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Design Innovation Paper

New Adjustable Unloader Knee Brace and Its Effectiveness OPEN ACCESS

[+] Author and Article Information
Gajendra Hangalur, Ryan Bakker, Naveen Chandrashekar

Mechanical and Mechatronics Engineering,
University of Waterloo,
Waterloo, ON N2 L 3G1, Canada
e-mail: nchandra@uwaterloo.ca

Sebastian Tomescu

Sunnybrook Health Sciences Centre,
University of Toronto,
43 Wellesley Street East,
Toronto, ON M4Y 1H1, Canada

Manuscript received November 8, 2016; final manuscript received October 16, 2017; published online November 22, 2017. Assoc. Editor: Elizabeth Hsiao-Wecksler.

J. Med. Devices 12(1), 015001 (Nov 22, 2017) (5 pages) Paper No: MED-16-1357; doi: 10.1115/1.4038439 History: Received November 08, 2016; Revised October 16, 2017

Unloader knee braces are prescribed for patients with unicompartmental osteoarthritis of the knee. These braces aim to reduce pain in patients by applying a coronal moment to the knee to unload the symptomatic knee compartment. However, existing unloading mechanisms use straps that go directly behind the knee joint, to apply the needed moment. This can impinge on the popliteal artery and peroneal nerves thereby causing discomfort to the patient. Hence, these braces cannot be worn for prolonged periods of time. This research focused on developing a new knee brace to improve comfort while unloading the osteoarthritic knee. A new knee brace was developed that uses a four-point bending approach to unload the knee. In this brace, unloading can be adjusted, and the unloading mechanism is away from the joint. The new brace was tested on a cadaver specimen to quantify its capability to unload the knee compartment. The brace was also worn by a patient with osteoarthritis who subjectively compared it to his existing unloader brace. During cadaver testing, the new brace design could reduce the force exerted on the medial condyle by 25%. Radiographic images of the patient's knee confirmed that the brace unloaded the medial condyle successfully. The patient reported that the new brace reduced pain, was significantly comfortable to wear and could be used for a longer duration in comparison to his existing brace.

FIGURES IN THIS ARTICLE
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Osteoarthritis is a common joint disease that results in degeneration of cartilage in the joint. Knee osteoarthritis is common among elderly patients. Studies suggest that about 6% of individuals older than 30 yr suffer from osteoarthritis of the knee [1]. In many cases, the disease affects only one condyle of the knee, usually the medial condyle, as most of the joint load during the stance phase of the gait is transmitted through the medial condyle of the knee [2,3]. Such pattern of arthritis is termed unicompartmental osteoarthritis.

Joint replacement surgery is a treatment option for knee osteoarthritis. However, in some cases, when surgery is not feasible or when the arthritis changes are mild, unloader knee braces are prescribed as a nonsurgical treatment for unicompartmental osteoarthritis. In cases of medial compartment osteoarthritis, the unloader brace applies an external valgus moment to the knee, unloading the medial compartment and thereby reducing the contact pressure. This unloading reduces the pain associated with osteoarthritis during weight bearing conditions [46]. Most existing unloader brace designs apply valgus moment using a three-point bending mechanism accomplished through two distinctive designs. The first design uses a force strap that wraps around the posterior aspect of the joint. However when tightened, this strap can cause discomfort to the patient as it interferes with the blood circulation in the popliteal artery and applies pressure on the peroneal nerve in the posterior aspect of the knee [79]. Since tightening of this strap is essential for unloading, the patient may experience discomfort wearing the brace for acute and prolonged lengths of time. Squyer et al. reported that about 60% of the patients discontinue the use of unloader braces due to this discomfort [10]. The second design uses a condylar pad to apply force against the lateral condyle resulting in condylar pain and discomfort during prolonged use [11].

The aim of the current research was, (i) to design a new unloader knee brace that applies adjustable valgus moment without the use of force straps behind the knee or condylar pads, (ii) to quantify the effectiveness of this brace in unloading the medial compartment using in vitro approach, and (iii) to test the effectiveness and comfort of the new design on a patient with unicompartmental osteoarthritis of the knee.

Brace Design.

The research was approved by the Office of Research Ethics at the University of Waterloo. A new adjustable unloader knee brace was designed and fabricated (Fig. 1). The new brace uses upright bars on the lateral side of the knee. The uprights are connected using a polycentric mechanical joint assembly. Both the tibial and femoral uprights are embedded in a rigid thermoplastic case that covers the front portion of thigh and shank. These cases have a pair of Velcro straps that can be secured across the thigh and the shank. The thermoplastic cases are padded with foam for comfort.

