Calculating rate and duration of distraction for deformity correction with the Ilizarov technique

Longitudinal bone lengthening with distraction histogenesis is typically carried out at a rate of 1 mm per day. Angular corrections require an adjustment of the rate of distraction according to the geometry of the external fixator relative to the bone or soft tissue being lengthened. Modeling the deformity correction construct using simple geometric principles allows calculation of both the rate of correction and the expected duration of distraction.