Abstract
Purpose of the study
To investigate the efficacy of pedicle screw instrumentation in correcting thoracolumbar/lumbar idiopathic scoliosis in adolescent patients.
Summary of Background Data
Thoracolumbar/lumbar scoliosis has been traditionally treated through an anterior approach and instrumented arthrodesis with the aim to include in the fusion the Cobb-to-Cobb levels and preserve distal mobile spinal segments. Posterior instrumentation has been extensively used for thoracic or thoracic and lumbar scoliosis. In the advent of all-pedicle screw constructs there is debate on whether thoracolumbar/lumbar scoliosis is best treated through an anterior or a posterior instrumented arthrodesis.
Methods
We reviewed the medical notes and radiographs of 19 consecutive adolescent patients with Lenke 5C idiopathic scoliosis (17 female-2 male, prospectively collected single surgeon's series). We measured the scoliosis, thoracic kyphosis and lumbar lordosis angles, apical vertebral rotation (AVR) and translation (AVT), trunk shift (TS), as well as the lower instrumented vertebra angle (LIVA) both pre-and post-operatively and at minimum 2-year follow-up. SRS 22 data was available for all patients.
Results
All patients underwent posterior spinal arthrodesis of the primary thoracolumbar/lumbar curve using all-pedicle screw constructs. Mean age at surgery was 15.1 years. We identified 3 separate groups: Group 1 (9 patients) had a fusion to include the preoperative Cobb-to-Cobb levels of the curve; in Group 2 (8 patients) the fusion extended 1-2 levels distal (all patients) +/− proximal (4 patients) to the end Cobb vertebrae; in Group 3 (2 patients) the fusion extended to one level proximal to the lower end Cobb vertebra. Eight patients had compensatory thoracic curves.
Mean Cobb angle before surgery was 60.3° (range: 43-91°). This was corrected by 79% to mean 13° (p<0.001) with no patient losing >2° correction at follow-up. Mean preoperative Cobb levels of the thoracolumbar/lumbar curve were 6.3; mean levels of instrumented fusion were 7 (mean extent of fusion: preoperative Cobb angle + 0.7 levels). Mean preoperative thoracic kyphosis was 34.7° and lumbar lordosis 45.3°. Mean postoperative thoracic kyphosis was 36.6° and lumbar lordosis 43°. Mean theatre time was 3.8 hours, hospital stay 7.5 days and intraoperative blood loss 0.26 blood volumes. There were no neurological complications other than one temporary brachial plexus neuropraxia (recovered before patient discharge from hospital), no wound infections or detected non-union at follow-up.
Mean preoperative SRS 22 score was 3.7; this was improved to 4.5 at 2-year follow-up (p=0.01). Pain and self-image demonstrated significant improvement (p=0.02, p=0.001 respectively) with mean satisfaction rate 4.8.
Comparison between Groups 1 and 2 showed similar age at surgery but higher preoperative scoliosis in Group 2 (Group 1: 54°/Group 2: 65°, p=0.05). Preoperative AVR, TS and LIVA were similar between the 2 groups (p>0.05). Preoperative AVT was significantly higher in Group 2 (Group 1: 3.3 cm/Group 2: 5 cm, p=0.01).
Conclusion
Pedicle screw instrumentation can achieve excellent correction of Lenke 5C idiopathic scoliosis which is maintained at follow-up. This is associated with high patient satisfaction and low complication rates. Greater preoperative AVT and scoliosis angle predicted the need for longer fusion both distally and proximally beyond the end vertebra of the preoperative Cobb angle.
Ethics: Audit/service standard in trust,
Interest statement: None
