Clinical outcome and changes of foraminal dimension in patients with foraminal stenosis after ACDF

Study Design: Prospective study. Objective: To determine the clinical outcome and change in foraminal dimension after anterior cervical discectomy and fusion (ACDF) and to investigate the correlation between clinical outcome and foraminal dimension. Summary of Background Data: No previous studies have evaluated the correlation between clinical outcome and foraminal dimension after ACDF in foraminal stenosis. Methods: A consecutive series of 44 patients (114 foramina) undergoing planned ACDF due to foraminal stenosis were studied. Clinical outcomes included the neck pain visual analogue scale (VAS), arm pain VAS, neck disability index (NDI), subjective improvement rate, dysphasia, and donor site pain. Radiologic outcomes included anterior and posterior disk height, height of foramen and anterior-posterior diameter of the foramen, and the Cobb angle of the fusion segment. Foraminal dimension was calculated. Results: The neck pain VAS decreased from 3.7 preoperatively to 2.3 postoperatively. Likewise, arm pain VAS decreased from 7.2 to 2.2, and NDI decreased from 31.0% to 17.2%. Mild dysphasia occurred in 3 patients. There was no donor site pain. Subjective improvement rate was 79.3%. The anterior disk height increased from 4.75 mm preoperatively to 7.01 mm postoperatively. Likewise, posterior disk height increased from 4.11 to 5.74 mm, height of foramen increased from 7.30 to 9.25 mm, anterior-posterior diameter of foramen increased from 3.56 to 4.92 mm, dimension of foramen increased from 20.50 to 35.58 mm², and segmental angle of fusion segment increased from 2.87 to 4.95 degrees. Posterior disk height was positively correlated with foraminal dimension. An increased segmental angle was negatively correlated with foraminal dimension. The foraminal dimension was negatively correlated with the arm pain VAS. Conclusions: ACDF in cervical foraminal stenosis was a useful surgical option to improve clinical outcomes and widen the foraminal dimension. The foraminal dimension was negatively correlated with the arm pain. Restoration of posterior disk height was necessary to widen the foraminal dimension, whereas increased lordosis of the fusion segment did not help to widen the foraminal dimension.