Each of the femoral and tibial uprights is in-fact made of two separate uprights; inner and outer uprights (Fig. 2). Inner uprights are connected to the polycentric joint, while the outer uprights are connected to the inner uprights through a floating hinge joint and held together using a spring plate and lever arm. The lever arm is secured to the outer upright and is connected to the inner upright through a setscrew. This arrangement allows for adjustment of the tilt between the inner and outer uprights by adjusting a pair of setscrews on the lever arm. The spring plate provides axial compressive forces to stabilize the floating hinge joint so that it does not disengage when the uprights are tilted. All major parts of the brace are custom made. The custom thermoplastic casing and straps were made by a professional brace manufacturer (Karl-Hager Limb and Brace, Edmonton, AB, Canada). Additional views and dimensions of the design are shown in Fig. 3.

The brace is mounted on the knee with the uprights set to the straight position (Fig. 4(a)) and straps are tightened. The setscrews of the uprights are then turned, tilting the outer uprights laterally (Fig. 4(b)). Since the outer uprights are embedded into the rigid thermoplastic case, the case tilt too. This will apply a couple moment to the thigh and the shank. Close to the knee joint, the lateral femoral and tibial cases push medially (Fig. 5(a)—dashed arrows). Away from the knee joint, the medial side of the cases pushes laterally (Fig. 5(a)—solid arrows). This creates a couple of moment which tries to put the knee into the valgus position, unloading the medial compartment.

Figure 5 shows that this brace uses four-point bending principle instead of the three-point bending mechanism used in most unloader braces. Further, the unloading mechanism is away from the knee joint. It is worthwhile to note that no strap passes behind the knee joint, and pressure is not applied to the lateral knee joint by the condylar pad. All the straps are 7.5–10 cm away from the knee joint. Each turn of the setscrew changes the orientation of the brace by 1.7 deg when unloaded. The setscrews can also change the applied valgus moment between 0 and 10 N·m; the same range applied in a commercially available knee brace [4].

Cyclic Testing.

Before testing the design on a live subject, a reliability test was performed to ensure the safety and integrity of the structure. A custom-made slider-crank mechanism (Fig. 6) driven by a 1.43 KW servo motor was used to cycle the upright-joint-upright structure seen in Fig. 2, between 0 deg and 90 deg of flexion and extension. The jig held the outer uprights using pin joints at either end. The setscrews of the lever arm were tightened so that valgus moment of 10 N·m was applied. The test was run for 100,000 cycles (equivalent to about 2 months of 1500 steps/day) at 0.5 Hz.

In Vitro Testing.

The effectiveness of the new brace in unloading the medial compartment was tested using a cadaver model. A cadaver knee specimen was prepared for brace testing as explained in Hangalur et al. [12]. Briefly, a fresh frozen cadaver knee (48-yr-old male) with no record or signs of injuries to soft tissues, cartilage, and bone was selected for the study. The knee was dissected and cast in a foam material that has similar stiffness as stiffened muscle. The cadaver specimen was mounted on dynamic knee simulator as explained in Cassidy et al. [13], and a Tekscan K-scan pressure sensor (Tekscan, Inc., South Boston, MA) was inserted between the medial femoral condyle and the tibial plateau, by an orthopaedic surgeon (author ST). A compressive force of 580 N (body weight of the donor) was applied to the specimen to simulate weight-bearing during standing. The force distribution on the medial condyles of the joint was recorded without the brace and with the new brace set to maximum unloading effect (setscrews fully tightened).

In Vivo Testing.

A 62-yr old male subject (body mass of 230 lb) with medial compartment osteoarthritis of the right knee was recruited for qualitative analysis of the new brace. Informed consent was obtained from the subject. The subject was using a commercially available unloader brace with three-point bending mechanism, (Neutralizer, Karl-Hager Limb and Brace, Edmonton, AB, Canada) at the commencement of the test. A custom fit brace was manufactured for the subject using the new design. He was asked to wear the new brace while performing activities of daily living for 1 month with a moderate level of unloading. The new brace was then readjusted to the maximum level of unloading for the next month. He was interviewed every 2 weeks to obtain feedback on comfort levels and pain reduction.

