Orthopedic Research Laboratory, Orthopedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Finsensgade 35, Esbjerg, Odense, Denmark.
J Biomech. 2013 May 31;46(8):1415-9. doi: 10.1016/j.jbiomech.2013.03.012. Epub 2013 Apr 1.
The mechanical properties of bone can largely be explained by bone density and the anisotropic orientation of the trabecular bone. The type of trabecular structure plays an important role in determining the mechanical properties of cancellous bone. Gap-healing and implant fixation could be affected by the various quality and quantity of bone in the local environment. Thus, implant fixation in one part might differ from the other part of the implant. This study aimed to investigate the influence of the sampling method on data evaluation.
Titanium alloy implants (Biomet Inc.) of 10mm in length and 6mm in diameter were inserted bilaterally into the proximal humerus of 8 skeletally mature sheep. Thus two implants with a concentric gap of 2mm were implanted in each sheep. The gap was filled with allograft. Standardised surgical procedure was used. At sacrifice, 6 weeks after surgery, both proximal humeri were harvested. The specimens were randomized to superficial or profound groups. In the superficial group, mechanical testing or histological analysis was carried out on the superficial part of the implant. In the profound group, the mechanical testing or histological analysis was performed on the profound part of the implant.
The mechanical fixation, bone volume and bone ongrowth showed no statistically significant differences. Mechanical test demonstrated a slight tendency to increased strength and failure energy were observed in the superficial group. Histomorphomety revealed bone ongrowth was slightly increased and volume fraction was decreased in the profound group.
Histological analysis and mechanical testing can be applied to the superficial or profound part of the implant.
骨骼的机械性能在很大程度上可以用骨密度和小梁骨的各向异性方向来解释。小梁结构的类型在确定松质骨的机械性能方面起着重要作用。间隙愈合和植入物固定可能会受到局部环境中各种骨的质量和数量的影响。因此，植入物在一个部位的固定可能与植入物的另一个部位不同。本研究旨在探讨采样方法对数据评估的影响。
将 10mm 长、6mm 直径的钛合金植入物（Biomet Inc.）双侧插入 8 只骨骼成熟绵羊的肱骨近端。因此，每只绵羊植入两个具有 2mm 同心间隙的植入物。间隙用同种异体填充。采用标准化手术程序。术后 6 周，处死绵羊，取出双侧肱骨近端。标本随机分为浅层或深层组。在浅层组中，对植入物的浅层进行力学测试或组织学分析。在深层组中，对植入物的深层进行力学测试或组织学分析。
机械固定、骨体积和骨生长没有统计学上的显著差异。力学试验表明，浅层组的强度和破坏能略有增加。组织形态计量学显示，深层组的骨生长略有增加，体积分数降低。
组织学分析和力学测试可应用于植入物的浅层或深层。
