SURGICAL CORRECTION OF SPINAL DEFORMITY IN NEUROFIBROMATOSIS: EXPERIENCE IN CDI APPLICATION

Objective. To analyze immediate and long-term results of surgical correction of spinal deformity in patients with neurofibromatosis type I. Material and Methods. A total of 24 patients (14 boys, 10 girls), mean age 14.2 years, were operated on during the period of 1996–2007. Out of them 16 patients had a rightsided curve, and 8 patients — left-sided one. Spinal deformity correction was performed with Cotrel — Dubousset instrumentation. In 14 cases main intervention was preceded by discectomy and interbody fusion with bone autograft at the apex of the primary scoliotic curve. In 10 cases both procedures were conducted under a single anesthetic event. Mean postoperative follow-up term was 1.4 years. Results. Mean initial value of the primary scoliotic curve was 102.6°, after surgery — 61.3°, and at final follow-up — 67.9°. Thoracic kyphosis before operation was 82.5°, after operation — 51.2°, and at final follow-up — 64.0°. The tilt of the lowest instrumented vertebra before operation was 16.7°, after operation — 9.5° and at final follow-up — 10.9°. Only mechanical complications were noted: rod fracture in 3 patients, and cranial hook dislocation in 1 patient. Histological analysis of surgical material showed that NF-I gene mutation led to the disturbance of organospecific differentiation of chondroblasts and to staging process of chondroblast — chondrocyte — osteoblast — osteocyte differentiation, which explains postoperative progression of the spinal deformity and formation of pseudoarthroses in the fusion mass. Conclusion. Spinal deformities associated with neurofibromatosis are rare but due to specificity of their pre- and postoperative course present significant challenge.