At the end of the second month, X-rays of the subject's knee in the coronal plane were taken under the weight bearing and nonweight bearing conditions, with and without the new brace. On the X-ray images, lines were drawn tangential to the condylar surfaces, and the angle between the tibial and femoral condyles for both the conditions was calculated by an orthopaedic surgeon (author ST).

No noticeable deformation or wear in the joint components was observed after 100,000 cycles. Therefore, the brace was deemed safe to be used on the live subject for the intended duration of testing (about 2 months). The Tekscan sensor pressure distribution plots from the cadaver specimen are shown in Fig. 7. Since about 83% of the load is transferred through the medial condyles during the stance phase [3], it was estimated that approximately 480 N was transferred through the medial condyle without the brace. Once the brace was mounted, the Tekscan results showed that the total load on the medial condyle was reduced by about 25% to about 360 N. Counting the sensels in the Tekscan pressure map reading greater than 4.2 N force revealed that areas with peak loads were reduced by about 85%.

The opinion from the test subject during the periodic interviews indicated that the new brace substantially reduced pain during gait in comparison to his existing unloader brace. Additionally, the patient commented that the newly designed brace was more comfortable, could be used for longer periods of time and resulted in a better knee position during gait in comparison to his existing unloader brace. Radiographs of the patient's knee reveal that under the nonweight bearing condition, valgus moment applied by the brace opens up the joint space on the medial side (Fig. 8). The angle between the condyles in the unbraced state was 5.6 deg, while under the braced condition it was 2.4 deg. There was no measurable condylar separation while wearing the brace under load bearing condition.

Unloader knee braces are widely used. Most of the designs commercially available use a three-point bending principle and cross-strap mechanism of unloading. Several reports have noted the effectiveness of unloader braces on pain reduction in the unicompartmental osteoarthritic knee [3,4]. The primary difference between the existing braces and the new brace presented here is the ability to apply various amounts of valgus moment to the knee without using the cross-strap that goes directly behind the joint. The new brace uses a four-point bending mechanism to apply valgus moment. This moves the point of load application away from the sensitive joint line, toward the muscular thigh and shank areas. Further, the brace is adjustable so that a varying amount of valgus moment could be applied according to patients' comfort level. While a four-point loading mechanism is used in some of the existing ligament braces (in the anterio-posterior direction) [14,15], no existing osteoarthritis braces use it. Our results show that the newly designed brace reduced the load on the medial compartment by 25% during weight-bearing. Also, the brace was reported to be much more comfortable to wear.

In existing designs, patients who need a large valgus moment (such as those with a larger body weight) require the cross-strap to be tightened to a high degree to produce the required valgus moment. This results in pressure on the popliteal artery and peroneal nerves of the knee, preventing prolonged usage of the brace. The new mechanism presented here eliminates the need for this strap. Rather, the only straps used here are the horizontal straps that secure the brace to the leg, thus allowing large moments to be applied to the knee. This explains why our patient experienced greater pain reduction in our brace compared to his existing brace. Since he was a heavy individual, unloading the medial condyle using the existing brace required him to overly tighten the cross-strap behind the knee joint. This caused him great discomfort, resulting in him under tightening and wearing it for shorter periods of time. Using the new brace, we could apply as much as 10 N·m moment on his knee without causing him great discomfort. Therefore, he not only experienced greater pain reduction, but also longer wear-ability.

Since the new design has extra joints in the upper and lower uprights compared to existing designs, and applied large moments, it was necessary that the reliability and safety of the device be established so that it could be tested on a subject. Therefore, the joint was cycled for 100,000 cycles at extreme loading and flexion (10 N·m moment, 90 deg flexion) to see if any early failures would occur. Since no failure or permanent damage was observed, the brace was deemed safe and reliable mechanically for the period of intended testing (about 2 months) on the subject who walks roughly 30,000 steps daily (1500 steps with the braced leg).

The primary objective of these braces is to apply sufficient valgus moment to unload the medial condyle under weight-bearing. To experimentally ascertain this, an in vitro approach was used. Our results show 25% decrease in the medial contact force due to the brace. While this does not seem like much, it is consistent with the maximum amount of unloading expected by the existing braces as measured by Kutzner et al. [3], using instrumented knee implants in in vivo subjects. The contour plots from the pressure sensor not only show a reduction in contact forces but also a reduction in areas with high pressure. This explains why patients report a reduction in pain while wearing OA braces.

