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Original Research Articles

Improvements in Function and Strength with Decompressive Bracing of the Osteoarthritic Knee

Lamberg, Eric M. EdD, PT; Streb, Robert PhD, PT; Werner, Marc CPO; Kremenic, Ian J. MEng; Penna, James MD

Author Information
Journal of Prosthetics and Orthotics: October 2016 - Volume 28 - Issue 4 - p 173-179
doi: 10.1097/JPO.0000000000000104
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Abstract

Knee osteoarthritis (OA) is a common progressive joint disease1 characterized by pain, loss of motion, diminished strength, and gait and balance alterations.2–4 These impairments commonly reduce an individual's activity,1 participation in society, and quality of life (QoL).5,6 Standard practice when treating knee OA typically involves exercise in combination with use of analgesic and anti-inflammatory agents, progressing to joint injections and eventually surgery.7

An additional method of treatment for knee OA is the use of a knee brace designed to alter the forces acting at the knee thereby decompressing the degenerating joint compartment during weight bearing. However, despite data on these braces confirming the biomechanical benefits8–22 and role in mediating pain and improving function and QoL,4,11,14,23,24 practitioners are slow to turn to this resource in the management of knee OA.25 Most likely, this is due to a lack of appropriate studies and conflicting evidence on their effects.4 The 2013 American Academy of Orthopaedic Surgeons osteoarthritis guidelines rate the quality of evidence supporting the routine use of valgus directing force braces as “inconclusive.” According to the guidelines, “An inconclusive recommendation means that there is a lack of compelling evidence that has resulted in an unclear balance between benefits and potential harm.”26 However, in 2014, guidelines were published from the Osteoarthritis Research Society International supporting biomechanical interventions with a recommendation of “appropriate,” although the quality of evidence was only rated as “Fair.”27 Further, recent meta-analyses and systematic reviews have determined that there are at least moderate positive effects sizes reported when using valgus bracing in the areas of pain, function, and biomechanical outcomes.28,29 Clearly, there is a debate regarding their use, and thus additional, well-designed studies are needed to inform practitioners regarding efficacy of decompressive bracing in knee OA.

Further, there is a common belief that prolonged use of a knee brace produces disuse muscle atrophy. In the arthritic knee, the presence of pain, in and of itself, reduces knee strength partly due to neural inhibition linked to the presence of joint swelling, inflammation, and damage to the structural integrity of the joint.30 Few investigations have systematically looked at whether the use of decompressive bracing for knee OA helps or hinders neuromuscular function. If the use of a brace decreases pain and symptoms, then individuals will be able to participate in functional activities, thereby improving neuromuscular function. There is limited support on the statement that the use of a knee brace can positively alter the muscle activation pattern during gait.31 Further, the findings from three studies that investigated decompressive knee bracing15,32,33 suggest that after use there is either no change or an improvement in knee strength—not a decrement.

Potentially, reducing pain and symptoms and improving knee strength can lead to improved gait and balance and reduced disability for those with knee OA.34,35 The primary purpose of this study was to systematically investigate if the Rebel Reliever decompressive knee brace (Townsend Design, Bakersfield, CA, USA) alters knee strength, walking endurance, balance abilities, perception of pain, symptoms, activities of daily living (ADLs), and QoL during 6 months of use.

METHODS

Individuals with diagnosed knee OA between the ages of 35 and 70 were recruited. Inclusion criteria were presence of unilateral, medial, or lateral compartment OA of the knee diagnosed by an orthopedic physician and classified on the Kellgren-Lawrence scale.36 Specific exclusion criteria included cardiac or pulmonary disease that limits the ability to walk; presence of hip, ankle, foot, or contralateral knee OA; surgical procedure in either leg within the past 6 months; or the presence of other lower-limb pathology that limits the ability to walk. All participants received a prescription for the brace and provided informed written consent. This study was approved by the institutional review board of Stony Brook University. The trial was registered as “Effects of Bracing on Knee Osteoarthritis” with ClincalTrials.gov identifier number NCT01886144.

