criteria such as, for example, activity level, physical characteristics of the residual limb, and/or treatment protocols, making the system  1000  more versatile, and easy to fit to a user. 
     In an embodiment, the tightening system  1050  comprises a first part  1024  of the strut  1008  that extends upward and radially outward from the base  1020  to a first connection point  1026  where it connects to a second part  1028 . From the first connection point  1026 , the second part  1028  extends radially inward and upward to a second connection point  1034  where the second part  1028  attaches to the distal support  1022 . From the second connection point  1034 , each strut  1008  extends generally upward and radially outward. The first connection point  1026  or the second connection point  1034  can define a pivot point. The pivot point can be hinged or pin connection. 
     With the struts  1008  in the expanded configuration, a user can load the distal support  1022 , moving the distal support  1022  downward along the axis  1006  toward the base  1020 . This downward movement of the distal support  1022  rotates the struts  108  toward the axis  1006 , decreasing the receiving volume  1014 . In the illustrated embodiment, downward movement of the distal support  1022  causes the second part  1028  to rotate in a first direction about the first connection point  1026 , moving the proximal ends  1012  of the struts  1008  toward the axis  1006  and decreasing the receiving volume  1014 . This allows the weight or load of the user on the distal support  1022  to automatically tighten the system  1000  on the residual limb. Moreover, the tightening of the system  1000  is proportional to the load. 
     When the distal support  1022  is unloaded, the distal support  1022  can move upward away from the base  1020 . This upward movement rotates the proximal ends  1012  of the struts  108  away from the axis  1006 , returning the system  1000  toward the expanded configuration and decreasing the receiving volume  1014 . Thus, the unloading of the distal support  1022  can loosen the fit of the system  1000  on the residual limb. 
     According to a variation, a biasing mechanism  1036  can be situated between the base  1020  and the distal support  1022 . The biasing mechanism  1036  is adapted to bias the struts  1008  toward the expanded configuration. The biasing mechanism  1036  can be a spring mechanism, a resilient foam member, or any other suitable resilient member. When the distal support  1022  is loaded, the biasing mechanism  1036  can be compressed as the distal support  1022  moves toward the base  1020 . When the distal support is unloaded or the load is reduced, stored energy in the biasing mechanism  1036  can tend to drive the distal support  1022  away from the base  1020 . 
     According to a variation, the first part  1024  can be fixedly connected to the second part  1028  at the first connection point  1026 . When the distal support  1022  is unloaded, the inherent properties of the struts  1008  can help move the struts  1008  toward the expanded configuration. To meet the stiffness/flexibility, strength, and weight requirements needed for use on the system  1000 , the struts  1008  can be made of a stiff, but elastically bendable or deformable material, such as carbon fiber, plastic, or metal. 
       FIGS. 39 and 40  illustrate another embodiment of an adjustable socket system  1100  with a tightening system  1150  that tightens and/or loosens the system  1100  in response to loading and unloading of the system  1100 . The system  1100  can be similar to and can include many of the same or similar features as any of the other adjustable socket systems described herein. 
     The system  1100  includes a distal portion  1102 , a proximal portion  1104 , and an axis  1106  extending between the distal and proximal portions  1102 ,  1104 . A plurality of struts  1108  are connected to the distal portion  1102  and generally extend between the distal portion  1102  and the proximal portion  1104 . The struts  1108  at least in part define a receiving volume  1114  adapted to receive a residual limb. The struts  1108  can rotate radially inward and/or outward to vary the receiving volume  1114  or expand a circumference of the system  1100 . The struts  1108  are movable between a relaxed or expanded configuration in which portions of the struts  1108  are moved away from the axis  1106  to loosen the fit of the system  1100  on a residual limb inserted in the receiving volume  1114 , and a closed configuration in which portions of the struts  1108  are moved radially inward toward the axis  1106  from the expanded configuration to tighten the fit of the system  1100  on the residual limb. Each strut  1108  includes a distal end  1110  and a proximal free end  1112 . 
     The struts  1108  are arranged to rotate relative to the axis  1106  via a connection point  1130  at or near the distal end  1110 . The connection point  1130  can comprise a pinned or hinged connection connecting the distal end  1110  to a proximal portion of a respective support member described below. 
