Using Satellite Rod Technique in Patients with Severe Kyphoscoliosis Undergoing Three‐Column Osteotomy: A Minimum of 2 Years' Follow‐up

OBJECTIVE: To introduce the satellite rod technique utilized in severe spinal deformity after three‐column osteotomy (3CO) and to evaluate the radiographic and clinical outcomes at 2‐year follow‐up, further discussing its utilization in this particular cohort. METHODS: A total of 32 (19 females and 13 males) with an average age of 32.9 ± 18.3 years from December 2012 to March 2016 were retrospectively reviewed. Radiographic measurements were performed on standing full‐spine anteroposterior and lateral radiographs preoperatively, postoperatively, and at last follow‐up. The coronal parameters including Cobb angle and distance between C(7) plumb line and center sacral vertical line (C7PL‐CSVL), as well as the sagittal parameters including global kyphosis (GK) and sagittal vertical axis (SVA) were measured at three time points. The Scoliosis Research Society‐22 questionnaire (SRS‐22) was fulfilled preoperatively and at each follow‐up. Paired t test would be used to determine whether there was a significant difference between time points. RESULTS: A total of 32 patients were enrolled in this study with mean age of 32.9 ± 18.3 (range, 12 to 66) years old. Twenty patients underwent pedicle subluxation osteotomy (PSO) and 12 patients underwent vertebral column resection (VCR). The pathogenesis of this cohort included neuromuscular scoliosis (11 cases), congenital kyphoscoliosis (seven with hemivertebrae and five with segmentation failure), degenerative spinal deformity (five cases), and thoracolumbar tuberculosis with angular kyphosis (four cases). The post‐operative Cobb angle decreased significantly from 49.1° ± 28.0° to 19.0° ± 16.7° with a correction rate of 65.2% ± 21.8%. At final follow‐up, the average Cobb angle was 19.4° ± 16.9° and no obvious loss of correction was found. The preoperative, postoperative, and last follow‐up C7PL‐CSVL were 23.9 ± 14.5 mm, 15.7 ± 11.1 mm, and 12.1 ± 7.4 mm, respectively. Significant postoperative improvement was attained while there was no change observed at last follow‐up. Postoperative GK significantly improved from 73.8° ± 28.1° to 23.2° ± 11.7° with the correction rate of 66.0% ± 17.9%. SVA decreased significantly from 42.9 ± 33.9 mm to 24.1 ± 21.1 mm. The average GK and SVA at final follow‐up were 22.7° ± 10.1° and 23.5 ± 21.1 mm, respectively and no obvious loss of correction was observed of them during follow‐up. In addition, no change or loss of motor or somatosensory evoked potential occurred during surgery. During the follow‐up, two malposition screws and one rod breakage were found. CONCLUSION: The satellite rod used in patients with severe kyphoscoliosis undergoing 3CO could yield favorable radiological and clinical outcomes. With the utilization of this technique, the coronal and sagittal balance could be well‐maintained during follow‐up.