Radiographic Features of Posttraumatic Knee Osteoarthritis More Than 10 Years After Anterior Cruciate Ligament Reconstruction: Osteophyte Enlargement With Preserved Joint Space

Background: Anterior cruciate ligament (ACL) injury is a major risk factor for knee osteoarthritis (OA). Although ACL reconstruction (ACLR) restores stability, it does not reliably prevent OA. This study investigated the radiographic features of patients with knee OA more than 10 years after ACLR. Materials and Methods: Thirty patients (21 female and 9 male; mean age, 45.4 ± 12.0 years) who underwent ACLR more than 10 years ago (mean postoperative period, 14.5 ± 4.0 years) were included. Standing anteroposterior radiographs of ACLR and contralateral healthy knees were evaluated for Kellgren-Lawrence (KL) grade, osteophyte width at the medial and lateral tibial and femoral surfaces, and minimum joint space width (mJSW). Lower limb alignment was assessed using medial proximal tibial angle (MPTA) and joint line convergence angle (JLCA). Subgroup analyses were based on KL grade concordance and history of partial meniscectomy. Results: KL grades were significantly higher in ACLR knees than in contralateral knees ( P < .001). Osteophyte widths were greater in ACLR knees at medial tibia (2.1 ± 1.1 mm vs 0.5 ± 0.7 mm), lateral tibia (2.3 ± 2.3 mm vs 0.5 ± 0.7 mm), medial femur (2.0 ± 1.7 mm vs 0.1 ± 0.4 mm), and lateral femur (1.4 ± 2.3 mm vs 0.2 ± 0.5 mm); all P < .001. No significant differences were observed in mJSW ( P = .904), MPTA ( P = .232), or JLCA ( P = .681). Subgroup analyses showed similar findings. Conclusion: Enlarged osteophytes without joint space narrowing were observed in ACLR knees, suggesting a posttraumatic OA radiographic pattern distinct from that of primary OA.