Fig. 2

Magnetic resonance imaging (MRI) measurement and articulating groove. a Sagittal MRI of the knee shows the measurement of the maximum length (red line), thickness (blue line) of fabella, and the distance between the fabella and the insertion of the lateral head of the gastrocnemius onto the femur (green line); b Axial MRI of the knee shows the measurement of the maximum width of the fabella (yellow line); MRI of the knee show (c) concave and (d) flat contours of the articulating groove of the lateral femoral condyle of the femur (arrow)