A Clinical Analysis of Long Segment Fusion with Pedicle Screw in Degenerative Lumbar Spine

Kim, Eung Ha; Cho, Duck Yun; Kim, Ji Hun

Abstract

STUDY DESIGN: This is a retrospective study.
OBJECTIVES
To identify complications of long segment fusion with pedicular screw fixation of lumbosacral spine and analyze causative factors of complications. SUMMARY OF LITERATURE REVIEW: An unexpected high rate of complication has been observed in pedicle screw fixations used in long segment fusion for degenerative lumbar diseases. Adjacent problem, fixation problem due to osteoporosis, insufficient bone stock may cause implant failure and pseudarthrosis.
MATERIALS AND METHODS
From January 1991 to March 1998, 62 patients underwent long segment fusion more than 3 segments for degenerative lumbar diseases, such as degenerative spinal stenosis, associated spondylolisthesis, spinal deformity(kyphoscoliosis), etc. 50 of them followed for more than one year after operation, average follow up period was 21.9 months(range: 12 to 58 months). 17 of them were male and 33 were female and average age was 59.76 years(range : 50 to 76 years). In all cases, pedicle screw fixation was performed with or without additional anterior/posterior lumbar interbody fusion. The number of fused segment was 25 three levels, 14 four levels, 6 five levels, 5 more than six levels.
RESULTS
Problem in implant was noted in 19 patients, of which 16(33 screws) showed screw loosening and 3(4 screws) showed screw breakage. 25 of 33 loosened screws were in most distal segment and 21 of them were sacral screws. All the screw breakages developed in sacrum. The problem of screw was associated with the number of fused segment(p=0.009) and sagittal imbalance(p=0.043). Pseudarthrosis rate was 20%(10 patients) and was associated with screw failure(p=0.030). On clinical results, 66% of good to excellent results were obtained, and revision rate of complicated cases was 24%.
CONCLUSIONS
In long segment fusion of degenerative lumbar spine, we need to restore more adequate sagittal balance, and need additional sacral fixation and anterior fusion to avoid implant failure and pseudarthrosis.