Study Design: A retrospective study.
Objective: To report the early postoperative results of scoliosis surgery in osteogenesis imperfecta (OI) patients utilizing all pedicle screw constructs and present a novel cementing technique to increase pedicle screw purchase in the osteoporotic OI spine.
Summary of Background Data: Scoliosis surgery utilizing hooks and wire systems have high complication rates in OI. Pedicle screw fixation systems have biomechanical advantage of three-column fixation and cement augmentation of pedicle screws provides additional pull-out strength in osteoporotic OI spine.
Methods: The clinical and radiologic results of ten consecutive OI patients treated with all pedicle screw instrumentation and fusion were retrospectively reviewed. The radiologic data included preoperative and postoperative major curve measurements: major curve Cobb angle, global coronal balance (GCB), apical vertebral translation (AVT) and lowest instrumentented vertebral (LIV) tilt. Operative findings included blood loss, surgery time and additional procedures. All patients received intravenous pamidronate therapy preoperatively to increase bone mineral density.
Results: Ten patients with OI were operated on between 2005 and 2009. Seven had cement-augmented pedicle screw insertion at the proximal and distal foundations. Mean hospital stay was 10+/-7.5 days (range 4-27[medium shade]d) and the average follow-up period was 25.7+/-13.1 months (range,14-507[medium shade]mo). Mean preoperative and postoperative major Cobb angles were 83.7[degrees]+/-23.8[degrees] and 40.3[degrees]+/-14.6[degrees] respectively (48% correction) (P<0.05). Mean preoperative and postoperative GCB deviation was26.7+/-18.67[medium shade]mm and 14.1+/-13.3[medium shade]mm respectively (P=0.097). Mean preoperative and postoperative AVT was 69.3+/-29.1[medium shade]mm and 29+/-12.27[medium shade]mm respectively (P<0.05). Preoperative and postoperative LIV tilt was 18.5+/-8.9 and 5.2+/-3.9[degrees] respectively (P<0.05). At the latest follow up, mean major curve Cobb angle was 37.7[degrees]+/-13.1[degrees], GCB deviation was 13.8[medium shade]mm+/-5.1[medium shade]mm, AVT was 31.7+/-13.3[medium shade]mm and LIV tilt was 11.3[degrees]+/-8.8[degrees]. There was no difference between early post operative and latest follow up major curve Cobb angle, GCB deviation, AVT or LIV tilt, indicating maintenance of correction. Mean blood loss was 23757[medium shade]mL (range 800-45007[medium shade]mL). Mean operative time was 375.4 minutes (range 262-4917[medium shade]min). Mean postoperative Scoliosis Research Society (SRS)-22 patient-based outcomes scores were 4.6+/-0.7 (out of 5). There were no instrumentation failures or permanent neurologic deficits in this series.
Conclusions: Pedicle screw instrumentation in OI scoliosis is safe and effective. Cement augmentation in these patients may help to increase pedicle pull-out strength and decrease screw failure rates especially at the proximal and distal ends of instrumentation.
(C) 2014 by Lippincott Williams & Wilkins, Inc.