Index for static and dynamic measurements of the lumbar foramina in patients with foraminal stenosis.

Introduction: lumbar foraminal stenosis refers to the constriction of the lateral canal through which the nerve root exits the spinal canal in the lumbar spine. It occurs in 8-11% of patients aged over 40 years. Failure to detect and alleviate foraminal constriction can contribute to up to 60% of instances of unsuccessful lumbar surgery. This study aimed to develop an index to assess the extent of foraminal narrowing, thereby aiding decisions regarding direct or indirect foraminal decompression.

Material and methods: a cross-sectional study was conducted, involving 49 patients, wherein measurements of all five lumbar foramina were taken using X-rays and simple magnetic resonance imaging. These measurements primarily focused on the foraminal width and the lower endplate, which were then correlated to establish a foraminal width/lower endplate index.

Results: the foraminal width/lower endplate index < 10% yielded an odds ratio (OR) of 3.07 on lateral radiography, 3.59 on flexion radiography, and 4.01 on extension radiography. In MRI, an OR of 0.195 was found for the left foramina, while an OR of 3.07 was observed for the right foramina.

Conclusion: this study paves the way for further exploration of preoperative and postoperative clinical outcomes across various surgical decompression methods guided by the FW/LE index. To enhance decision making, it is recommended to conduct research comparing pre- and postoperative clinical findings in individual patients, considering their FW/LE index measurements.