Surgical Outcome of Spinal Fusion for Osteogenesis Imperfecta With Scoliosis: Is the Hybrid System With Pedicle Screws Applicable to Weak, Tiny, and Fragile Vertebrae?

Introduction: Corrective surgery for spinal deformity associated with osteogenesis imperfecta (OI) is challenging due to the severe and rigid deformity combined with extreme bone fragility. However, surgical outcomes still remain unclear. In addition, the applicability of pedicle screws (PSs) to the tiny and fragile vertebrae in patients with OI is poorly understood. This study evaluated the surgical outcome, and the accuracy and safety of PS placement in patients with OI. Methods: Twenty-five patients with OI were included in this study. Mean age was 21.0 +/- 9.3 (10 to 49) years. Mean follow-up was 5.8 +/- 2.0 years. The Sillence classification showed 16 patients had the mildest type I, 1 patient had moderate type IV, and 8 patients had the most severe type III. Fifteen patients underwent anterior release followed by posterior fusion, and 10 patients underwent only posterior fusion. The accuracy of PS placement was evaluated with postoperative computed tomography. Results: Scoliosis was corrected from 95.6 to 65.8 degrees after surgery (correction rate 32.5%) and 68.1 degrees at final follow-up (both, P<0.01). Space available for the lung was improved from 76.3% to 84.9% (P<0.05). No implant dislodgement occurred after surgery. A total of 290 screws were placed, of which 213 screws (73.4%) were placed completely. However, 30 screws (10.3%) penetrated >2 mm. In particular, rates of >2 mm penetration was much higher in type III than type I and IV (27.8% vs. 3.0%; P<0.01). Complications related to spinal surgery included 2 transient neurological disturbances. Conclusions: PSs were applicable to spinal fusion surgery in patients with OI. However special care should be taken in placing PSs because of the weakness of the pedicle cortex, which was easily penetrated especially in Sillence type III.