Validation of the Macroscopic Anterior Cruciate Ligament Status Using the Oxford Classification System in Relation to Cartilage Defects on the Medial Tibial Plateau in Osteoarthritic Knees.

This study evaluated the relationships between anterior cruciate ligament (ACL) grading using the Oxford classification system and cartilage defects on the medial tibial plateau to clarify the validity of the system. We studied the location and size of a full-thickness cartilage defect of the medial tibial plateau in 154 knees (97 patients) treated by unicompartmental (113) or total (41) knee arthroplasty between April 2017 and January 2018, and analyzed their relationship to the anterior cruciate ligament (ACL) grade, Grade 1 (normal), Grade 2 (synovial damage), Grade 3 (longitudinal split), Grade 4 (friable and fragmented), and Grade 5 (absent). Significant trends in decreased posterior preserved cartilage, increased defect length, and posteriorized defect center were associated with increasing ACL grade. Multiple comparison analysis revealed that the measurements were significantly different between ACL functional (Grades 1-3) and ACL deficient (Grades 4 and 5). On the other hand, the anterior preserved cartilage was consistent among the Grades. The macroscopic Oxford ACL classification system well described the disease progression where the cartilage defect extends posteriorly with ACL damage. However, 38% of ACL deficient knees had well-preserved posterior cartilage with no evident tibial anterior translation.