     In an embodiment, the struts  1108  can include a distal part  1144  defining the distal end  1110  and a proximal part  1146  defining the proximal end  1112 . According to a variation, the proximal part  1146  can be removably attached to the distal part  1144 . This beneficially allows the proximal parts  1146  to be interchanged with different proximal parts  1146  of varying lengths or widths to adjust the height or fit of the struts  1108 . This also allows the proximal parts  1146  to be removed for repair or replacement without having to replace the entire strut  1108  of system  1100 . The proximal parts  1146  can be removably attached to the distal parts  1144  via one or more fasteners  1148 . 
     The distal portion  1102  can include a base  1120  and a distal support  1122  proximal to the base  1120 . The distal support  1122  is arranged to move along the axis  1106  relative to the base  1120 . The distal support  1122  can have a cup-like configuration. The base  1120  includes a base plate  1124  and a plurality of generally upright support members  1126  distributed circumferentially about the base plate  1124  and the distal support  1122 . The base  1120  includes a base connector  1125  adapted to connect to prosthetic components. 
     The tightening system  1150  includes an actuating part  1121  arranged to move the struts  1108  of the system  1100  between the expanded and closed configurations in response to load and unloading of the system  1100 . 
     The actuating part  1121  can comprise the distal support  1122 . A plurality of teeth  1128  are defined on an outer surface of the distal support  1122 . The teeth  1128  can extend circumferentially about the distal support  1122 . The distal end  1110  of the struts  1108  can define a plurality of teeth  1140  arranged to mesh with the teeth  1128  of the distal support  1122 . The distal end  1110  can have a cylindrical or convex shape. The teeth  1140  can extend across a width of the distal end  1110 . The teeth  1140  can be generally linear. The teeth  1140  can be generally helical. The distal end  1110  can include between about 4 and about 12 teeth, about 5 teeth and about 11 teeth, or about 6 teeth and about 10 teeth. In other embodiments, the distal end  1110  can include more or less teeth. 
     The interaction or tooth loads between the distal ends  1110  and the distal support  1122  create a driving force on the struts  1108  as the distal support  1122  moves along the axis  1106  relative to the base  1120 . As the distal support  1122  moves up and down relative to the base  1120 , the interaction between the teeth  1128 ,  1140  generates the driving force that in turn rotates the struts  1108  about the connection point  1130 , moving the system  1100  between the closed configuration and the expanded configuration. The distal end  1110  can have an enlarged configuration to better accommodate the teeth  1140  and/or the interaction between the distal support  1122  and the struts  1108 . 
     The dimension and configuration of the interaction between the distal support  1122  and the struts  1108  can at least in part define the strength of the tightening system  1150  to maintain the position of the system  1000 . For instance, the length, angle, depth, thickness, curvature, pressure angle, and/or pitch of the teeth can in part define the load the strut  1108  can support. 
     In an embodiment, the teeth  1140  of the strut  1108  are engaged with the teeth  1128  of the distal support  1122  along substantially the entire length of the teeth  1140  extending in a direction across the distal end  1110 . This greater contact area helps form a solid connection between the distal support  1122  and the struts  1108 , which, in turn, helps the tightening system  1150  to better control movement of the system  1000  between the expanded configuration and closed configuration. As such, the tightening system  1150  can be made simpler. For instance, distal portions of the struts  1108  and/or the distal support  1122  can be made of plastic material or other lightweight material that can resist deformation during use. This can result in adjustable socket systems that are more cost effective to manufacture, less bulky, lighter-weight, and more comfortable to wear. It will be appreciated that that the struts  1108  and/or the base  1120  can be made of metal, plastic material, carbon fiber, combinations thereof, or any other suitable material. 
     As seen in  FIG. 40 , with the struts  1108  in the expanded configuration, a user can load the distal support  1122 , moving the distal support  1122  downward toward the base  1120 . This downward movement of the distal support  1122  causes the struts  1108  to rotate toward the axis  1106  about the connection points  1130 , which, in turn tightens the fit of the system  1110  on a residual limb positioned in the receiving space  1114 . When the distal support  1122  is unloaded or the load is decreased, the distal support  1122  can move upward and away from the base  1120  along the axis  1106 , causing the struts to rotate away from the axis  1106 . This loosens the fit of the system  1110  on the residual limb. 
