KNEE BRACE LOAD SENSOR

Abstract: A method and apparatus is provided for measuring the treatment force exerted by the contact pad (98, 222) of an orthopedic brace (10) upon the joint (130) of a wearer. The apparatus generally comprises an analog pad (222) having approximately the same thickness as the contact pad (98) and which is configured and adapted to be substituted for the contact pad or otherwise interposed between the orthopedic brace (10) and the joint (130) of the wearer. A force or pressure sensor (220) is provided in operative communication with the analog pad (222) for sensing the force or pressure exerted by the analog pad on the joint. In this manner, the knee brace (10) and/or the contact pad (222) can be adjusted to provide a desired treatment force or pressure to the patient's knee when the analog pad is replaced with the contact pad. The load sensor (210) may comprise a fluid-filled pad and a fluid-pressure sensor (224) with a port (230) for fluid communication with the fluid-filled pad. The fluid-pressure sensor (224) has a display (226) that indicates the magnitude of the force corresponding to the fluid pressure sensed by the fluid-pressure sensor (224). The load sensor may also have a stopcock (244) with a first fitting (236) connected to the fluid-filled pad, a second fitting (232) connected to the fluid-pressure sensor, and a third fitting (242) adapted to connect to a pump. The stopcock (244) may be adjustable to selectively permit fluid communication between the first fitting and the second fitting, or between the first fitting, the second fitting and the third fitting.

Description: KNEE BRACE LOAD SENSOR BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to knee orthotics, and more particularly to a device and method for measuring the force applied to a bodily joint by an orthopedic brace, as well as a method for fitting the orthopedic brace to a patient. Description of the Related Art In the treatment of orthopedic disorders such as osteoarthritis, it is often necessary for a patient to wear a brace on the affected joint. In a case of osteoarthritis, the cartilage which normally lines the contact surfaces of the bones breaks down. Frequently this breakdown occurs unevenly across the bone surface, resulting in uneven boπe-to- bone contact, which may alter the angle at which the bones meet and causes the patient to suffer stiffness and pain when using the joint. To treat this condition an orthopedic specialist often prescribes the wearing of a brace on the joint. The brace generally supports the joint structure and may adjust the joint load distribution to address problems such as pain associated with degeneration of cartilage and misalignment of the bones making up the joint. The brace often has a frame supporting one or more pads which apply a corrective force to the joint at a desired area to reduce the loads in the damaged section of the joint and to relieve pain. These pads may be foam-filed or fluid-filled, and are often pneumatic. A physician can change or adjust the amount of the corrective force applied to the knee by changing the thickness of the pads, adjusting the configuration of the brace or by other means. The process of fitting such a brace to a patient and making the necessary changes and adjustments is highly iterative and it is difficult for the physician to quantify the magnitude of the actual treatment load applied. SUMMARY OF THE INVENTION The present invention recognizes the desirability for a physician to prescribe a brace wearing regimen wherein a known treatment force is applied to the joint. Thus, in accordance with one embodiment the invention provides a quantitative, reproducible, quick, easy, and unobtrusive way to measure the force applied to a patient's leg in an orthopedic brace. Accordingly, one aspect of the invention is to provide a load sensor for an orthopedic brace. Another aspect of the invention is to provide a load sensor for an orthopedic brace which is easily incorporated into existing brace structures and which is easy to use and maintain. The particular construction and configuration of the load sensor is relatively unimportant and many suitable load sensing devices may be used to achieve the desired functionality described herein. Thus, in accordance with one embodiment of the invention an apparatus is provided for measuring the treatment force exerted by the contact pad of an orthopedic brace upon the joint of a wearer. The apparatus comprises an analog pad having approximately the same thickness as the contact pad and which is configured and adapted to be substituted for the contact pad or otherwise interposed between the orthopedic brace and the joint of the wearer. A force or pressure sensor is provided in operative communication with the analog pad for sensing the force or pressure exerted by the analog pad on the joint. In this manner, the knee brace and/or the contact pad can be adjusted to provide a desired treatment force or pressure