To assess the mechanical effect of the brace, X-rays of weight bearing and nonweight bearing, braced and unbraced scenarios were taken under the supervision of an orthopedic surgeon. While radiographs in nonweight bearing condition clearly show increased medial compartment separation due to the brace, X-rays from the weight bearing scenario showed no evident medial compartment separation. This observation remains consistent with the results of cadaver testing, wherein the medial condyles were observed to be in contact during the weight-bearing braced condition. The magnitude of the joint separation attained in our case was about 3.2 deg. This magnitude is consistent with results obtained by Dennis et al. [5]. A much larger moment (about 50 N·m) would be needed to completely separate the condyles under load bearing, and it is neither mechanically feasible nor safe to apply such large moments to the knee. Kutzner et al. stated that it is unreasonable to expect a greater than 25% unloading due to the physiological tolerance of the subject to valgus moments [3].

An adjustable osteoarthritis knee brace that uses a new mechanism to apply valgus moment was designed. The new design eliminates the need for straps crossing behind the knee joint and pressure applied to condylar pads. Cadaveric testing indicated that the brace reduced the loads on the medial condyle by 25%. Patient testing of the brace indicated that the brace reduced pain and was comfortable to wear, allowing it to be worn for longer durations. A long-term follow-up study, with a formal survey, on a wider population using gait analysis and motion capture techniques is needed to ascertain the preliminary results of this pilot study.

The study was supported by Deep Creek Precision Manufacturing (Crysler, ON, Canada) and Karl Hager Limb and Braces (Edmonton, AB, Canada).

  • Natural Sciences and Engineering Research Council of Canada (Grant No. 448129-13).
  • Ontario Centres of Excellence (Grant No. 22865).

Felson, D. T. , Lawrence, R. C. , Dieppe, P. A. , Hirsch, R. , Helmick, C. G. , Jordan, J. M. , Kington, R. S. , Lane, N. E. , Nevitt, M. C. , Zhang, Y. , Sowers, M. , McAlindon, T. , Spector, T. D. , Poole, A. R. , Yanovski, S. Z. , Ateshian, G. , Sharma, L. , Buckwalter, J. A. , Brandt, K. D. , and Fries, J. F. , 2000, “ Osteoarthritis: New Insights. Part 1: The Disease and Its Risk Factors,” Ann. Intern. Med., 133(8), pp. 635–646. [CrossRef] [PubMed]
Shelburne, K. B. , Torry, M. R. , and Pandy, M. G. , 2005, “ Muscle, Ligament, and Joint-Contact Forces at the Knee During Walking,” Med. Sci. Sports Exercise, 37(11), pp. 1948–1956. [CrossRef]
Kutzner, I. , Kuther, S. , Heinlein, B. , Dymke, J. , Bender, A. , Halder, A. , and Bergmann, G. , 2011, “ The Effect of Valgus Braces on Medial Compartment Load of the Knee Joint—In Vivo Load Measurements in Three Subjects,” J. Biomech., 44(7), pp. 1354–1360. [CrossRef] [PubMed]
Pollo, F. E. , Otis, J. C. , Backus, S. I. , Warren, R. F. , and Wickiewicz, T. L. , 2002, “ Reduction of Medial Compartment Loads With Valgus Bracing of the Osteoarthritic Knee,” Am. J. Sports Med., 30(3), pp. 414–421. [CrossRef] [PubMed]
Dennis, D. A. , Komistek, R. D. , Nadaud, M. C. , and Mahfouz, M. , 2006, “ Evaluation of Off-Loading Braces for Treatment of Unicompartmental Knee Arthrosis,” J. Arthroplasty, 21(4), pp. 2–8. [CrossRef] [PubMed]
Finger, S. , and Paulos, L. E. , 2002, “ Clinical and Biomechanical Evaluation of the Unloading Brace,” J. Knee Surg., 15(3), pp. 155–159. [PubMed]
Edwards, P. H. , Wright, M. L. , and Hartman, J. F. , 2005, “ A Practical Approach for the Differential Diagnosis of Chronic Leg Pain in the Athlete,” Am. J. Sports Med., 33(8), pp. 1241–1249. [CrossRef] [PubMed]
Englund, J. , 2005, “ Chronic Compartment Syndrome: Tips on Recognizing and Treating,” J. Fam. Pract., 54(11), pp. 955–960. [PubMed]
McCrory, P. , Bell, S. , and Bradshaw, C. , 2002, “ Nerve Entrapments of the Lower Leg, Ankle and Foot in Sport,” Sport Med., 32(6), pp. 371–391. [CrossRef]
Squyer, E. , Stamper, D. L. , Hamilton, D. T. , Sabin, J. A. , and Leopold, S. S. , 2013, “ Unloader Knee Braces for Osteoarthritis: Do Patients Actually Wear Them?,” Clin. Orthop. Relat. Res., 471(6), pp. 1982–1991. [CrossRef] [PubMed]
Draganich, L. , Reider, B. , Rimington, T. , Piotrowski, G. , Mallik, K. , and Nasson, S. , 2006, “ The Effectiveness of Self-Adjustable Custom and Off-the-Shelf Bracing in the Treatment of Varus Gonarthrosis,” J. Bone Jt. Surg. Am., 88(12), pp. 2645–2652.
Hangalur, G. , Brenneman, E. , Nicholls, M. , Bakker, R. , Laing, A. , and Chandrashekar, N. , 2016, “ Can a Knee Brace Reduce the Strain in the Anterior Cruciate Ligament? A Study Using Combined In Vivo/In Vivo Method,” Prosthet. Orthot. Int., 40(3), pp. 349–399. [CrossRef]
Cassidy, K. , Hangalur, G. , Sabharwal, P. , and Chadrashekar, N. , 2013, “ Combined In Vivo/In Vivo Method to Study Anteriomedial Bundle Strain in the Anterior Cruciate Ligament Using a Dynamic Knee Simulator,” ASME J. Biomech. Eng., 135(3), p. 035001. [CrossRef]
Ramsey, D. K. , Briem, K. , and Axe, M. J. , 2007, “ A Mechanical Hypothesis for the Effectiveness of Knee Bracing for Medial Compartment Knee Osteoarthritis,” J. Bone Jt. Surg. Am., 89(11), pp. 2398–2407.
Birmingham, T. B. , Bryant, D. M. , Giffin, J. R. , Litchfield, R. B. , Kramer, J. F. , Donner, A. , and Fowler, P. J. , 2008, “ A Randomized Controlled Trial Comparing the Effectiveness of Functional Knee Brace and Neoprene Sleeve Use After Anterior Cruciate Ligament Reconstruction,” Am. J. Sports Med., 36(4), pp. 648–655. [CrossRef] [PubMed]
Copyright © 2018 by ASME
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References

