Gosain A K, Song L, Capel C C, Corrao M A, Lim T H
Department of Plastic and Reconstructive Surgery, Medical College of Wisconsin, Milwaukee 53226, USA.
Plast Reconstr Surg. 1998 May;101(6):1561-71. doi: 10.1097/00006534-199805000-00020.
Potential alteration of the underlying recipient bone resulting from a graft or implant has significant clinical relevance. The present study was designed to evaluate the biomechanical and histologic alteration of facial recipient bone with autogenous bone graft and alloplastic implants over a 1-year period. The bilateral arches of 15 rabbits were randomized between four groups: (1) control (n = 6), subperiosteal exposure of the zygomatic arch was made; (2) onlay (n = 12), bone graft was placed as an onlay to the zygomatic arch; (3) inlay (n = 6), bone graft was placed as an inlay within the zygomatic arch; (4) implant (n = 6), a stainless steel plate was placed as an onlay to the zygomatic arch. Animals were killed 1 year after grafting. In the onlay groups, all steel implants and half of the onlay bone grafts (n = 6) were separated from the zygomatic arch; the remaining onlay bone grafts (n = 6) were left on the zygomatic arch. Three-point breaking strength was measured through the center of the graft/implant site on the zygomatic arch, followed by histologic evaluation and histometric assessment of residual bone density. The findings demonstrated no difference in the breaking strength per unit bone area between the control zygomatic arch group and the onlay group in which the bone graft was left in place. Breaking strength of the zygomatic arch in the former two groups was significantly greater than that in either group in which the onlay bone graft or implant had been removed, and was also greater than the breaking strength in that group in which inlay bone had been placed (p < 0.05). Histologic assessment showed full-thickness conversion in architecture of the zygomatic arch from compact to woven bone beneath onlays of either autogenous bone graft or steel implant; histometric assessment demonstrated an accompanying decrease in bone density in the latter groups relative to the control zygoma (p < 0.05). We conclude that onlay autogenous bone graft and alloplastic implants to the facial skeleton induce transformation of both graft and recipient bone from compact to woven architecture, accompanied by a reduction in bone density. The biomechanical strength of recipient facial bone is significantly weakened if an onlay bone graft or implant is removed. Weakening occurs per unit area of remaining bone, and is therefore independent of any thinning that may occur within the recipient bone because of graft/implant placement. These findings may impact upon decisions to augment stress-bearing regions of the facial skeleton with bone graft or implants, particularly if the graft/implant may eventually require removal.
移植或植入物导致的受体骨潜在改变具有重大临床意义。本研究旨在评估自体骨移植和异体植入物在1年时间内对面部受体骨的生物力学和组织学改变。将15只兔子的双侧颧弓随机分为四组：（1）对照组（n = 6），进行颧弓骨膜下暴露；（2）覆盖组（n = 12），将骨移植片作为覆盖物置于颧弓上；（3）嵌入组（n = 6），将骨移植片作为嵌入物置于颧弓内；（4）植入组（n = 6），将一块不锈钢板作为覆盖物置于颧弓上。移植后1年处死动物。在覆盖组中，所有钢制植入物和一半的覆盖骨移植片（n = 6）与颧弓分离；其余的覆盖骨移植片（n = 6）留在颧弓上。通过颧弓上移植/植入部位的中心测量三点断裂强度，随后进行组织学评估和残余骨密度的组织计量学评估。结果表明，对照颧弓组与骨移植片留在原位的覆盖组之间，单位骨面积的断裂强度没有差异。前两组中颧弓的断裂强度显著高于覆盖骨移植片或植入物已被移除的任何一组，也高于嵌入骨移植片的那一组（p < 0.05）。组织学评估显示，在自体骨移植片或钢制植入物覆盖下，颧弓结构从致密骨完全转变为编织骨；组织计量学评估表明，后几组相对于对照颧骨，骨密度随之降低（p < 0.05）。我们得出结论，对面部骨骼进行覆盖自体骨移植和异体植入物会导致移植骨和受体骨从致密结构转变为编织结构，同时骨密度降低。如果移除覆盖骨移植片或植入物，受体面部骨的生物力学强度会显著减弱。这种减弱发生在剩余骨的单位面积上，因此与由于移植/植入物放置可能在受体骨内发生的任何变薄无关。这些发现可能会影响对面部骨骼承重区域进行骨移植或植入物增强的决策，特别是如果移植/植入物最终可能需要移除。
