Proximal and distal muscle thickness is different in women with patellofemoral pain but is not associated with knee frontal plane projection angle.

Objective: The aim of this study was to compare proximal and distal muscle thickness between patellofemoral pain (PFP) and asymptomatic women (CG) and to verify the possible association between morphology and lower limb alignment during single leg-squat.

Methods: Thirty women (PFP, n = 15 and CG, n = 15) performed the following evaluations: (i) muscle thickness of external oblique (EO), gluteus medius (GMed), tensor fascia latae (TFL), peroneus (PER) and tibialis anterior (TA); (ii) knee frontal plane projection angle (FPPA) during single-leg squat.

Results: Compared with the CG, PFP showed: (1) smaller GMed (-10.02%; p = 0.04; effect size = 0.82), greater TFL (+18.44%; p = 0.02; effect size = 0.92) and PER (+14.23%; p = 0.02; effect size = 0.87) muscle thickness and greater knee FPPA during single-leg squat (+31.8%; p = 0.04; effect size = 1.12). No differences were observed in EO (+7.17%; p = 0.37; effect size = 0.34) and TA (-1.35%; p = 0.81; effect size = 0.12) muscle thickness. Additionally, we failed to observe significant associations between muscle morphology and knee FPPA in both groups.

Conclusion: PFP patients showed alterations in proximal and distal muscle thickness, despite the lack of association with poor lower limb alignment. Prospective studies are necessary to determine if differences in muscle morphology are the cause or the consequence of PFP and to confirm the absence of relationship with lower limb alignment.