STUDY DESIGN

Participants were assessed at baseline and subsequently fit with the Rebel Reliever (Townsend Design, Bakersfield, CA, USA) decompressive knee brace to be worn throughout the study period of 6 months. Participants attended 4 sessions—baseline, brace fitting, 2 weeks after brace fitting (post), and 8 weeks after brace fitting (final). In addition, participants completed mail-in surveys 3 months and 6 months after brace fitting. At baseline, participants were measured for the knee brace and completed a 6-minute walk test (6MWT), a balance assessment, knee strength testing, and two different patient report outcome measures. One week after baseline, participants returned and were fitted with the knee brace by a certified orthotist. The Rebel Reliever (Figure 1) is a rigid type of brace that consists of a thigh shell and a calf shell attached by adjustable medial and lateral uprights that allow for the alteration of the frontal plane alignment to impart a decompressive force on the affected compartment. Velcro strapping exists on both the anterior and posterior portions of the thigh and calf components to position and hold the brace on the limb. Valgus alignment was used for participants with medial compartment disease and varus alignment for those with lateral compartment disease. The orthotist taught the participant how to don and doff the brace and provided instructions to wear the brace for a minimum of 3 hours per day, emphasizing use when engaged in weight-bearing activities.

Figure 1
Figure 1:
Photo of the Rebel Reliever.

PHYSICAL OUTCOME MEASURES

Muscle function test, 6MWT, and balance assessment were performed at baseline, post, and final. Muscle performance of the knee flexor and extensors on the osteoarthritic side was assessed using a Biodex System 3 isokinetic dynamometer (Biodex Medical Systems, Ronkonkoma, NY, USA) at 60° per second for a set of six repetitions. Participants sat with 90° of hip and knee flexion, and the axis of the dynamometer was aligned with the center of the anatomical knee joint. Before testing, participants became acclimated to the task by performing 2 submaximal and 2 maximal repetitions. The average power generated for extension (power-ext) and flexion (power-flex) and the average peak torque normalized to body weight (ft lb/lb × 100) produced for extension (torque-ext) and flexion (torque-flex) were calculated for the 6 repetitions.

The 6MWT requires participants to walk as far as they could in 6 minutes and was completed to assess overground functional mobility and walking capacity.37 The 6MWT is a performance-based measure used in those with knee OA.38,39 In a recent study, the 6MWT demonstrated the smallest measurement error of outcome measures for assessing people with knee OA.40 In the current study, the 6MWT was performed without the knee brace at baseline. At post and final, the knee brace was worn. The distance walked was recorded in feet and converted to meters.

Static and dynamic balance abilities were assessed using the BioSway (Biodex Medical Systems, Shirley, NY, USA). Static balance abilities were assessed by using the modified clinical test of sensory integration in balance (CTSIB). During the CTSIB, participants stood on the BioSway platform with feet-shoulder width apart and the amount of postural sway was quantified as participants remained as still as possible for 20 seconds under 4 conditions: eyes open (EO), eyes closed (EC), eyes open while standing on foam (EO-F), and eyes closed while standing on foam (EC-F). Dynamic balance abilities were assessed using the limits of stability test (LOS). During the LOS, participants stood on the BioSway platform with feet-shoulder width apart and weight being directed through a centrally displayed target on a computer screen. Without moving their feet, participants shifted their weight from the center position as quickly and with as little deviation as possible to various targets. The BioSway generates a proprietary LOS score based on the participant's accuracy and speed in moving from target to target. At baseline, balance was assessed without the use of the brace. At post and final, balance was assessed both with (post brace; final brace) and without the brace. The order of testing with or without the brace at post and final was counterbalanced.

PATIENT-REPORTED OUTCOMES

The Knee Osteoarthritis Outcomes Survey (KOOS) and the Activities-specific Balance Confidence (ABC) scale were given to the participants at baseline, post, final, 3 months, and 6 months. The KOOS is a reliable and valid tool for measuring outcomes in people living with knee OA.41,42 The KOOS assesses five dimensions: pain (frequency and severity), symptoms (stiffness, swelling, clicking, and motion restriction), difficulty during ADLs, difficulty during sport activity, and QoL. Items are scored on a 5-point (0–4) Likert scale and transformed onto a 0-to-100 scale where 0 = extreme problems and 100 = no problems.42 Because the study participants were not engaged in sport, we did not analyze this section. In addition, we calculated an average score (KOOS4) for each participant across the four dimensions. The ABC measures perceived ability to maintain balance during various functional activities.43,44 Scores range from 0 to 100, where higher scores indicate greater confidence in balance capabilities.

