Lamerigts N M, Buma P, Huiskes R, Schreurs W, Gardeniers J, Slooff T J
Department of Orthopaedics, University Hospital Nijmegen, The Netherlands.
Biomaterials. 2000 Apr;21(7):741-7. doi: 10.1016/s0142-9612(99)00247-1.
The aim of this study was to develop a new animal model in which we could assess the in vivo effects of mechanical stimuli in the incorporation process of impacted morsellized bone grafts. The subcutaneous pressure implant SPI was developed for use in the goat. This device can generate controlled loading conditions onto a fixed amount of bone graft in the distal femur. Twenty goats were divided into three groups: non-loaded, 2 or 4 MPa loads (1 Hz, 1 h/day). The goats were sacrificed after 3, 6 or 12 weeks. The results were documented by clinical observations, quantitative bone density from QCT-scanning and histomorphometry. Nine post-mortem knee specimens were prepared in a similar manner to the experimental knees to determine the reproducibility and mechanical stability of the grafting method. Three goats were lost due to complications, the others functioned clinically well. Histology showed invasion of the bone graft by a front of vascular fibrous tissue after which osteoclasts resorbed the dead bone graft, followed by woven bone apposition on the graft remnants. At 12 weeks the loaded grafts had transformed into a vital trabecular structure. QCT bone density measurements revealed persistently high densities in the 12-weeks 4 MPa specimens, but reduced densities in the 2 MPa and non-loaded specimens. Morphometrically, the mineralising surface was larger in the 4 MPa group (P = 0.02) and the incorporation and remodelling processes had advanced more rapidly in the 2 MPa specimens (P = 0.04). Although the numbers investigated in this study in each group were low, statistical differences were found in the amount of graft left after incorporation and in the apposition rate of the new bone. In the future this model will be used to study the incorporation potential of different types of bone graft and bone graft substitutes.
本研究的目的是开发一种新的动物模型，以便我们能够在嵌压碎骨移植的植入过程中评估机械刺激的体内效应。为山羊开发了皮下压力植入物（SPI）。该装置可以在股骨远端的固定量骨移植物上产生可控的加载条件。20只山羊被分为三组：无负载组、2或4兆帕负载组（1赫兹，每天1小时）。在3、6或12周后处死山羊。通过临床观察、QCT扫描的定量骨密度和组织形态计量学记录结果。以与实验膝关节相似的方式制备了9个死后膝关节标本，以确定移植方法的可重复性和机械稳定性。3只山羊因并发症死亡，其他山羊临床功能良好。组织学显示血管纤维组织前沿侵入骨移植物，随后破骨细胞吸收死骨移植物，接着编织骨在移植物残余物上附着。在12周时，加载的移植物已转变为有活力的小梁结构。QCT骨密度测量显示，在12周的4兆帕标本中密度持续较高，但在2兆帕和无负载标本中密度降低。形态计量学上，4兆帕组的矿化表面更大（P = 0.02），2兆帕标本中的植入和重塑过程进展更快（P = 0.04）。尽管本研究中每组调查的数量较少，但在植入后剩余的移植物量和新骨的附着率方面发现了统计学差异。未来，该模型将用于研究不同类型骨移植物和骨移植替代物的植入潜力。
