Incidence and Risk Factors for Posttraumatic Osteoarthritis After Primary ACL Reconstruction in Pediatric Patients: A National Database Study.

Background: The development of posttraumatic osteoarthritis (PTOA) of the knee after anterior cruciate ligament (ACL) reconstruction (ACLR) leads to additional morbidity in adults. Purpose: To determine the 5-year incidence of and risk factors for PTOA diagnoses after primary ACLR in pediatric patients. Study Design: Case control study, Level of evidence, 3. Methods: A United States-based insurance database was used to identify patients aged ≤16 years who underwent primary ACLR from 2010 to 2019 and had at least 5 years of follow-up data. Patients with multiligament knee injuries, tibial eminence avulsion fractures, congenital/syndromic ACL absence syndrome, juvenile idiopathic arthritis, previous knee osteoarthritis or PTOA diagnoses, or previous knee injuries/surgeries were excluded. Demographic factors and concomitant meniscal and cartilage procedures at the time of primary ACLR were recorded. Delayed ACLR was defined as ≥3 months between initial ACL injury diagnosis and ACLR. We also recorded the presence of subsequent motion restoration reoperations, including lysis of adhesions and/or manipulation under anesthesia, after primary ACLR but before PTOA diagnosis. Risk factors for PTOA were evaluated using multivariable logistic regression. Results: Included were 16,935 patients (mean age at surgery, 15.1 ± 1.2 years; 62% women). PTOA was diagnosed in 267 patients (1.6%) within 5 years after ACLR; 148 of these patients (55.4%) were diagnosed within 2 years after ACLR. Independent risk factors associated with PTOA diagnosis included subsequent motion restoration procedures (odds ratio [OR], 5.03 [95% CI, 3.31-8.25]; Conclusion: The incidence of PTOA diagnoses was low within 5 years after primary ACLR in patients ≤16 years old with no subsequent cartilage, meniscus, and/or revision ligament procedures. The need for subsequent motion restoration procedures, age ≥12 years at the time of ACLR, delayed ACLR, obesity, and male sex were significant risk factors associated with a PTOA diagnosis.