To compare the post-operative results of decompression and decompression and fusion, with and without instrumentation, to establish a treatment of choice for degenerative lumbar spinal stenosis.

MEDLINE was searched from 1975 to 1995 for studies published in English, French or German, using the following keywords: 'lumbar spinal stenosis', 'fusion/decompression of the spine', 'claudicatio spinalis' and 'radicular signs'.

Study designs of evaluations included in the review

Studies with at least seven patients and which reported cases of degenerative lumbar stenosis with no precedent operations of the lumbar spine ('virgin backs') were eligible for inclusion. Studies which included cases of degenerative spondylolisthesis with resulting spinal stenosis were excluded from this review.

Specific interventions included in the review

Decompression and fusion with and without instrumentation.

Participants included in the review

Patients undergoing treatment for degenerative lumbar spinal stenosis diagnosed through physical examination, computed tomography scan, myelography and electrophysiological neurologic investigations. The participants' age ranged from 19 to 87 years (mean: 55.7) and the gender ratio ranged from 29 to 85% male (mean: 58.2).

Outcomes assessed in the review

The outcomes assessed were leg or back pain, neurologic symptoms, ability to work (job functioning), functional disability, and pre-operative duration of symptoms.

The post-operative outcome was classed as poor, fair or good.

The incidence of complications was listed for deep vein thrombosis, infections, operative mortality, neurologic disorders, and others (e.g. reoperation).

How were decisions on the relevance of primary studies made?

The authors do not state how the papers were selected for the review, or how many of the authors performed the selection.

The authors do not state that they assessed quality.

Two clinicians independently read the individual studies and extracted information on the study morphology, pre-operative patient characteristics, surgical methods, and patient outcomes. The reviewers met to agree the information, and any disagreements were resolved by discussion. When agreement could not be reached, the article was sent to a third reviewer for arbitration.

How were the studies combined?

The studies were combined according to the procedures described by Mosteller and Chalmers, Glass et al., and Fleiss (see Other Publications of Related Interest nos.1-3, respectively).

The standard error for a proportion was calculated. For the combined estimate based on all studies, the weighted pooled proportion and its variance were computed.

The Z-value for comparing two weighted pooled proportions was calculated for decompression only versus decompression and fusion with instrumentation. It was also calculated for decompression and fusion with instrumentation versus decompression and fusion without instrumentation.

Different factors predicting patient outcome were compared using the Student t-test, and a level of statistical significance set at p less than 0.01.

How were differences between studies investigated?

The authors do not state how differences between the studies were investigated.

Thirty studies with 1,668 participants met the inclusion criteria. The sample sizes of the individual studies ranged from 8 to 184 patients (mean: 67.5). The methodological design of the included studies was not reported.

Decompression only was the procedure with the highest rate of good post-operative results (Z=2.033), followed by decompression and fusion with instrumentation (Z= -0.854). Decompression and fusion without instrumentation showed the lowest rate of good post-operative results (Z= -2.312).

In those patients that underwent surgery in the first 7 years of the disease, the best results were obtained by decompression only (p=0.01). In those with a duration of symptoms of 15 years or more, instrumented fusion showed the best post-operative outcome (p=0.01). For a duration of symptoms of 8 to 15 years, none of the three analysed surgical procedures was superior.

Decompressive laminectomy only showed the best results for patients with degenerative spinal stenosis if the duration of symptoms was less than 8 years.

The authors stated their research question and the inclusion and exclusion criteria. The literature search was limited to one database, which may have missed publications published outside of the USA. The study was also limited by language restrictions, and there is no mention of searches for unpublished data.

The authors did not report who selected the articles for inclusion, and there was no quality assessment of the included studies. Details of the individual studies, and the data extracted from these studies, were not reported in the review; the included studies were listed only by reference at the end of review.

The synthesis of the data was appropriate, but there was no test or discussion of heterogeneity between the included studies or the types of treatment being analysed.

The results of the review follow from the data presented, but should be viewed with caution because of the lack of transparency and details concerning the review review.

Practice: The authors state that clinicians should aim to diagnose the condition early and also offer the operation early, to achieve the best results post-operatively.

Research: The authors did not state any implications for further research.

1. Mosteller F, Chalmers TC. Some progress and problems in meta-analysis of clinical trials. Stat Sci 1992;7:227-36. 2. Glass GV, McGaw B, Smith ML. Meta-analysis in social research. Beverly Hills (CA): Sage; 1981. 3. Fleiss JL. The statistical basis of meta-analysis. Stat Methods Med Res 1993;2:121-45.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.