Kasashima T, Minami A, Kato H, Kaneda K
Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Sapporo, Japan.
J Reconstr Microsurg. 2000 Feb;16(2):121-8. doi: 10.1055/s-2000-7546.
The mechanism underlying hypertrophy of experimentally vascularized bone grafts was studied in 15-week-old rats. The segmental ulna was grafted to the tibial defect with an external fixator. In experiment 1, 24 rats were classified into four groups to evaluate conventional (non-vascularized), cuff (periosteum-encased, non-vascularized), and vascularized bone grafts, and vascularized segmental grafts with fracture. In experiment 2, 12 rats were classified into two groups according to the presence of mechanical loading. This involved vascularized bone grafts with external fixators, and vascularized bone grafts with external fixators removed after bone union. The bone dynamics of the grafts were investigated by several methods, including roentgenographic analysis, histologic studies, and fluorochrome labeling. In experiment 1, a slight bone formation was recognized in the conventional bone graft, while irregular bone formation with creeping substitution was observed in the cuff graft. The vascularized bone graft showed significant hypertrophy; hypertrophy of the vascularized bone with fracture was greater than that without fracture. In experiment 2, markedly circumferential bone formation was observed after removal of the external fixator, while slight new bone formation was observed during the late postoperative period in bone with an external fixator. These results suggest that hypertrophy can be promoted by artificial fracture of the grafted bone, and that mechanical loading is an important factor for remodeling of grafted bone.
在15周龄大鼠中研究了实验性血管化骨移植肥大的潜在机制。将节段性尺骨用外固定器移植到胫骨缺损处。在实验1中，将24只大鼠分为四组，以评估传统（非血管化）、袖套式（骨膜包裹，非血管化）和血管化骨移植，以及伴有骨折的血管化节段移植。在实验2中，根据机械负荷的存在将12只大鼠分为两组。这包括带有外固定器的血管化骨移植，以及骨愈合后去除外固定器的血管化骨移植。通过几种方法研究移植骨的骨动力学，包括X线分析、组织学研究和荧光素标记。在实验1中，在传统骨移植中可识别出轻微的骨形成，而在袖套式移植中观察到伴有爬行替代的不规则骨形成。血管化骨移植显示出明显的肥大；伴有骨折的血管化骨的肥大大于无骨折的情况。在实验2中，去除外固定器后观察到明显的周向骨形成，而在带有外固定器的骨中术后晚期观察到轻微的新骨形成。这些结果表明，移植骨的人工骨折可促进肥大，并且机械负荷是移植骨重塑的重要因素。
