Characterisation of pes planovalgus by patients with Juvenile Idiopathic Arthritis with the Oxford Foot Model

Abstract

Physical Therapy Department, Center of Human Motion Science, Shi-raz University of Medical Sciences, Shiraz, IranIntroduction: Foot hyper pronation may cause malalignment ofthe lower extremity, frequently leading to structural and func-tional deficits both in standing and walking [1]. Based on couplingbetween rear foot frontal plane motion and rotation of tibia, itis speculated that excessive pronation results in abnormal tib-ial rotation which increases stress on the joints of the lowerextremity during weight bearing [2]. It has been postulated thatabnormal subtalar joint motion is linked to knee joint prob-lems like patellofemoral pain syndrome as it may affect kneemechanics. The purpose of this study was therefore to measurepatellofemoral joint forces during stance phase of walking in sub-jects with hyper pronated foot and to compare them to the healthysubjects.Patients/materials and methods: 10 subjects with neutrallyaligned feet and 10 with hyperpronated feet aged 23±2.5 yearswere selected via clinical examination. Kinetic and kinematic datawere collected by using a force platform (Kistler, Switzerland)and six camera motion capture system (Qualisys, Ltd., Sweden)while subjects walked at their preferred speed. Mean and peakknee extensor mechanism forces were quantified using Newto-nian inverse dynamics during stance phase of walking. Then, meanandpeakpatellarmechanismanglesandpatellofemoraljointforceswere calculated in both groups.Results: Significant higher amount of mean patellar mechanismangle and also mean and peak forces across the knee extensormechanism were found in flat footed group compared to normalgroup [P 0.05]. Moreover, statistical analysis revealed a signifi-cant difference in mean patellofemoral joint force between normal(178.3±93.27N)andhyperpronatedfootgroups(478.1±191.5N)[P=0.001]. Peak patellofemoral joint force was also significantlyhigher in flat footed group (561.8±279.6N) compared to normalgroup (269.8±193.8) [P=0.019].Discussion and conclusion: Increased patellofemoral joint forcecauses the patellofemoral joint pathologies like arthritis. It canbe concluded that changes of the medial longitudinal arch heightwould alter the net external flexion moment, force applied to theextensor mechanism, patellar mechanism angle and consequentlythe patellofemoral joint forces during stance phase of walking,through which developing a tendency towards musculoskeletalinjuries.Disclosure: No significant relationships.References