A technique for enhancing union of allograft to host bone.

The aim of limb-salvage surgery in malignant bone tumours in children is to restore function and eradicate local disease with as little morbidity as possible. Allografts are associated with a high rate of complications, particularly malunion at the allograft-host junction. We describe a simple technique which enhances union of allograft to host bone taking advantage of the discrepancy in size between the adult allograft and the child's bone. This involves lifting a flap of periosteum before resection from the host bone, which is then telescoped into the allograft medullary canal, which may require internal burring or splitting, for a distance of 1.5 to 2 cm and covering the bone junction with the periosteal flap. This is more stable than conventional end-to-end opposition. For each centimetre of telescoping the surface area available for bony union is increased more than three times. The periosteal flap also augments union. Additional surface fixation with a plate and screws is not necessary. We have used this technique in nine children, in eight of whom there was complete union at a mean of 16 weeks. Delayed union, associated with generalised limb osteoporosis, occurred in one. Early mobilisation, with weight-bearing by three weeks, was possible. There was only one fracture of the allograft.