[Reduction of the period of treatment for leg lengthening. Technique and advantages]. / Réduction de la durée du traitement dans les allongements osseux progressifs. Technique et advantage.

ABSTRACT

PURPOSE OF THE STUDY We assessed an adaptation of the Ilizarov method aimed at a considerable reduction in the period of treatment for leg lengthening in order to limit complications related to the duration of the external fixation. This technique associates multiple segment lengthening, automatic high-frequency lengthening, and stimulation of bone regeneration by extemporaneous compression at the end of traction. MATERIAL AND METHODS: We analyzed 78 cases of automatic fémur lengthening in 40 patients and simultaneous fémur and tibia lengthening in 38 patients. There were 51 men and 27 women, mean age 13.2 years (6 - 43 years). Mean length deficiency was 4.3 cm for the fémur and 3.5 cm for the tibia. Femoral and/or tibial deformations were observed in 32 patients. Minimal follow-up was 1.5 years. The automatic traction device was composed of the conventional Ilizarov fixator and complementary elements. Different assemblies were used depending on the associated deformations allowing their progressive correction. For 17 patients, radioimmunoassay of thyrocalcitonin and parathormone was performed to compare the time courses. RESULTS: Mean femoral lengthening achieved was 49 mm (8.5 to 20%). Mean tibial lengthening was 42 mm (7.2 to 18.8%). The consolidation index was 18.1 to 21.3 days/cm for single-segment lengthenings and 11.5 days/cm (mean) for two-segment lengthenings (taking into account both the femoral and tibial gain in length). The ideal moment of compression was 5.6 N/cm(2). Acceleration of the bone repairing process was evidenced by activation of the osteotrop hormone system. According to the SOFCOT classification of complications (1990), 60 patients (76.9%) were in category I, 15 (19.3%) in category II, and 3 (3.8%) in category III. DISCUSSION: Improvement of lengthening procedures with external fixators remains an important issue. Treatment periods are often long with consolidation indices for the femur ranging from 39.6 d/cm to 45 d/cm, which can lead to many types of complications. Use of a high-frequency progressive lengthening procedure based on the Ilizarov method considerably reduces the rate of complications compared with progressive lengthening methods and has allowed achieving more satisfactory results in a shorter treatment period. CONCLUSION: Multiple-segment lengthening using an automatic lengthening procedure set at 1 mm per day in four times provides an important reduction in the treatment delays since distraction is performed more rapidly and fewer steps are needed. Automatic high-frequency lengthening with the Ilizarov method provides optimal conditions for tissue regeneration Treatment periods are shorter and anatomic and functional outcome is very satisfactory. Stimulation by extemporaneous compression of the regeneration zone allows a significant reduction in the duration of consolidation. Shorter delays to consolidation help avoid device-related complications.