Distraction osteogenesis of the lower extremity with use of monolateral external fixation. A study of two hundred and sixty-one 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. The 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 related to the femoral lengthenings, which led to eighty-seven additional operations. The tibiae were lengthened an average of nine centimeters (range, 3.0 to 15.6 centimeters), or 41 per cent (range, 9 to 100 per 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 were 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 femoral lengthenings that were performed to treat a limb-length discrepancy were associated with significantly higher rates of complications overall (p = 0.010) and additional operations (p = 0.023) for each percentage of length gained than those that were performed to treat achondroplasia 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 overall and additional operations than those performed to treat skeletal dysplasias, but the rates were lower than those for lengthenings performed to treat limb-length discrepancy. The rate of complications overall associated with femoral lengthening in patients who were fourteen years old or more was significantly higher than that associated with lengthening in patients who were less than fourteen years old (p = 0.047). Femoral lengthening through the metaphysis was associated with significantly higher rates of complications overall (p = 0.031) and additional operations (p = 0.042) for each percentage of length gained than femoral 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 overall (p = 0.026) and additional operations (p = 0.003) for each percentage 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 complications or additional operations. The femoral healing indices (in terms of both days per centimeter [p = 0.002] and days for each percentage of length gained [p = 0.019]) were significantly higher in the patients who were fourteen years old or more than in those who were less the fourteen years old. These values could not be used to predict an increase in the complications because of poor bone formation. The results of the present review suggest that the use of healing indices to gauge the final outcome of distraction osteogenesis is questionable; we were unable to discern significance or clinical importance from appropriately adjusted values.