to the patient's knee when the analog pad is replaced with the contact pad. In accordance with another embodiment of the invention an orthopedic brace is provided including means for measuring the treatment force applied to a patient's knee. The brace comprises a brace frame adapted to be worn by a wearer to brace a bodily structure, such as a knee. A contact pad is secured relative to the brace frame and is adapted to exert a force upon the bodily structure. A force or pressure sensor is provided in operative association with the contact pad. The force or pressure sensor is adapted to measure the magnitude of the force or pressure exerted by the contact pad upon the bodily structure, whereby the brace and/or the contact pad can be adjusted to provide a desired treatment force or pressure to the patient's knee. In accordance with another embodiment of the invention a method is provided for fitting an orthopedic knee brace to a patient. According to the method, the brace is first applied to the knee of the patient. The brace is configured to accommodate insertion of a contact pad having a first thickness between the brace and the patient's knee. An analog pad having a second thickness approximately equal to the first thickness is inserted between the brace and the patient's knee. Then, the force or pressure exerted by the analog pad on the patient's knee is measured. Optionally, after measuring the force or pressure exerted by the analog pad on the patient's knee, the contact pad may be substituted for the analog pad in the knee brace. In this manner, the contact pad exerts a force or pressure substantially equal to the measured force or pressure, whereby the knee brace and/or the contact pad can be adjusted to provide a desired treatment force or pressure to the patient's knee. In accordance with another embodiment of the invention a method is provided for sensing the force exerted by a contact pad of an orthopedic brace on the joint of a wearer. According to the method a force or pressure sensor is provided in operative association with the contact pad in such a manner as to sense the force or pressure exerted by the contact pad on the joint of the wearer. The measured force or pressure is then displayed, whereby the brace and/or the contact pad can be adjusted to provide a desired treatment force or pressure to the wearer's joint. In accordance with another embodiment of the invention an orthopedic brace is provided comprising a brace frame adapted to attach to and brace a bodily structure. A fluid-filled pad is attached to the brace frame and adapted to exert a force upon the bodily structure. A fluid-pressure sensor is in fluid communication with the fluid-filled pad. The fluid-pressure sensor has a display that indicates the magnitude of the force corresponding to the fluid pressure sensed by the fluid-pressure sensor. For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed. BRIEF DESCRIPTION OF THE DRAWINGS Having thus summarized the general nature of the invention and its essential features and advantages, certain preferred embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which: Figure 1 is a front view of a knee brace for use in accordance with one embodiment of the invention; Figure 2 is a right side view of the knee brace of Figure 1; Figure 3 is a front view of the knee brace of Figure 1 applied to the right leg of a wearer; Figure 4 is a schematic view of a knee brace worn on the knee of a patient and incorporating a load sensor in accordance with the invention; Figure 5 is a front elevation view of the load sensor of Figure 4; Figure 6 is a front elevation view of the load sensor of Figure 4 illustrating one preferred method of calibration; Figure 7 is a front elevation view of a gauge face for the load sensor of Figure 4; Figure 8 is a perspective view of a case for use with the load sensor of Figure 4; Figure 9 is a top view of a front shell of the case of Figure 8; Figure 10 is a perspective view of a rear shell of the case of Figure 8; Figure 11 is a perspective view of an indicator switch of the case of Figure 8; Figure 12 is a perspective view of the reverse side of the indicator switch of Figure 11; Figure 13 is a top view of a stopcock handle for use with the load sensor of Figure 4; Figure 14 is a plan view of a condyle pad for use with the load sensor of Figure 4; Figure 15 is a cross-sectional view of the condyle pad of Figure 14 taken along line 15-15; and Figure 16 is a cross-sectional view of an alternate embodiment of a condyle pad for use with the load sensor of Figure 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For purposes of illustration, the invention will be described and its use exemplified in the context of an orthopedic knee brace having adjustable arms as illustrated in Figure 1. It will be understood, however, that the invention described and claimed herein is equally applicable to many body joints generally, including, but not limited to, the knee, elbow, wrist, ankle, hip