OBJECTIVE To determine the correlation between patellar tendon-lateral femoral condyle friction syndrome (PLFFS) and the morphological characteristics of the antero-inferior part of the lateral femoral condyle (ALFC) to explore the potential pathogenesis. METHODS A total of 170 knees of 140 patients with PLFFS (PLFFS group) were retrospectively analyzed using magnetic resonance imaging (MRI) data for a 4-year period from our database. The Insall-Salvati ratio, shape of the ALFC (SALFC, defined as two subtypes: sharp versus blunt), lateral femoral condyle angle (LFCA), lateral trochlear length (LTL), and lateral trochlear height (LTH) were measured on MRI. Two groups were enrolled as controls: pure patella alta group (n = 192) and normal group (n = 172). All the parameters of the PLFFS group were compared with those of the two control groups. RESULTS The LFCA was significantly lower (p < 0.001) in the PLFFS group than in the pure patella alta group. The SALFC was significantly different (p < 0.001) in these two groups, whereas the Insall-Salvati ratio, LTH, and LTL showed no significant difference. The LFCA, LTH, SALFC, and the Insall-Salvati ratio in the PLFFS group were also significantly different (p < 0.001) with the normal group. Receiver operating characteristic (ROC) analysis showed the efficacy of the Insall-Salvati ratio and SALFC was better than that of the other parameters. CONCLUSIONS The morphological characteristics of ALFC are correlated with PLFFS. The sharp shape of ALFC may be an important causative co-factor along with patella alta in the pathogenesis of PLFFS. KEY POINTS • A sharp margin of the antero-inferior lateral femoral condyle is an important risk factor for the development of PLFFS in patients with patella alta. • Antero-inferior femoral condyle shape can easily be assessed with high intra- and inter-reader reliability PLFFS. • PLFFS is more common in young adults.

中文翻译：

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股骨外侧髁前下缘尖锐边缘是髌腱-股骨外侧髁摩擦综合征的危险因素。

目的确定髌腱-股骨外侧髁摩擦综合征（PLFFS）与股骨外侧髁（ALFC）前下部形态特征的相关性，探讨其潜在的发病机制。方法 使用我们数据库中为期 4 年的磁共振成像 (MRI) 数据对 140 名 PLFFS 患者（PLFFS 组）的 170 个膝关节进行回顾性分析。在 MRI 上测量了 Insall-Salvati 比率、ALFC 的形状（SALFC，定义为两种亚型：尖锐与钝钝）、股骨外侧髁角 (LFCA)、外侧滑车长度 (LTL) 和外侧滑车高度 (LTH)。纳入两组作为对照组：纯高位髌骨组 (n = 192) 和正常组 (n = 172)。将PLFFS组的所有参数与两个对照组进行比较。结果 PLFFS 组的 LFCA 显着低于单纯高位髌骨组 (p < 0.001)。这两组的 SALFC 有显着差异 (p < 0.001)，而 Insall-Salvati 比率、LTH 和 LTL 没有显着差异。PLFFS 组的 LFCA、LTH、SALFC 和 Insall-Salvati 比率也与正常组有显着差异 (p < 0.001)。接受者操作特征 (ROC) 分析显示 Insall-Salvati 比率和 SALFC 的疗效优于其他参数。结论 ALFC的形态特征与PLFFS相关。ALFC 的尖锐形状可能是 PLFFS 发病机制中与高位髌骨一起的重要致病辅助因素。要点 • 前下外侧股骨髁的锐利边缘是高位髌骨患者发生 PLFFS 的重要危险因素。• 前下股骨髁形状可以很容易地进行评估，并具有较高的读者内部和读者间可靠性 PLFFS。• PLFFS 在年轻人中更为常见。