Academic Unit of Bone Metabolism, University of Sheffield Medical School, Sheffield, United Kingdom.
J Bone Joint Surg Am. 2013 Jan 2;95(1):19-27. doi: 10.2106/JBJS.K.00657.
This two-year randomized clinical trial was performed to examine whether the geometry of the cemented femoral prosthesis affects the pattern of strain-adaptive bone remodeling in the proximal aspect of the femur after primary total hip arthroplasty.
One hundred and twenty patients were randomized to receive a Charnley (composite-beam), Exeter (double-tapered), or C-Stem (triple-tapered) prosthesis. The change in proximal femoral bone mineral density over two years was measured by dual x-ray absorptiometry (DXA). Bone turnover markers were measured in urine and serum samples collected at the preoperative baseline and during the first postoperative year. N-telopeptide of type-I collagen was measured in urine as a marker of osteoclast activity, and osteocalcin was measured in serum as a marker of osteoblast activity. Clinical outcome was measured with use of the Harris and Oxford hip scores and prosthesis migration was measured with use of digitized radiographs during the first two postoperative years.
The baseline characteristics of the subjects in each group were similar (p > 0.05). Decreases in femoral bone mineral density were observed over the first year for all prosthesis designs, with no further loss during the second year. The decreases were similar in regional distribution and magnitude between the composite-beam and sliding-taper designs (p > 0.05). Bone loss was greatest (14%) in the proximal medial aspect of the femur (Gruen zone 7). Transient increases in both N-telopeptide of type-I collagen and osteocalcin activity also occurred over the first year, and these increases were similar in pattern among the three prosthesis groups (p > 0.05). All prostheses showed migration patterns that were consistent with their design type, and similar improvements in clinical hip scores were observed over the two-year course of the study.
Differences in the mechanism of load transfer between the prosthesis and host bone in composite-beam or sliding-taper cemented femoral prosthesis designs were not a major determinant of proximal femoral bone loss after total hip arthroplasty, and the design that included a third taper exhibited a remodeling profile that was similar to those of the double-tapered design.
本为期两年的随机临床试验旨在研究初次全髋关节置换术后，骨水泥型股骨假体的几何形状是否会影响股骨近端的应变适应性骨重塑模式。
将 120 例患者随机分为 Charnley（复合梁）、Exeter（双锥形）或 C-Stem（三锥形）假体组。通过双能 X 线吸收法（DXA）测量两年内股骨近端骨密度的变化。在术前基线和术后第一年采集尿液和血清样本，测量尿Ⅰ型胶原 N 端肽（作为破骨细胞活性的标志物）和血清骨钙素（作为成骨细胞活性的标志物）的骨转换标志物。采用 Harris 和 Oxford 髋关节评分评估临床结果，在术后头两年使用数字化射线照相术测量假体迁移。
每组受试者的基线特征相似（p＞0.05）。所有假体设计在第一年都观察到股骨骨密度下降，第二年没有进一步丢失。复合梁和滑动锥形设计的区域分布和幅度相似（p＞0.05）。股骨近端内侧（Gruen 区 7）的骨丢失最大（14%）。在第一年还观察到Ⅰ型胶原 N 端肽和骨钙素活性的短暂增加，这三种假体组的增加模式相似（p＞0.05）。所有假体都表现出与设计类型一致的迁移模式，在研究的两年过程中观察到临床髋关节评分的相似改善。
复合梁或滑动锥形骨水泥型股骨假体设计中假体与宿主骨之间的负荷传递机制的差异不是全髋关节置换术后股骨近端骨丢失的主要决定因素，而包括第三个锥度的设计表现出与双锥形设计相似的重塑特征。