STATISTICAL ANALYSIS

Separate one-way repeated measures analyses of variance (ANOVAs) were used to detect differences in 6MWT, muscle power, and torque from baseline to post and final. To detect differences on the ABC and KOOS, baseline was compared with fitting, post, final, and 3- and 6-month follow-up. To detect differences in balance, a separate one-way ANOVA was used for each condition (EO, EC, EO-F, EC-F, and LOS) comparing baseline to post, final, post brace, and final brace. For all statistical tests, when significant, Bonferonni post hoc tests were performed. Significance was considered at P < 0.05.

RESULTS

Fifty-five individuals were screened for eligibility. Twenty-six individuals were enrolled, participated in baseline assessment, and received the knee brace. Seven participants were removed from the study; 3 participants reported difficulty putting the brace on and, although remediation was offered, chose not to wear it; and 4 participants reported a fall and injury unrelated to brace wear but as a result became limited in their ability to walk. Characteristics for the 19 participants that completed the testing protocol through final are included in Table 1. Sixteen participants (84%) returned the 3-month survey, and 14 (74%) returned the 6-month survey. Data from all 19 participants were used to analyze the 6MWT and balance assessments. Muscle function data were analyzed using 17 participants; one participant reported verbally that they were not pushing or pulling their best, and data on a second participant were excluded due to computer malfunction. Survey data were analyzed using the 14 participants that returned the surveys through the 6-month period.

Table 1
Table 1:
Participant characteristics (n = 19)

PHYSICAL OUTCOME MEASURES

The amount of knee extension and flexion muscle power and peak torque normalized to body weight differed significantly (P < 0.001 for all) throughout the study (Table 2). Post hoc analysis revealed a significant increase in both power and torque into knee extension and flexion at final when compared with that at baseline (P < 0.05 for all comparisons). In addition, there was a significant increase in power into knee extension and flexion when comparing post to baseline (P < 0.05).

Table 2
Table 2:
Data from 6MWT and strength testing

Distance covered during the 6MWT differed significantly (P < 0.001) throughout the study (Table 2). Post hoc analysis revealed a significant improvement in the mean 6MWT distance at post and final when compared with that at baseline (40.2 m and 68.0 m improvement, respectively, P < 0.001 for both) and when comparing distance at final to post (27.8 m, P = 0.007).

Overall, the use of the knee brace did not alter balance abilities (P > 0.05 for all) as measured through CTSIB (EO, EC, and EO-F) and LOS assessments (Table 3). Under all conditions of the CTSIB and during the LOS testing, balance assessment was similar to baseline testing with the exception of testing performed with EC-F. During EC-F, sway differed significantly (P < 0.05). Post hoc analysis revealed a significant reduction in sway during the EC-F condition at final when compared with baseline both when wearing the brace (final brace; P = 0.033) and in the no brace condition (final; P = 0.048).

Table 3
Table 3:
Data from balance testing (n = 19)

SURVEY MEASURES

Scores on the various dimensions of the KOOS, the KOOS4, and the ABC significantly differed (P < 0.001 for all) throughout the study (Table 4). Post hoc analysis revealed that scores did not significantly change (P > 0.05) from baseline to fitting, indicating that the baseline data were stable during the week before participants started using the brace. However, scores on the KOOS and ABC significantly improved at post, final, 3 months, and 6 months when compared with that at baseline (P < 0.01 for all).

Table 4
Table 4:
Data from patient report outcome measures (n = 14)

DISCUSSION

Decompressive braces are intended to modulate and dampen forces that otherwise are directed through the diseased compartment of the knee, thereby reducing pain and symptoms.

The results of this study support the concept that using a decompressive knee brace is beneficial for people with knee OA. Specifically, we found that through 2 months of brace use there is an increase in knee muscle strength and walking capacity. Further, we found that using a knee brace does not negatively affect one's balance abilities. Moreover, we found that after 6 months of brace use there were improvements with regard to pain reduction, symptom mitigation, ability to perform ADLs, reported balance confidence, and QoL.

