Georgiou Cs, Evangelou Kg, Theodorou Eg, Provatidis Cg, Megas Pd
Department of Orthopaedics and Traumatology, University Hospital of Patras, Greece.
Open Orthop J. 2012;6:593-600. doi: 10.2174/1874325001206010593. Epub 2012 Dec 14.
Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed.
由于其理论优势，结合模块化颈和大直径股骨头的髋关节系统逐渐受到欢迎。然而，人们提出了诸多担忧，其中包括对负荷传递模式变化的担忧。近期的应力分析确实表明，使用模块化颈和大股骨头会导致沿股骨的应变分布发生显著变化。我们最初的假设是，这些变化可能会影响模块化柄的早期远端迁移。我们在一个包含116例患者（125髋）的病例系列中，对116例接受了初次金属对金属全髋关节置换术、使用模块化喷砂处理的Profemur®E柄并结合大直径股骨头（>36mm）的患者进行了为期两年的随访，研究了股骨头直径和颈几何形状对柄迁移的影响。我们发现，颈几何形状和股骨头直径的选择对柄的迁移没有影响。一项包括体重指数、骨质、髓腔填充和柄定位等潜在混杂变量的多变量回归分析显示，仅在柄中部区域的下沉与髓腔填充之间存在负相关。尽管存在局限性，但统计分析并未证实我们的假设，即颈几何形状和/或股骨头直径的选择会影响模块化柄的早期远端迁移。然而，正确的柄尺寸选择的重要性得以显现。