and shoulder and many different types of orthotic braces. Consequently the description which follows should not be considered as limited only to knee braces. FIG. 1 shows an orthopedic knee brace 10 that is suitable for use with a load sensor having features and advantages of the present invention. FIG. 1 also illustrates a joint loading methodology that can be used to exploit the features and advantages of the present invention. The knee brace 10 is configured to be applied either to the right leg of a wearer to treat osteoarthritis in the medial compartment of the right knee, or to the left leg to treat osteoarthritis in the lateral compartment of the left knee. However, it will be apparent to those skilled in the art that the knee brace 10 can also be modified to treat osteoarthritis in the lateral compartment of the right knee or the medial compartment of the left knee. For purposes of discussion herein, it will be assumed that the brace 10 is to be applied to the right leg of the wearer to treat osteoarthritis in the medial compartment of the right knee. Referring to FIG. 1, the knee brace 10 includes an upper support portion 12, a lower support portion 14, and medial and lateral hinge assemblies 16, 18. The upper and lower support portions 12, 14 are pivotally connected to one another via the medial and lateral hinge assemblies 16, 18. The upper support portion 12 includes an upper leg cuff 20 for positioning over the front of the thigh of the wearer (see FIG. 3) and medial and lateral support arms 22, 24 extending from the upper leg cuff 20 to the medial and lateral hinge assemblies 16, 18. The lower support portion 14 includes a lower leg cuff 26 for positioning over the calf of the wearer and medial and lateral support arms 28, 30 extending from the lower leg cuff 26 to the medial and lateral hinge assemblies 16, 18. A first adjustment device 32 is located between the upper leg cuff 20 and the upper lateral support arm 24, and a second adjustment device 34 is located between the lower leg cuff 26 and the lower lateral support arm 30. The upper support portion 12 is secured to the upper leg of the wearer with adjustable straps 36 which extend around the back of the upper leg. The lower support portion 14 is secured to the lower leg by adjustable straps 38 which extend around the front and back of the lower leg. For ease of adjustment, the straps 36, 38 are preferably fastened with a hook and pile fastener such as VELCRO™. The upper and lower support portions 12, 14 are preferably made of aluminum, but can be made from any light-weight, high-strength metal, plastic, or composite material. The interior surface of each of the upper and lower support portions 12, 14 is covered with padding 40 to provide a comfortable fit against the leg of the wearer. The padding 40 is preferably made from a resilient foam material. However, inflated bladders, gels or other types of padding may also be used. FIG. 2 is a lateral side view of the knee brace 10 showing the first and second adjustment devices 32, 34. In a preferred embodiment, the adjustment devices 32, 34 are of a type described in U.S. Patent No. 5,766,140 assigned to the assignee of the present invention and hereby incorporated by reference herein. FIG. 3 is a front view of the knee brace 10 applied to the right leg of a wearer. The femur 130, tibia 132, and fibula 134 of the right leg are shown. To treat osteoarthritis in the medial compartment of the right knee, the brace 10 is fitted to the right leg with the support arms 24, 30 and adjustment devices 32, 34 located on the lateral side of the leg. The medial support arms 22, 28 can be bent or otherwise shaped, as desired or necessary, to comfortably fit the shape of the wearer's leg. A force is then applied to the opposite (lateral) side of the knee by turning the adjustment screws (not shown) of the first and second adjustment devices 32, 34 clockwise. The hinge pins 100 of the adjustment devices 32, 34 are thereby drawn toward the arch bars 116 causing the upper and lower support arms 24, 30 to rotate toward the leg relative to the upper and lower leg cuffs 20, 26. The lateral hinge assembly 18 is moved toward the knee by the rotation of the upper and lower support arms 24, 30. The lateral hinge assembly 18 applies a force to the lateral side of the knee via the condyle pad 98. Counteracting forces are applied above and below the knee on the medial side of the leg by the upper and lower leg cuffs 20, 26. The resulting three-point load on the leg serves to reduce the load in medial compartment of the knee. FIG. 4 shows a load sensor 220 in accordance with the invention, as employed with the knee brace 10. The knee brace 10 has a condyle pad 98 as disclosed above and an analog pad comprising, force-sensing condyle pad 222 - - is preferably a fluid-filled sac of flexible plastic film or other suitable fluid-tight material - having approximately the same thickness as the pad 98 or other pad to be