Changing Complication Trends After Anterior Vertebral Body Tethering

This is the authors' abstract. We don't add key points for this paper.

STUDY DESIGN: Single-center retrospective study. OBJECTIVE: Identify changes in complication profiles after anterior vertebral body tethering (VBT). BACKGROUND: VBT is associated with complications such as overcorrection and breakage. We reviewed our decade-long series of complications after VBT and hypothesize that overall complication rates have decreased over time, transitioning from overcorrection to undercorrection and tether breakages. MATERIALS AND METHODS: We reviewed all patients who underwent VBT between 2011 and 2020 with minimum two-year follow-up and divided them into three groups by treatment epoch: 2011 to 2015, 2016 to 2017, and 2018 to 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 angle change between any follow-up. Baseline demographics, radiographic parameters, and complication rates were compared across groups. RESULTS: 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. Sixty-five percent 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), and 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% (2016-2017) and subsequently 2% (2018-2020) ( P <0.05). Incidence of breakage was 49% (2011-2015), 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 angle of the entire cohort was 24°±14°. CONCLUSION: Our 10-year experience reflects lessons learned where overcorrection diminished over time with a subsequent increase in tether breakages. LEVEL OF EVIDENCE: Level III, prognostic.