Associations of overweight status with spinal curve correction and complications in patients undergoing vertebral body tethering: a multicenter retrospective review.

Purpose: Our purpose was to determine associations between body mass index (BMI) category and outcomes of vertebral body tethering (VBT), a non-fusion treatment for adolescent idiopathic scoliosis (AIS) and juvenile idiopathic scoliosis (JIS).

Methods: Using a multicenter database, we identified patients with AIS or JIS who underwent VBT from 2012 to 2018 and had minimum 2-year follow-up (median, 3.0 [interquartile range 2.2, 3.8]). BMI percentiles were used to classify patients as overweight (≥ 85th percentile) or non-overweight (< 85th percentile). Univariate and multivariate regressions assessed associations between complication rates and curve correction between groups, controlling for sex, triradiate cartilage closure, and preoperative curve magnitude.

Results: Of 271 patients, 48 (18%) were overweight. Complication rates did not differ between groups. Factors associated with less correction from preoperative to first postoperative-erect imaging were overweight (β = - 10, p < 0.001), male sex (β = - 8.8 p < 0.01), closed triradiate cartilage (β = 6.0, p = 0.01), and smaller preoperative curve (β = 0.3, p < 0.01). Factors associated with a larger curve at latest follow-up were overweight (β = 4.0, p = 0.02) and larger preoperative curve (β = 0.5, p < 0.001), but tether breakage did not differ between groups (p = 0.31).

Conclusion: In patients who were overweight, VBT was associated with less curve correction at first erect imaging and larger final curve. However, complications and curve correction during the modulation phase were not different from those of non-overweight patients. These findings suggest that surgeons should expect less correction with VBT in patients who are overweight but similar correction over time.

Level of evidence: Prognostic, Level III.