substituted therefore. Alternatively, the pad 222 may comprise any number of other suitable structures capable of load sensing, such as a condyle pad with an adjacent or embedded piezoelectric transducer, force sensing resistor, or other similar component or components sensitive to compressive loads. The fluid contained within the pad 222 may be a gas, a liquid, or a highly-deformable gel. The preferred fluid is a gas at ambient temperature, such as air. For additional detail on the construction of a suitable inflatable condyle pad, refer to U.S. Patent No. 5,527,268 assigned to the assignee of the present invention, and incorporated herein by reference. When the fluid-filled pad 222 is urged against the knee by manipulation of the first and second adjustment devices 32, 34 or by other means, a user can directly measure the magnitude of the corrective load applied to the knee by using the load sensor 220. The greater the force applied to the fluid-filled pad 222 by the frame of the knee brace 10, the greater the fluid pressure inside the pad 222. Thus, the fluid pressure in the fluid-filled condyle pad 222 can be measured to determine the force corresponding to the fluid pressure. Where the pad 222 is equipped with a piezoelectric transducer, force sensing resistor, or other similar component as disclosed above, those skilled in the art will recognize that other similar methods of sensing the corrective load may be used to determine the force corresponding to the voltage generated by, or change in resistance, capacitance, or inductance observed in the component in question. However configured, the load sensor 220 preferably enables a physician to substantially precisely determine the force on the patient's knee, thereby improving the accuracy of the knee-brace treatment technique. FIG. 5 shows the components of the load sensor 220 with the case (discussed in further detail below) removed for clarity. The load sensor 220 consists of a bourdon-tube type fluid-pressure gauge body 224 which is of standard construction but has a gauge face 226 calibrated in units of force, preferably pounds or newtons, as opposed to units of pressure such as PSI or kilopascals. Of course, many other types of pressure gauges and calibrated displays may be used, as desired. Preferably, the fluid-pressure gauge 224 is sensitive in the 0-12 PSI (0-82JKPa) range. A suitable fluid-pressure gauge is Ashcroft product no. 20W1005PH00LXZ012#-6155, available from Dresser Corp.'s Instruments Division. The fluid-pressure gauge 224 connects to a four-way stopcock 228 via a hose barb 230 and a short gauge hose 232. The stopcock 228 connects to the pad 222 via a pad hose 234 and hose barbs 236, 238. The pad 222 has a port 240 to support connection to the pad hose 234. The stopcock 228 also has a side port 242 that serves as a connection for a hand pump (not shown), which may be used for pressurizing the pad 222. The stopcock 228 has a handle 244 which allows the user to selectively permit fluid communication between the fluid-pressure gauge 224, the pad 222, and the hand pump, when connected to the side port 242. Thus, the user can initially pressurize the pad 222 to a predetermined level by turning the handle 244 to a position which permits fluid flow between the pad 222, the fluid-pressure gauge 224 and the hand pump. The user then operates the hand pump to force fluid into the pad 222. When inflation is complete the user turns the handle 244 to a position that prevents flow to the side port 242 (and permits flow between the fluid-pressure gauge 224 and the pad 222), sealing the fluid in the pad-sensor system while allowing the load sensor 220 to function. Desirably, the stopcock 228 may also be configured to permit fluid communication between all three of the pad 222, fluid-pressure gauge 224, and the hand pump during the pressurization procedure, so as to permit the user to monitor the force exerted by the pad 222 while pumping fluid into the system. FIG. 6 shows a preferred method of calibrating the load sensor 220. A pad-sensor system 245 is constructed which is similar to that described above in all respects except that the original gauge face 246 remains on the fluid-pressure gauge 224 (marked in units of pressure, i.e., PSI or kilopascals). The pad 222 is pressurized so that it takes on a thickness and resilience roughly equal to that it would have while in use on a brace. For the knee brace 10 described above the baseline pressure is preferably about 1.5 PSI. The handle 244 is turned to a position which permits fluid flow between the pad 222 and the fluid-pressure gauge 224 while sealing off the side port 242. A force gauge 248 is used to apply a known amount of force to the pad 222. The force gauge 248 has an armature 250 which bears on the pad 222 with a knee brace upright portion 252 that simulates the location of the pad 222 on the knee brace 10 during actual use conditions. This ensures that the force and pressure profile applied by the force gauge 