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ORIGINAL RESEARCH ARTICLES

Combined Effects of a Valgus Knee Brace and Lateral Wedge Insole on Walking in Patients with Medial Compartment Knee Osteoarthritis

Mirzaei, Fatemeh MSc; Arazpour, Mokhtar PhD; Baghei Roodsari, Roshanak PhD; Bahramizadeh, Mahmood PhD; Mardani, Mohammad Ali PhD

Author Information
Journal of Prosthetics and Orthotics: January 2018 - Volume 30 - Issue 1 - p 39-45
doi: 10.1097/JPO.0000000000000170
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Abstract

Knee osteoarthritis (OA) is a degenerative joint disease that leads to the degradation of articular cartilage in the knee joint. Individuals with OA have pain and stiffness due to change in the structure of the cartilage and narrowing of the joint space. These mechanical factors play an important role in the development and progression of the disease state.1 The knee joint OA has been shown to develop in approximately 10% of adults older than 55 years.2 Prevalence of knee OA in the medial compartment is 5 to 10 times higher than disease in the lateral compartment.3 The suggested reason for this fact is approximately 60% of load passes through the medial side of the knee during ambulation.4

Medial compartment OA is more prevalent than lateral compartment disease due to the mechanism of load distribution in normal walking. Approximately 60% of the total load passes through the medial compartment of the knee in normal subjects, leading to further degenerative changes with medial compartment type. This results in the mechanical load passing more medially through the knee than normal.4,5 Pain, immobility, disability, a reduced quality of life, and negative changes in kinetic and kinematic parameters are the symptoms of medial compartment OA.6,7

Treatment options for knee OA consist of operative and nonoperative approaches. Operative treatment includes arthroscopy, joint replacement, and osteotomies. Nonoperative methods are often prescribed (indicated) in mild to moderates stages or when surgery is not feasible. These nonoperative treatments consist of drug therapy, physiotherapy, and orthotics conservative treatments.8 The overall aim of the conservative treatment of OA is to reduce pain, improve functioning, and reduce disease progression rates.9 In orthotic conservative treatment, these methods aim to reduce the externally applied knee adduction moment (KAM) acting on the medial aspect of the knee. The use of laterally wedged insoles and specifically designed knee braces is a common conservative method to treat medial compartment knee OA.10

Lateral wedges change the position of the center of pressure by redirecting it more laterally to reduce the KAM.11,12 A study reported that a 5° inclined lateral wedge-type insole significantly reduced the KAM.13 Other studies demonstrated the ineffectiveness of a 5° lateral wedge in reducing the external KAM.14–16 On comparing the different lateral wedges with 3°, 5°, 6°, and 10° inclinations, it was found that a 6° lateral wedge reflected the minimum correction angle proven to be effective by previous studies.13,17

Knee braces can be divided into four classes, consisting of prophylactic, functional, rehabilitative, and valgus off-loader knee braces. These knee braces are a common nonsurgical strategy for treating people with medial knee OA.18 Knee braces have also been shown to decrease the net adduction moment applied by the ground reaction force by applying a constant abduction (valgus) moment closer to the knee joint center.10 Previous studies have reported that the wearing of knee braces reduced the load on the medial compartment for ambulation19 and increased confidence in loading and the ability to push off vertically.20

The use of valgus knee brace and lateral wedge foot orthosis has been reported as a novel treatment strategy for knee OA. According to a study, the separate evaluation of valgus knee braces, lateral wedge foot orthoses, and variable stiffness shoes decreased the external KAM.21 On using a knee brace, the position of the knee joint center changed in the medial direction. However, the use of a lateral wedge insole altered the orientation of the ground reaction force in the lateral direction. Therefore, there might be a possibility of additive effects on reducing the KAM when these interventions are used together. Moyer et al.22 evaluated the combined effect of knee orthosis and lateral wedge insole on 16 medial compartment knee OA patients and reported that the use of knee brace and foot orthosis at the same time can produce a greater overall reduction in the KAM.

