What Prognostic Indicators and Treatment Mechanisms Exist for Efficacious Treatments in People With Patellofemoral Pain? A Secondary Meta-regression With an Updated Search

OBJECTIVE: To investigate the prognostic and mechanistic variables associated with efficacious treatments in people with patellofemoral pain (PFP). DESIGN: Updated intervention systematic review with de novo meta-regression. LITERATURE SEARCH: We searched MEDLINE, Web of Science, and Scopus from inception until October 2023 for randomized controlled trials (RCTs) involving people with PFP. STUDY SELECTION CRITERIA: High-quality RCTs (scoring ≥7 on the PEDro scale) involving participants with PFP and at least 1 treatment arm involving an efficacious intervention. DATA SYNTHESIS: We extracted homogenous pain and function data to calculate effect sizes to regress with baseline prognostic (eg, symptom duration) and mechanistic (eg, strength change) data. RESULTS: Thirty-four high-quality RCTs involving 1526 people with PFP were included. For knee-targeted exercise, we identified symptom duration (R 2 = 0.68), older age (R 2 = 0.31), and low baseline knee extensor strength (R 2 = 1.0) as significant prognostic variables. For hip-and-knee–targeted exercise, we identified older age (R 2 = 0.37), greater mass (R 2 = 0.28), and greater baseline hip abduction torque (R 2 = 1.0) as significant prognostic variables. We also identified a significant mechanistic association between pain and increased knee extensor torque (R 2 = 0.99). For hip-targeted exercise, we identified lower height as a significant prognostic variable (R 2 = 0.96-0.99) and a significant mechanistic association between both pain and function and increased hip abduction (R 2 = 0.93-0.96) and hip external rotation (R 2 = 0.96-0.97) strength. CONCLUSIONS: Prolonged symptom duration, older age, and greater mass are prognostic variables for people with PFP. Increasing hip and knee muscle strength may be mechanisms underpinning positive responses to exercise therapy. JOSPT Open 2025;3(2):193-209. Epub 6 February 2025. doi:10.2519/josptopen.2025.0119