Nazmy Hamad, Solitro Giovanni, Domb Benjamin, Amirouche Farid
Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, IL 60612, USA.
Department of Orthopaedics, LSU Health Shreveport, Shreveport, LA 71103, USA.
Bioengineering (Basel). 2024 Aug 21;11(8):853. doi: 10.3390/bioengineering11080853.
Our study addresses the lack of consensus on measuring leg length discrepancy (LLD) after total hip arthroplasty (THA). We will assess the inter-observer variability and correlation between the five most commonly used LLD methods and investigate the use of trigonometric principles in overcoming the limitations of current techniques.
LLD was measured on postoperative AP pelvic radiographs using five conventional methods. CT images created a 3D computer model of the pelvis and femur. The resulting models were projected onto a 2D, used to measure LLD by the five methods. The measurements were evaluated via Taguchi analysis, a statistical method identifying the process's most influential factors. The approach was used to assess the new trigonometric method.
Conventional methods demonstrated poor correlation. Methods referenced to the centers of the femoral heads were insensitive to LLD originating outside the acetabular cup. Methods referencing either the inter-ischial line or the inter-obturator foramina to the lesser trochanter were sensitive to acetabular and femoral components. Trigonometry-based measurements showed a higher correlation.
Our results underscore clinicians' need to specify the methods used to assess LLD. Applying trigonometric principles was shown to be accurate and reliable, but it was contingent on proper radiographic alignment.
我们的研究旨在解决全髋关节置换术（THA）后测量下肢长度差异（LLD）缺乏共识的问题。我们将评估五种最常用的LLD测量方法之间的观察者间变异性和相关性，并研究三角测量原理在克服现有技术局限性方面的应用。
使用五种传统方法在术后前后位骨盆X线片上测量LLD。CT图像创建了骨盆和股骨的三维计算机模型。将生成的模型投影到二维平面上，用于通过这五种方法测量LLD。通过田口分析对测量结果进行评估，田口分析是一种识别过程中最具影响力因素的统计方法。该方法用于评估新的三角测量方法。
传统方法显示出较差的相关性。以股骨头中心为参考的方法对髋臼杯外起源的LLD不敏感。以坐骨间线或闭孔间孔至小转子为参考的方法对髋臼和股骨组件敏感。基于三角测量的方法显示出更高的相关性。
我们的结果强调临床医生需要明确用于评估LLD的方法。应用三角测量原理被证明是准确可靠的，但这取决于正确的影像学对齐。