Felson, D. T. , Lawrence, R. C. , Dieppe, P. A. , Hirsch, R. , Helmick, C. G. , Jordan, J. M. , Kington, R. S. , Lane, N. E. , Nevitt, M. C. , Zhang, Y. , Sowers, M. , McAlindon, T. , Spector, T. D. , Poole, A. R. , Yanovski, S. Z. , Ateshian, G. , Sharma, L. , Buckwalter, J. A. , Brandt, K. D. , and Fries, J. F. , 2000, “ Osteoarthritis: New Insights. Part 1: The Disease and Its Risk Factors,” Ann. Intern. Med., 133(8), pp. 635–646. [CrossRef] [PubMed]
Shelburne, K. B. , Torry, M. R. , and Pandy, M. G. , 2005, “ Muscle, Ligament, and Joint-Contact Forces at the Knee During Walking,” Med. Sci. Sports Exercise, 37(11), pp. 1948–1956. [CrossRef]
Kutzner, I. , Kuther, S. , Heinlein, B. , Dymke, J. , Bender, A. , Halder, A. , and Bergmann, G. , 2011, “ The Effect of Valgus Braces on Medial Compartment Load of the Knee Joint—In Vivo Load Measurements in Three Subjects,” J. Biomech., 44(7), pp. 1354–1360. [CrossRef] [PubMed]
Pollo, F. E. , Otis, J. C. , Backus, S. I. , Warren, R. F. , and Wickiewicz, T. L. , 2002, “ Reduction of Medial Compartment Loads With Valgus Bracing of the Osteoarthritic Knee,” Am. J. Sports Med., 30(3), pp. 414–421. [CrossRef] [PubMed]
Dennis, D. A. , Komistek, R. D. , Nadaud, M. C. , and Mahfouz, M. , 2006, “ Evaluation of Off-Loading Braces for Treatment of Unicompartmental Knee Arthrosis,” J. Arthroplasty, 21(4), pp. 2–8. [CrossRef] [PubMed]
Finger, S. , and Paulos, L. E. , 2002, “ Clinical and Biomechanical Evaluation of the Unloading Brace,” J. Knee Surg., 15(3), pp. 155–159. [PubMed]
Edwards, P. H. , Wright, M. L. , and Hartman, J. F. , 2005, “ A Practical Approach for the Differential Diagnosis of Chronic Leg Pain in the Athlete,” Am. J. Sports Med., 33(8), pp. 1241–1249. [CrossRef] [PubMed]
Englund, J. , 2005, “ Chronic Compartment Syndrome: Tips on Recognizing and Treating,” J. Fam. Pract., 54(11), pp. 955–960. [PubMed]
McCrory, P. , Bell, S. , and Bradshaw, C. , 2002, “ Nerve Entrapments of the Lower Leg, Ankle and Foot in Sport,” Sport Med., 32(6), pp. 371–391. [CrossRef]
Squyer, E. , Stamper, D. L. , Hamilton, D. T. , Sabin, J. A. , and Leopold, S. S. , 2013, “ Unloader Knee Braces for Osteoarthritis: Do Patients Actually Wear Them?,” Clin. Orthop. Relat. Res., 471(6), pp. 1982–1991. [CrossRef] [PubMed]
Draganich, L. , Reider, B. , Rimington, T. , Piotrowski, G. , Mallik, K. , and Nasson, S. , 2006, “ The Effectiveness of Self-Adjustable Custom and Off-the-Shelf Bracing in the Treatment of Varus Gonarthrosis,” J. Bone Jt. Surg. Am., 88(12), pp. 2645–2652.
Hangalur, G. , Brenneman, E. , Nicholls, M. , Bakker, R. , Laing, A. , and Chandrashekar, N. , 2016, “ Can a Knee Brace Reduce the Strain in the Anterior Cruciate Ligament? A Study Using Combined In Vivo/In Vivo Method,” Prosthet. Orthot. Int., 40(3), pp. 349–399. [CrossRef]
Cassidy, K. , Hangalur, G. , Sabharwal, P. , and Chadrashekar, N. , 2013, “ Combined In Vivo/In Vivo Method to Study Anteriomedial Bundle Strain in the Anterior Cruciate Ligament Using a Dynamic Knee Simulator,” ASME J. Biomech. Eng., 135(3), p. 035001. [CrossRef]
Ramsey, D. K. , Briem, K. , and Axe, M. J. , 2007, “ A Mechanical Hypothesis for the Effectiveness of Knee Bracing for Medial Compartment Knee Osteoarthritis,” J. Bone Jt. Surg. Am., 89(11), pp. 2398–2407.
Birmingham, T. B. , Bryant, D. M. , Giffin, J. R. , Litchfield, R. B. , Kramer, J. F. , Donner, A. , and Fowler, P. J. , 2008, “ A Randomized Controlled Trial Comparing the Effectiveness of Functional Knee Brace and Neoprene Sleeve Use After Anterior Cruciate Ligament Reconstruction,” Am. J. Sports Med., 36(4), pp. 648–655. [CrossRef] [PubMed]

