Technical Considerations
The goal of surgery for degenerative spondylolisthesis is the removal of the mechanical pressure on the lumbar spinal nerves and stabilization of the spinal segment with the spondylolisthesis.. Different surgical options are available to the patient.

Literature Review
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The progression of the slipping of one vertebra on another can progress or stabilize. Since degenerative spondylolisthesis is an arthritic condition, the formation of spurs and further narrowing ot the disc might prevent further slipping (stabilization of the spinal segment by nature). In one study, 30% of patients with spondylolisthesis had furhter slippage of the vertebra. (ref #9) Xrays and CAT scans were reviewed and abnormal motion of the motion segment (excess motion) and the alignment of the facet joints predisposes to slipping.(the facet joints act as a restraining barrier, if they are oriented in a way that limits their ability to restrain than slippage can occur) (ref #4)

Patients with spondylolisthesis may not have clinical symptoms and still have the structural changes. The trend in surgery is towards the following with progression towards the larger surgery.

Reviews of surgical results spotted a trend towards the value of bone grafting (attempt to fuse) in addition to decompression. (ref #7, ref#8) The failure to fuse in the presence of bone grafting did not initially seem to matter. (ref#5, ref#8) Further reviews have emphasized the value of additional instrumentation and most recently, the difference between a solid fusion and failure to fuse was linked to better results. (ref #1, ref#2, ref#6)

Other authors have tried more minimal surgical intervention with reasonable short-term results. (ref# 3)

Complications
The complications of lumbar decompression and stabilization for degenerative spondylolisthesis depend on the magnitude of the procedures used. The standard risks are death, paralysis, infection, failure to improve, nerve root injury, spinal fluid leak, future instability, etc. Stabilization involves bone grafting with or without instrumentation and includes the complications of grafting and hardware failure.

Author’s Comment
Surgery for degenerative spondylolisthesis involves lumbar decompression and stabilization. The literature has historically supported decompression only and various progressions of stabilization (bone grafting only, bone grafting with instrumentation). The general trend is to combine decompression with stabilization but individual clinical decisions may lead to the choice of any of the surgical options.

References
1. Bassewitz, H. and H. Herkowitz, Lumbar stenosis with spondylolisthesis: current concepts of surgical treatment. Clin Orthop, 2001(384): p. 54-60.
2. Booth, K.C., et al., Minimum 5-year results of degenerative spondylolisthesis treated with decompression and instrumented posterior fusion. Spine, 1999. 24(16): p. 1721-7.
3. McCulloch, J.A., Microdecompression and uninstrumented single-level fusion for spinal canal stenosis with degenerative spondylolisthesis. Spine, 1998. 23(20): p. 2243-52.
4. Cinotti, G., et al., Predisposing factors in degenerative spondylolisthesis. A radiographic and CT study. Int Orthop, 1997. 21(5): p. 337-42.
5. Fischgrund, J.S., et al., 1997 Volvo Award winner in clinical studies. Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective, randomized study comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation. Spine, 1997. 22(24): p. 2807-12.
6. Bridwell, K.H., et al., The role of fusion and instrumentation in the treatment of degenerative spondylolisthesis with spinal stenosis. J Spinal Disord, 1993. 6(6): p. 461-72.
7. Caputy, A.L., A., Long-term evaluation of decompressive surgery for degenerative lumbar spinal stenosis. J Neurosurg, 1992. 77: p. 669-676.
8. Herkowitz, H.K., L., Degenerative lumbar sponylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J.B.J.S. (Am), 1991. 73: p. 802-808.
9. Matsunaga, S., et al., Natural history of degenerative spondylolisthesis. Pathogenesis and natural course of the slippage. Spine, 1990. 15(11): p. 1204-10.