Innmann Moritz M, Merle Christian, Ratra Akaash, Speirs Andrew, Adamczyk Andrew, Murray David, Gill Harinderjit S, Grammatopoulos George
Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Ontario, Canada.
Department of Orthopaedic Surgery, University of Heidelberg, Heidelberg, Germany.
JB JS Open Access. 2024 Jul 11;9(3). doi: 10.2106/JBJS.OA.23.00120. eCollection 2024 Jul-Sep.
This study aimed to establish an equation for calculating cup ante-inclination (AI) from radiographic cup inclination and anteversion, to validate this equation in a total hip arthroplasty (THA) cohort, and to test whether achieving previously described radiographic cup inclination and anteversion targets would also satisfy sagittal cup AI targets.
A mathematical equation linking cup AI, radiographic inclination (RI), and anteversion (RA) was determined: tan(AI) = tan(RA)/cos(RI). Supine and standing anteroposterior and lateral radiographs of 440 consecutive THAs were assessed to measure cup RI and RA and spinopelvic parameters, including cup AI, using a validated software tool. Whether orientation within previously defined RI and RA targets was associated with achieving the AI target and satisfying the sagittal component orientation (combined sagittal index, 205° to 245°) was tested.
The cups in the THA cohort had a measured mean inclination (and standard deviation) of 43° ± 7°, anteversion of 26° ± 9°, and AI of 34° ± 10°. The calculated cup AI was 34° ± 12°. A strong correlation existed between measured and calculated AI (r = 0.75; p < 0.001), with a mean error of 0° ± 8°. The inclination and anteversion targets were both satisfied in 194 (44.1%) to 330 (75.0%) of the cases, depending on the safe zone targets that were used, and 311 cases (70.7%) satisfied the AI target. Only 125 (28.4%) to 233 (53.0%) of the cases satisfied the AI target as well as the inclination and anteversion targets. Satisfying inclination and anteversion targets was not associated with increased chances of satisfying the AI target.
Achieving optimal cup inclination and anteversion does not ensure optimal orientation in the sagittal plane. The equation and nomograms provided can be used to determine and visualize how the 2 planes used for evaluating the cup orientation and the pertinent angles relate, potentially aiding in preoperative planning.
本研究旨在建立一个根据影像学杯状假体倾斜度和前倾角计算杯状假体前倾角（AI）的方程，在全髋关节置换术（THA）队列中验证该方程，并测试达到先前描述的影像学杯状假体倾斜度和前倾角目标是否也能满足矢状面杯状假体AI目标。
确定了一个将杯状假体AI、影像学倾斜度（RI）和前倾角（RA）联系起来的数学方程：tan(AI) = tan(RA)/cos(RI)。使用经过验证的软件工具，对440例连续THA的仰卧位和站立位前后位及侧位X线片进行评估，以测量杯状假体RI和RA以及包括杯状假体AI在内的脊柱骨盆参数。测试先前定义的RI和RA目标范围内的方向是否与实现AI目标以及满足矢状面组件方向（联合矢状指数，205°至245°）相关。
THA队列中的杯状假体测量平均倾斜度（及标准差）为43°±7°，前倾角为26°±9°，AI为34°±10°。计算得到的杯状假体AI为34°±12°。测量的AI与计算的AI之间存在强相关性（r = 0.75；p < 0.001），平均误差为0°±8°。根据所使用的安全区目标，194例（44.1%）至330例（75.0%）的病例同时满足倾斜度和前倾角目标，311例（70.7%）满足AI目标。仅125例（28.4%）至233例（53.0%）的病例同时满足AI目标以及倾斜度和前倾角目标。满足倾斜度和前倾角目标与满足AI目标的几率增加无关。
实现最佳的杯状假体倾斜度和前倾角并不能确保矢状面的最佳方向。提供的方程和列线图可用于确定和可视化用于评估杯状假体方向的两个平面以及相关角度之间的关系，可能有助于术前规划。
