Changing Complication Trends after Anterior Vertebral Body Tethering: 10-Year Experience.

Abstract

Single center retrospective study. Identify changes in complication profiles following anterior vertebral body tethering (VBT). VBT is associated with complications such as overcorrection and breakage. We reviewed our decade-long series of complications following VBT and hypothesize that overall complication rates have decreased over time, transitioning from overcorrection to undercorrection and tether breakages. We reviewed all patients who underwent VBT between 2011-2020 with minimum 2-year follow-up and divided them into 3 groups by treatment epoch: 2011-2015, 2016-2017, and 2018-2020. Complications were categorized as tether breakage, overcorrection, adding-on, curve progression, and miscellaneous. Breakage was defined as >5° interscrew angle change or >5° Cobb change between any follow-up. Baseline demographics, radiographic parameters, and complication rates were compared across groups. 200/388 patients (52%) developed radiographic complications and 75 (19%) required revision. Mean follow-up was 55.9±22.3 months. Mean age was 12.6±1.4 years, and most patients were skeletally immature. 65% of patients underwent single thoracic tethers. Over time, there has been an increase in age at surgery (P<0.05), curve magnitude (P<0.05), closed triradiates (P<0.05) as well as a trend towards more lumbar curves (P=0.09). Complication types changed significantly over time with overcorrection occurring in 13% (2011-2015) then decreasing to 4% and subsequently 2% (P<0.05). Incidence of breakage was 49% (2011-2016), then 55% (2016-2017), and then 59% (2018-2020), with respective revision rates of 6%, 11%, and 13% (P>0.05). There was a significant increase in lumbar breakage and decrease in thoracic breakage (P<0.05), likely related to more double and lumbar VBTs. At last follow-up, mean thoracic Cobb of the entire cohort was 24°±14°. Our 10-year experience reflects lessons learned where overcorrection diminished over time with a subsequent increase in tether breakages. 3, prognostic.