No deficit in hip isometric strength or concentric endurance in young females with mild patellofemoral pain

Abstract

Previous research has linked deficits in hip muscle strength and endurance to patellofemoral pain syndrome (PFPS). This study investigated if females with mild PFPS displayed hip isometric strength and endurance deficits compared to uninjured controls. Hip abduction, internal rotation (IR) and external rotation (ER) were assessed using an isokinetic dynamometer in 12 females with PFPS and 12 age- and gender-matched controls. Independent t-tests were used to examine between-group differences and Pearson’s Correlation Coefficient examined the relationship between isometric strength and endurance. No significant between-group differences for IR, ER and abduction strength or endurance were found (all p > 0.05). Strength and endurance measurements showed significant moderate correlations for abduction (R = 0.496, p = 0.014) and ER (R = 0.592, p = 0.002) only. The PFPS subjects had mild pain (Numerical Rating Scale: mean 1.3 cm) and disability (Anterior Knee Pain Scale: mean 81/100), which may partly explain the lack of significant between-group differences. The results suggest that female subjects with PFPS associated with mild pain and disability do not demonstrate hip IR, ER or abduction endurance or isometric strength deficits. Further research is required to clarify the role of factors including hip strength and endurance in the management of more severe PFPS.