Despite the current evidence, studies evaluating the combined effect of the knee braces and inlays compared with the effectiveness of knee orthoses or inlays in treating knee OA are scarce. Therefore, additional research is required to demonstrate their effectiveness on the kinetics and kinematics of the lower limb.

Accordingly, the primary objective of this proof-of-concept study was to test the hypothesis of using two different mechanisms (direct force and indirect force) for correcting the knee valgus position so as to decrease the external KAM during gait when used simultaneously. The secondary objective was to explore the changes in the walking parameters (temporal-spatial, kinetic, and kinematic) in the medial compartment knee OA. Therefore, the purpose of this present study was to analyze and compare the combined effects of the two orthotic treatment strategies, laterally wedged inlay or a knee brace, on certain primary outcome measures in volunteer subjects with medial compartment OA. The primary outcome measures are knee pain, KAM, lower-limb sagittal plane kinematics, the speed of walking, and cadence and step length.

METHODS

SUBJECTS

The study included 18 subjects with varus alignment, symptomatic medial compartment knee OA, and those prescribed for a conservative treatment, who were referred to the Department of Orthotics and Prosthetics in the University of Social Welfare and Rehabilitation Sciences. Radiological evaluation combined with reported knee symptoms associated with radiological evaluation were used to diagnose knee OA. The inclusion criteria for this study included localized pain in the medial side of the tibiofemoral joint, greater joint space narrowing on the medial side compared with the lateral side, and the existence of medial compartment knee OA of Kellgren-Lawrence grade 2 or 3 confirmed by radiological examination. Anteroposterior radiographs of the hip-to-ankle joints in the standing position were used to evaluate alignment of the knee joint in the frontal plane. A mechanical axis angle of ≥1° varus in the knee joint was considered as varus alignment. Kellgren-Lawrence grades were also detected according to the full-length standing radiographs. The exclusion criteria for this study included arthroscopic surgery in the past 6 months; knee trauma and lower-limb amputation; neurological disease; symptomatic spine, hip, ankle, and foot disease; intra-articular steroid injection in the past 3 months; hyaluronic acid injection in the last 9 months; previous fracture of the tibia; skin disease; peripheral vascular disease; blindness; severe cardiovascular defect; and an inability to apply a brace (due to arthritis in the hand or difficulty in bending). Signed consent forms were obtained from all the study participants. The ethics committee of the University of Social Welfare and Rehabilitation Sciences approved the performance of this study.

TESTING PROTOCOL

The orthotic devices were fitted to the patients' body, and they were advised to wear the devices for 2 weeks (8 hours per day) immediately before the time of the initial formal biomechanical evaluation. The usage of these devices was properly checked by researcher via telephone in this study. The 2-week period was considered sufficient to verify the wearing compliance and permit adequate acclimation to the brace and insole. The orthotic devices were worn bilaterally in the patients having bilateral knee pain. Three different groups were considered in this study: (1) lateral wedge insole (no intervention, with intervention), (2) valgus knee brace (no intervention, with intervention), and (3) both knee brace and foot orthotic (no intervention, with intervention). Block randomization was used to achieve the same number of K/L grade 2 versus 3 ratios in each of the 3 groups.

VALGUS KNEE BRACE

All subjects were fitted with a custom-fit valgus knee brace by an experienced orthotist before the gait analysis was performed. The knee orthosis was fabricated on a 3-point bending mechanism to provide a medially directed force to the lateral aspect of the knee joint. The components of the knee brace were included in the hard shell cuff around the thigh and shank, with medially placed hinge and lateral crossover strap. The casting of the lower limb was performed in the weight-bearing condition for each subject, and the casted mold was sent to the brace manufacturer. The knee brace was constructed as per the casted mold that was custom fit and adjustable. This orthosis was set to vary at 4° and 7° valgus angles. The orthotist asked the subjects to walk in the clinic and then adjusted the knee valgus angle as per the comfort level of the patients. The subjects were advised to wear the knee orthosis while performing their daily activities.

