Criteria to be successful

Successful lengthening requires:

• rigid fixation to prevent non-axial stressing
• healing to be initiated before distraction - about 5-14 days after surgery
• suitable distraction rate - if too slow, the distraction site will unite prematurely; if too quick, the resultant bone will be of poor quality - with cysts and large amounts of fibrous tissue - as in the original procedures devised by Wagner. Suitable rates are 0.25 mm four times per day for callotasis; 0.25 mm twice per day for chondrodiatasis
• modification of distraction rate according to osteogenetic potential of the bone - in Ollier's disease, for example, distraction rates should be relatively high since new bone is formed rapidly