Long-segment spinal fixation using pelvic screws.

OBJECTIVE: Long spinal constructs that extend to the sacrum place added stress on sacral screws. To prevent premature loosening of sacral fixation in these cases, the addition of pelvic screw (iliac screw) fixation has gained in popularity. Pelvic screw fixation has also been used in cases where sacral screw fixation is not possible (e.g., in sacral tumors). Pelvic screw fixation is more straightforward than prior pelvic rod fixation techniques (e.g., the Galveston technique). We describe our technique for pelvic screw fixation and review our experience with this technique.

METHODS: Twenty consecutive patients who underwent spinal-pelvic fixation were followed over a 3-year period (2004-2007). The patient population consisted of 11 men and 9 women with an average age of 58.8 years. Indications for spinal-pelvic fixation in this series included kyphoscoliosis, lumbosacral pseudoarthrosis, sacral fractures, lumbosacral spondylolisthesis, sacral tumors, and lumbar osteomyelitic fractures. Radiographic outcomes were assessed using flexion-extension x-rays and computed tomographic scans. Clinical outcomes were assessed using Odom's criteria and modified Prolo scale.

RESULTS: One patient was lost to radiographic follow-up. One patient died after surgery. The mean follow-up for the remaining patients was 13 months (range, 1-21 mo). Odom's outcomes were rated as good to excellent in 11 (58%), fair in 7 (37%), and poor in 1 (5%) (one patient died). Preoperative and postoperative modified Prolo scores were 10.4 and 12.9, respectively (mean improvement, 2.5). Radiographic fusion across the lumbosacral junction was obtained in 16 (89%) of the 18 patients with follow-up. One patient required revision of a pelvic screw. There was one infection requiring explantation of hardware.

CONCLUSION: Pelvic screw fixation is a safe and effective technique that provides added structural support to S1 screws in long-segment spinal fusions. Furthermore, pelvic screw fixation provides a distal point of fixation in cases where sacral screw fixation is not possible. The use of polyaxial screws and connectors makes this technique easier than Galveston rod fixation of the pelvis.