LATERAL WEDGE FOOT ORTHOSIS

Full-length lateral wedge foot orthoses were made from a cork composite (Thermocork; Aetrex Worldwide, Inc, Teaneck, NJ) with a density of 60 durometers. An experienced orthotist fitted the wedges to each subject during standing, walking, and while wearing the valgus knee brace. The orthotist initially evaluated the subjective influences of the lateral wedges using two prefabricated full-length lateral wedges of 6 and 10 mm. The purpose of having a maximum lateral wedge height was to provide comfort to the subject. The foot orthosis with no wedge was used for the nonaffected side. All subjects in the test conditions were fitted with a pair of comfortable, identically styled lightweight shoes pitched with a 1-inch heel height. Figure 1 demonstrates the valgus knee orthosis and lateral wedge insole used in this study.

F1
Figure 1:
Valgus knee orthosis (left side) and lateral wedge insole (right side) used in the study.

GAIT ANALYSIS

For each patient, gait analysis was conducted under two conditions in the baseline and after 2 weeks of wearing the conservative devices. Five walking trials were considered for each condition. A Vicon digital motion capture system (Oxford Metrics, United Kingdom), using eight cameras (Vicon, Infrared) at a frequency of 100 Hz, and two force platforms set apart and positioned to capture a left and right heelstrike (Kistler 9286BA, Switzerland) were used for capturing data. Fourteen markers were placed bilaterally over the position of the greater trochanter, lateral condyle of the femur, head and lateral malleolus of the fibula, the second metatarsal, anterior superior iliac spine, and calcaneus. The following parameters were analyzed: knee pain levels (using the visual analog scale), sagittal plane hip, knee and ankle joints range of motion (ROM), maximum externally applied KAM, walking speed, cadence, and step length. The means of the resulting data were calculated from both left and right sides for the five walks using each device.

The external adduction moment about the knee was calculated by using inverse dynamics. Each lower-limb segment (foot, shank, and thigh) was modeled as a rigid body with a local coordinate system that coincided with anatomically relevant axes. Inertial properties of each limb segment were approximated anthropometrically, and translations and rotations of each segment were reported relative to neutral positions defined during the initial standing static trial. For each trial, the KAM waveform was normalized to body weight and height (%BW*Ht) and inspected visually. The peak magnitudes of the external KAM in the first and second halves of stance were identified using an algorithm that identified values immediately preceded by a minimum of 5 continuously ascending values and followed by a minimum of 5 continuously descending values.

SUBJECTIVE ASSESSMENT

Before the biomechanical evaluations, the patients were evaluated regarding the quality of orthoses fitting and comfort. A visual analog scale (VAS) ranging from 0 (“no pain”) to 10 (“worst pain imaginable”) was also used for pain assessment when walking.

DATA ANALYSIS

Because of the normality of data (which was confirmed using the Kolmogorov-Smirnov technique), a paired t test was used for comparing the outcome measures of the intergroup comparison. The univariate analysis was used for analyzing the efficacy of the intragroup comparison. SPSS statistical software was used for analysis of the data. The level of significance was set at 0.05.

RESULTS

The baseline data showed no significant differences in the means of the age, sex, body mass index, or knee OA grade between the randomly assigned test groups (Table 1). The two groups were therefore appropriately similar to facilitate the comparison of the primary outcome measures. In addition, Table 2 demonstrates the mean (SD) of the mentioned parameters in the three test conditions with and without interventions. Table 3 shows the intergroup and intragroup comparison of the mentioned parameters in this study.

