Hooks at the Upper Instrumented Vertebra Can Adjust Postoperative Shoulder Balance in Patients with Adolescent Idiopathic Scoliosis: 5 Years or More of Follow-up

Abstract

This study aims to investigate postoperative shoulder imbalance (PSI) ≥5 years postoperatively in patients who underwent posterior spinal fusion using hooks at the upper instrumented vertebra (UIV) for Lenke type 1 adolescent idiopathic scoliosis (AIS). Overview of Literature: Studies have reported PSI due to excessive correction of the main thoracic curve. Methods: We examined 56 patients with AIS who underwent a posterior spinal fusion with hooks at the UIV from 2004 to 2010. Of these, we enrolled 14 patients who underwent surgery, at least, 5 years ago. X-rays and Scoliosis Research Society-22 (SRS-22) questionnaire were administered. To evaluate the shoulder balance, T1 vertebral tilt angle (T1 tilt), clavicle angle, and radiographic shoulder height (RSH) were measured. PSI was considered as the absolute value of the postoperative RSH being ≥20 mm. Based on radiographs obtained immediately postoperatively, we divided patients into two groups as follows: the balanced group (absolute value of RSH <20 mm) and imbalanced group (absolute value of RSH ≥20 mm). Results: The frequency of PSI was 28.6% immediately postoperatively, 0% 2 years postoperatively, and 7.1% at the last follow-up. In the balanced group, PSI did not occur even at 2 years postoperatively or at the last follow-up. In the imbalanced group, PSI was improved in all patients 2 years postoperatively and all patients, except one patient, at the last follow-up. No significant differences were noted in the frequency of distal adding-on at 2 years postoperatively or the last follow-up between the balanced group and the imbalanced group. We observed moderate negative correlations between the absolute value of T1 tilt and the SRS-22 pain and satisfaction at the last follow-up. Conclusions: Hooks at the UIV could adjust the shoulder balance to avoid long-term PSI in patients with AIS.

Evidence Behind Upper Instrumented Vertebra Selection in Adolescent Idiopathic Scoliosis

“…Matsumoto 18 Similar correction when UIV was at Lenke recommendation versus 1 level below Matsumoto 12 Gotfryd 19 Chan 22 UIV selection was not a risk factor for postoperative lateral shoulder imbalance Kuroya 24 At a mean 7.6 years of follow-up, medial and lateral shoulder balance were found to improve over time and suggested that long-term follow-up is important when reporting shoulder balance Cho 33 Zhao 35 UIV did not correlate with cervical spine imbalance Ketenci 36 Cervical lordosis decreased significantly with the UIV at T2 or T3 but not with it at T4…”

“…Kuroya et al performed a retrospective cohort study (Level IV) exploring how shoulder balance changed with time following posterior spinal fusion in Lenke-1 curves and found that medial and lateral shoulder balance improved from immediate postoperatively to an average 7.6-year follow-up 24 . Similarly, Tang et al retrospectively studied a cohort of 75 patients to evaluate a short fusion and found that “cosmetic shoulder balance” on clinical photographs improved from immediate postoperatively to final follow-up in their cohort 25 .…”

Is the Combination of Convex Compression for the Proximal Thoracic Curve and Concave Distraction for the Main Thoracic Curve Using Separate-rod Derotation Effective for Correcting Shoulder Balance and Thoracic Kyphosis?

“…We also did not include patients who underwent direct vertebral rotation and fixation using a wire or hook because this is not a routine procedure. Using a different anchor system on the vertebral body may affect the correction rate and shoulder balance; for this reason, we used only a pedicle screw system [8, 13]. Previous studies have demonstrated that direct vertebral rotation has no benefit in terms of postoperative shoulder balance and thoracic kyphosis [4, 24].…”

“…Using a different anchor system on the vertebral body may affect the correction rate and shoulder balance; for this reason, we used only a pedicle screw system [8,13].…”

Shoulder Balance Following Correction Surgery for Adolescent Idiopathic Scoliosis

“…Matsumoto et al 28 reported that hybrid methods using hooks and pedicle screws led to lower T1 tilt and CA up to 2 years postoperatively, when compared with segmental pedicle screw fixations, therefore suggesting that hooks may allow slightly greater flexibility and more shoulder rebalancing after correction surgery. Likewise, Kuroya et al 29 studied 56 AIS patients who underwent a posterior spinal fusion and found that the use of hooks at the UIV could improve rebalancing of shoulders in the long term. However, unlike the present study, the authors lacked a control group treated with pedicle screws at the UIV.…”