A comparison of the biomechanical and clinical effects of a biaxial ankle-foot orthosis and lateral wedge insole in individuals with medial knee osteoarthritis

Abstract

Purpose

This study aimed to compare a biaxial ankle-foot orthosis (AFO) with a lateral wedge insole in terms of the biomechanical and clinical outcomes in individuals with knee osteoarthritis.

Materials and methods

A cross-over randomized design was used where 31 individuals (25 females and six males, mean age of 52.19 ± 4.12 years) with knee osteoarthritis wore each intervention for two weeks with two weeks washout period. Three-dimensional kinematic and kinetic data and clinical outcomes were collected to evaluate the effects of each intervention on knee adduction moment (KAM), pain, stiffness, and function.

Results

Both orthoses significantly improved pain by 17 and 22%, function by 11 and 14%, the first peak KAM by 15.7 and 19.2%, the second peak KAM by 10.4 and 16.7%, and KAM impulse by 14.8 and 22.2%, respectively. However, the biaxial AFO significantly reduced the KAM and improved function compared to the lateral wedge insole (p < 0.01).

Conclusions

The results of this study have shown that both orthoses have a potential role in the conservative management of medial knee osteoarthritis. The biaxial AFO proved statistically better at improving function and KAM; though these differences do not seem to be clinically significant.

IMPLICATION FOR REHABILITATION

• Orthotic interventions have been reported to be effective in the management of medial knee osteoarthritis.

• Lateral wedge insole and biaxial ankle-foot orthosis (AFO) are effective in the improvement of pain, function, and knee adduction moment (KAM) in people with medial knee osteoarthritis.

• The biaxial AFO, compared with lateral wedge insole, contributes to statistically more improvement of function and KAM. However, these differences do not seem to be clinically significant.

Keywords:

• Knee
• pain
• rehabilitation
• orthotics
• osteoarthritis

Ethical approval

The Ethics Committee of the Iran University of Medical Sciences (IUMS) approved the research protocol.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, A.S., upon reasonable request.

Additional information

Funding

This study was financially supported by the Iran University of Medical Sciences (Grant No. 97-4-15-14030) and the Iranian National Science Foundation (Grant No. 96012164).