AJSM Webinar Series: ACL Injury and PTOA: Bridging Biology, Imaging, and Machine Learning to Improve Outcomes (Recording)-Lu Y et al. Posttraumatic Arthritis After ACL Injury: Machine Learning Comparison Between Surgery and Nonoperative Management. AJSM 2025. PMID: 40079334

Lu Y et al. Posttraumatic Arthritis After ACL Injury: Machine Learning Comparison Between Surgery and Nonoperative Management. AJSM 2025. PMID: 40079334

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This retrospective cohort study compared long-term outcomes after primary ACL injury in patients treated with ACL reconstruction (ACLR) versus nonoperative care, using machine learning and targeted maximum likelihood estimation (TMLE) to reduce confounding. The cohort came from the Rochester Epidemiology Project and included 1,194 patients with at least 7.5 years of follow-up: 974 underwent ACLR and 220 were treated without surgery.<br /><br />At baseline, the surgical group was younger, had lower BMI, and was more active than the nonoperative group. Over follow-up, symptomatic posttraumatic osteoarthritis (PTOA) developed in 22.1% of ACLR patients versus 63.6% of nonoperative patients. Total knee arthroplasty (TKA) occurred in 2.6% of ACLR patients versus 22.6% of nonoperative patients. TKA also occurred later in the ACLR group.<br /><br />After adjustment with TMLE, ACL reconstruction was associated with an 11% absolute reduction in the risk of PTOA compared with nonoperative management. However, TMLE did not show a significant effect of ACLR on progression to TKA. Time-to-event machine learning analyses also showed that ACLR delayed both PTOA onset and progression to TKA.<br /><br />Important risk factors for PTOA and TKA, regardless of treatment, included older age at injury, higher BMI, residual knee laxity, additional arthroscopic surgeries, concomitant meniscal or cartilage injury, greater pain at presentation, and sedentary activity level.<br /><br />Overall, the study suggests that ACL reconstruction may reduce and delay posttraumatic arthritis after ACL injury, though it may not clearly prevent eventual knee replacement.

Keywords

anterior cruciate ligament injury

ACL reconstruction

nonoperative management

posttraumatic osteoarthritis

total knee arthroplasty

retrospective cohort study

targeted maximum likelihood estimation

machine learning

knee laxity

meniscal injury