Evaluation of Hip Frontal Plane Flexibility and Strength in Male Sprinter Runners With Unilateral Patellofemoral Arthropathy: A Case-Control Study

Background and Objectives: Patellofemoral Arthropathy (PFA) is the most common knee disorder in runners and various factors can lead to the development of its symptoms. It has been proposed that frontal plane motions of the hip and knee can raise the dynamic quadriceps angle during functional tasks. The aim of this study was to evaluate frontal plane acting hip muscle flexibility and strength differences in male sprinter runners with unilateral PFA. Methods: A total of 38 male runners complaining of peripatellar pain or showing positive unilateral patellar grind test, assigned to the normal and sound legs, and 20 matched control groups were compared in this case-control study. Participants’ hip abductor and adductor muscles strength and their flexibility were evaluated through a hand-held dynamometer and 2D motion analysis tracker software. To measure the strength, participants were positioned side-lying position, performing abduction and adduction, while a dynamometer was placed on the lateral and medial femoral epicondyle. Active and passive abduction and adduction range of motion were recorded via a camera in the supine position and the film was analyzed by the software. Results: Abductor muscle strength and abduction-to-adduction ratio on the involved side were significantly lower than the uninvolved side (P=0.029, P=0.008, d=-0.388, d=-0.459), while greater adduction and lower abduction to adduction ratio were found in the control group (P<0.001, F=3.599). Also, lesser passive abduction and active adduction range of motion were found in the control group on both sides (P<0.001, F=2.792, F=8.979). Conclusion: Strength changes of the involved side compared with uninvolved side and less flexible side, but more probably inhibited and stronger adductors in the control group may suggest impaired muscular interaction based on frontal plane muscles torque/length curve function in unilateral PFA. Changes in the strength of the involved side compared to the healthy side and the adductor muscles with more flexibility and strength but more inhibited by the abductor’s muscles in the control group could indicate.