Usefulness of patellar cartilage cross-sectional area for knee tibiofemoral osteoarthritis in elderly

PURPOSE: Knee tibiofemoral osteoarthritis (KOA) is a major health problem, affecting approximately 30% of elderly. Several studies have reported that the loss of patellar cartilage is associated with an increased risk of KOA. However, no study has reported the optimal cut off value of patellar cartilage cross-sectional area (PCA) in KOA. We hypothesize that PCA is a new sensitive morphologic parameter in the diagnosis of KOA. The purpose of this study was to determine whether PCA could be used as an important adjuvant morphological parameter in the diagnosis of KOA. PATIENTS AND METHODS: Data regarding PCA were collected from 88 subjects with KOA. A total of 77 subjects in the control group underwent knee MRI as part of nonsymptomatic medical examination. T2-weighted axial images were acquired from both groups. Using a picture archiving communications system, we analyzed the cross-sectional area of the patellar cartilage on MRI. RESULTS: The average PCA was 98.66±22.18 mm(2) in the control group, which was significantly (p<0.001) higher than that (59.43±16.11 mm(2)) in the KOA group. Receiver operator haracteristic curve analysis was computed to determine the validity of PCA as a predictor of KOA. In the KOA group, the optimal cut offpoint was 76.06 mm(2), with sensitivity of 83.0%, specificity of 83.1%, and AUC of 0.94 (95% CI: 0.90–0.97). CONCLUSIONS: Lower PCA values were associated with a higher possibility of KOA. The optimal cutoff score of PCA might be used to facilitate the evaluation of patients with KOA.