A predictive model with radiographic signs can be a useful supplementary diagnostic tool for complete discoid lateral...

To investigate the diagnostic accuracy of radiographic signs for complete discoid lateral meniscus and whether a predictive model combining the radiographic signs can improve its diagnostic accuracy in adults.

A total of adult 119 knees with complete discoid lateral meniscus confirmed by arthroscopy and 119 age- and sex-matched knees with normal meniscus were included. The radiographic signs of lateral joint space, fibular head height, lateral tibial spine height, lateral tibial plateau obliquity, lateral femoral condyle squaring, lateral tibial plateau cupping, lateral femoral condyle notching, and the condylar cut-off sign were evaluated. The receiver-operating characteristic (ROC) curves and area under the curve (AUC) were evaluated for best accuracy. A prediction model was developed by multivariable regression with generalized estimating models, and was validated using data from 111 knees of children with complete discoid lateral meniscus and 111 normal controls.

The fibular head height, lateral joint space, lateral tibial plateau obliquity, and the condylar cut-off sign were significantly different between the complete discoid lateral meniscus and the normal groups (p < 0.05). Among the four radiographic signs, the fibular head height showed the highest accuracy with 78.9% sensitivity and 57.3% specificity. The prediction models developed by logistic regression showed significantly improved accuracy for complete discoid lateral meniscus compared to the fibular head height (sensitivity: 69.8%, specificity: 82.9%, p = 0.001). For validation, the AUC of children seemed to be larger than that of adults, which indicated that the prediction models could be applied for children to detect complete discoid lateral meniscus.

Among several radiographic signs, the fibular head height can be used as a screening tool for complete discoid lateral meniscus. The prediction models combined with lateral joint space, fibular head height, lateral tibial plateau obliquity, and/or the condylar cut-off sign yielded a much higher diagnostic value than each radiographic sign. Therefore, fibular head height and prediction models combined with radiographic signs can provide improved diagnostic value for complete discoid lateral meniscus.

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