Outcomes of Growth-friendly Instrumentation in Osteogenesis Imperfecta: A Preliminary Report

Background: There is limited literature on the outcomes in patients with osteogenesis imperfecta (OI) undergoing growth-friendly instrumentation (GFI). The purpose of this study was to report the outcomes of GFI in patients with early-onset scoliosis (EOS) and OI. We hypothesized that similar trunk elongation could be obtained in OI patients, but with higher complication rates. Methods: A multicenter database was studied for patients with EOS and OI etiology who had GFI from 2005 to 2020, with a minimum 2-year follow-up. Demographic, radiographic, clinical, and patient-reported outcomes data were collected and compared with an idiopathic EOS cohort matched 2:1 for age, follow-up duration, and curve magnitude. Results: Fifteen OI patients underwent GFI at a mean age of 7.3±3.0 years, with an average follow-up of 7.3±3.9 years. OI patients had a mean preoperative coronal curve of 78.1±14.5 and achieved 35% correction after index surgery. There were no differences in major coronal curves and coronal percent correction between the OI and idiopathic groups at all time points. T1-S1 length (cm) was lower for the OI group at baseline (23.3±4.6 vs. 27.7±7.0; P=0.028) but both groups had similar growth (mm) per month (1.0±0.6 vs. 1.2±1.1; P=0.491). OI patients had a significantly increased risk of proximal anchor failure, which occurred in 8 OI patients (53%) versus 6 idiopathic patients (20%) (P=0.039). OI patients who underwent preoperative halo-traction (N=4) had greater T1-S1 length gain (11.8±3.2 vs. 7.3±2.8; P=0.022) and greater percent major coronal curve correction (45±11 vs. 23±17; P=0.042) at final follow-up versus patients with no halo-traction (N=11). Staged foundation fusion was performed in 2 cases. Conclusion: Compared with matched idiopathic EOS patients, OI patients undergoing GFI achieved similar radiographic outcomes but sustained greater rates of anchor failures, likely due to weakened bone. Preoperative halo-traction was a useful adjunct and may improve final correction. Staged foundation fusion is an idea to consider for difficult cases. Level of Evidence: Therapeutic-III.