J Korean Soc Plast Reconstr Surg.  1998 Jun;25(4):557-565.

Biological factors influencing the fate of onlay bone graft on the craniofacial skeleton

• Kim JH
• Kang JS
• Park KK

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 embryololgical 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. Futhermore, 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-graftiong material, independent of its embryololgic origin.

MeSH Terms

Adult
Animals
Biological Factors*
Densitometry
Durapatite
Humans
Ileum
Inlays*
Mandible
Rabbits
Skeleton*
Skull
Transplants*
Biological Factors
Durapatite