Department of Orthopedic Surgery, School of Medicine, Pontificia Universidad Católica de Chile, 8330077, Chile.
Department of Orthopedic Surgery, School of Medicine, Pontificia Universidad Católica de Chile, 8330077, Chile.
J ISAKOS. 2024 Jun;9(3):272-278. doi: 10.1016/j.jisako.2024.01.006. Epub 2024 Jan 14.
Patellofemoral (PF) instability recurrence depends on several factors including the relative lateralisation of tibial tubercle (TT) regarding the trochlear groove (TG). TT relative lateralisation quantification has long been a topic of debate. Multiple measuring techniques have been described including TT-trochlear groove (TT-TG), TT-posterior cruciate ligament (TT-PCL) and TT-roman arch (TT-RA), with no clear consensus regarding the most reliable index or pathologic threshold. We set out to determine the normal value range of each index and their association with age, sex and PF instability status. Also, this study aims to determine a reliable pathologic distance threshold to effectively predict patellar dislocation.
Skeletally mature patients up to 45 years of age who presented a CT Scan and an MRI of the same knee between 2014 and 2018 were included and divided into subgroups based on history of PF instability. Three indexes (TT-TG, TT-PCL and TT-RA) were assessed by two independent observers blinded to instability history. ROC curves were performed for each index to obtain the cut point that better predicts instability. Univariate and multivariate models adjusted by age, sex, instability history and type of imaging technique were performed to test the influence of these variables.
208 patients were included. Mean age was 27.93 ± 8.48 years, 67.3% were female and 71 patients (34.1%) presented major instability history. Good or excellent inter and intraobserver reliability was found for all three indexes. All indexes presented significantly different distributions between subjects with and without major instability (p < 0.001), except for TT-PCL. Different cut point values differing between imaging modalities were found: 11.4 mm for MRI TT-TG, 17 mm for CT TT-TG, 15.6 mm for MRI TT-RA and 18.2 mm for CT TT-RA.
All indexes studied had good or excellent inter and intraobserver reliability. Measurements between imaging techniques (CT and MR) are not interchangeable. Both TT-TG and TT-RA correctly distinguish between subjects with and without major instability, while TT-PCL does not, recommending caution when evaluated on its own. Specific threshold values depending on imaging technique should be considered for surgical decision-making.
Level IV, Diagnostic Test.
髌股（PF）不稳定的复发取决于多个因素，包括胫骨结节（TT）相对于滑车沟（TG）的相对外侧化。TT 相对外侧化的定量一直是一个有争议的话题。已经描述了多种测量技术，包括 TT-滑车沟（TT-TG）、TT-后十字韧带（TT-PCL）和 TT-罗马拱门（TT-RA），但对于最可靠的指数或病理阈值没有明确的共识。我们旨在确定每个指数的正常范围及其与年龄、性别和 PF 不稳定状态的关系。此外，本研究旨在确定一个可靠的病理距离阈值，以有效地预测髌骨脱位。
纳入 2014 年至 2018 年间接受 CT 扫描和同一膝关节 MRI 的骨骼成熟患者，年龄不超过 45 岁，并根据 PF 不稳定史分为亚组。由两名独立的观察者评估三个指数（TT-TG、TT-PCL 和 TT-RA），观察者对不稳定史不知情。对每个指数进行 ROC 曲线分析，以获得更好地预测不稳定的切点。进行单变量和多变量模型分析，调整年龄、性别、不稳定史和成像技术类型，以测试这些变量的影响。
共纳入 208 例患者。平均年龄为 27.93±8.48 岁，67.3%为女性，71 例（34.1%）有主要不稳定史。所有三个指数的观察者内和观察者间的可靠性均良好或优秀。所有指数在有和无主要不稳定史的患者之间的分布均有显著差异（p<0.001），除 TT-PCL 外。不同成像方式的不同切点值：MRI TT-TG 为 11.4mm，CT TT-TG 为 17mm，MRI TT-RA 为 15.6mm，CT TT-RA 为 18.2mm。
所有研究的指数均具有良好或优秀的观察者内和观察者间可靠性。成像技术（CT 和 MRI）之间的测量值不可互换。TT-TG 和 TT-RA 均能正确区分有和无主要不稳定的患者，而 TT-PCL 则不能，因此在单独评估时应谨慎。应根据成像技术考虑特定的手术决策阈值。
IV 级，诊断性试验。