T1
Table 1:
Subjects demographic information who participated in this study
T2
Table 2:
Mean (SD) of mentioned parameters in the three test conditions with and without interventions
T3
Table 3:
Intergroup and intragroup comparison of mentioned parameters in this study

INTERGROUPS COMPARISON AND MEAN (SD) OF MENTIONED PARAMETERS IN BASELINE

A significant difference was observed between with and without interventions of lateral wedge insole with respect to KAM in the lateral wedge group. There was a statistically significant difference favoring with and without interventions of the valgus brace group and were noted for the KAM, speed of walking, cadence, and knee joint ROM. There was no significant difference in step length and hip and ankle ROM with and without intervention. In the valgus brace plus lateral wedge insole group, there was a significant difference in KAM and hip, knee, and ankle joints ROM. There was no significant difference in the speed of walking, cadence, and step length between with and without intervention.

INTRAGROUPS COMPARISON AND MEAN (SD) OF THE MENTIONED PARAMETERS IN BASELINE

The comparison between lateral wedge insole group and valgus brace group revealed a significant difference in knee joint ROM. There was no significant difference in residual mentioned parameters (eg, pain, KAM, speed of walking, step length, cadence, ankle joint ROM, and hip joint ROM). The comparison between lateral wedge insole group with valgus brace plus lateral wedge group showed a significant difference in KAM, step length, speed of walking, and knee joint ROM. There was no significant difference in pain, cadence, ankle joint ROM, and hip joint ROM. The comparison between valgus brace group and valgus brace and lateral wedge group showed a significant difference in KAM.

DISCUSSION

The results of this study provide the concept of using a valgus knee brace and lateral wedge concurrently to enhance the magnitude of decrease in the KAM.

Three different teams of investigators have considered the combined effects of knee braces and foot orthotics on walking parameters in medial compartment knee OA. While evaluating the combined effect of the rigid ankle foot orthoses and lateral wedge insole in healthy subjects, Schmalz et al.23 reported changes in the KAM during walking. Moyer et al.22 evaluated the combined effect of the knee brace and orthotic foot inlay on medial compartment knee OA and showed a reduction in the KAM. In a recent randomized crossover trial, Hunter et al.24 evaluated the combined effect of wearing a valgus knee brace, neutral foot orthosis, and motion control shoe. Their results showed significant improvement in knee pain that was more than the placebo treatment. Despite their positive effects, the valgus unloader braces are also found to be associated with some functional disadvantages. They can cause a significant reduction in knee flexion during the swing phase. This restriction can result in reduced foot clearance and a shorter stride.20,25

The use of orthosis and lateral wedge separately and in combination has been found to reduce step length as an immediate effect after the wearing condition. The patients did not undergo long accommodation time after wearing the two interventions. Only 2 weeks of wearing the orthoses was considered for this study. Similar to our study, Gaasbeek et al.25 reported the negative effects of knee braces on step length and stride length. They demonstrated a decrease in the duration of the swing phase, which would explain the decreased step and stride length during walking with a brace. In contrast with our study, Schmalz et al.23 reported an increased value from 0.71 m (without brace condition) to 0.73 m (with orthosis) while the step length of the contralateral limb reduced from 0.75 to 0.73 m.

Table 2 presents the speed of walking on immediately wearing the lateral wedge and valgus knee brace, separately and combined. The use of valgus knee brace reduced the hip, knee, and ankle joints ROM, and the step length. Therefore, the speed of walking reduced with immediate effect of the wearing conditions. Compared with other knee OA participants in published studies, the cohort in this study exhibited relatively slow gait speed (the preintervention gait speed ranged from 0.804 to 0.980 m/s). All participations were grade 3 and 4 medial compartment knee OA in this study. The severity of cartilage compromise and resultant knee pain may explain the slow speed of the subjects' ambulation. Schmalz et al.23 found that the mean walking speed significantly increased from 1.27 m/s (without brace) to 1.36 m/s (with orthosis). Gaasbeek et al.25 demonstrated that patients with a valgus unloader brace walked at a faster pace. In addition, Arazpour et al.26 found that the speed of walking in baseline was 0.90 m/s, and after 6 weeks of brace usage, it increased to 1.08 m/s. Pagani et al.27 showed that the average walking speeds in test conditions without an orthosis, with 4° valgus angulation and a neutral flexible test condition were 1.45 ± 0.15, 1.47 ± 0.12, and 1.45 ± 0.14 m/s, respectively.

