[Observation on maintenance of scoliosis curve correction and preservation of spinal mobility after removing plate-rod system for scoliosis].

Objective: To investigate the effect of removing the implanted plate-rod system for scoliosis (PRSS) on maintaining scoliosis curve correction and preserving spinal mobility in patients with scoliosis.

Methods: From June 1998 to February 2002, 119 cases of scoliosis were treated with the implant of PRSS, which was removed 26-68 months later (average 46.8 months). Complete follow-up data were obtained in 21 patients, including 6 males and 15 females aged 11-17 years old (average 13.8 years old). The disease course was 9-16 years (average 12.1 years). There were 2 cases of congenital scoliosis and 19 cases ofidiopathic scoliosis, which included 5 cases of IA, 2 of IB, 1 of IIA, 2 of IIB, 2 of IIC, 2 of IIIA, 3 of IIIB, and 2 of IVA according to Lenke classification. There were 13 cases of thoracic scoliosis and 8 of thoracolumbar scoliosis. AP view and the lateral and anterior bending view of X-ray films before and at 3 to 6 months after removing PRSS were comparatively analyzed, the coronal and the sagittal Cobb angle were measured, and the height of vertebral body on the concave side and the convex side were measured, so as to know the effect of PRSS on the growth of the vertebral endplates.

Results: All the implants were removed successfully with an average operation time of 2.5 hours (range 2-4 hours) and a small amount of intraoperative blood loss. Twenty-one cases were followed up for 6-72 months (average 34.4 months). The coronal Cobb angle before and after the removal of PRSS was (20.25 +/- 8.25) degrees and (23.63 +/- 8.41) degrees, respectively, indicating there was no significant difference (P > 0.05); while the sagittal Cobb angle was (39.44 +/- 12.38) degrees and (49.94 +/- 10.42) degrees, respectively, indicating there was a significant difference (P < 0.05). The height of the top vertebral body on the concave side before and after the removal of PRSS was (1.78 +/- 0.40) cm and (2.08 +/- 0.35) cm, respectively, and there was a significant difference (P < 0.01); while the height on the convex side was (2.16 +/- 0.47) cm and (2.18 +/- 0.35) cm, respectively, indicating no significant difference was evident (P > 0.05). All the 21 patients had good prognosis and no major operative complication occurred.

Conclusion: PRSS is an effective instrumentation for the management of scoliosis. After the removal of the PRSS, the correction of scoliosis can be maintained, and the spinal mobility can be protected and restored.