SAN FRANCISCO – Investigators who used standardized pedicle-to-pedicle preoperative and postoperative CT scans to image the foramen and also measured it with specialized software found anterior lumbar interbody fusion resulted in significant indirect foraminal decompression.
At the American Association of Neurological Surgeons Annual Meeting, Prashanth J. Rao, MD, of Sydney, Australia, presented the results of the study of 140 patients treated at 184 levels. Results showed foraminal area, height and width improved from preoperatively to postoperatively by 67%, 21% and 38%, respectively.
“[Anterior lumbar interbody fusion] ALIF results in significant indirect foraminal decompression. It improves in all dimensions. A standardized measurement technique is presented here and the restoration of posterior disc height is a key factor in establishing foraminal height,” Rao said. “The strength of this study is prospective data collection, standardized technique, fine cut CT scans are used, and it is a large cohort of patients.”
For the study, Rao and colleagues analyzed data in a prospectively maintained database for patients who were a mean age of 56.7 years at the time they underwent ALIF (63 men and 77 women). The investigators obtained Human Research Ethics Committee approval for the study and patients needed full radiographic follow-up in order to be included.
Rao said they undertook the study to develop a standardized technique that could be used to measure the foramen and the resultant disc height (DH), and thereby assess the effectiveness of decompression following ALIF.
“Our hypothesis was ALIF does result in indirect foraminal decompression,” Rao said.
The goal of decompression with ALIF and other procedures is to restore disc height and decompress the nerve roots, Rao said. “Our goals were to standardize the technique of measuring these foramen and to look at what factors affect disc restoration of the foraminal area,” he said.
A radiologist and neurosurgeon performed the radiological follow-up in the study and compared each patient’s preoperative pedicle-to-pedicle CT scan to their last available CT scan using ImageJ software. The investigators also measured such parameters as DH, local disc angle and lumbar lordosis on radiographs using Surgimap (Nemaris Inc.) software, Rao said. – by Susan M. Rapp
Rao PJ. Paper #628. Presented at: American Association of Neurological Surgeons Annual Meeting; April 5-9, 2014; San Francisco.
Disclosure: Rao has no relevant financial disclosures.