Aims: To obtain data on the bone mineral density state in a group of patients with neuroþbromatosis-1 spinal curves, to search for possible accompanying changes in the bone mineral turnover and to determine whether the genotypes at three known polymorphic loci are associated with a decreased bone mineral density in scoliotic patients with neuroþbromatosis. Methods: As part of the preoperative evaluation, dual X-ray absorptiometry was used to assess the bone mineral density of the lumbar spine in 12 patients with neuroþbromatosis- 1, supplemented by laboratory blood/urine investigations. In the pilot study, genetic polymorphisms were tested in the VDR gene, the COL1A1 gene and the OER gene by standard PCR technique. Results: A signiþcant decrease in bone mineral density of lumbar spine was measured. An inverse relation was suggested between the severity of scoliosis and the lumbar spine Z-scores. A three-fold prevalence of the homozygous polymorphism (CC) over the heterozygous form (Cc) of the COL1A1 gene was observed in the nonscoliotic NF1 patients as compared to the patients with scoliosis, presenting with an almost equal distribution in this genotype. Conclusions: The bony tissue abnormality observed intraoperatively in neuroþbromatosis-1 patients may be described as a diminution of the axial bone mineral density. The increased prevalence of the CC genotype of the COL1A1 gene in nonscoliotic NF patients appears to have a possible protective role against spinal deformities in NF1 patients. The evaluation of bone mineral density in the course of the preoperative planning is proposed in neuroþbromatosis-1.

Aimes: To give a 3D analysis of this particular deformity and to evaluate the coronal, sagittal and horizontal plane corrections in these speciþc curves. Methods: 32 patients with severe scoliosis combined with hyperrotatory paradoxic kyphosis were treated with posterior multilevel hook instrumentation. 9 patients had had preceding anterior release and fusion. The derotational maneuver could be accomplished in 21 cases. The coronal Cobb angle and the extents of apical vertebral rotation, sagittal hyper-kyphosis, upper and lower compensatory lordosis, and sagittal trunk balance were measured after an average follow-up period of 5 years and 9 months. Results: The mean coronal deformity decreased from 89.9û preoperatively to 40.7û. The mean preoperative hyperkyphosis was 70.9û in the thoracic spine, 45.9û in the thoracolumbar and 55û in the lumbar region. These values were reduced to 39.7û, 6.8û and -15û, respectively. The lateral spinal balance changed from Ð21.3 mm to Ð8.5 mm. The average rotational correction measured by the method of Jackson was 51% before, and 39% after surgery (correction: 23.5%). There was a positive correlation between the preoperative kyphosis angle and the apical rotation (r=0.58), and between the decrease of kyphosis and the correction of the rotation (r=0.67) in cases when the derotational maneuver could be accomplished. If the apex of the scoliosis and the kyphosis are on the same level, the vertebral hyperrotation is responsible for the sagittal malalignment. Satisfactory results can be achieved with posterior multilevel hook instrumentation.