In the presence of OA, people commonly present with knee muscle weakness when compared with the unaffected side and to healthy peers.32,45 Reduced knee muscle strength is associated with decreased function and QoL, and contributes to the progression of OA.30 We found in this study that using a knee brace for 2 months improved knee muscle strength. This is contrary to the notion that bracing results in disuse atrophy. However, in this case, the use of the decompressive knee brace resulted in a reduction in pain and symptoms, as supported through KOOS responses. This reduction in pain and symptoms allowed the participants to perform increased activity as supported through 6MWT distance and KOOS responses. Thus, we hypothesize that participants in this study were using their leg more and as a result increased knee muscle strength. Our results are similar to those found in a study by Cherian et al.32 that investigated quadriceps and hamstring muscle strength throughout the range of motion after 3 months of using an unloader type of brace. Subjects in that study demonstrated a 54% improvement in quadriceps strength and 28% improvement in hamstring strength. Further, in a study completed by Matsuno et al.,33 the mean isokinetic quadriceps strength improved 16% following 12 months of using an unloader type of brace. Here, we found a 22% improvement in quadriceps strength and a 48% improvement in hamstring strength. Contrary to these studies showing improvement in muscle strength, there is one recent study completed by Hurley et al.15 in which participants used an unloader brace for approximately 6 months. In this study, knee strength did not change; however, strength testing was completed only at static positions not through the range of motion.

In the present study, we demonstrated that through the use of the knee brace improvements in pain, symptoms, ADLs, and QoL were realized on the KOOS patient-reported outcome measure. The KOOS is a validated measure that has published minimal detectable change (MDC) scores. In this study, the change in KOOS score at 6 months when compared with baseline for pain (change in this study 21.6, MDC = 13.4), symptoms (16.9, MDC = 15.5), ADLs (20.6, MDC = 15.4), and QoL (19.6, MDC = 21.1) exceeded the published MDCs.41 Because the KOOS change score exceeded the MDC, we are more confident in suggesting that these changes were not due to measurement error and thus the participants improved in these domains as a result of using the brace.

As indicated by the results, we also demonstrated that as a result of using the brace, participants had a mean improvement in distance walked on the 6MWT at final when compared with that at baseline (68.0 m). As with the KOOS values, this change in distance capabilities exceeded published MDC values (66.3 m) for individuals with knee OA who were on a wait list for total knee arthroplasty.40 Because we did not provide any type of rehabilitation training, it is likely that the improvements in distance walked on the 6MWT are attributable to decreased pain and symptoms. Further, we were interested in assessing balance. As the results indicate, balance abilities did not change from baseline. However, participants did report that they were more confident in their balance capabilities when performing various activities. This, in addition to the reduction in pain and symptoms, may be attributable to why we found significant improvements in function.

CONCLUSIONS

Participants reported reduced pain, reduced symptoms, improved ADLs, and improved QoL. In addition, participants demonstrated improvements in knee muscle strength and walking capacity. Providing a decompressive knee brace to individuals with unicompartment knee OA may be beneficial and improve QoL.

