Treatment of Lenke 5 curves with short versus long posterior fusion

Adolescent Idiopathic Scoliosis (AIS) patients with a Lenke 5 curve pose a unique challenge due to their distinct alignment characteristics and the ambiguity surrounding whether to include the compensatory thoracic curve in the fusion construct. The aims of this study are to evaluate radiographic, alignment, and patient-reported outcome characteristics of Lenke 5 patients undergoing long vs. short posterior spinal fusion.

A total of 277 Lenke 5 AIS patients were classified by surgical approach. Long fusion (LF) was defined as the upper instrumented vertebra (UIV) at levels T5 and above. Short fusion (SF) was defined as UIV at T9 or caudal. Patients were analyzed pre-operatively and at 2-year follow-up.

159 (57%) underwent SF, while 118 (43%) underwent LF. The median number of levels fused was 6 in SF group, and 12 in LF group. Preoperatively, there were significant differences in the SF vs. LF groups in magnitude of: upper thoracic curve [8° ± 6° vs. 12° ± 9°, (p < 0.000)]; main thoracic curve [25° ± 9° vs. 35° ± 11° (p < 0.000)]; and thoracic curve on bending film [13° ± 7° vs. 16° ± 6°, (p < 0.001)]. Preoperative thoracic apical translation to CSVL (TAT) was greater in LF (p < 0.000), while T2-T12 kyphosis was lower (32° vs. 38°, p < 0.000). At the 2-year follow-up, thoracic curves improved from 25° ± 9° to 18° ± 9° (SF) and from 35° ± 11° to 15° ± 7° (LF), p = 0.005. Thoracic kyphosis increased in both groups: from 38° ± 12° to 42° ± 13° (SF) and from 32° ± 15° to 36° ± 12° (LF), p < 0.000. Multivariable Logistic regression (pseudo R² = 0.52) identified preoperative TAT (OR = 1.91, p < 0.0001), thoracic curve magnitude (OR = 1.06, p = 0.011), and lumbar curve magnitude (OR = 1.06, p = 0.033) as significant predictors of choosing LF. No significant differences in patient-reported outcomes were observed between SF and LF cohorts.

Lenke 5 patients with larger thoracic and lumbar curve magnitude and greater thoracic apical translation were more likely to undergo LF. Both SF and LF groups demonstrated significant curve correction and improved patient reported outcomes. There were no significant differences in patient reported outcomes (PRO)s between long and short fusion cohorts.