Evaluation of skull strength following parietal bone graft harvest.

BACKGROUND

Parietal bone grafts are commonly used in craniomaxillofacial surgery. The primary aim of this study was to quantify the loss of strength following monocortical parietal bone graft harvest. The secondary aim was to establish a correlation between strength and thickness of calvaria.

METHODS

Thirty fresh human cadaver heads (nonfrozen, unembalmed heads) were used for this study. Loss of strength was determined by comparing the maximum impact resistance of bone on the donor side versus the intact side, using a precalibrated pendulum Charpy impact testing machine. Thickness was measured using a surgical navigation system with optoelectronic tracking.

RESULTS

Loss of strength at the donor site was 36 percent (p=0.0000000001) for a 40 percent loss of thickness. Although correlation between these two parameters is rather moderate (r=0.46), it is highly significant (p<0.0001).

CONCLUSIONS

Although loss of strength is quite significant, serious complications at the donor site are rare. As shown in this study, these risks are nonnegligible. However, because of strong legal pressure, surgeons must carefully weigh the risks incurred by the patient against the expected benefits, whether immediate or deferred. Therefore, the patient should receive well-documented information before such monocortical parietal bone graft harvest is performed.