Quantitative magnetic resonance imaging in patellar tendon-lateral femoral condyle friction syndrome: relationship with subtle patellofemoral instability

To investigate the correlation of patellar tendon-lateral femoral condyle friction syndrome (PTLFCFS) with subtle patellofemoral instability to explore its pathogenesis. One hundred knees of 80 patients with PTLFCFS were analyzed retrospectively by retrieving magnetic resonance imaging (MRI) data over a 3-year period from our database. Seven quantitative parameters for evaluating patellofemoral stability were measured on MR images, including the Insall–Salvati ratio, tibial tuberosity–trochlear groove (TT–TG) distance, trochlear groove depth, medial trochlear/lateral trochlear length (MT/LT) ratio, medial trochlear/lateral trochlear height (MH/LH) ratio, lateral patellofemoral angle (LPA), and lateral trochlear inclination (LTI) angle. These patellofemoral parameters of the PTLFCFS group and the normal control group were compared (n = 88), and receiving-operator characteristic (ROC) curve analysis was conducted to determine the specificity and sensitivity of these parameters. The trochlear depth, MT/LT, LPA, and LTI angle were significantly lower (p