ABSTRACT
Lumbosacral fixation or spinopelvic fixation is frequently required for the surgical treatment of neuromuscular scoliosis and degenerative lesions, trauma and tumor in the lumbosacral vertebrae. However, the establishment of stable fixation with these procedures is difficult due to the anatomic characteristics of the sacrum and this is even more problematic for the cases with long segmental fixation, severe instability and bone defects. Although the emergence of pedicle screws makes spinal fixation easier and more rigid, S1 pedicle screws alone do not provide enough stability for lumbosacral fixation. For the purposes of reinforcing lumbosacral fixation, procedures using rods or screws can be used: the procedures using rods include the Galveston method, the McCarthy S-rod and the Jackson intrasacral rod, and the procedures using screws include sacral alar screws, transdiscal screws and iliac screws. The purpose of this study was to ascertain the proper fixation methods, according to each indication, for spinopelvic fixation and we analyzed the advantages and drawbacks of each fixation method. In addition, the fixation method of iliac screws, which has recently become more popular, is presented in detail to enhance the availability and reduce the complication of this technique.
Subject(s)
Sacrum , Scoliosis , Spine , SuccinatesABSTRACT
STUDY DESIGN: This is a retrospective study comparing the radiologic results of sacral fixation using anteromedially directedsingle screw and triangulated double sacral screws. OBJECTIVES: To know whether the single screw fixation is enough for short level lumbosacral fusion. SUMMARY OF LITERATURE REVIEW: Method of sacral fixation is one of a hot issue in spinal instrumentation because of high complication rate. So, many kinds of sacral fixation methods were developed for long level spinal instrumentation. But, it is unclear whether we should use the special sacral fixation techniques instead of simple single screw fixation for the short level lumbosacral fusion. MATERIALS AND METHODS: Inclusion criteria of this study were fixation down to sacrum or sacralized L5, less than three segments fixation and minimum radiologic follow-up for one year. Of those patients treated with lumbosacral fixation using pedicle screw instrumentation from March 1989 to June 1998, forty-four patients met these criteria. They were divided into two groups according to the method of sacral fixation, Group I for single screw fixation and Group II for double screw fixation. Number of patients were 37 in Group I and 7 in Group II. The mean follow-up was 36.5 and 66.6 months, respectively. The radiologic results were evaluated by metal failure, change of lumbar lordosis, change of lumbosacral angle and change of L5-S1 disc space height. RESULTS: metal failure were identified in five patients(13.5%), all in sacral screws of Group I. There were 4 screw breakages and 1 screwrod dissociation. The change of lumbar lordosis was averaged 2.3 degrees(-17~38) in Group I and -4.0 degrees(-25~17) in Group II(p=0.194). The change of lumbosacral angle was averaged 2.3 degrees(-7~12) and 3.7 degrees(-1~12), respectively(p=0.596). The change of disc height was 5.6%(-13~33) and 8.8%(-5~16), respectively(p=0.381). CONCLUSIONS: Group I has much higher rate of instrumentation failure than Group II and all the instrumentation failures were occured at sacral screws. Other radiologic measurements were not statistically significant between the two groups. Stable fixation of the sacrum is necessary to prevent instrumentation failure at the sacrum even though the fusion is less than three levels.