Surgical Revascularization in Structural Orthotopic Bone Allograft Increases Bone Remodeling
详细信息    查看全文
文摘
Background Osseous defects reconstructed with cryopreserved structural allografts are poorly revascularized and therefore are prone to nonunion, infection, deterioration of mechanical properties, and fracture. Whether this can be mitigated by specific interventions such as intramedullary surgical revascularization has been incompletely evaluated. Questions/purposes We aimed to study surgical revascularization as a means to improve bone remodeling in cryopreserved allograft. Second, we questioned whether spatial histomorphometric differences occur in cortical bone areas after intramedullary surgical revascularization. Third, biomechanical properties of the graft-recipient construct in surgically revascularized allograft were compared with those of conventional allografts. Methods Allografts were harvested from 10 Brown Norway rats, cryopreserved, and transplanted orthotopically in a 10-mm defect in two groups of 10 Lewis rats each (major histocompatibility mismatch). In the control group, no surgical revascularization was performed, whereas in the experimental group, a saphenous arteriovenous bundle was transposed in the bone marrow cavity. Bone remodeling was measured with histomorphometry, histology, and microcomputed tomography at 16?weeks. Spatial differences were analyzed with histomorphometry. To determine biomechanical properties, load at failure and structural stiffness in bending were evaluated by the three-point bend testing. In both groups, normal values of the contralateral femur also were analyzed. Results Surgically revascularized allografts had increased bone remodeling (bone formation rate to bone surface ratio: 130?±?47?μm3/μm2/year versus 44?±?43?μm3/μm2/year, p?=?0.006) and higher cortical osteocyte counts (18.6%?±?12.7% versus 3.1%?±?2.8%, p?=?0.002) than nonrevascularized grafts. In nonrevascularized grafts, the bone formation rate to bone surface ratio was 35% of the contralateral normal values, whereas in surgically revascularized grafts, the bone formation rate to bone surface ratio in the grafts exceeded the contralateral values (110%). Microcomputed tomography did not show differences in bone volume between groups, however in both groups, bone volume was less in grafts compared with the contralateral femurs. Inner cortical bone formation rate to bone surface ratio was greater in surgically revascularized grafts (65?±?30?μm3/μm2/year versus 13?±?16?μm3/μm2/year in the control group, p?=?0.012). Outer cortical bone formation rate to bone surface ratio also increased in surgically revascularized grafts (49?±?31?μm3/μm2/year versus 19?±?21?μm3/μm2/year, p?=?0.032). No differences were found in load at failure and structural stiffness between both groups. In the control group, load at failure and structural stiffness were lower in grafts than in the contralateral femurs (p?=?0.004 and p?=?0.02, respectively). In the experimental group, surgically revascularized grafts also had lower load at failure and structural stiffness than the contralateral femurs (p?=?0.008 and p?=?0.02, respectively). Conclusions Surgical revascularization of large segmental allografts improved bone remodeling and viability without an adverse effect on total bone volume or bending strength and stiffness in this short-term analysis. Clinical Relevance Cryopreserved allografts remain largely necrotic and are associated with a high rate of complications. Surgical revascularization increases graft healing which could contribute to graft survival with time.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址：北京市海淀区学院路29号 邮编：100083

电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700