Postoperative sagittal alignment of congenital thoracolumbar to lumbar kyphosis or kyphoscoliosis: a minimum 10-year follow-up study.

STUDY

DESIGN

Retrospective case series.

OBJECTIVE

To elucidate the postoperative course of sagittal alignment in patients with congenital thoracolumbar to lumbar kyphosis or kyphoscoliosis. Acquisition of acceptable sagittal alignment is essential to treat spinal deformity. Little evidence exists regarding long-term surgical outcomes on sagittal alignment in congenital kyphosis or kyphoscoliosis.

METHODS

Sixteen consecutive patients (mean age 10.5 ± 3.5 years) with congenital kyphosis or kyphoscoliosis who underwent vertebra resection and osteotomy with instrumentation by single posterior or combined anterior and posterior approach were included. Preoperative radiographs identified kyphosis in 3 patients and kyphoscoliosis in 13 patients. All patients had clinical and radiologic follow-up for > 10 years (mean 16.3 ± 4.0 years).

RESULTS

Segmental kyphosis was significantly improved from 33.9° ± 20.1° to 14.9° ± 17.6° by surgery and was finally maintained at 16.8° ± 22.2° and sagittal vertical axis (SVA) of 13.1 ± 33.7 mm at preoperation and 18.3 ± 22.1 mm at postoperation significantly increased to 26.8  ±  45.7 mm during follow-up. Of the 16 patients, 5 (31%) were identified as those with SVA > 40 mm, and SVA increases > 30 mm during follow-up. In patients with sagittal malalignment, radiographs demonstrated decreased lumbar lordosis at the lower foundation from 28.8° ± 39.0° to 17.0° ± 17.6°, significant increased pelvic tilt from 25.8° ± 5.4° to 37.4° ± 7.4° during follow-up (p < 0.05), and larger residual segmental kyphosis than those in the 11 patients without sagittal malalignment with statistical significance. Of the five cases, progression of local kyphosis (one case) and sagittal decompensation, including decreased lumbar lordosis with disc degeneration (four cases), increased pelvic tilt (three cases), or proximal junctional kyphosis (two cases), were observed.

CONCLUSION

Based on this > 10-year follow-up study, residual kyphosis and sagittal decompensation are revealed to be risk factors for postoperative sagittal malalignment in patients with congenital thoracolumbar to lumbar kyphosis or kyphoscoliosis.

LEVEL OF EVIDENCE: Level IV, case series.