248 will closely resemble that exerted by the knee brace 10 on the pad 222 when a patient wears the brace. When the force is applied, the fluid-pressure gauge 224 indicates the system pressure corresponding to the force magnitude. By repeating this measurement for a range of known forces, one can construct a data set for producing a gauge face 226 (see FIG. 7) accurately marked with units of force. The new gauge face 226 then replaces the original one on the fluid-pressure gauge 224, completing the calibration process. This empirical calibration method is preferable to a straight application of a force/pressure calculation, as it compensates for an observed nonlinearity in the pad-sensor system pressure response to varying forces. Thus, such direct measurement and correlation of the system response provides the most accurate calibration of the gauge face 226. The load sensor 220 as described herein facilitates various methods of treating patients with high-precision corrective load regimens. One preferred method is to prescribe the fluid-filled pad 222 to be worn on the brace full- time. In this method it is contemplated that the load sensor 220 is connected to the pad 222 either permanently or from time to time so as to measure the force exerted on the knee by the pad. Fluid can then be added to or bled from the pad 222 as necessary to maintain the corrective load within the limits specified by the regimen of the individual patient. In addition, the user may alter the brace frame geometry as either an alternative or a supplement to the addition and/or removal of fluid from the pad 222, when adjusting the corrective force. Another preferred method is to prescribe a standard foam-filled or rubberized pad, or a sealed fluid-filled pad for day-to-day use on the knee brace. In this method, a user (e.g., an orthopedic physician) preferably adjusts the corrective force applied to the knee by varying the geometry of the knee brace frame, to move the condyle pad 98 toward or away from the knee as disclosed above (FIG. 1). To measure the corrective load during adjustment, the user substitutes the fluid-filled pad 222 as temporary analog for the standard pad 98 on the knee brace 10. Preferably, the pads 98 and 222 are of approximately the same thickness and resilience. The load sensor 220 is first initialized by connecting a hand pump to the side port 242, and turning the stopcock 228 to a position which permits fluid communication between the hand pump, the pad 222, and the fluid- pressure gauge 224. Then by using the hand pump, air is added to the pad 222 until the gauge face reads zero. When this pressure is reached the stopcock 228 is turned to a position which seals off the side port 242 but permits fluid communication between the pad 222 and the fluid-pressure gauge 220. At this point the user installs the fluid-filled pad 222 on the brace frame, in place of the standard pad 98. Next, the adjustment devices 32, 34 are manipulated to vary the geometry of the brace frame, moving the pad 222 relative to the knee until the desired corrective force (read simultaneously from the gauge face) is reached. Upon reaching the desired corrective force the resulting brace frame geometry is maintained and a standard pad 98 of the same approximate thickness and resilience as the fluid-filled pad 222 used during the adjustment, is substituted. In this manner, a precision treatment regimen is achieved without increasing the cost or complexity of the orthopedic brace FIG. 8 shows a case 262 which provides a suitable structure for containing components of the load sensor 220. The particular construction and configuration of the case is relatively unimportant. In the particular embodiment illustrated, the case 262, preferably constructed of injection-molded high impact ABS plastic, includes a gauge opening 264 which receives and supports the fluid-pressure gauge 224, as well as a side port opening 266 and a pad hose opening 268. The case 262 rotatably receives an indicator switch 270 in a switch opening 271; the indicator switch 270 serves as a decorative and easy-to-grasp extension of the stopcock handle 244. Labels 272, 274 may be molded into or printed on the case 262 to assist in operation of the load sensor 220. The case 262 is preferably divided into a front shell 276 and a rear shell 278, to promote ease of assembly and to provide a sturdy construction. FIGS. 9 and 10 show the front and rear shells 276, 278 in greater detail. The rear shell 278 has a perimeter lip 280 which coacts with a rim 282 formed by the front shell 276 to create an overlapping fit and to facilitate alignment of the two shells during assembly. The front shell 276 forms a number, preferably four, of screw bosses 284 which correspond to a like number of screw bores 286 in the rear shell 278. This configuration permits the fastening of the two shells 276, 278 via a number of screws which enter from the rear of the case 262 and remain unseen to a user of the load