Optimum ratio of distraction in double level tibial lengthening

The authors reviewed 43 double level tibial lengthenings by Ilizarov techni que in 34 consecutive patients (6-31 years old), and investigated the facto rs affecting regenerate bone healing to determine the optimum ratio of dist raction rate or magnitude of lengthening at the proximal and distal osteoto my sites. Length gain averaged 6.1 cm (range, 2.5-12.3 cm), equivalent to a 28% increase of the segment, The variables investigated included age, gend er, concomitant deformity correction, etiology, and the amount of length ga in. The healing index averaged 1.8 months per centimeter proximally and 2.8 months per centimeter distally, Age and the amount of length gain affected the healing index at proximal and distal lengthening sites. However, the p roximal to distal healing index ratio, which averaged 0.72, was not affecte d by any parameters investigated. This study suggests that to minimize exte rnal fixation treatment time, the distraction rate, or amount of length gai n, of the distal osteotomy site should be approximately 3/4 that of the pro ximal site in the double level tibial lengthening.