Fixation effects on membranous and endochondral onlay bone-graft resorption

Area of Science:

• Oral and Maxillofacial Surgery
• Biomaterials Science
• Regenerative Medicine

Background:

• Bone graft resorption poses challenges in facial contour reconstruction.
• Predicting long-term graft volume maintenance is difficult.
• Graft movement is a suspected contributor to resorption.

Purpose of the Study:

• To investigate the effect of graft fixation on the resorption of onlay bone grafts.
• To compare the volume maintenance of fixed versus nonfixed endochondral and membranous bone grafts.

Main Methods:

• Onlay bone grafts (endochondral and membranous) were applied to the sheep mandible bilaterally.
• Grafts were either fixed using the lag-screw technique or left unfixed.
• Graft volume was measured 20 weeks postoperatively using a caliper technique.

Main Results:

• Fixed bone grafts showed significantly greater volume maintenance than nonfixed grafts (p < 0.001).
• Fixed membranous grafts retained 85.9% volume, fixed endochondral 76.2%.
• Nonfixed membranous grafts retained 55% volume, nonfixed endochondral 16.6%.

Conclusions:

• Graft fixation significantly reduces resorption and improves volume maintenance in onlay bone grafts.
• Stabilizing bone grafts is recommended for enhanced outcomes in facial reconstruction.
• Biomechanical principles, particularly strain effects, likely explain the observed differences.