Relationship between radiographic classification and arthroscopic findings of articular cartilage lesions in osteoarthritis of the knee.

OBJECTIVE: To examine the relationship between radiographic abnormalities and arthroscopic findings of the cartilage lesions in patients with osteoarthritis (OA) of the knee. METHODS: Arthroscopy was performed in 190 patients with primary medial compartment (MC) OA of the knee to assess the severity of the cartilage lesion. Standing radiographs of all patients were graded according to the joint space narrowing (JSN) and Kellgren-Lawrence (K/L) scales. In addition to evaluating the correlation between arthroscopic articular cartilage lesions and the radiographic scale, multiple regression analysis was used to identify the arthroscopic findings and clinical factors that influenced the cartilage lesions. RESULTS: The positive predictive values of the JSN and K/L scales of the MC for the presence of essentially abnormal articular cartilage in the MC by arthroscopy were high (0.98, 0.96, respectively). The sensitivity and specificity of the JSN scale and the sensitivity and negative predictive value of the K/L scale were also high in the MC. In contrast, the positive predictive values of these radiographic scales for the presence of arthroscopic lesions in the lateral compartment (LC) were poor (0.20 and 0.19). In this study population with severe OA, there were more patients with a high K/L score than with a high JSN score in the MC. CONCLUSION: In MC-OA of the knee, the JSN and K/L scores for the MC correlated highly with cartilage lesions of the MC by arthroscopy. However, the cartilage lesion of the LC correlated poorly with both of these radiographic scales.