REFERENCES

1. Cross M, Smith E, Hoy D, et al. The global burden of hip and knee osteoarthritis: estimates from the global burden of disease 2010 study. Ann Rheum Dis 2014;73(7):1323–1330.
2. Baert IA, Jonkers I, Staes F, et al. Gait characteristics and lower limb muscle strength in women with early and established knee osteoarthritis. Clin Biomech (Bristol, Avon) 2013;28(1):40–47.
3. Kaufman KR, Hughes C, Morrey BF, et al. Gait characteristics of patients with knee osteoarthritis. J Biomech 2001;34(7):907–915.
4. Brouwer RW, van Raaij TM, Verhaar JA, et al. Brace treatment for osteoarthritis of the knee: a prospective randomized multi-centre trial. Osteoarthritis Cartilage 2006;14(8):777–783.
5. Farr Ii J, Miller LE, Block JE. Quality of life in patients with knee osteoarthritis: a commentary on nonsurgical and surgical treatments. Open Orthop J 2013;7:619–623.
6. Guccione AA, Felson DT, Anderson JJ, et al. The effects of specific medical conditions on the functional limitations of elders in the Framingham Study. Am J Public Health 1994;84(3):351–358.
7. Hunter DJ. Osteoarthritis. Best Pract Res Clin Rheumatol 2011;25(6):801–814.
8. Lamberg EM, Streb R, Werner M, et al. The 2- and 8-week effects of decompressive brace use in people with medial compartment knee osteoarthritis. Prosthet Orthot Int 2016;40(4):447–453.
9. Segal NA. Bracing and orthoses: a review of efficacy and mechanical effects for tibiofemoral osteoarthritis. PM R 2012;4(5 Suppl):S89–S96.
10. Hewett TE, Noyes FR, Barber-Westin SD, Heckmann TP. Decrease in knee joint pain and increase in function in patients with medial compartment arthrosis: a prospective analysis of valgus bracing. Orthopedics 1998;21(2):131–138.
11. Kirkley A, Webster-Bogaert S, Litchfield R, et al. The effect of bracing on varus gonarthrosis. J Bone Joint Surg Am 1999;81(4):539–548.
12. Rannou F, Poiraudeau S. Non-pharmacological approaches for the treatment of osteoarthritis. Best Pract Res Clin Rheumatol 2010;24(1):93–106.
13. Pollo FE, Otis JC, Backus SI, et al. Reduction of medial compartment loads with valgus bracing of the osteoarthritic knee. Am J Sports Med 2002;30(3):414–421.
14. Gaasbeek RD, Groen BE, Hampsink B, et al. Valgus bracing in patients with medial compartment osteoarthritis of the knee. A gait analysis study of a new brace. Gait Posture 2007;26(1):3–10.
15. Hurley ST, Hatfield Murdock GL, Stanish WD, Hubley-Kozey CL. Is there a dose response for valgus unloader brace usage on knee pain, function, and muscle strength? Arch Phys Med Rehabil 2012;93(3):496–502.
16. Kutzner I, Kuther S, Heinlein B, et al. The effect of valgus braces on medial compartment load of the knee joint—in vivo load measurements in three subjects. J Biomech 2011;44(7):1354–1360.
17. Schmalz T, Knopf E, Drewitz H, Blumentritt S. Analysis of biomechanical effectiveness of valgus-inducing knee brace for osteoarthritis of knee. J Rehabil Res Dev 2010;47(5):419–429.
18. Toriyama M, Deie M, Shimada N, et al. Effects of unloading bracing on knee and hip joints for patients with medial compartment knee osteoarthritis. Clin Biomech (Bristol, Avon) 2011;26(5):497–503.
19. Orishimo KF, Kremenic IJ, Lee SJ, et al. Is valgus unloader bracing effective in normally aligned individuals: implications for post-surgical protocols following cartilage restoration procedures. Knee Surg Sports Traumatol Arthrosc 2013;21(12):2661–2666.
20. Brouwer RW, Jakma TS, Verhagen AP, et al. Braces and orthoses for treating osteoarthritis of the knee. Cochrane Database Syst Rev 2005;25(1):CD004020.
21. Choi EH, Kim KK, Jun AY, et al. Effects of the off-loading brace on the activation of femoral muscles—a preliminary study. Ann Rehabil Med 2011;35(6):887–896.
22. Fantini Pagani CH, Hinrichs M, Bruggemann GP. Kinetic and kinematic changes with the use of valgus knee brace and lateral wedge insoles in patients with medial knee osteoarthritis. J Orthop Res 2012;30(7):1125–1132.
23. Richards JD, Sanchez-Ballester J, Jones RK, et al. A comparison of knee braces during walking for the treatment of osteoarthritis of the medial compartment of the knee. J Bone Joint Surg Br 2005;87(7):937–939.
24. Briggs KK, Matheny LM, Steadman JR. Improvement in quality of life with use of an unloader knee brace in active patients with OA: a prospective cohort study. J Knee Surg 2012;25(5):417–421.
