Progressive Cartilage Degeneration After Anterior Cruciate Ligament Reconstruction: Longitudinal Evidence From the Swedish Knee Ligament Registry

BACKGROUND: Chondral lesions and subsequent knee osteoarthritis often occur after anterior cruciate ligament (ACL) injuries, and although ACL reconstruction (ACLR) is common, cartilage degeneration remains more prevalent than in the general population, with inconsistent evidence on whether surgery offers a protective effect. PURPOSE/HYPOTHESIS: This study aimed to evaluate the progression of cartilage damage after ACLR using second-look arthroscopy in patients who underwent both primary and revision procedures and to identify risk factors for cartilage degeneration. It was hypothesized that chondral lesions would progress between primary and revision surgery, primarily influenced by characteristics of the initial injury and primary surgery. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective cohort study was conducted using prospectively collected data from the Swedish Knee Ligament Registry. All patients who underwent both primary and revision ACLR between January 1, 2005, and December 31, 2023, were included. Patients with multiligament injuries or missing key data were excluded. The prevalence, location, and severity of cartilage lesions assessed intraoperatively at both primary and revision ACLR were reported and compared. Secondarily, potential risk factors for cartilage damage at the time of revision surgery were evaluated using multivariate logistic regression analysis, incorporating available patient and surgical variables from the registry. RESULTS: A total of 2845 patients were included. The prevalence, size, and severity of cartilage lesions increased markedly across all knee compartments between primary and revision ACLR, which occurred at a median of 2.4 years later. We found 4 independent risk factors for cartilage damage at revision surgery: older age, meniscal and cartilage lesions at primary surgery, and longer time from primary injury to revision ACLR. Each additional month from the initial injury to revision ACLR was associated with a 0.7% increase in the odds of cartilage damage, underscoring a time-dependent degenerative process. CONCLUSION: This study showed a clear progression of cartilage degeneration between primary and revision ACLR. Although limited to patients requiring revision surgery, these findings contribute to the broader understanding of posttraumatic joint deterioration and reinforce the need for interdisciplinary approaches to mitigate long-term cartilage damage.