DISTRACTION OSTEOGENESIS OF THE LOWER-EXTREMITY WITH USE OF MONOLATERAL EXTERNAL FIXATION - A STUDY OF 261 FEMORA AND TIBIAE

We reviewed the results of distraction osteogenesis of 114 femora and 147 tibiae that had been lengthened to treat a variety of diagnoses. T he femora had been lengthened an average of eleven centimeters (range, 3.5 to 17.0 centimeters), or 48 per cent (range, 8 to 86 per cent) of the original femoral length. The average total time for the treatment of the femora (use of the fixator and any subsequent immobilization) was 257 days (range, 105 to 420 days). There were 114 complications re lated to the femoral lengthenings, which led to eighty-seven additiona l operations. The tibiae were lengthened an average of nine centimeter s (range, 3.0 to 15.6 centimeters), or 41 per cent (range, 9 to 100 pe r cent) of the original tibial length. The average total time for the treatment of the tibiae was 268 days (range, 110 to 497 days). There w ere 196 complications related to the tibial lengthenings, which led to 219 additional operations. The Achilles tendon was lengthened during or after seventy-three (50 per cent) of the tibial lengthenings. The f emoral lengthenings that were performed to treat a limb-length discrep ancy were associated with significantly higher rates of complications overall (p = 0.010) and additional operations (p = 0.023) for each per centage of length gained than those that were performed to treat achon droplasia or another skeletal dysplasia, The femoral lengthenings that were performed to treat short stature (of an endocrine or idiopathic etiology) were also associated with higher rates of complications over all and additional operations than those performed to treat skeletal d ysplasias, but the rates were lower than those for lengthenings perfor med to treat limb-length discrepancy, The rate of complications overal l associated with femoral lengthening in patients who were fourteen ye ars old or more was significantly higher than that associated with len gthening in patients who were less than fourteen gears old (p = 0.047) . Femoral lengthening through the metaphysis was associated with signi ficantly higher rates of complications overall (p = 0.031) and additio nal operations (p = 0.042) for each percentage of length gained than f emoral lengthening through the diaphysis, The tibial lengthenings that were performed to treat Turner syndrome and idiopathic short stature were associated with significantly higher rates of complications overa ll (p = 0.026) and additional operations (p = 0.003) for each percenta ge of length gained than those performed to treat skeletal dysplasias. The rate of joint-related problems (p = 0.044) and that of additional operations (p = 0.053) after tibial lengthening in patients who were fourteen years old or more were significantly higher than those rates after tibial lengthening in patients who were less than fourteen years old. The site of the tibial osteotomy did not affect the rate of comp lications or additional operations. The femoral healing indices tin te rms of both days per centimeter [p = 0.002] and days for each percenta ge of length gained [p = 0.019]) were significantly higher in the pati ents who were fourteen years old or more than in those who were less t he fourteen years old. These values could not be used to predict an in crease in the complications because of poor bone formation. The result s of the present review suggest that the use of healing indices to gau ge the final outcome of distraction osteogenesis is questionable; we w ere unable to discern significance or clinical importance from appropr iately adjusted values.