Elevated risk of patellofemoral osteoarthritis following ACL reconstruction compared to contralateral knees: A systematic review and meta-analysis.

Purpose: To investigate the development of patellofemoral osteoarthritis (PFOA) in the affected knee of anterior cruciate reconstruction (ACL-R) patients compared to their contralateral knee. The impact of graft choice on PFOA progression was also examined. Methods: A systematic literature search was performed up to 1 June 2025. Studies at level of evidence II and III reporting imaging outcomes of the patellofemoral (PF) joint following ACL-R and contralateral knees were included. Studies involving isolated primary ACL-R procedures, regardless of meniscus status, were considered. The meta-analysis was performed to assess if ACL-R was associated with a higher likelihood of PFOA compared to contralateral knees. Furthermore, a sub-analysis was conducted to evaluate whether the patellar tendon autograft was associated with a higher chance of PFOA than hamstring autografts. The random effects model was used to calculate the pooled odds ratio of PFOA in patients following ACL-R compared to the control group. Meta-regression analysis was performed to determine whether sample size, follow-up duration and population age significantly influenced the odds ratio. Results: Eleven studies met the inclusion criteria and were included in this review. A total of 1206 participants were included, with an average male/female ratio of 57/49 and a pooled weighted mean age of 27 years. The follow-up duration varied from 1 to 17.8 years, with an average of 5 years. Radiographic definitions of PFOA were determined using the Kellgren-Lawrence and the Osteoarthritis Research Society International (OARSI) classifications, while the magnetic resonance imaging (MRI) PFOA definition was derived from the MRI Osteoarthritis Knee Score (MOAKS) grading. Patients undergoing ACL-R demonstrated a significantly higher likelihood of PFOA compared to their contralateral knees ( Conclusions: Patients undergoing ACL-R are more likely to develop PFOA than their contralateral knees. No significant difference in risk of PFOA development was found between hamstrings tendon and patellar tendon autografts. Level of Evidence: Level II and III, systematic review and meta-analysis studies.