The impact of upper instrumented vertebra device type on shoulder balance in Lenke type 1 scoliosis: A comparison of hooks vs. screws

Mohammadreza Chehrassan; Farshad Nikouei; Mohammadreza Shakeri; Ali Valiollahpour Amiri; Seyed Matin Sadat Kiaei; Hasan Ghandhari

doi:10.1016/j.jcot.2025.103189

The impact of upper instrumented vertebra device type on shoulder balance in Lenke type 1 scoliosis: A comparison of hooks vs. screws

J Clin Orthop Trauma. 2025 Sep 3:70:103189. doi: 10.1016/j.jcot.2025.103189. eCollection 2025 Nov.

Authors

Mohammadreza Chehrassan^{1

2}, Farshad Nikouei^{1

2}, Mohammadreza Shakeri^{1

2}, Ali Valiollahpour Amiri^{1

3}, Seyed Matin Sadat Kiaei¹, Hasan Ghandhari^{1

2}

Affiliations

¹ Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of Medical Sciences, Tehran, Iran.
² Department of Orthopedic, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
³ Akhtar Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

PMID: 40979892
PMCID: PMC12448016 (available on 2026-09-03)
DOI: 10.1016/j.jcot.2025.103189

Abstract

Study design: Retrospective Cohort Study.

Objectives: This study aims to evaluate how using hooks versus screws at the upper instrumented vertebra (UIV) influences postoperative shoulder alignment in individuals with Lenke Type 1 adolescent idiopathic scoliosis (AIS).

Methods: A total of 61 patients with Lenke Type 1 adolescent idiopathic scoliosis who underwent posterior spinal fusion (PSF) between 2017 and 2022 were analyzed in this retrospective cohort study. Subjects were grouped based on UIV device type: hook or screw. Shoulder imbalance was measured prior to surgery, three days after the procedure, and at the one-year postoperative follow-up using radiologic shoulder height (RSH) as the primary measure. Statistical analysis compared outcomes between the groups.

Results: Both hook and screw instrumentation effectively corrected shoulder imbalance. Nonetheless, there were no statistically significant differences between groups in correction outcomes either immediately post-surgery (P = 0.301) or at the one-year follow-up (P = 0.431). Likewise, changes in RSH from preoperative to postoperative and from postoperative to follow-up were not significantly different (P = 0.784 and P = 0.201, respectively). These findings suggest the choice of UIV device does not significantly impact shoulder balance correction in the short to mid-term.

Conclusions: Hook and screw constructs appear equally effective in correcting shoulder imbalance in Lenke Type 1 AIS. The choice of instrumentation at the UIV may have minimal influence on shoulder alignment after surgery. Further prospective research involving larger cohorts and extended follow-up durations is needed to validate these results and explore the long-term effects of UIV constructs on shoulder balance.

Keywords: Adolescent idiopathic scoliosis; Lenke 1; Shoulder imbalance; Upper instrumented vertebra.