Grochola L F, Habermann B, Mastrodomenico N, Kurth A
Department of Visceral and Transplantation Surgery, The University Hospital of Ulm, Ulm, Germany.
Arch Orthop Trauma Surg. 2008 Apr;128(4):383-92. doi: 10.1007/s00402-007-0507-4. Epub 2007 Nov 24.
Total hip arthroplasty changes bone loading conditions in the proximal femur and induces adaptive remodelling of the periprosthetic bone. These remodelling processes depend on many implant-specific qualities, e.g. material and elasticity of the stem. The objective of this study was to investigate the effect of the stem design on periprosthetic bone remodelling after insertion of an anatomic stem with proximal fixation and the direct comparison to a straight stem prosthesis.
In a prospective study, the changes in periprosthetic bone mineral density (BMD) after implantation of 68 CTX-S anatomic and 22 PPF straight stem prostheses were assessed in the first post-operative year by means of DEXA and zone analysis by Gruen (Clin Orthop 141:17-27, 1979) "Modes of failure" of cemented stem-type femoral components: a radiographic analysis of loosening. Furthermore all patients with CTX-S prostheses were monitored in the second post-operative year. The correlation of adaptive bone remodelling and the systemic bone density was also investigated.
In the distal one-third of the straight stem prosthesis, a clearly greater, although not significant, hypertrophy of the periprosthetic bone was observed. No differences in the extent of bone loss between the two prostheses in the regions of interest (ROI) of the proximal bone were observed. The greatest decrease in BMD was registered in the medial femoral neck in both groups. Bone atrophy decreased progressively as the ROI moved distally, ending in a slight increase in BMD in the distal ROI. No significant changes in periprosthetic BMD occurred in the second post-operative year. A strong positive correlation in the regions with the greatest BMD decrease with the systemic BMD was ascertained.
After implanting a CTX-S prosthesis, as opposed to PPF prostheses, a different pattern of periprosthetic bone remodelling with a slighter hypertrophy of the distal periprosthetic parts was observed. This implies that the extensive proximal, more physiological bone loading of the anatomic stem as well as the removal of less bone while implanting the stem reduces the negative effects of unphysiological strain distribution and stress shielding. The BMD loss in the medial proximal neck cannot be avoided with this stem design either. The lack of significant BMD changes in the second post-operative year suggests that a stabilisation of bone remodelling processes occurs.
全髋关节置换术改变了股骨近端的骨负荷条件，并诱导假体周围骨的适应性重塑。这些重塑过程取决于许多植入物特有的特性，例如柄的材料和弹性。本研究的目的是调查近端固定解剖型柄植入后柄的设计对假体周围骨重塑的影响，并与直柄假体进行直接比较。
在一项前瞻性研究中，通过双能X线吸收法（DEXA）和Gruen分区分析（《临床骨科》141:17 - 27, 1979年，“骨水泥柄型股骨假体的失效模式：松动的影像学分析”）评估了68例CTX - S解剖型和22例PPF直柄假体植入后第一年假体周围骨密度（BMD）的变化。此外，对所有植入CTX - S假体的患者在术后第二年进行了监测。还研究了适应性骨重塑与全身骨密度之间的相关性。
在直柄假体的远侧三分之一处，观察到假体周围骨有明显更大（尽管不显著）的肥大。在近端骨的感兴趣区域（ROI），两种假体之间观察到的骨丢失程度没有差异。两组中股骨内侧颈的BMD下降最大。随着ROI向远侧移动，骨萎缩逐渐减轻，在远侧ROI处BMD略有增加。术后第二年假体周围BMD没有显著变化。在BMD下降最大的区域与全身BMD之间确定存在强正相关。
与PPF假体相比，植入CTX - S假体后，观察到假体周围骨重塑模式不同，假体远侧部分的肥大较轻。这意味着解剖型柄广泛的近端、更符合生理的骨负荷以及在植入柄时去除较少的骨减少了非生理应变分布和应力遮挡的负面影响。这种柄设计也无法避免近端内侧颈的BMD丢失。术后第二年BMD没有显著变化表明骨重塑过程趋于稳定。
