두개안면골격에 중첩이식된 골이식편의 운명에 영향을 미치는 요인

Abstract

The superior volume maintenance of membranous over endochondral bone grafts, which was shown in several studies has provided the basis for its preferred clinical use as an onlay grafting material on the craniofacial skeleton. The scientific rationale for this seeming embryological advantage, however, has never been proven. Since the cortical component of membranous bone is proportionally greater than that of endochondral bone, it follows that membranous grafts would show greater volume maintenance over time. Our hypothesis is that the pattern of onlay bone graft resorption is primarily determined by a graft’s micro-architecture (relative cortical and cancellous composition) rather than its embryological origin(membranous versus endochondral). Fourty adult New Zealand white rabbits were used for this study. There were 8 animals in each of 4 groups. The rabbits of each group were sacrificed at 3, 8, and 16 weeks. Four types of grafts were placed subperosteally, onto each rabbit’s cranium: a hydroxyapatite, a cortical bone graft of membranous origin, a cortical bone graft of endochondral origin and a cancellous bone graft of endochondral origin. Membranous bone grafts were obtained from the lateral mandible and endochondral bone grafts were obtained from the ileum. In order to determine post-sacrifice volume and density of the bone grafts, a caliper technique and bone densitometry(bone densitometer: LUNAR, DPX-L, U.S.A) were performed on all of the bone grafts. Bone graft specimens were histologically examined at 3, 8, and 16 weeks. The measurement of volume and density show that there is a statistically greater resumption in the cancellous endochondral bone grafts for all parameter, compared to either the endochondral or membranous cortical bone grafts or hydroxyapatite at all time points(p< 0.05). In addition, there is no significant difference in the resorption rates between the endochondral and membranous cortical bone grafts for all parameters at all time points. By placing cortical bone grafts and cancellous bone grafts on the recipient sites separately, we have shown that the former grafts maintain their volumes, widths and projections significantly better than the latter grafts. Furthermore, we found no statistical difference in resorption rates between the two cortical bone grafts of different embryologic origins, a finding which has never been previously shown. Bone volume fraction, measured with bone densitometry, was shown to be higher in cortical bone than in cancellous bone at all time points, further illustrating the differences between cortical and cancellous bone. From our results, we believe cortical bone to be a superior onlay-grafting material, independent of its embryologic origin. Key words: Onlay bone graft, Volume maintenance, Embryological origin, Micro-architecture

저자들은 토끼 40마리를 4군으로 나누어 각 군에 막성골의 피질골편, 연골내골의 피질골편, 연골내골의 해면골편을 이식하고 이들과 대조하기 위해서 hydroxyapatite를 넣어 주었다. 수술후 3주, 8주, 16주에 육안, 광학현미경 및 골밀도측정기로 관찰하여 다음과 같은 결과를 얻었다. 피질골과 해면골의 흡수율을 비교한 실험 결과 막성골에서 채취하든 연골내골에서 채취하든 피질골편이 해면골편보다 골 흡수가 적게된 것을 볼 수 있었다. 그러나 흥미롭게도 발생학적으로 기원이 다른 막성골에서 채취한 피질골이식편과 연골내골에서 채취한 피질골이식편간의 흡수율에는 유의적인 차이가 없었다. 중첩골이식을 한 경우에 골이식편의 흡수율의 차이는 개개 골이식편의 구조적 차이, 즉 이식편에 피질골이 얼마만한 비율로 들어 있느냐 하는 것이 골흡수율과 관계가 있다고 여겨졌다. 그러므로 두개 안면부에 있는 변형을 교정 내지는 재건하기 위해 중첩골이식을 할 경우에 흡수가 적게 되는 피질골을 얻기 위해 채취하기가 어렵고 양도 한정돼 있는 두개안면골에서 구태여 채취하려고 애쓸 필요없이 채취하기도 쉽고 양도 넉넉한 연골내골에서 피질골을 채취해서 사용하면 결과적으로는 마찬가지라 여겨졌다.