The timing of distraction of an osteotomy.

New methods of limb lengthening are being adopted in the hope of overcoming the poor osteogenic responses characteristic of distraction. Delay between the osteotomy and starting distraction is said to be important but there is little experimental evidence. We have compared immediate with delayed distraction in the rabbit tibia and shown that delay is an important factor in promoting osteogenesis. It seems that its effects are partly mediated by an improvement in the extra-osseous blood supply.