Immediate Effects of Anti-Pronation Foot Orthoses with Different Inclination Angles on Ground Reaction Force Components during Walking

Excessive foot pronation is one of the major risk factors for anterior cruciate ligament's injuries.The purpose of the present study was to investigate the immediate effects of anti-pronation foot orthoses with various angles on ground reaction force components during walking.
A total of 15 healthy volunteers (age: 28.2±8.8 years; height: 179.5±8.4 cm; weight: 76.3±13.5 kg; BMI: 23.7±9.1 kg/m2) participated in the study. A Vicon motion analysis system, including four cameras, and two Kistler force plates were used to measure the ground reaction force components in walking with shoes without foot orthoses as well as walking with shoes and three different foot orthoses (10º, 15º, and 20º of lateral inclinations).
In foot orthoses with 20º inclination, the ground reaction force in vertical and medial-lateral directions at initial heel contact was greater than those without foot orthoses by 5% (p=0.02) and 110% (p=0.02), respectively. Impulse, loading rate, and free moment were not different between walking with different foot orthoses compared with those of walking without foot orthoses (p>0.05).
The application of anti-pronation foot orthoses (20º inclination) can reduce the loading rate at propulsion; however, it may impose loads to the knee which consequently place the knee on genu varum position, facilitating medial knee osteoarthritis.