Outcomes and complications of vertebral body tethering by patient gender

Purpose: Non-fusion surgical options for pediatric scoliosis management such as vertebral body tethering (VBT) offer an alternative to spinal fusion. With this study, we aim to evaluate the postoperative outcomes in boys versus girls who have undergone VBT. Our hypothesis is that girls and boys will have similar outcomes by 2-year follow-up.

Methods: This study employed a review of retrospective data for patients who underwent VBT at 10 sites between 2011 and 2020. Patients were stratified based on gender. All patients had preoperative and 2-year follow-up and were evaluated for curve correction, complications, surgery metrics, and patient reported outcomes.

Results: 328 patients were included in this study: 277 girls and 51 boys. Mean age at surgery was 12.2 years for girls and 13.4 years for boys. Mean preoperative curve magnitude and curve flexibility was similar between both groups. Compared to girls, boys were older, heavier and taller at the time of surgery; BMI was not different between the groups. Skeletal maturity was not different preoperatively or at 2 years. There were no significant differences for mean operative time, mean estimated blood loss, or levels instrumented. Postoperative stay was longer in the girls averaging 4.5 days compared to 3.9 days for the boys (p = 0.026). There were no statistically significant differences between boys and girls for the curve magnitude at final follow-up (28° vs 25° thoracic, 21° both groups lumbar) or percent correction (45% vs 38% thoracic, 38% vs 31% lumbar) at 2-year follow-up. Overall, 98 girls (35%) experienced medical or surgical complications compared to 18 boys (39%) (p = 0.599). Boys experienced higher rates of tether breakage at latest follow-up (33% vs. 17%, p = 0.008) and more loss of correction > 10° (10% vs. 3%, p = 0.03). Rates of reoperation were 15.9% in the girls and 15.7% in the boys (p = 0.972).

Conclusion: Our study found that boys on average had higher body weight than girls and also higher rates of tether cord breakage and loss of correction. Despite these differences, curve correction, modulation, and reoperation rates were similar in both groups. Further work is needed to determine the relative impact of patient gender and weight on incidence of tether breakage.