Growth modulation increases clinical success in vertebral body tethering.

Abstract

Purpose: The relationship between skeletal maturity and postoperative growth modulation (GM) in patients treated with Vertebral Body Tethering (VBT) is poorly understood. We aimed to: (1) identify preoperative skeletal maturity factors associated with GM, and (2) assess the relationship between GM and postoperative success in patients treated with VBT.

Methods: We retrospectively reviewed radiographic data from 55 patients with a minimum follow-up of 2 years (2.6 ± 0.5). Changes in standing height and skeletal maturity (Sanders Stage [SS], Triradiate Cartilage [TRC], and Risser Stage [RS]) were assessed at all timepoints. Patients that exhibited GM were defined by ≥ 6° of deformity correction from first erect to any postoperative timepoint. Successful outcomes were defined by a Cobb Angle of ≤ 30° at latest follow-up.

Results: We observed GM in 42% (23 of 55) of patients. GM was influenced by SS (p = 0.017) and TRC (p = 0.013), but not RS (p = 0.104). We observed a successful outcome in 91% of patients that exhibited GM compared to 44% of those that did not (p < 0.001; OR 12.9). No difference was identified in preoperative deformity magnitude or amount of initial correction achieved between patients that did and did not exhibit GM. Patients who exhibited GM had a higher revision rate (30.4%) than when compared to those who did not (3.0%, p = 0.005, OR 9.7).

Conclusion: Postoperative success after VBT is directly related to GM. Patients who modulate their deformity are 12.9 times more likely to exhibit a successful outcome and can be identified preoperatively based on SS or TRC.