Field Richard E, Cronin Michael D, Singh Parminder J, Burtenshaw Christine, Rushton Neil
Orthopaedic Research Unit, South West London Elective Orthopaedic Centre, Epsom, Surrey, UK.
Acta Orthop. 2006 Oct;77(5):726-32. doi: 10.1080/17453670610012908.
In a prospective 2-year study we have used dual-energy X-ray absorptiometry to measure periprosthetic bone mineral density (BMD) following implantation of a novel, "physiological", acetabular component designed using composite materials.
The acetabular components were implanted in hydroxyapatite (HA) and HA-removed options. They were implanted in conjunction with a cemented femoral component in 50 female patients who presented with displaced, subcapital, fractures of the neck of the femur. Regions of interest (ROI) were defined according to De Lee and Charnley. BMD during follow-up was compared with immediate postoperative values for the affected limb.
The mean precision error (CV%) was 1.01%, 2.26% and 1.12%, for ROI I, II and III respectively. The mean change in BMD, for both cups, was analyzed. There was no significant difference between the BMD changes induced with the HA- and non-HA-coated cups.
After an initial fall in BMD in all 3 ROI at 6 months, ROI I and ROI II showed return to baseline BMD by 2 years. ROI III showed no significant decrease in BMD beyond 6 months, but did not return to baseline levels. Statistical analysis revealed no significant decrease in BMD in ROI I and ROI II at 2 years, compared with immediate postoperative values. The changes in BMD reflect a pattern of maximally reduced stress in the non-weight-bearing zone (ROI III), with preservation of bone density in weight bearing zones ROI I and ROI II. These results support the design principles of the Cambridge cup.
在一项为期2年的前瞻性研究中，我们使用双能X线吸收法测量了一种采用复合材料设计的新型“生理性”髋臼假体植入后的假体周围骨密度（BMD）。
髋臼假体以羟基磷灰石（HA）涂层和无HA涂层两种形式植入。在50例因股骨颈移位、头下型骨折就诊的女性患者中，将其与骨水泥固定型股骨假体联合植入。根据德莱（De Lee）和查恩利（Charnley）的方法定义感兴趣区域（ROI）。将随访期间患侧肢体的骨密度与术后即刻值进行比较。
ROI I、II和III的平均精确误差（CV%）分别为1.01%、2.26%和1.12%。分析了两种髋臼杯的骨密度平均变化情况。HA涂层杯和无HA涂层杯引起的骨密度变化之间无显著差异。
所有3个ROI的骨密度在6个月时均出现初始下降，之后ROI I和ROI II在2年时恢复至基线骨密度。ROI III在6个月后骨密度无显著下降，但未恢复至基线水平。统计分析显示，与术后即刻值相比，2年时ROI I和ROI II的骨密度无显著下降。骨密度变化反映了非负重区（ROI III）应力最大程度降低的模式，而负重区ROI I和ROI II的骨密度得以保留。这些结果支持了剑桥杯的设计原则。
