A narrative review and scoring proposal for secondary lumbar instability after lumbar decompression surgery

Lumbar spinal stenosis (LSS) is a common condition in the aging population, where decompressive surgery (DS) is widely regarded as the gold standard due to its effectiveness in relieving symptoms. However, DS carries the risk of secondary lumbar instability (SLI), while fusion surgery, although mitigating this risk, may lead to overtreatment and complications such as adjacent segment disease. The aim of the present study was to review the current literature on preoperative radiological and clinical variables, thus accounting for SLI after lumbar decompression surgery and to derive a score for SLI risk prediction.

A literature review using online databases was performed in order to identify risk factors for the emergence of SLI. Risk factors were then graded for relevance. Consequently, a risk score for predicting SLI was developed from these results.

25 studies including 9754 patients were identified. The most commonly described predictors for SLI were preoperative instability, disc height > 6.5 mm, surgical invasiveness as well as patient-related risk factors such as BMI, age, gender and presence of mechanical low back pain. Based on these results, a 14-point scale was created using the most relevant risk factors selected by the research group using a peer-review process.

The proposed score identifies known risk factors for SLI, rated according to their importance on clinical decision making. This represents an initial theoretical approach that has to be validated by prospective clinical studies. Nevertheless, decision making may already be supported by the awareness of the characterized risk factors.