     According to a variation, a biasing mechanism can bias the struts toward the expanded configuration or closed configuration. For instance, a biasing mechanism  1136  can be situated between the base  1120  and the distal support  1122  that is arranged to bias the system  1110  toward the expanded configuration when the distal support  1122  is unloaded or a load on the distal support  1122  decreases. It should be appreciated that the biasing mechanism can be any suitable member. 
       FIGS. 41-43  illustrate another embodiment of an adjustable socket system  1200  with a tightening system  1250  arranged to tighten and/or loosen the system  1200  in response to loading and unloading of the system  1200 . The system  1200  can be similar to and can include many of the same or similar features as any of the other adjustable socket systems described herein. Moreover, it will be appreciated that the tightening system  1250  can be used alone or in combination with other tightening systems. For instance, the system  1200  can include the tightening system  1250  and the tightening system  130 . 
     The system  1200  includes a distal portion  1202 , a proximal portion  1204 , and an axis  1206  extending between the distal and proximal portions  1202 ,  1204 . A plurality of struts  1208  are connected to the distal portion  1202  and extend generally between the distal portion  1202  and the proximal portion  1204 . The struts  1208  at least in part defined a receiving volume  1214  arranged to receive a residual limb therein. The struts  1208  are movable between a relaxed or expanded configuration in which portions of the struts  1208  are moved away from the axis  1206  to loosen the fit of the system  1200  on the residual limb, and a closed configuration in which the portions of the struts  1208  are moved toward the axis  1206  to tighten the fit of the system  1200  on a residual limb inserted in the receiving volume  1214 . Each strut  1208  includes a distal end  1210  and a proximal free end  1212 . 
     The struts  1208  are arranged to rotate relative to the axis  1206  via a connection point  1230  at or near the distal end  1210 . The connection point  1230  can comprise a pinned or hinged connection connecting the distal end  1210  of the strut  1208  to the distal portion  1202 . According to a variation, the struts  1208  can define a plurality of through holes  1256  formed along a length of the struts  1208 . The through holes  1256  can be adapted to help attach textile and/or material to the struts  1208 . The through holes  1256  can be adapted to attach one or more tensioning elements described below to the struts  1208 . 
     The distal portion  1202  can include a base  1220 , a stem portion  1222  attached to the base  1220 , and a distal support  1224  positioned on and arranged to move relative to the stem portion  1222 . The distal support  1224  is adapted to receive and support a distal end of the residual limb inserted in the receiving volume  1214 . The distal support  1224  can have a cup-like configuration and can define a radial flange  1252  having a plurality of through holes  1254  distributed circumferentially about the flange  1252 . 
     The tightening system  1250  comprises at least one tensioning element  1258  connected between the struts  1208  and an actuating part comprising the distal support  1224 . The at least one tensioning element  1258  can be threaded or passed through at least some of the through holes  1254  on the distal support  1124  to connect the at least one tensioning element  1258  to the distal support  1224 . The at least one tensioning element  1258  can be threaded or passed through at least some of the through holes  1256  to connect the at least one tensioning element  1258  to the struts  1208 . The at least one tensioning element  1258  can be a textile or material segment, a band member, a knitted fabric, lacing, an elastic cord, an elastomer material, and/or any other suitable material. 
     With the struts  1208  in the expanded configuration, the distal end of a user&#39;s residual limb can load the distal support  1224 , which, in turn, moves the distal support  1224  downward on the stem portion  1222  toward the base  1220 . This downward movement of the distal support  1224  causes the at least one tensioning element  1258  extending between the distal support  1224  and the struts  1208  to tension or pull the struts  1208  radially inward toward the closed configuration, tightening the fit of the system  1200  on the residual limb. When the distal support  1224  is unloaded or the load on the distal support  1224  decreases, the distal support  1224  can move upward on the stem portion  1222  or away from the base  1220 . This upward movement of the distal support  1224  reduces tension on the struts  1208  from the at least one tensioning element  1258 , allowing the struts  1208  to return to the expanded configuration, loosening the fit of the system  1200 . 
     According to a variation, a biasing mechanism can bias the struts toward the expanded configuration or the closed configuration. For instance, the biasing mechanism can comprise a residual limb. To secure the residual limb within the system  1200 , the residual limb may be under some degree of compression. When tension from the at least one tensioning element  1258  is released, the residual limb can expand and push the struts  1208  radially outward toward the expanded configuration. In other embodiments, properties of the at least one tensioning element  1258  can at least in part bias the struts  1208  toward the expanded configuration. 
     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”).