The results of anterior fusion and Cotrel-Dubousset-Hopf instrumentation in idiopathic scoliosis

Anterior instrumentation for the correction of scoliotic curves has recentl y been gaining in popularity. The problems of high mortality and morbidity that were associated with the employment of anterior instrumentation in the first years it was used have now been overcome. Efforts are now being conc entrated on increasing the correction rates in the frontal plane and decrea sing the kyphotic effect in the sagittal plane. The anterior Cotrel-Dubouss et-Hopf (CDH) system is a recently developed instrumentation that has been claimed to decrease the kyphotic effect through the use of double rods. Thi s study aimed to investigate the impact of the anterior CDH system on idiop athic scoliotic curves in frontal and sagittal planes. To this end, 26 idio pathic scoliosis patients treated with the CDH system were followed for a m ean period of 32.8 +/- 5.3 months. In the frontal plane, Cobb angles of maj or and secondary curves were measured, and postoperative and final correcti on rates determined. In the sagittal plane, sagittal contours of both the i nstrumented region and the thoracic and lumbar regions were measured, and t heir preoperative, postoperative and final control values were determined. In addition to clinical examination, lateral trunk shift (LT), shift of hea d (SH) and shift of stable vertebra (SS) were measured in vertebral units ( VU), on the preoperative and postoperative radiographs in order to evaluate the effect of the system on trunk balance. It was established that in pati ents with single flexible thoracolumbar and lumbar curves and those with ri gid thoracic curves, the correction rates obtained in the frontal plane wer e respectively 79.4 +/- 14.8%, 68.0 +/- 9.4% and 61.5 +/- 8.0%, with statis tical significance. Their final corrections at the last control were 76.3 /- 17.4%, 56.9 +/- 9.1% and 52.3 +/- 8.3%, respectively. Although the corre ctions in the lumbar rigid curves were relatively low, they were still stat istically significant. Taking all the patients together, the mean preoperat ive Cobb angle of the major curves of 67.2 degrees +/- 20.2 degrees improve d to a mean of 28.6 degrees +/- 21.0 degrees, which was a statistically sig nificant difference (P < 0.05), giving a mean correction rate of 61.2 +/- 2 0.3%. The mean correction loss of major curves in the frontal plane in all patients was 6.0<degrees> +/- 3.8 degrees and the mean final correction rat e was 52.6 +/- 23.2%. In the sagittal plane, there was a favorable kyphotic effect on the thoracic region of patients with hypokyphosis and lordosis p attern, whilst in patients with kyphotic pattern, this effect was minimal. In patients with a single flexible lumbar curve, kyphotic effect was not ob served except in two patients. In these two patients, it was thought that e xcessive compression force may have been used. As to the patients with a ri gid lumbar curve, there was a slight decrease in lumbar lordosis. No postop erative complaints were made about imbalance, and the mean overall correcti on in LT values was 60.1 +/- 21.7%. While preoperatively, the SH and SS val ues of all patients were over 0.5 VU, postoperatively, 12 patients (46.2%) were completely balanced (SH = 0 VU, SS = 0 VU) and 8 patients (30.8%) were balanced (0 VU < SH and SS < 0.5 VU). The remaining six patients, whose ba lance values were corrected with statistical significance but were still ov er 0.5 VU, were found to be the ones with rigid lumbar curves. Implant fail ure and systemic complications were not noted in the follow-up period. In v iew of these findings, it was determined that CDH instrumentation achieves significant correction rates in the frontal and sagittal planes, particular ly in single flexible lumbar, thoracolumbar and thoracic rigid curves. It was found that the kyphotic effect was minimized with a double rod syste m. Significant clinical and radiological corrections were achieved in balan ce values, without any imbalance and decompensation problems.