Original article
Combined Effects of a Valgus Knee Brace and Lateral Wedge Foot Orthotic on the External Knee Adduction Moment in Patients With Varus Gonarthrosis

Presented to the World Congress for Osteoarthritis, September 15–18, 2011, San Diego, CA; and to the Congress for Scientific Testing of Orthotic Devices, March 23–25, 2011, Aix Les Bains, France.
https://doi.org/10.1016/j.apmr.2012.09.004Get rights and content

Abstract

Objective

To test the hypothesis that a custom-fit valgus knee brace and custom-made lateral wedge foot orthotic will have greatest effects on decreasing the external knee adduction moment during gait when used concurrently.

Design

Proof-of-concept, single test session, crossover trial.

Setting

Biomechanics laboratory within a tertiary care center.

Participants

Patients (n=16) with varus alignment and knee osteoarthritis (OA) primarily affecting the medial compartment of the tibiofemoral joint (varus gonarthrosis).

Interventions

Custom-fit valgus knee brace and custom-made full-length lateral wedge foot orthotic. Amounts of valgus angulation and wedge height were tailored to each patient to ensure comfort.

Main Outcome Measures

The external knee adduction moment (% body weight [BW]*height [Ht]), frontal plane lever arm (cm), and ground reaction force (N/kg), determined from 3-dimensional gait analysis completed under 4 randomized conditions: (1) control (no knee brace, no foot orthotic), (2) knee brace, (3) foot orthotic, and (4) knee brace and foot orthotic.

Results

The reduction in knee adduction moment was greatest when concurrently using the knee brace and foot orthotic (effect sizes ranged from 0.3 to 0.4). The mean decrease in first peak knee adduction moment compared with control was .36% BW*Ht (95% confidence interval [CI], –.66 to –.07). This was accompanied by a mean decrease in frontal plane lever arm of .59cm (95% CI, –.94 to –.25).

Conclusions

These findings suggest that using a custom-fit knee brace and custom-made foot orthotic concurrently can produce a greater overall reduction in the knee adduction moment, through combined effects in decreasing the frontal plane lever arm.

Section snippets

Participants

Patients with varus alignment, symptomatic medial compartment knee OA, and who were provided with a prescription for a valgus knee brace were recruited from a tertiary care center specializing in orthopedics. Standing hip-to-ankle anteroposterior radiographs were used to assess frontal plane alignment.43 Varus alignment was defined as a mechanical axis angle of ≥1° varus. Kellgren and Lawrence grades were also determined from the full-length standing radiographs.44 All patients had to have

Results

Patient demographics and clinical characteristics are presented in table 3. Sixteen patients (8 men, 8 women) met our inclusion criteria and participated in the study. Eight 9-mm lateral wedge foot orthotics, seven 6-mm lateral wedge foot orthotics, and one 3-mm lateral wedge foot orthotic were custom-made for patients. The final knee brace angles ranged from 2° to 9° of valgus. Ensemble average curves for the external knee adduction moment, frontal plane lever arm, and ground reaction force

Discussion

The present findings support the concept of using a custom-fit knee brace and custom-made foot orthotic concurrently to enhance the magnitude of reduction in the knee adduction moment. We are aware of limited previous research evaluating the combined effects of knee braces and foot orthotics. Schmalz et al49 reported changes in the knee adduction moment during walking with combined use of a heel wedge and rigid ankle-foot orthosis in healthy participants. In a recent randomized crossover trial,

Conclusions

The present findings suggest that using a custom-fit valgus knee brace and custom-made lateral wedge foot orthotic concurrently can produce a greater overall reduction in the knee adduction moment, through combined effects in decreasing the frontal plane lever arm. The observed changes were small, and the clinical importance is presently unclear; however, given the reported difficulties with compliance with braces and orthotics, these results do lend support to future work investigating

Suppliers

  • a.

    Össur Corporate, 19762 Pauling Rd, Foothill Ranch, CA 92610-2611.

  • b.

    Sole Science, 1182 Frances St, London, ON N5W 2M1, Canada.

  • c.

    Motion Analysis Corp, 3617 Westwind Blvd, Santa Rosa, CA 95403.

  • d.

    Advanced Medical Technology Inc, 176 Waltham St, Watertown, MA 02472-4800.

  • e.

    New Balance, 3660 Hurontario St, Mississauga, ON L5B 3C4, Canada.

Acknowledgment

We thank Ian Jones, MA for providing assistance with data collection and processing.

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    Supported by the Canadian Institutes of Health Research (CIHR) through a university industry grant (grant no.: ISO-63721) with Arthrex, Inc; and in part by the Canada Research Chairs Program and the Joint Motion Program, a CIHR strategic training initiative in health research.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.

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