Figures

Grahic Jump Location
Fig. 1

The new adjustable unloader brace. “U” are the uprights, P is the polycentric joint, and “T” are the thermoplastic cases for thigh and shank.

Grahic Jump Location
Fig. 2

New adjustable knee brace upright link. Assembly components: (1) thermoplastic case, (2) outer upright, (3) spring plate, (4) floating hinge, (5) lever arm, (6) set screw, (7) inner upright, and (8) polycentric joint

Grahic Jump Location
Fig. 3

Additional views of the assembly: (a) medial, (b) sagittal, and (c) lateral views. All dimensions are in millimeter.

Grahic Jump Location
Fig. 4

Unloader mechanism: (a) straight position and (b) unloaded position

Grahic Jump Location
Fig. 5

(a) Frontal, (b) sagittal, and (c) backside view of the newly designed brace. The arrows in (a) show the direction of the forces applied by the rigid case on the leg. “S” are the straps.

Grahic Jump Location
Fig. 6

Cyclic testing machine: (1) brace linkage, (2) and (3) slider crank mechanism, and (4) tester frame

Grahic Jump Location
Fig. 7

Tekscan pressure distribution plot of cadaver knee with 580 N compressive load: (a) without brace, indicating 480 N force in the medial condyle and (b) with brace, showing 360 N through the medial condyle. P, posterior; L, lateral. Each sensel is 1.29 mm2.

Grahic Jump Location
Fig. 8

X-rays of unbraced (a) and braced (b) knee under nonweight bearing condition. The dark lines show the change in angle between the condylar surfaces.

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