sensor viewing the gauge face 226 and indicator switch 270 from the front. Each of the screw bores 286 preferably has a larger-diameter rear bore portion 288 which permits the screws to be countersunk into the rear shell 278, thus promoting a neat appearance for the back of the case 262. The rear shell 278 also has a hook 290 for attachment of the load sensor 220 to the knee brace 10 (see FIG. 4), as well as a series of integrally formed ribs 292 which hold the fluid-pressure gauge 224 securely in the case 262, aligned with the gauge opening 264. The rear shell 278 also forms a support 294 for maintaining the stopcock 228 in position in the case 262. FIGS. 11 and 12 show the indicator switch 270 in greater detail. The indicator switch 270 has a relatively large, raised arrow-shaped handle 296 to provide a secure gripping point and clear indication of the stopcock position. The indicator switch also has a disc 298 that is sized to fit concentrically and on the surface of the switch opening 271, and a number of brackets 300 and a shaft 302 that align with arms 304 and hole 306 in the stopcock handle 244 (see FIG. 13). This configuration allows an interference fit between the indicator switch 270 and the stopcock handle with a secure angular alignment between the handle 296 and the corresponding position of the stopcock 244. An interference fit is preferred due to the difficulty of gluing HDPE (which is often used to construct stopcock handles) to other plastics. Preferably, there is a .008" diametrical clearance between the outside diameter 308 of the stopcock handle 244 and the inner face of the brackets 300, and a .008" (0.20 mm)clearance between the arms 304 of the stopcock handle and the gaps between the brackets 300. In addition, the preferred diametrical clearance between the shaft 302 and the inside diameter 310 of the stopcock handle is about .009" (0.22 mm) A correspondingly larger gap 312 is provided in the indicator switch to accommodate the large arm 314 of the stopcock handle 244. For assembling the case, the preferred fasteners are 1 /_ Phillips panhead Plastite screws, which have a recommended minimum thread engagement of 70%. This calls for a maximum hole diameter of 0.105" (2.7 mm). To facilitate easy removal of the front shell from a mold, draft angles of about 0.5° are incorporated into the screw bosses. With a threaded depth of about 0.305" (7.7 mm), the result is a hole diameter which decreases from about 0.104" (2.6 mm) at the top to about 0.099" (2.5 mm) at the bottom of the threaded portion. Of course, a variety of other fastening devices and fastening methods may also be used, such as bonding, welding, gluing, riveting and the like. The configuration and construction of the condyle pads 222 are described hereafter with reference to FIGS. 14-16. Referring initially to FIGS. 14 and 15, a first embodiment of a condyle pad 222 is shown to comprise a fluid- containing, closed-curve primary bladder 352 having an outer plan perimeter and an inner plan perimeter defined by a primary seam 354 and a secondary seam 356, respectively. The primary seam 354 continuously surrounds the primary bladder 352 following an oval-shaped, closed-loop pathway, thereby defining the entire peripheral outer plan perimeter of the primary bladder 352. The secondary seam 356 also follows a continuous, somewhat oval-shaped, closed-loop pathway and is encircled by the primary seam 354. The secondary seam 356, however, is centrally offset from the primary seam 354. The secondary seam 356 defines the inner plan perimeter of the primary bladder 352 and also defines the outer plan perimeter of an interior opening that is a depression substantially encircled by the primary bladder 352. The interior opening has a number of alternate configurations as described hereafter, but in all cases the interior opening is characterized as having a substantially lesser height or thickness than the primary bladder 352 when the condyle pad 222 is in an uncompressed state. The primary and secondary seams 354, 356 are fluid-tight to effectively seal the selected fluid contained within the interior of the primary bladder 352 from the external environment. The fluid enables the uncompressed primary bladder 352 to retain a substantially irregular toroid shape, as shown here, or alternatively a regular toroid shape. The configuration of the primary bladder 352 is termed "an irregular toroid" because its radial cross-section is not uniform about the entire rotation of the primary bladder 352 due to the off center position of the secondary seam 356. A tubular port 240 is provided through the primary bladder 352, and in particular through the primary seam 354, to enable fluid communication between the interior of the primary bladder 352 and the external environment. The port 240 may be modified as necessary to accept the hose barb 238 (see FIG. 6). In accordance with the embodiment of the condyle pad 222 shown in FIGS. 14 and 15, the interior opening is occupied