Lower limb muscles' thicknesses are weakly associated with dynamic knee valgus during single-leg squat in women with patellofemoral pain.

INTRODUCTION: Patellofemoral pain (PFP) patients often show an altered lower limb alignment during the single-leg squat (SLS). There is evidence that proximal and distal-to-the-knee muscle alterations can modify the lower limb alignment in PFP patients. However, we observed a lack of studies investigating the possible association between the thickness and strength of proximal and distal-to-the-knee muscles and lower limb alignment during SLS in women with PFP. Therefore, this study aimed to investigate the association between the thickness and strength of lower limb muscles and dynamic knee valgus (DKV) during SLS in women with PFP. METHODS: Cross-sectional study, where fifty-five women with PFP were submitted to the following evaluations: (1) muscle thickness (MT) of Gluteus Medius (GMed), Gluteus Maximus (GMax), Vastus Lateralis (VL), and Tibialis Anterior (TA); (2) isometric peak torque of hip abductors, hip external rotators, knee extensors, and foot inversors; and (3) DKV during SLS. RESULTS: There was a significant negative association between GMax's MT and DKV (r = -0.32; p = 0.01), and between TA's MT and DKV (r = -0.28; p = 0.03). No significant correlations were observed between isometric torques and DKV. Regression analysis found that GMax's MT explained 10% of the DKV's variance during SLS. DISCUSSION: Poor lower limb alignment during SLS is weakly associated with proximal and distal-to-the-knee muscle thicknesses, with no association with isometric torque in PFP women. CONCLUSION: Our results suggest that other factors besides strength and muscle thicknesses may explain and improve lower limb alignment in women with PFP.

Can we replace exercises targeted on core/hip muscles by exercises targeted on leg/foot muscles in women with patellofemoral pain? A randomized controlled trial.

OBJECTIVE: To verify the effects of replacing exercises targeted on core/hip muscles by exercises targeted on leg/foot muscles in a rehabilitation program for patellofemoral pain (PFP). DESIGN: Randomized Controlled Trial. PARTICIPANTS: Fifty women with PFP. METHODS: PFP participants were randomized into the standard rehabilitation group (SRG, n = 25) or distal exercise group (DEG, n = 25). Knee pain, patient-reported function, dynamic knee valgus and muscle strength were measured at baseline and after six and twelve weeks of the program start. RESULTS: SRG and DEG presented similar responses to rehabilitation (except for muscle strengthening). Knee pain reduced after 6 weeks (SRG: -37.7%, ES = 1.23; DEG: -30%, ES = 0.93) and 12 weeks (SRG: -47.4%, ES = 1.53; DEG: -43.3%, ES = 1.46). Patient-reported function improved after 6 weeks (SRG: +7.3%, ES = 0.45; DEG: +3.8%, ES = 0.22) and 12 weeks (SRG: +14.1%, ES = 0.80; DEG: +8.8%, ES = 0.50). Dynamic knee valgus reduced after 12 weeks (SRG: -29.7%, ES = 0.38; DEG: -34.5%, ES = 0.32). Both groups experienced increases in knee extension strength (SRG: +9%, ES = 0.28; DEG: +6%, ES = -0.29), but only SRG had strength gains for hip abduction (+10%, ES = 0.36) and extension (+11%, ES = 0.44). CONCLUSION: Exercises targeted on core/hip muscles can be replaced by exercises targeted on leg/foot muscles in a lower limb exercise-based rehabilitation program for women with PFP. CLINICAL TRIAL REGISTRATION: NCT03663595.