Abstract

Background: Lateral wedged insoles are one of the biomechanical interventions recommended for individuals with medial knee osteoarthritis to reduce external knee adduction moment. Several approaches have already been tested to reduce the forces that crosses the knee. However, an approach based on individual biomechanical assessment of the acute effects of different angles of lateral wedge insoles is necessary.

Purpose: To assess the intra-session reliability of different angles of lateral wedge insoles on knee biomechanics during gait in healthy adults.

Methods: Twenty-five healthy volunteers (15 males, with mean age of 21.6±5.5 years, body mass of 65.2±8.7 kg, and height 169±7.5 cm) were recruited. A Qualisys Oqus motion analysis system was used for kinematic and kinetic data collection during gait with the six experimental conditions: 0°, 2°, 4°, 6°, 8° and 10-degree wedge insoles. The intraclass correlation (ICC) and their 95% confidence intervals, the standard error of measurement (SEM) and the minimal detectable change (MDC) were calculated for each insole.

Results: For all kinematic parameters, ICC was superior to 0.924, showed an excellent consistency. For the kinetic parameters, the external knee abduction moment was the least consistent (ICC>0.540). It was found that the estimated value for SEM was 0.014 Nm/kg for the first and second peak of external knee adduction moment with a corresponding MDC of 0.039 Nm/kg for both.

Conclusions: This study provides preliminary data which may be useful for clinical interpretation and decision to recommend the insole that best fits to the condition of the patient with medial knee osteoarthritis.

Keywords: External knee adduction moment, Gait analysis, Standard error of measurement, Minimal detectable change, Outcome assessment