The quality of life improvement of subjects with OA is considered important. However, the main aim of this conservative approach (combined knee orthosis and lateral wedge) is to reduce the load in one knee compartment that would further decrease the disease progression. Although the separate use of lateral wedge and valgus knee orthosis have shown to efficiently decrease the subjective pain, their combined use has not been evaluated in their study.28 The findings of the present study provide evidence that pain reduction and improvement of the function are not necessarily associated with a decrease in joint load. It seems that long-term wearing of these two interventions together can be effective for pain relief.

STUDY LIMITATIONS

The main limitation of this study could be the small sample size. This present study, being a pilot study, will lead to further research with a large sample size. No control group was declared without any intervention in this study. In addition, the patients with only grade 2 and 3 OA were included in the study. Apart from this, the long-term effects of using this intervention model should be analyzed.

Not controlling for gait speed in the preintervention and postintervention gait assessments is a major concern that may potentially invalidate the study findings. Slowed gait speed will reduce knee moments and ROM, as evidenced in data presented in Table 2; hip, knee, and ankle ROM all decreased and KAM decreased. It is impossible to disentangle whether the KAM and ROM reductions were a result of the biomechanical benefits of the orthoses or slower gait speed. Future study in this field with this goal will be beneficial.

CONCLUSIONS

The patients with medial compartment knee OA showed lower walking velocity, reduced knee ROM, decreased cadence, reduced step length and stride length, and increased peak varus moments about the knee during the stance phase of walking in the affected leg.

This study demonstrated that the use of either laterally wedged insole or valgus knee brace separately or combined improve knee pain in subjects with medial compartment knee OA, but the combined wearing of these interventions was not more effective in decreasing the pain compared with the separate using of the lateral wedge and knee orthosis in this study. The findings of the present study showed that the use of valgus knee brace and lateral wedge insole can produce a greater overall reduction in KAM. The observed results demonstrated that wearing two types of orthoses either separately or in a combined condition does not improve the speed of walking, step length and hip, knee, and ankle joints ROM.

ACKNOWLEDGMENT

We would like to thank the University of Social Welfare and Rehabilitation Sciences for the financial support in this study.