25. Beaudreuil J, Bendaya S, Faucher M, et al. Clinical practice guidelines for rest orthosis, knee sleeves, and unloading knee braces in knee osteoarthritis. Joint Bone Spine 2009;76(6):629–636.
26. Treatment of Osteoarthritis of the Knee. In: Evidence-Based Guideline. 2nd Ed. Rosemont, IL: Published 2013 by the American Academy of Orthopaedic Surgeons; 2013.
27. McAlindon TE, Bannuru RR, Sullivan MC, et al. OARSI guidelines for the non-surgical management of knee osteoarthritis. Osteoarthritis Cartilage 2014;22(3):363–388.
28. Moyer RF, Birmingham TB, Bryant DM, et al. Biomechanical effects of valgus knee bracing: a systematic review and meta-analysis. Osteoarthritis Cartilage 2015;23(2):178–188.
29. Moyer RF, Birmingham TB, Bryant DM, et al. Valgus bracing for knee osteoarthritis: a meta-analysis of randomized trials. Arthritis Care Res (Hoboken) 2015;67(4):493–501.
30. Rice DA, McNair PJ. Quadriceps arthrogenic muscle inhibition: neural mechanisms and treatment perspectives. Semin Arthritis Rheum 2010;40(3):250–266.
31. Fantini Pagani CH, Willwacher S, Kleis B, Bruggemann GP. Influence of a valgus knee brace on muscle activation and co-contraction in patients with medial knee osteoarthritis. J Electromyogr Kinesiol 2013;23(2):490–500.
32. Cherian JJ, Bhave A, Kapadia BH, et al. Strength and functional improvement using pneumatic brace with extension assist for end-stage knee osteoarthritis: a prospective, randomized trial. J Arthroplasty 2015;30(5):747–753.
33. Matsuno H, Kadowaki KM, Tsuji H. Generation II knee bracing for severe medial compartment osteoarthritis of the knee. Arch Phys Med Rehabil 1997;78(7):745–749.
34. Farrokhi S, Voycheck CA, Tashman S, Fitzgerald GK. A biomechanical perspective on physical therapy management of knee osteoarthritis. J Orthop Sports Phys Ther 2013;43(9):600–619.
35. Fransen M, Crosbie J, Edmonds J. Physical therapy is effective for patients with osteoarthritis of the knee: a randomized controlled clinical trial. J Rheumatol 2001;28(1):156–164.
36. Petersson IF, Boegård T, Saxne T, et al. Radiographic osteoarthritis of the knee classified by the Ahlbäck and Kellgren & Lawrence systems for the tibiofemoral joint in people aged 35–54 years with chronic knee pain. Ann Rheum Dis 1997;56(8):493–496.
37. ATS Committee on Proficiency Standards for Clinical Pulmonary Function Laboratories. ATS statement: guidelines for the six-minute walk test. Am J Respir Crit Care Med. 2002;166(1):111–117.
38. Dobson F, Hinman RS, Hall M, et al. Measurement properties of performance-based measures to assess physical function in hip and knee osteoarthritis: a systematic review. Osteoarthritis Cartilage 2012;20(12):1548–1562.
39. Dobson F, Hinman RS, Roos EM, et al. OARSI recommended performance-based tests to assess physical function in people diagnosed with hip or knee osteoarthritis. Osteoarthritis Cartilage 2013;21(8):1042–1052.
40. Naylor JM, Hayen A, Davidson E, et al. Minimal detectable change for mobility and patient-reported tools in people with osteoarthritis awaiting arthroplasty. BMC Musculoskelet Disord 2014;15:235.
41. Collins NJ, Misra D, Felson DT, et al. Measures of knee function: International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Knee Injury and Osteoarthritis Outcome Score (KOOS), Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS), Knee Outcome Survey Activities of Daily Living Scale (KOS-ADL), Lysholm Knee Scoring Scale, Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Activity Rating Scale (ARS), and Tegner Activity Score (TAS). Arthritis Care Res (Hoboken) 2011;63(Suppl 11):S208–228.
42. Roos EM, Roos HP, Lohmander LS, et al. Knee Injury and Osteoarthritis Outcome Score (KOOS)—development of a self-administered outcome measure. J Orthop Sports Phys Ther 1998;28(2):88–96.
43. Powell LE, Myers AM. The Activities-specific Balance Confidence (ABC) Scale. J Gerontol A Biol Sci Med Sci 1995;50A(1):M28–M34.
44. Nguyen US, Felson DT, Niu J, et al. The impact of knee instability with and without buckling on balance confidence, fear of falling and physical function: the Multicenter Osteoarthritis Study. Osteoarthritis Cartilage 2014;22(4):527–534.
45. Slemenda C, Brandt KD, Heilman DK, et al. Quadriceps weakness and osteoarthritis of the knee. Ann Intern Med 1997;127(2):97–104.
Keywords:

braces; unloader brace; muscle strength; pain

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