Risk factors for radiographic joint space narrowing and patient reported outcomes of post-traumatic osteoarthritis after ACL reconstruction: Data from the MOON cohort.

The Multicenter Orthopaedic Outcomes Network (MOON) is an NIH-funded prospective, longitudinal cohort of over 3,500 patients who have undergone anterior cruciate ligament reconstruction (ACLR) by 14 sports medicine surgeons at 7 academic medical centers. Patient reported outcome questionnaires (PRO's) are completed at baseline and multiple timepoints after surgery, and a nested cohort of patients return for radiographs to assess the development of joint space changes. We review the risk factors for worse patient reported outcomes, the predictors of clinically significant symptoms of post-traumatic osteoarthritis (PTOA), and the factors associated with more radiographic joint space narrowing. Baseline PRO's were highly predictive of follow-up scores. Factors associated with worse PRO's at 2 and 6 years included female sex, higher BMI, smoking, less education, allograft, medial meniscectomy, or repair, and chondral injury. Partial lateral meniscectomy was unexpectedly associated with better PRO's. Factors associated with clinically significant symptoms of PTOA at 2 and 6 years included subsequent surgery, meniscal pathology, and chondral injury. Factors associated with narrower medial compartment joint space width included medial meniscectomy, medial meniscus repair, and increased age. Medial joint space width was slightly wider overall for the ACLR knees compared to the contralateral normal knees. Future studies will evaluate PRO's and radiographs at 10-year follow-up.