Variables affecting time to bone healing during limb lengthening

Abstract

Radiographs and charts of 114 consecutive patients who underwent 140 lower-extremity bone-segment lengthening procedures using the Ilizarov external fixator were reviewed. Patient age, bone segment (femur, tibia), corticotomy level (metaphyseal, diaphyseal, double level), and distraction gap (DG) were recorded. Distraction-consolidation time (DCT) was defined as the interval in months from the date of the corticotomy until the DG was healed according to radiographic and manual testing criteria. Distraction-consolidation time had a direct linear relationship with the magnitude of the DG. Distraction--consolidation time versus DG was significantly less for femoral than tibial lengthening. Patients 20 years and older healed slower than patients younger than the age of 20 years. Patients 20 to 29 years old healed faster than patients older than 30 years and slower than patients younger than 20 years. Diaphyseal lengthening healed more slowly than metaphyseal lengthening. Double-level lengthening reduced the DCT when the DG was greater than 4 cm. Distraction--consolidation index--DCT divided by DG--was not a constant. Distraction--consolidation index decreased with increasing DG. To facilitate prediction of bone-healing time, graphs were developed demonstrating the average treatment time +/- 2 SD expected for a specific amount of lengthening, considering the bone segment, the level of osteotomy, and the age of the patient.