Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, University of Turku, Kiinamyllykatu 10, Turku, Finland.
J Biomech. 2011 Jan 11;44(2):221-7. doi: 10.1016/j.jbiomech.2010.10.012. Epub 2010 Nov 11.
In cementless total hip arthroplasty, osteoporosis may jeopardize the achievement of immediate stability and lead to migration of anatomically shaped femoral stems. Poor quality of proximal cancellous bone per se may also affect the rate of osseointegration. In a selected group of female total hip arthroplasty patients (mean age 64 years) with unremarkable medical history, intertrochanteric cancellous bone biopsy was taken from the site of stem implantation. Local bone quality, determined by structural μCT imaging and destructive compression testing of the biopsy tissue, was used as the predictor of three-dimensional stem migration determined by radiostereometric analysis (RSA) up to 24 months. The patients exhibited major differences in mechanical properties of the intertrochanteric cancellous bone, which were closely related to the structural parameters calculated from μCT data. Unexpectedly, the major differences observed in the quality of trochanteric cancellous bone had only minor reflections in the RSA migration of the femoral stems. In statistical analysis, the μCT-based bone mineral density quartile (low, middle, high) was the only significant predictor for stem translation at 24 months (p=0.022) but only a small portion (R(2)=0.16) of the difference in translation could be explained by changes in bone mineral density quartile. None of the other parameters investigated predicted stem migration in translation or rotation. In conclusion, poor quality of intertrochanteric cancellous bone seems to contribute to the risk of implant migration less than expected. Probably also the importance of surgical preservation of intertrochanteric cancellous bone has been over-emphasized for osseointegration of cementless stem.
在非骨水泥全髋关节置换术中，骨质疏松症可能会危及即刻稳定性，并导致解剖形状的股骨柄迁移。松质骨近端本身的质量差也可能会影响骨整合的速度。在一组女性全髋关节置换术患者（平均年龄 64 岁）中，选择了一组无明显病史的患者，从柄植入部位取股骨转子间松质骨活检。通过结构 μCT 成像和活检组织的破坏性压缩测试确定局部骨质量，作为通过放射立体测量分析（RSA）确定的三维柄迁移的预测指标，随访时间长达 24 个月。患者的转子间松质骨机械性能存在较大差异，这与从 μCT 数据计算得出的结构参数密切相关。出乎意料的是，观察到的转子间松质骨质量的主要差异仅在股骨柄的 RSA 迁移中略有反映。在统计学分析中，基于 μCT 的骨密度四分位数（低、中、高）是 24 个月时柄迁移的唯一显著预测因子（p=0.022），但只能解释一部分（R(2)=0.16）骨密度四分位数变化引起的翻译差异。其他研究的参数均不能预测翻译或旋转中的柄迁移。总之，转子间松质骨质量差似乎对植入物迁移的风险贡献小于预期。可能也过分强调了手术保留转子间松质骨对非骨水泥柄骨整合的重要性。
