Femoral medial deviation angle during a one-leg squat test in individuals with patellofemoral pain syndrome

Objectives Patients with patellofemoral pain syndrome (PFPS) often demonstrate a collapse of the knee in the medial direction during a one-leg squat. This study investigated the medial displacement magnitude of the knee during a one-leg squat test in females with PFPS. Design The study design was a cross sectional comparative investigation. Participants Thirteen healthy females and 12 females with PFPS. Main measures Participants were tested during a one-leg squat test using a single camera. The thigh segment alignment in the frontal plane was measured by the angle projected between the long axis of the thigh and the foot (femoral frontal angle) and the horizontal deviation (femoral deviation) of the distal thigh relative to the foot. Results A one-way ANOVA showed that the femoral frontal angle was significantly larger (p=0.019) for the PFPS group with no significant differences for the femoral deviation (p=0.288). Both measurements showed good trial-to-trial reliability while the femoral frontal angle showed good test–retest reliability. Conclusion The increased femoral frontal angle magnitude during the one-leg squat demonstrates that the one-leg squat may be a useful clinical tool for the evaluation process of PFPS.