Early Patellofemoral Osteoarthritis Following ACL Reconstruction: A Narrative Review

Background/Objectives: Early patellofemoral osteoarthritis (PFOA) following anterior cruciate ligament reconstruction (ACLR) is increasingly recognized as an important contributor to knee osteoarthritis (OA) in young individuals. This narrative review aimed to summarize the current evidence on early PFOA following ACLR including its prevalence, definition, risk factors, treatment, ongoing research, and future directions. Methods: A non-systematic literature search of PubMed/MEDLINE was conducted for English-language peer-reviewed original studies and reviews on early PFOA following ACLR, published through May 2026. Titles and abstracts were screened for relevance and full-text articles were reviewed when appropriate. ClinicalTrials.gov was searched for ongoing randomized controlled trials (RCTs). Results: Early PFOA following ACLR had a prevalence of 17-44% within 5 years postoperatively. Definitions remain highly heterogeneous with no universally accepted classification, although MRI-based assessment tools such as the MRI Osteoarthritis Knee Score (MOAKS) appear to be increasingly utilized. Proposed risk factors include older age, higher body mass index, concomitant meniscal injury, quadriceps weakness, altered biomechanics, and autograft choice, although findings remain inconsistent across studies. Current prevention and treatment strategies are largely extrapolated from general knee OA principles, reflecting the limited evidence specific to early PFOA. Ongoing research is increasingly focused on rehabilitation-based prevention and pharmacological interventions targeting early OA following ACLR. Conclusions: Early PFOA following ACLR is common in young individuals, yet evidence regarding its definition, risk factors, prevention, and treatment remains limited. The early disease stage may allow modification of structural and biomechanical changes, enabling disease-modifying pharmacological and targeted rehabilitation approaches, but standardized classification criteria and future research are needed.