The importance of delay in distraction of osteotomies.

The factor of timing of the commencement of distraction of an osteotomy is evaluated. Experimental osteotomies subjected to immediate distraction result in the production of a small volume of callus with deficient vascularity. Delay alters this response, and there is a more cellular osteogenic reaction with proliferative vascularization during lengthening. A delay is advocated in all gradual leg lengthening procedures, in progressive correction of deformity controlled by external skeletal fixation following osteotomy, and in bone transport procedures. The period of delay should be carefully determined according to each individual case.