Measurement of the lateral recess angle as a possible alternative for evaluation of the lateral recess stenosis on a CT scan.

Stenosis of the lateral recess in the lumbar spinal canal is a clinical problem, especially in terms of surgical management. Criteria for the diagnosis and surgical treatment of lateral recess stenosis (LRS) are not clearly defined. Several authors have suggested measurement of the lateral recess height (LRH) on computed tomography (CT) scans as a helpful tool for making decisions in regard of management. The present study is based on the assumption that measurement of the lateral recess angle (LRA) may be useful in the clinical management of lateral recess stenosis. The reliability and significance of the results have been analyzed. In 35 patients, the stenosis was confirmed by intraoperative measurement of the lateral recess height. Fifty-three affected lateral recesses were analyzed. Before surgery, the heights on CT scans were measured. The mean value was 3.3 mm (SD = 0.9 mm), while 41 of them were 3.6 mm or less. Furthermore, the angles on CT scans were evaluated. The mean value was 25.9 degrees (SD = 4.9 degrees), 48 of them were 30 degrees or less and only 5 of them achieved more than 30 degrees. Results reveal that the best quantitative determination of a lateral recess stenosis is a CT scan angle measurement with a critical value of 30 degrees. A CT scan height of 3.6 mm or less is also indicative of stenosis. Statistical evaluation of the data by multiple regression analysis revealed agreement between intraoperative findings and measured heights (p = 0.02), while even better results were noted for angles (p < 0.01). Interfacet distance (IF) was found to be least predictive (p = 0.04).