by a secondary bladder 362 that is in fluid isolation from the primary bladder 352. The plan perimeter of the secondary bladder 362 is defined by the secondary seam 356 and the secondary bladder 362 has a substantially continuous radial cross section. The secondary bladder 362 contains a lesser quantity of fluid than the primary bladder 352 and is substantially less thick than the primary bladder 352 when the condyle pad 222 is in an uncompressed state. Unlike the primary bladder 352, the secondary bladder 362 is substantially permanently sealed, having no port therein, such that the quantity of fluid within the secondary bladder 362 is substantially constant throughout the life of the pad 222. Specifically referring to FIG. 15, the condyle pad 222 is shown to have a laminar construction comprising a facing 364 and a backing 366. It is noted that the thickness of the laminate layers have been exaggerated for purposes of illustration. The facing 364 is a sheet of a soft, pliant, absorbent material, such as synthetic suede or chamois, anteriorly laminated to both the primary and secondary bladders 352, 362. The backing 266 is likewise a sheet of pliant material posteriorly laminated to the bladders 352, 362 in substantially the same manner as the facing 364. A preferred backing 366 is the loop component of a hook and loop fastener, commonly termed VELCRO, configured as a cloth patch. A cloth patch of the hook component (not shown) is similarly laminated to the inner face of the knee brace frame opposite the backing 366. It is understood that the positions of the hook and loop components can alternatively be reversed such that the loop component is laminated to the inner face of the knee brace frame and the hook component is laminated to the outside of the second sheet 364. In a preferred construction of the condyle pad 222, the primary and secondary bladders 352, 362 are shown in FIG. 15 to be integrally formed from two continuous sheets 368, 370 of a film-like skin. The skin is a highly-flexible, elastically-collapsible, fluid-impervious material such as a plastic, e.g., polyurethane or polyvinyl chloride. Construction of the condyle pad 222 is initiated by laminating the facing 364 onto the outside of the first sheet 368 and correspondingly laminating the backing 366 onto the outside of the second sheet 370 by an adhesive such as a conventional glue, or by flame bonding. The bladders 352, 362 are then constructed by overlaying the first sheet 368 atop the second sheet 370. The primary seam 354 is formed by positioning the port 240 and enclosed valve (not shown) between the two sheets 368, 370 at the outer plan perimeter thereof and joining the sheets 368, 370 around the port 240 and along the continuous oval path of the outer plan perimeter using conventional means, such as radio frequency (r.f.) welding. The secondary seam 356 is formed in substantially the same manner as the primary seam 354, but absent the port, such that the secondary seam 356 is positioned off center from the primary seam 354 and encircled thereby. It is noted that when the primary and secondary seams 354, 356 are formed, a quantity of fluid, typically ambient air, can be trapped within the interiors of the seams 354, 356. The fluid retained within the interior of the secondary seam 356 remains therein without the further addition or withdrawal of fluid for substantially the life of the pad. The fluid within the interior of the primary seam 354, however, can subsequently be supplemented by injecting additional fluid via the port 240 and valve in the manner described above to achieve a desired increase in the thickness of the primary bladder 352. Consequently, the distance separating the first and second sheets 368, 370 within the primary bladder 352 is substantially greater than the distance of separation within the secondary bladder 362. Although not shown, the condyle pad 222 of FIG. 15 can alternately be configured by evacuating the secondary bladder 362 and laminating the inside of the first sheet 368 to the inside of the second sheet 370 across the entire interior opening. Thus, the secondary bladder is excluded from this embodiment and the interior opening is occupied by the resulting laminate comprising the first and second sheets 368, 370, facing 364, and backing 366. Referring to FIG. 16 having substantially the same cross-sectional view as FIG. 15, another embodiment of a condyle pad is shown and generally designated 372. Identical reference characters are used to identify elements common to both the condyle pad 372 and the condyle pad 222 insofar as the condyle pad 372 is configured substantially the same as the condyle pad 222 with the exception of the interior opening. The condyle pad 372 excludes the secondary bladder from the interior opening and substitutes an interior void space 374 therefor. Accordingly, the pad 372 contains only one bladder, i.e., the primary bladder 352. Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.

