Selective Thoracic Fusion with Segmental Pedicle Screw Fixation in the Treatment of Thoracic Idiopathic Scoliosis: More than 5 year Follow-Up

Segmental pedicle screw fixation has been proven to enable true segmental control and greater correction both in coronal and sagittal plane of scoliosis. However, there is no long-term study of selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis.

Purpose: To evaluate outcomes of selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis with a more than 5-year follow-up.

Materials and Methods: Two hundred three thoracic idiopathic scoliosis patients with 236 thoracic curves subject to segmental pedicle screw fixation were retrospectively analyzed. Mean patient age at the time of procedure was 13.8 years (range: 8.9~18) and the minimum follow-up was 5 years (range: 5~11.6). All patients were Risser V at most recent follow-up. Curve types were single thoracic in 170 and double thoracic in 33. Preoperative and postoperative standing anteroposterior and lateral radiographs were used to assess thoracic and lumbar curve magnitude, sagittal alignment of thoracic, thoracolumbar and lumbar spine, junctional kyphosis, coronal balance, evidence of adding-on, distal fusion level with reference to the standing neutral rotated vertebra (NV), shoulder balance in double thoracic curves, and screw malposition. Measurements were made preoperatively and at 1 month, 1 year, 2 year, and most recent follow-up after surgery. The medical records were reviewed for the presence of complications.

Results: The preoperative thoracic curve of 51±12º was corrected to 15±6º (72% correction) at 1 month after surgery and 16±8º (69% correction, 3% loss of correction) at most recent follow-up. The non-instrumented lumbar curve of 30±10º was corrected to 11±8º (63% correction) at 1 month after surgery and 14±12 (53% correction) at most recent follow-up. Preoperative thoracic kyphosis of 18±11º, thoracolumbar kyphosis of -1±10º, and lumbar lordosis of -43±10º were improved to 24±8º, -3±8º, -42±10º at 1 month after surgery and 23±8º, -1±10º, -46±9º respectively at most recent follow-up. Junctional kyphosis was observed neither at 1 month after surgery nor at most recent follow-up. For 34 patients who had preoperative coronal decompensation, 6 patients had decompensation postoperatively. Postoperative decompensation occurred in 4 patients. Postoperative adding-on occurred in 17 patients, who were fused down to NV-2 or shorter. The decompensation or adding-on related neither to progression of the clinical imbalance nor to increased incidence of back pain during follow-up. Preoperative shoulder height difference of 1.2cm in double thoracic curve was improved to 0.3cm at most recent follow up. Deep wound infection occurred in 3 patients, among whom 1 patient needed removal of device. The removal cases showed solid fusion, and the correction was well maintained until the most recent follow-up. Thirty-one screws(1.1%) were malpositioned but they did not cause neurologic impairment or adversely affect the long-term results.

Conclusions: Selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis had satisfactory radiographic and clinical outcomes after surgery and has been well maintained for more than 5-year follow-up. It is a safe and effective method for preservation of lumbar motion segments as well as for restoration and maintenance of both coronal and sagittal alignment.