Soft tissue degeneration 10+ years after ACLR and their association with radiographic PTOA and knee pain development: radiomic analysis using qMRI approach in MOON nested on-site cohort

Anterior cruciate ligament reconstruction (ACLR) is the standard treatment for ACL injuries; however, over 50% of patients develop post-traumatic osteoarthritis (PTOA) within 10–20 years. Quantitative MRI (qMRI) enables early detection of cartilage and soft tissue changes, and radiomics may enhance understanding of PTOA and knee pain development. This study investigates structural and soft tissue changes associated with radiographic PTOA and examines their relationship to knee pain in patients 10 years post-ACLR using qMRI-based radiomics analysis. We analyzed 162 patients from the MOON nested on-site cohort. qMRI acquisitions of the knee and thigh were harmonized across sites to minimize variability. A total of 17656 Radiomic features were extracted from T1ρ and T2 maps from cartilage and menisci, thigh muscle fat fraction maps, and thigh muscle morphology images. Radiomics models for radiographic PTOA (Kellgren-Lawrence ≥ 2) and knee pain (KOOS pain ≤ 85) were developed using Boruta, minimum redundancy maximum relevance, and XGBoost. Eight radiomic features from cartilage, menisci, and muscle regions (quadriceps/adductors) were associated with radiographic PTOA. Six radiomic features from cartilage and menisci were linked to knee pain. Radiomics models outperformed clinical models with AUROC = 0.85 (95% CI: 0.84–0.87) and 0.79 (95% CI: 0.77–0.81) for radiographic PTOA and knee pain, respectively. qMRI-based radiomics identifies cartilage, menisci, and muscle features linked to PTOA and knee pain post-ACLR. Future studies should explore additional tissue features and contralateral knee analyses to further elucidate PTOA progression and pain mechanisms.