Midterm surgical outcomes of a short fusion strategy for adolescent idiopathic scoliosis with Lenke 5C curve

Abstract

Background context: A previous study examined the short-term (2 years) outcomes of a short fusion strategy for Lenke type 5C curves. This strategy had a little less correction rate with no difference in coronal and sagittal balance and SRS-22 scores to those of a conventional strategy and was superior in operative time and intraoperative bleeding. However, its effectiveness in longer follow-up periods was unknown.

Purpose: To assess midterm surgical outcomes of a short fusion strategy for adolescent idiopathic scoliosis (AIS) with Lenke type 5C curve, involving posterior correction and fusion surgery (PSF) using pedicle-screw constructs.

Study design: Retrospective case series.

Patient sample: Twenty-nine patients who underwent PSF for AIS with Lenke type 5C curve with a minimum 5-year follow-up.

Outcome measures: Radiographic parameters and SRS-22.

Methods: We compared radiographic parameters and clinical outcomes between patients with an upper instrumented vertebra (UIV) at the end vertebra (EV) (n=12) and those treated by short fusion (S), with a UIV one level caudal to the EV (n=17).

Results: A preoperative mean Cobb angle of 51.9±13.8° was corrected to 11.7±7.7° in the EV group, and an angle of 46.0±6.6° was corrected to 9.3±5.2° in the S group. The correction was maintained in both groups at the final follow-up, and the mean correction loss was 2.8±6.8° in the EV and 6.5±6.5° in the S group (p=.143). The mean correction rate at the final follow-up was not significantly different between the EV (71.4±11.8%) and S (64.9±13.7%) groups (p=.199). A Cobb angle of a thoracic curve was significantly improved immediately after surgery and maintained during the follow-up period in the both groups. Coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, L4 tilt, UIV/LIV tilt, shoulder balance, and SRS-22 had no difference between the two groups.

Conclusions: There was no difference in radiographic parameters and SRS-22 between patients treated with a UIV at the UEV and patients treated using a short fusion strategy, in which the UIV was one level caudal to the UEV. The short fusion strategy can be one of the alternatives in PSF for Lenke type 5C curves, at least in 5-year time frame.

Keywords: Adolescent idiopathic scoliosis; Lenke type 5C curve; Pedicle-screw fixation; Posterior spinal fusion; Short fusion strategy; Thoracolumbar/lumbar curve; Upper instrumented vertebra (UIV).