REFERENCES

1. Grodzinsky AJ, Levenston ME, Jin M, Frank EH. Cartilage tissue remodeling in response to mechanical forces. Annu Rev Biomed Eng 2000;2:691–713.
2. Peat G, McCarney R, Croft P. Knee pain and osteoarthritis in older adults: a review of community burden and current use of primary health care. Ann Rheum Dis 2001;60(2):91–97.
3. Felson DT, Nevitt MC, Zhang Y, et al. High prevalence of lateral knee osteoarthritis in Beijing Chinese compared with Framingham Caucasian subjects. Arthritis Rheum 2002;46(5):1217–1222.
4. Prodromos CC, Andriacchi TP, Galante JO. A relationship between gait and clinical changes following high tibial osteotomy. J Bone Joint Surg Am 1985;67(8):1188–1194.
5. Krohn K. Footwear alterations and bracing as treatments for knee osteoarthritis. Curr Opin Rheumatol 2005;17(5):653–656.
6. Raja K, Dewan N. Efficacy of knee braces and foot orthoses in conservative management of knee osteoarthritis: a systematic review. Am J Phys Med Rehabil 2011;90(3):247–262.
7. Bejek Z, Paróczai R, Illyés Ã, et al. Gait parameters of patients with osteoarthritis of the knee joint. Facta Universitatis-Series: Physical Education and Sport 2006;4(1):9–16.
8. 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.
9. Brouwer R, Jakma T, Verhagen A, et al. Braces and orthoses for treating osteoarthritis of the knee. Unicompartmental Osteoarthritis of the Knee 2006:37.
10. Maleki M, Arazpour M, Joghtaei M, et al. The effect of knee orthoses on gait parameters in medial knee compartment osteoarthritis: a literature review. Prosthet Orthot Int 2016;40:193–201: 0309364614547411.
11. Yasuda K, Sasaki T. The mechanics of treatment of the osteoarthritic knee with a wedged insole. Clin Orthop Relat Res 1987;(215):162–172.
12. Self BP, Greenwald RM, Pflaster DS. A biomechanical analysis of a medial unloading brace for osteoarthritis in the knee. Arthritis Care Res 2000;13(4):191–197.
13. Kerrigan DC, Lelas JL, Goggins J, et al. Effectiveness of a lateral-wedge insole on knee varus torque in patients with knee osteoarthritis. Arch Phys Med Rehabil 2002;83(7):889–893.
14. Baker K, Goggins J, Xie H, et al. A randomized crossover trial of a wedged insole for treatment of knee osteoarthritis. Arthritis Rheum 2007;56(4):1198–1203.
15. Kakihana W, Akai M, Nakazawa K, et al. Inconsistent knee varus moment reduction caused by a lateral wedge in knee osteoarthritis. Am J Phys Med Rehabil 2007;86(6):446–454.
16. Maly MR, Culham EG, Costigan PA. Static and dynamic biomechanics of foot orthoses in people with medial compartment knee osteoarthritis. Clin Biomech (Bristol, Avon) 2002;17(8):603–610.
17. Kakihana W, Akai M, Yamasaki N, et al. Changes of joint moments in the gait of normal subjects wearing laterally wedged insoles. Am J Phys Med Rehabil 2004;83(4):273–278.
18. Ramsey DK, Russell ME. Unloader braces for medial compartment knee osteoarthritis: implications on mediating progression. Sports Health 2009;1(5):416–426.
19. 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.
20. 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.
21. Jenkyn TR, Erhart JC, Andriacchi TP. An analysis of the mechanisms for reducing the knee adduction moment during walking using a variable stiffness shoe in subjects with knee osteoarthritis. J Biomech 2011;44(7):1271–1276.
22. Moyer RF, Birmingham TB, Dombroski CE, et al. Combined effects of a valgus knee brace and lateral wedge foot orthotic on the external knee adduction moment in patients with varus gonarthrosis. Arch Phys Med Rehabil 2013;94(1):103–112.
23. Schmalz T, Blumentritt S, Drewitz H, Freslier M. The influence of sole wedges on frontal plane knee kinetics, in isolation and in combination with representative rigid and semi-rigid ankle-foot-orthoses. Clin Biomech (Bristol, Avon) 2006;21(6):631–639.
24. Hunter D, Gross K, McCree P, et al. Realignment treatment for medial tibiofemoral osteoarthritis: randomised trial. Ann Rheum Dis 2012;71(10):1658–1665.
25. 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.
26. Arazpour M, Bani MA, Maleki M, et al. Comparison of the efficacy of laterally wedged insoles and bespoke unloader knee orthoses in treating medial compartment knee osteoarthritis. Prosthet Orthot Int 2013;37(1):50–57.
27. Pagani CH, Böhle C, Potthast W, Brüggemann GP. Short-term effects of a dedicated knee orthosis on knee adduction moment, pain, and function in patients with osteoarthritis. Arch Phys Med Rehabil 2010;91(12):1936–1941.
28. Arazpour M, Hutchins SW, Bani MA, et al. The influence of a bespoke unloader knee brace on gait in medial compartment osteoarthritis: A pilot study. Prosthet Orthot Int 2014;38(5):379–386.
Keywords:

valgus knee brace; lateral wedge insole; walking; medial compartment knee osteoarthritis; kinematics and kinetics

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