Claims: WHAT IS CLAIMED IS: 1. An apparatus for measuring a treatment force exerted by a contact pad of an orthopedic brace upon the joint of a wearer, the apparatus comprising: an analog pad having approximately the same thickness as the contact pad, the analog pad being configured and adapted to be substituted for the contact pad or otherwise interposed between the orthopedic brace and the joint of the wearer; and a force or pressure sensor in operative communication with the analog pad for sensing the force or pressure exerted by the analog pad on the joint. 2. The apparatus of Claim 1, wherein the analog pad comprises a fluid-filled bladder and wherein the force or pressure sensor comprises a fluid pressure sensor in fluid communication with the bladder. 3. The apparatus of Claim 2, wherein the analog pad comprises a port for fluid communication with the fluid pressure sensor. 4. The apparatus of Claim 3, further comprising a stopcock having a first fitting connected to the fluid- filled bladder, a second fitting connected to the fluid pressure sensor, and a third fitting adapted to connect to a pump, the stopcock being adjustable to selectively permit fluid communication between the first fitting and the second fitting, or between the first fitting, the second fitting and the third fitting. 5. The apparatus of Claim 1, wherein the analog pad comprises a resilient foam or pneumatic pad and wherein the force or pressure sensor comprises a pressure transducer in operative association with the analog pad. 6. The apparatus of Claim 1, further comprising a display for indicating the magnitude of a force corresponding to the pressure or force sensed by the force or pressure sensor. 7. A method for fitting an orthopedic knee brace to a patient using the measuring apparatus of Claim 1 comprising the following steps: applying the brace to the knee of the patient, the brace being configured to accommodate insertion of a contact pad having a first thickness between the brace and the patient's knee; inserting the analog pad having a second thickness approximately equal to the first thickness between the brace and the patient's knee; and measuring the force or pressure exerted by the analog pad on the patient's knee; whereby the knee brace and/or the contact pad can be adjusted to provide a desired treatment force or pressure to the patient's knee. 8. The method of Claim 7, wherein the analog pad comprises a fluid-filled bladder and wherein the force or pressure is measured using a fluid pressure sensor in fluid communication with the bladder. 9. The method of Claim 8, wherein the analog pad further comprises a port for fluid communication with the fluid pressure sensor. 10. The method of Claim 7, wherein the analog pad comprises a resilient foam or pneumatic pad and wherein the force or pressure sensor comprises a pressure transducer in operative association with the analog pad. 11. The method of Claim 7, further comprising the step, after measuring the force or pressure exerted by the analog pad on the patient's knee, of substituting the contact pad for the analog pad in the knee brace, whereby the contact pad exerts a force or pressure substantially equal to the measured force or pressure. 12. The measuring apparatus of Claim 1 in combination with an orthopedic brace, comprising: a brace frame adapted to be worn by a wearer to brace a bodily structure; a contact pad comprising the analog pad secured relative to the brace frame and adapted to exert a force upon the bodily structure; and the force or pressure sensor being provided in operative association with the contact pad and the brace frame, and adapted to measure the magnitude of the force or pressure exerted by the contact pad upon the bodily structure. 13. The orthopedic brace of Claim 12, wherein the contact pad comprises a fluid-filled bladder. 14. The orthopedic brace of Claim 13, wherein the orthopedic brace is a knee brace adapted to be fitted to a human knee. 15. The orthopedic brace of Claim 13, further comprising a stopcock having a first fitting connected to the fluid-filled pad, a second fitting connected to a fluid-pressure sensor, and a third fitting adapted to connect to a pump, the stopcock being adjustable to selectively permit fluid communication between the first fitting and the second fitting, or between the first fitting, the second fitting and the third fitting.

Inventors: ERWIN ALEXIS L, PFLASTER DANIEL S, ERWIN, ALEXIS, L., PFLASTER, DANIEL, S.
Applicants: DJ ORTHOPEDICS LLC, DJ ORTHOPEDICS, LLC
Application year: 2000
Main classification: A61F5
IPC codes: A61F5