Younger age at spinal cord detethering is potentially associated with a reduced risk of curve progression in children with early onset scoliosis

Purpose In children with early onset scoliosis (EOS) who have tethered spinal cord (TSC), spinal cord detethering is commonly performed prior to spinal deformity correction (SDC). The purpose of this study was to investigate whether age or curve magnitude at the time of detethering is associated with curve progression at a follow-up of at least 2 years. It was hypothesized that patients who undergo detethering at a younger age, or those with a smaller curve magnitude, would experience a reduced rate of curve progression when compared with those who are older or with larger curves. Methods Patients with EOS who underwent detethering at least 2 years prior to SDC were identified in a multicenter international registry. Radiographs were assessed just prior to the detethering procedure (pre-detether) and at the most recent visit prior to SDC (most recent post-detether). The rate of curve progression > 10?degrees was examined. Owing to unequal follow-up in individual patients, Cox regression was used to investigate associations between primary variables (age and magnitude of major coronal curve) and rate of curve progression. Results 37 patients met inclusion criteria and 18 (mean age: 3.7 +/- 2.9 years, 66.7% female, mean follow-up: 3.4 +/- 1.3 years) had radiographic data available for analysis. Pre-detether and most recent post-detether major coronal curves were 44.8 degrees +/- 18.5 degrees and 47.6 degrees +/- 23.9 degrees, respectively. 5 (27.8%) patients had curve progression > 10 degrees at a follow-up of 3.2 +/- 1.2 years. Patients with progression > 10 degrees were older at the time of detethering when compared with those without (5.6 +/- 2.8 vs. 3 +/- 2.7 years, p = 0.084). Regression analysis demonstrated that as age at detethering increased by 1 year, the rate of curve progression > 10 & DEG; increased by 28.6% [95% confidence interval (CI) 0.899; 1.839, p = 0.169]. There was no evidence of an association between pre-detethering curve magnitude and rate of curve progression > 10 degrees [HR: 1.027, 95% CI 0.977; 1.079, p = 0.297]. Conclusion In a small multicenter cohort of EOS patients with TSC, younger age, but not curve size, at the time of detethering was associated with a lower rate of scoliosis progression. Although these results indicate a potential role for early spinal cord detethering in the EOS population, they require further prospective investigation with a larger number of patients.