Preoperative Fulcrum Flexibility >80% Is Associated With Clinical Success in Vertebral Body Tethering
Abstract
Study design Single-centre prospective study. Objectives Our study aims to investigate the relationship between preoperative and intraoperative factors with VBT surgical outcomes. Methods This is a single-centre prospective study involving consecutive VBT patients. All patients included were followed up for >2 years postoperatively. Primary outcomes were changes in radiographic parameters from pre-operative to immediate post-operative and between subsequent follow-ups . Secondary outcomes were the relationships between preoperative and intraoperative factors with coronal correction rate. Preoperative factors included fulcrum flexibility and skeletal maturity. Intraoperative factors were intraoperative tensioning, screw positioning, screw length and immediate coronal correction. Presence of growth modulation was defined as >5° further curve correction postoperatively, while postoperative clinical success was defined as <30° coronal curve magnitude and avoidance of revision surgery. Results Forty-one patients (35 females, 6 males) with 53 curves were included. Preoperative curve magnitude was 49.0 ± 7.4° and improved to 17.4 ± 8.0° immediately post-op ( P < 0.001), with mean correction rate at 64.6 ± 15.4%. Coronal correction rate was persistently maintained at 62.1 ± 29.0% at 2-year. Preoperative flexibility correlated with correction rate at immediate post-operatively up to 18-month (correlation coefficient (r) = 0.768 to 0.933; P = 0.002 to P = 0.044). Strength of intraoperative tensioning at upper and apical curve segments was negatively associated with correction rate up till 9-month ( r = −0.409 to −0.620) but could be explained by decision to tension more in less flexible curves. Preoperative fulcrum flexibility >79.8% (i.e. 80%) predicted postoperative clinical success (AUC 0.760; P < 0.001). Conclusion VBT improved curve magnitude and shoulder imbalance in scoliosis with progressive spinal growth. Flexible curves were associated with persistent coronal correction, while flexibility above 80% increases chance of clinical success with minimal risk of further progression. Growth modulation was associated with skeletal immaturity.
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BibTeX
@article{hk2026preoperative,
title = {{Preoperative Fulcrum Flexibility >80% Is Associated With Clinical Success in Vertebral Body Tethering}},
author = {Kai Chun Augustine Chan MBBS (HK) and Chi Chun Garvin Cheung and Kai Him Ambrose Chan and Long Ki James Lin and Elvis Kai Yeung Tse and Chi Wai Natalie Leung and Prudence Wing Hang Cheung BDSc (Hons), PhD and Jason Pui Yin Cheung MBBS, MMedSc, MS, PDipMDPath, MD, MEd, FHKAM(orth), FRCSEd(orth), FHKCOS},
journal = {Global Spine Journal},
year = {2026},
month = oct,
doi = {10.1177/21925682261450865},
url = {https://doi.org/10.1177/21925682261450865},
note = {CC BY},
}
RIS
TY - JOUR
TI - Preoperative Fulcrum Flexibility >80% Is Associated With Clinical Success in Vertebral Body Tethering
AU - Kai Chun Augustine Chan MBBS (HK)
AU - Chi Chun Garvin Cheung
AU - Kai Him Ambrose Chan
AU - Long Ki James Lin
AU - Elvis Kai Yeung Tse
AU - Chi Wai Natalie Leung
AU - Prudence Wing Hang Cheung BDSc (Hons), PhD
AU - Jason Pui Yin Cheung MBBS, MMedSc, MS, PDipMDPath, MD, MEd, FHKAM(orth), FRCSEd(orth), FHKCOS
PY - 2026
DA - 2026/10/31
JO - Global Spine Journal
DO - 10.1177/21925682261450865
UR - https://doi.org/10.1177/21925682261450865
AB - Study design Single-centre prospective study. Objectives Our study aims to investigate the relationship between preoperative and intraoperative factors with VBT surgical outcomes. Methods This is a single-centre prospective study involving consecutive VBT patients. All patients included were followed up for >2 years postoperatively. Primary outcomes were changes in radiographic parameters from pre-operative to immediate post-operative and between subsequent follow-ups . Secondary outcomes were the relationships between preoperative and intraoperative factors with coronal correction rate. Preoperative factors included fulcrum flexibility and skeletal maturity. Intraoperative factors were intraoperative tensioning, screw positioning, screw length and immediate coronal correction. Presence of growth modulation was defined as >5° further curve correction postoperatively, while postoperative clinical success was defined as <30° coronal curve magnitude and avoidance of revision surgery. Results Forty-one patients (35 females, 6 males) with 53 curves were included. Preoperative curve magnitude was 49.0 ± 7.4° and improved to 17.4 ± 8.0° immediately post-op ( P < 0.001), with mean correction rate at 64.6 ± 15.4%. Coronal correction rate was persistently maintained at 62.1 ± 29.0% at 2-year. Preoperative flexibility correlated with correction rate at immediate post-operatively up to 18-month (correlation coefficient (r) = 0.768 to 0.933; P = 0.002 to P = 0.044). Strength of intraoperative tensioning at upper and apical curve segments was negatively associated with correction rate up till 9-month ( r = −0.409 to −0.620) but could be explained by decision to tension more in less flexible curves. Preoperative fulcrum flexibility >79.8% (i.e. 80%) predicted postoperative clinical success (AUC 0.760; P < 0.001). Conclusion VBT improved curve magnitude and shoulder imbalance in scoliosis with progressive spinal growth. Flexible curves were associated with persistent coronal correction, while flexibility above 80% increases chance of clinical success with minimal risk of further progression. Growth modulation was associated with skeletal immaturity.
SN - 2192-5682
SN - 2192-5690
ER -