Arthroscopy. 2024 Nov;40(11):2715-2716. doi: 10.1016/j.arthro.2024.03.008. Epub 2024 Mar 12.
Patella alta is a known risk factor for patellar instability, contributing to increased length changes of the medial patellofemoral complex, and associated with high rates of failure after medial patellofemoral complex reconstruction. Distalization through tibial tuberosity osteotomy (TTO) is a surgical option to address patella alta during patellar stabilization surgery. However, distalization has been shown to have greater complication rates than other types of TTO, and therefore precise indications through proper assessments of patellar height are needed. The Caton-Deschamps index is a commonly used measurement and is independent of patellar tendon length, allowing for assessment of patellar height before and after distalizing TTO. Additional options that may offer this ability are femoral-based measurements such as the patellotrochlear index and sagittal patellar engagement, which also do not rely on the position of the tubercle and may better represent the functional engagement of the patellofemoral joint. However, femoral-based measurements depend on trochlear morphology; theoretically, an advantage of femoral-based measurements is that they may reflect the functional engagement of the patella within the trochlea. However, in knowing the common relation between patella alta and trochlear dysplasia, the question becomes whether an overlap between the patella and a dysplastic proximal trochlea on a sagittal measurement truly represents functional engagement and stability of the patellofemoral joint. Measurement of patella alta and determining indications for distalization can be influenced by measurement techniques including magnetic resonance imaging versus radiography, tibial- versus femoral-based measurements, and positional and morphologic considerations. Increased understanding of trochlear morphology and sagittal knee balance as they relate to patella alta will be important for defining the factors that affect patellofemoral stability.
高位髌骨是髌骨不稳定的已知危险因素，导致内侧髌股复合结构的长度变化增加，并与内侧髌股复合结构重建后高失败率相关。通过胫骨结节截骨术（TTO）来实现髌骨的远移是在髌骨稳定手术中解决高位髌骨的一种手术选择。然而，与其他类型的 TTO 相比，远移的并发症发生率更高，因此需要通过适当的髌骨高度评估来确定准确的适应证。Caton-Deschamps 指数是一种常用的测量方法，它不依赖于髌腱长度，可以评估 TTO 远移前后的髌骨高度。其他可能具有这种能力的选择是基于股骨的测量，如髌股指数和矢状面髌骨啮合，它们也不依赖于滑车的位置，可能更好地代表髌股关节的功能啮合。然而，基于股骨的测量取决于滑车形态；理论上，基于股骨的测量的一个优点是它们可能反映了滑车内髌骨的功能啮合。然而，由于知道高位髌骨和滑车发育不良之间的常见关系，问题就变成了在矢状面上测量时，髌骨和发育不良的近端滑车之间的重叠是否真正代表了髌股关节的功能啮合和稳定性。髌骨高位的测量和确定远移的适应证可能会受到测量技术的影响，包括磁共振成像与 X 线摄影、胫骨-与股骨为基础的测量以及位置和形态的考虑。增加对滑车形态和矢状面膝关节平衡与高位髌骨的关系的理解，对于确定影响髌股稳定性的因素将非常重要。
