Which factors correlate with muscle strength capacity in people with patellofemoral pain? A systematic review with meta-analysis.

Abstract

Individuals with patellofemoral pain (PFP) commonly exhibit muscle weakness; however, the relationship between muscle strength deficits and other factors in this population remains unclear. The present systematic review aimed to identify factors correlated with muscle strength capacity in individuals with PFP. A systematic search was conducted in Medline, Embase, CINAHL, SPORTDiscus, and Web of Science from their inception to September 2025. Correlational studies that included individuals with PFP and reported quantitative measures of muscle strength correlated with other quantitative variables were eligible for inclusion. Out of 9370 records screened, 57 studies met the inclusion criteria, and 37 were included in the meta-analyses. The findings indicated that knee extensor strength is trivially to moderately correlated with functionality, pain, pain duration, and kinesiophobia; knee flexor strength is weakly to moderately correlated with functionality and pain; hip abductor strength is trivially to moderately correlated with function, hip frontal and transverse plane movements; hip extensor strength is weakly correlated with function; hip external rotation strength is weakly correlated with function; hip posterolateral strength is moderately correlated with function; and trunk lateral flexion strength is weakly correlated with knee frontal plane movement. Despite the generally weak correlations observed, muscle strength capacity in individuals with PFP presents significant associations with key factors such as pain, function, kinesiophobia, and lower limb movement patterns.