Association of Physical Function and Pain with Lower Muscle Strength and Trunk Muscle Endurance in Subjects with Patellofemoral Pain Syndrome

Abstract

Objectives: This study investigated the relationship between knee pain severity and functional performance, as well as hip and knee muscle strength and trunk endurance, in individuals with patellofemoral pain syndrome (PFPS). Methods: This cross-sectional study included 50 participants diagnosed with PFPS. An 11-point visual analog scale (VAS) was used to assess the severity of knee pain, and the Anterior Knee Pain Scale (AKPS) was used to quantify functional ability. Hip extensors, abductors, medial and lateral rotators, and knee extensors were tested for strength using a handheld dynamometer. Trunk endurance was assessed through plank tests in anterior, posterior, and lateral positions. Results: A significant inverse relationship was identified between pain intensity and functional performance (r = -0.504, p < 0.001). Body mass index (BMI) exhibited a negative relationship with performance (B = -7.459, p = 0.021). Knee extensor strength (B = 0.156, p < 0.0001) and lateral plank endurance (B = 1.457, p = 0.002) showed a positive relationship with functional performance. Conclusion: Higher pain levels and BMI were related to poorer function in individuals with PFPS. In contrast, greater quadriceps strength and increased lateral core endurance were correlated with better functional outcomes.