Anterior Vertebral Body Tethering for Scoliosis Patients With and Without Skeletal Growth Remaining: A Retrospective Review With Minimum 2-Year Follow-Up.

Background: Anterior vertebral body tethering (AVBT) has been approved for skeletally immature (IM) adolescent idiopathic scoliosis patients, but the role of AVBT in patients with minimal remaining skeletal growth is controversial. The purpose of this study was to compare minimum 2-year (YR2) outcomes in skeletally IM patients vs those with minimal remaining skeletal growth.
Methods: Patients with single thoracic AVBT were grouped by their preoperative (PR) skeletal maturity: IM ( n = 16, Risser 0-2) vs mature (M, n = 19, Risser 3-5). Outcomes were assessed at PR, first erect (FE), and YR2. Median (range) was compared with nonparametric tests ( P < 0.05).
Results: The PR age was 12.5 (9-16) vs 15 (12-18) years with major Cobb 51° (36°-69°) and 49° (40°-69°) for IM and M, respectively. At FE, there was no difference in correction; however, at YR2, the IM group yielded a lower residual curve (15° [-16° to 38°] vs 29° [12°-42°], P = 0.008). Thoracolumbar/lumbar curves were corrected without group differences. Clinically successful correction (<35°) (15 [94%] vs 15 [79%]) and suspected cord breakages (2 [13%] vs 2 [12%]) were similar at YR2. Two overcorrections occurred, both in IM patients. Scoliosis Research Society-22 outcomes at final follow-up were similar between groups. No revision reoperations or conversions to spinal fusion were needed.
Conclusions: Skeletally IM patients benefit from greater growth-modulated curve correction than M patients, however, at the increased risk of overcorrection. M patients maintained clinically significant correction at latest follow-up. Longer-term follow-up is required to determine durability of outcomes for patients undergoing AVBT who have minimal remaining growth at the time of index surgery.
Clinical Relevance: This study is relevant to spine surgeons, spine physiotherapists, and patients with idiopathic scoliosis. It offers evidence of clinical correction of scoliosis in mature patients.
Competing Interests: Declaration of Conflicting Interests: Dr Lonner reports personal fees, royalty fees, and research grant support from Zimmer Biomet for The Tether implant. Dr Lonner also reports personal fees, nonfinancial support and other from Depuy Synthes, personal fees and non-financial support from OrthoPediatrics, other from Paradigm Spine, non-financial support and other from Spine Search, and other from Setting Scoliosis Straight Foundation outside the submitted work.
(This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2023 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)