Ankle motion influences the external knee adduction moment and may predict who will respond to lateral wedge insoles?: an ancillary analysis from the SILK trial

G.J Chapman,M.J Parkes,L Forsythe,D.T Felson,R.K Jones

doi:10.1016/j.joca.2015.02.164

Abstract

SummaryObjectiveLateral wedge insoles are a potential simple treatment for medial knee osteoarthritis (OA) patients by reducing the external knee adduction moment (EKAM). However in some patients, an increase in their EKAM is seen. Understanding the role of the ankle joint complex in the response to lateral wedge insoles is critical in understanding and potentially identifying why some patients respond differently to lateral wedge insoles.MethodParticipants with medial tibiofemoral OA underwent gait analysis whilst walking in a control shoe and a lateral wedge insole. We evaluated if dynamic ankle joint complex coronal plane biomechanical measures could explain and identify those participants that increased (biomechanical non-responder) or decreased (biomechanical responder) EKAM under lateral wedge conditions compared to the control shoe.ResultsOf the 70 participants studied (43 male), 33% increased their EKAM and 67% decreased their EKAM. Overall, lateral wedge insoles shifted the centre of foot pressure laterally, increased eversion of the ankle/subtalar joint complex (STJ) and the eversion moment compared to the control condition. Ankle angle at peak EKAM and peak eversion ankle/STJ complex angle in the control condition predicted if individuals were likely to decrease EKAM under lateral wedge conditions.ConclusionsCoronal plane ankle/STJ complex biomechanical measures play a key role in reducing EKAM when wearing lateral wedge insoles. These findings may assist in the identification of those individuals that could benefit more from wearing lateral wedge insoles.

Highlights

Knee osteoarthritis (OA) affects approximately 12.5% adults over the age of 65 years old1e3
Expressed as a percentage change from the control shoe, these changes reflect a reduction in peak external knee adduction moment (EKAM) of 5.85%, and a reduction in knee adduction angular impulse (KAAI) of 7.95%
The final part of the analysis revealed participants with a higher peak ankle eversion angle or a higher ankle angle at peak EKAM in the control condition, were more likely to classified as a biomechanical responder (i.e., EKAM more likely to decrease) to the lateral wedge insole, no clear-cut threshold in ankle angle in the control condition between groups was found

Summary

Introduction

Knee osteoarthritis (OA) affects approximately 12.5% adults over the age of 65 years old1e3. This progressive condition is characterised by pain and stiffness in the joint resulting in difficulty in weight bearing activities including walking and stair climbing[1,2,4], resulting in adverse effects on loss of function, personal independence and a reduction in quality of life. One common conservative treatment for medial knee OA is the use of lateral wedge insoles which are placed inside patient's shoes in an attempt to redistribute the load on the knees and decrease the EKAM. Past research has demonstrated that lateral wedge insoles decrease EKAM in patients with medial knee OA13e22

Results

Discussion

Conclusion