Early outcome in the surgical treatment of idiopathic scoliosis by "bone on bone" anterior interbody fusion.

Background. The aim of our study was to evaluate a new surgical method developed by Robert Gaines for the treatment of idiopathic scoliosis, called the "bone on bone" procedure. Material and methods. We examined 100 patients (81 female and 19 male) selected from 259 scoliotic patients operated at our center between 2002 and 2004. The mean age at surgery was 16 years and 2 months (range: 12 yrs, 2 months to 39 yrs). The mean follow-up was 18 months (range: 15-24). The average range of fusion was 5 vertebrae (range 3-6). The mean Cobb angle was 63 degrees (range: 49 degrees -98 degrees ). The mean Cobb angle of upper secondary curve was 32 degrees (range: 9 degrees -70 degrees ), the lower 32 degrees (range: 7 degrees -740). The mean apical vertebral rotation (AVR) was 30 degrees (range: 15 degrees -55 degrees ), apical vertebral translation (AVT) 58 mm (range: 8-110). The average thoracic kyphosis was 19 degrees (range: 8 degrees -40 degrees ), and lumbar lordosis 23 degrees (range: 18 degrees -38 degrees ). Technical note. The anterior transthoracic and /or retroperitoneal approach was performed; all discs on the apex of curvature were removed and no bone grafts were used (fusion by contact of vertebrae surfaces). Transvertebral screws were implanted with stabilization by means of a rod. Results. After surgical treatment the mean Cobb angle was 27 degrees (range 0 degrees -58 degrees ), and the correction of the base angle was 58%. The mean Cobb angle of the upper secondary curve was 25 degrees (range: 4 degrees -60 degrees ), the lower 19 degrees (range: 1 degrees -56 degrees ). The average AVR was 20 degrees (range: 5 degrees -45 degrees ), correction was 33%. The mean AVT was 16 mm (range: 0-62 mm), accounting for a 72% correction of basic translation. The average kyphosis after surgical treatment was 26 degrees (range: 15 degrees -45 degrees ), lordosis 20 degrees (range: 7 degrees -35 degrees ). After a mean 18 months follow-up, the average Cobb angle was 31 degrees (range: 0 degrees -73 degrees ), with average 12% loss of correction. The mean upper secondary curve was 25 degrees (range: 5 degrees -62 degrees ), the lower 21 degrees (range: 2 degrees -55 degrees ). The average thoracic kyphosis was 28 degrees (range: 14 degrees -48 degrees ), lordosis 21 degrees (range: 7 degrees -37 degrees ). The mean AVR and AVT remained at the same level after follow-up. Conclusions. The "bone on bone" procedure allows the surgeon to decrease the number of segments involved in spinal fusion, and gives high correction of idiopathic scoliosis with a low rate of operative complications.