Lower extremity kinetics and kinematics in runners with patellofemoral pain: a retrospective case-control study using musculoskeletal simulation

Abstract

Patellofemoral pain (PFP) is a common atraumatic knee pathology in runners, with a complex multifactorial aetiology influenced by sex differences. This retrospective case-control study therefore aimed to evaluate lower limb kinetics and kinematics in symptomatic and control male and female runners using musculoskeletal simulation. Lower extremity biomechanics were assessed in 40 runners with PFP (15 females & 25 males) and 40 controls (15 females & 25 males), whilst running at a self-selected velocity. Lower extremity biomechanics were explored using a musculoskeletal simulation approach. Four between group comparisons 1. Overall PFP vs. Control, 2. Male PFP vs. Male Control, 3. Female PFP vs. Female Control and 4. Male PFP vs. Female PFP were undertaken using linear mixed models. The overall (stress per mile: PFP=1047.49 & Control=812.93) and female (peak stress: PFP=13.07KPa/BW & Control=10.82KPa/BW) comparisons showed increased patellofemoral joint stress indices in PFP runners. A significantly lower strike index was also shown in PFP runners in the overall (PFP=17.75% & Control=33.57%) and female analyses (PFP=15.49% & Control=40.20%), which revealed a midfoot strike in control, and a rearfoot pattern in PFP runners. Peak rearfoot eversion and contralateral pelvic drop range of motion (ROM) were shown to be greater in PFP runners in the overall (eversion: PFP=-8.15° & Control=-15.09°/ pelvic drop ROM: PFP=3.64° & Control=1.88°), male (eversion: PFP=-8.05° & Control=-14.69°/ pelvic drop ROM: PFP=3.16° & Control=1.77°) and female (eversion: PFP=8.28° & Control=-15.75°/ pelvic drop ROM: PFP=3.64° & Control=1.88°) PFP runners, whilst female PFP runners (11.30°) exhibited a significantly larger peak hip adduction compared to PFP males (7.62°). The findings from this investigation identify biomechanical differences between control and PFP runners as well as demonstrating distinctions in PFP presentation for many parameters between sexes. Highlighting potential risk factors for PFP that may be addressed through focused intervention modalities and also the need where appropriate, for sex specific targeted treatment approaches.