MacIsaac Zoe M, Henderson Sarah E, Shakir Sameer, Naran Sanjay, Smith Darren M, Camison Liliana, Cray James J, Almarza Alejandro J, Cooper Gregory M, Losee Joseph E
Pittsburgh, Pa.; and Augusta, Ga.
From the Departments of Plastic Surgery, Bioengineering, Oral Biology, Anthropology, and Orthodontics, University of Pittsburgh; and the Georgia Health Sciences University.
Plast Reconstr Surg. 2017 May;139(5):1141-1150. doi: 10.1097/PRS.0000000000003261.
The limitations of autologous and alloplastic reconstruction for craniofacial bone defects have created a clinical need for viable tissue-engineering strategies. Recombinant human bone morphogenetic protein-2 (rhBMP-2) has shown promise in this setting. The aim of this study was to determine the long-term biomechanical properties of rhBMP-2-mediated calvarial reconstruction.
Twelve-week-old New Zealand White rabbits underwent subtotal calvarectomy. Defects were repaired in one of several groups: immediate reconstruction with autologous graft, immediate reconstruction with cryopreserved bone graft, immediate reconstruction with rhBMP-2 (favorable), and delayed reconstruction with rhBMP-2 following infection and subsequent débridement (unfavorable). Cryopreserved reconstructions were measured at 6 weeks; autologous reconstructions were measured at 6 weeks and 6 months; and both favorable and unfavorable rhBMP-2 reconstructions were assessed at 6 weeks, 6 months, and 1 year after reconstruction. Healing was assessed with computed tomography. An unconfined compression test was performed for biomechanical analysis. Stress at 20 percent strain, percentage relaxation, tangent modulus, and final strain at 1800 N were compared between groups.
Nearly complete radiographic coverage was achieved by 6 months for autologous reconstruction and by 6 weeks for rhBMP-2 reconstruction. Favorable rhBMP-2 reconstruction demonstrated a larger final strain at 1800 N through 1 year compared with native bone. Bone in unfavorable rhBMP-2 reconstruction was more compressible than native bone, with a larger final strain at 1800 N at 1 year. There were no significant differences between favorable and unfavorable groups.
Despite providing radiographic coverage, the biomechanical properties of rhBMP-2 bone differ from those of native bone. Further studies are warranted to determine how these properties affect overall strength and structural integrity.
自体和异体骨重建颅面骨缺损存在局限性，这使得临床上对可行的组织工程策略有了需求。重组人骨形态发生蛋白-2（rhBMP-2）在这种情况下已显示出前景。本研究的目的是确定rhBMP-2介导的颅骨重建的长期生物力学特性。
对12周龄的新西兰白兔进行颅骨次全切除术。缺损在以下几组中进行修复：用自体移植物立即重建、用冷冻保存的骨移植物立即重建、用rhBMP-2立即重建（有利组），以及在感染并随后清创后用rhBMP-2延迟重建（不利组）。冷冻保存重建组在6周时进行测量；自体重建组在6周和6个月时进行测量；有利和不利的rhBMP-2重建组在重建后6周、6个月和1年时进行评估。通过计算机断层扫描评估愈合情况。进行无侧限压缩试验以进行生物力学分析。比较各组在20%应变时的应力、松弛百分比、切线模量和1800 N时的最终应变。
自体重建在6个月时几乎实现了完全的影像学覆盖，rhBMP-2重建在6周时实现了完全覆盖。与天然骨相比，有利的rhBMP-2重建在1年时在1800 N下显示出更大的最终应变。不利的rhBMP-2重建中的骨比天然骨更易压缩，在1年时在1800 N下具有更大的最终应变。有利组和不利组之间无显著差异。
尽管rhBMP-2骨在影像学上实现了覆盖，但其生物力学特性与天然骨不同。有必要进一步研究以确定这些特性如何影响整体强度和结构完整性。
