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According to Grob and Humke in 1998, the indications for a translaminar screw fixation as a primary fixation procedure are segmental dysfunction, lumbar spinal stenosis with painful degenerative changes, segmental revision surgery after diskectomies and painful disc related syndromes such as internal disc disruption and lumbar disc herniation with concomitant degenerative changes.
Posterior internal fixation to increase fusion was first attempted in 1891 by Hadra. King first reported facet screws in 1948. In the same paper they state that motion between two or more anatomic structures causes wear and tear and a gradual change in their micral and macral structures, which may or may not lead to altered function, possibly associated with pain. They state that in disc related symptoms, in the presence of long-standing back pain and degenerative changes in the involved segment, an additional fusion may help to achieve satisfactory operative results. Even when the underlying pathology, such as with disc resorption and internal disc disruption is suspected to be anteriorly, a posterior fusion may help to relieve pain by immobilization of the segment. They clearly demonstrate in their paper fusions at multiple levels with illustrations at six levels.
Gelalis and Kang in 1998 state that spinal fusion surgery for the most part implies that there exists some degree of instability of the functional spinal unit that is being fused and that this instability is causing the predominant clinical symptoms. They state that causes of this instability are degenerative lumbar spinal stenosis, degenerative spondylolisthesis, degenerative scoliosis, degenerative disc disease. Nuclear degeneration, annular tears, facet arthritis characterize this functional phase. The instability phase has a reduction in disc height, laxity of ligaments and facet capsules, degeneration of the facet joints and increased motion. The confounding dilemma for the clinician, however, is that the radiographic criterion often does not correlate with symptoms. The authors believe that the majority of patients with lumbar spinal stenosis without pre-existing instability can be decompressed without mechanically destabilizing the spine, but patients with severe stenosis that require a more extensive decompression, which may destabilize the spine, do exist. If a complete facetectomy or resection of the pars is required, the surgeon must recognize this and perform a concomitant spinal fusion. They state that other authors believe that the pain generator in degenerative disc disease is the disc and the treatment must focus on eliminating the pain source by diskectomy and fusion techniques, such as anterior interbody fusion, PLIF and combined posterior/anterior fusion.
Eisenstein and Parry stated that an instability syndrome is a facet arthrosis syndrome. This is a syndrome that is aggravated by rest in any posture, including recumbency, and is relieved by repeated or (Continued on page 69)
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