Does skeletal maturity influence vertebral body tethering outcomes? evaluating the role of risser and sanders stages

Vertebral body tethering (VBT) is a scoliosis correction technique that purportedly leverages spinal growth modulation to correct curves over time. Therefore, measures of skeletal maturity such as Risser and Sanders stages are often used in VBT patient selection. VBT in skeletally mature patients is sometimes seen as controversial or less predictable due to their limited remaining growth. This study compares VBT outcomes in Risser 0-2 vs. 3-5 and Sanders 1-4 vs. 5-8 patients.

Single institution retrospective review of 138 post-VBT patients with minimum 2-year follow-up. Patients were grouped by preop Risser and Sanders stages. Independent t-tests (alpha = 0.05) and Fisher's exact test were used for analysis of outcomes.

No significant differences were observed in BMI, number of levels instrumented, preop major curve magnitude, preop major curve flexibility, estimated blood loss (EBL), % correction at first erect (FE), % correction at 2-year follow-up, or reoperation rates, complication rates, or cord breakage rates between the skeletally mature and immature patients. Operative time was shorter in Sanders 5-8 patients compared to Sanders 1-4 patients (p = 0.0478). Length of hospital stay was slightly shorter in Risser 3-5 patients (p = 0.0080), with no difference between Sanders groups.

At our center, Risser and Sanders stages did not significantly affect most VBT outcomes. Curve correction, reoperation rates, and complication rates were similar, suggesting that VBT can achieve comparable 2-year outcomes across a spectrum of skeletal maturity. However, given the shorter follow-up for the more skeletally mature patients, it remains possible that they may encounter issues such as cord breakage or require reoperation/fusion at rates similar to the less mature patients with longer follow-up. Larger studies are needed to determine the required degree of growth remaining for successful long-term outcomes and explore other factors associated with long-term success following VBT.