A mass guide for the harvest of cortico-cancellous bone from the posterior iliac crest for mandibular reconstruction

This study sought to find the mass of particulate cortico-cancellous bone graft required per 1 cm continuity defect of the mandible. Harvested bone was weighed, milled and maximally compressed in a syringe. The defect length (DL) was measured in centimetres, and the compressed bone volume (CBV) used was recorded. The wet bone mass (WBM) of bone required per centimetre of mandibular defect, and the mass of bone yielding 1cc of compressed bone was calculated. Results were analysed statistically to determine if clinically meaningful differences exist between male and female iliac crest. Forty three patient records were reviewed (28 female). Thirty patients had bilateral, and 13 patients had unilateral iliac crest harvest. Mean WBM used per centimetre of mandible defect was 6.9 g.WBM required to produce 1cc of CBV was 2.0 g. For the bilateral harvest group the mean DL was 10.3 cm, the mean WBM was 66.7 g, and the mean CBV was 33.9cc. There was no significant difference in mean WBM between male (72.8 g) and female (62 g) patients. The mean CBV for males (39.7 g) was significantly higher than females (29.5 g). For patients who had unilateral harvest the mean DL was 7.7 cm, the mean WBM harvested was 59.1 g, and the mean CBV was 29.4cc. The mean wet bone mass of posterior iliac crest required to graft each centimetre of mandibular segmental defect is 6.9 grams. A unilateral posterior iliac crest harvest will yield on average 59.1 grams of bone whilst a bilateral posterior iliac crest harvest will yield on average 66.7 gram