SRS-Schwab Grade 4 osteotomy for congenital thoracolumbar kyphosis: a minimum of 2 years follow-up study.

BACKGROUND CONTEXT: Several osteotomy techniques including pedicle subtraction osteotomy and vertebral column resection have been employed in the correction of congenital kyphosis (CK) and satisfying outcomes have been demonstrated. However, the Scoliosis Research Society (SRS)-Schwab Grade 4 osteotomy, defined as resection of posterior elements, partial vertebral body, and superior adjacent disc, is rarely reported in the treatment of CK.

PURPOSE: The present study aimed to evaluate the efficiency and safety of SRS-Schwab Grade 4 osteotomy in patients with CK, and to propose its optimal indication.

STUDY DESIGN: This is a retrospective analysis of clinical and radiographic outcomes of patients with CK undergoing SRS-Schwab Grade 4 osteotomy.

PATIENTS SAMPLE: Patients with thoracolumbar CK undergoing SRS-Schwab Grade 4 osteotomy from January 2010 to May 2015 followed up for at least 2 years were retrospectively reviewed.

OUTCOME MEASURES: The thoracic kyphosis, lumbar lordosis, segmental kyphosis (SK), sagittal vertical axis (SVA), pelvic incidence, pelvic tilt, and sacral slope were measured on lateral spinal x-rays. Patients were required to fulfill the SRS-22 questionnaire at preoperation and the last follow-up.

MATERIALS AND METHODS: The sagittal spinal-pelvic parameters were assessed at preoperation, postoperation, and last follow-up. The comparison between preoperation and postoperation was performed by paired samples t test.

RESULTS: A total of 38 patients with CK (17 male and 21 female) with an average age of 16.5±9.9 years were included. The mean operating time was 242.7±88.1 minutes and blood loss was 634.5±177.8 mL. The mean follow-up was 38.8±20.3 months. The SK was 49.5±11.7° at preoperation, 6.8±7.4° at postoperation (p<.001), and 8.0±8.1° at the last follow-up. No significant correction loss during follow-up was found in SK (p=.125). The SVA was improved from -36.0±18.3 mm at preoperation to 3.7±17.8 mm at postoperation (p<.001), and the correction was well maintained during follow-up (p=.113). Compared with preoperation, the mean postoperative scores of each domains of SRS-22 questionnaire improved at different levels. Intraoperative complications included one case with incidental dural tear and another with transient root injury. Proximal junctional kyphosis occurred in three patients at 6 months after operation and remained stable during the follow-up. At the last follow-up, all patients were identified to have achieved solid bony fusion.

CONCLUSIONS: The SRS-Schwab Grade 4 osteotomy, if selected appropriately, could provide satisfying correction of congenital kyphosis. The correction could be well maintained during the longitudinal follow-up.