Posterior Decompression and Spinopelvic Fixation Using Commercial Pedicle Screw Instead of Iliac Screw for Metastatic Sacral Tumor

Background: Mechanical stabilization of metastatic pathological fracture of the sacrum is technically challenging. There is often inadequate purchase in the sacrum, and instrumentation has to be achieved between the lumbar vertebrae and the ilium. In addition, commercial iliac screws are usually unavailable at most institutes in Taiwan. The purpose of this study is to evaluate the feasibility and efficacy of the original pedicle screw instead of the iliac screw for spinopelvic fixation in patients with metastatic sacral tumor. Methods: From January 2006 to December 2012, we performed posterior decompression and supplemental instrumentation to treat 15 patients with metastatic sacral tumor at our institutes. The original pedicle screw, with 65 mm in length and 7 mm in diameter, was used instead of the iliac screw for spinopelvic fixation. The visual analog score (VAS), modified Brodsky's criteria, Frankel scale, and Oswestry Disability Index (ODI) were recorded before surgery, before discharge, and 6 months after surgery to evaluate the clinical outcomes. Results: The average VAS was 8.1 (range, 7 to 9) before surgery; it significantly decreased to 3.3 (range, 3 to 4) after surgery (p ＜ 0.001), and continued to decrease to 1.9 (range, 1 to 3) at 6 months after surgery (p=0.001). The average ODI measured 82.9% (range, 76% to 92%) before surgery, significantly decreased to 27.2% (range, 20% to 36%) after surgery (p=0.001), and continued to decrease to 20.8% (range, 16% to 28%) 6 months after surgery (p=0.001). All patients achieved a good or excellent outcome based on modified Brodsky's criteria, and the improvement was significant after surgery (p ＜ 0.001). No patient experienced surgery-related complications or neurologic deterioration. Three patients expired due to tumor progression at 10 months, 12 months, and 19 months after surgery. Conclusions: Spinopelvic fixation using commercial pedicle screw and associated neurologic decompression can provide good clinical outcomes and a low complication rate for patients with metastatic sacral tumor.