The Changes in Neural Foramen Shown on Computed Tomography Depending on the Changes in the Height of Intervertebral Disc after Anterior Cervical Discectomy and Fusion (ACDF)

STUDY DESIGN: A prospective radiological assessment. OBJECTIVES: Changes in the height, area, and width--captured using computed tomography (CT)--of the neural foramen with respect to changes in the intervertebral disc height, after undergoing an anterior cervical disc removal and fusion procedure. SUMMARY OF LITERATURE REVIEW: The multiple authors of this study, by obtaining central canal and area of neural foramen by increasing the disc spacing height and area of the neural foramen, attempted to assess the height increase of disc spacing. It is necessary to consider the synergistic effects of decompression through dissection of the posterior longitudinal ligament (PLL). MATERIALS AND METHODS: The authors studied 17 patient cases that underwent one segment anterior cervical discectomy and fusion (ACDF) for degenerative cervical disease from June 2006 to March 2007. All patient cases underwent autogenous iliac bone graft or cage insertion with plate fixation procedure. We measured the areas of the neural foramen, heights of the vertebra body above and below the removed intervertebral disc with CT before and after ACDF. Radiographic measurements were averaged. RESULTS: Among the 17 cases, the height of the cervical disc increased in 15 cases and decreased in 2 cases. The heights of the neural foramen increased in 19 cases and showed no changes in 13 cases. The areas of the neural foramen increased in 23 cases and decreased in 6 cases. The heights of vertebral body above and below the removed disc increased by 5.4% (p=0.734), and the heights of the neural foramen increased by 13.3% (p=0.002). The area of the neural foramen increased by 13.6% (p=0.192). The widths of the neural foramen increased by 2.3% (p=0.586). The intervertebral disc height, neural foramen height, and neural foramen area increased by 39.6%, 8.4%, and 17.9%, respectively, after a 2mm lengthening of bone transplant. The intervertebral disc height, neural foramen height, and neural foramen area increased by 59.8%, 22.9%, and 10.3%, respectively, after a 3mm lengthening of bone transplant. The height and area of neural foramen increased by 18.3% and 18.2%, respectively, after the PLL removal and dissection. CONCLUSIONS: The follow-up observations of the intervertebral disc height, neural foramen height, and neural foramen area showed increases after one segment ACDF in cervical disease cases, when compared to the preoperative radiographic findings. As the height of bone transplant increased, the intervertebral disc height, neural foramen height, and neural foramen area increased. The neural foramen height and neural foramen area significantly increased, when PLL was dissected.

The Comparison of Changes in the Dimensions of the Intervertebral Disc and Neural Foramen between Anterior Lumbar Interbody Fusion and Posterolateral Fusion in the Lumbar Spine / 대한척추외과학회지

STUDY DESIGN: A prospective radiologic assessment. OBJECTIVES: To compare the changes of dimensions of the intervertebral disc and neural foramen between the anterior lumbar interbody fusion and the posterolateral fusion in the lumbar spine. SUMMARY OF LITERATURE REVIEW: There are few reports comparing an anterior lumbar interbody fusion with pedicle screw fixation and a posterolateral fusion with pedicle screw fixation. MATERIALS AND METHODS: We studied 62 patients with degenerative lumbar diseases who underwent minimal anterior lumbar interbody fusion with pedicle screw fixation (group I, 40 patients) or who underwent posterolateral fusion with pedicle screw fixation (group II, 22 patients). We measured the height of disc and the height, width, and area of the neural foramen measured in 1-mm reconstructive sagittal images of computed tomography before and 6 months after the operation. The factors were independently measured by three different observers. RESULTS: Disc height was increased by a mean of 39.1+/-3.28% in group I and 3.1+/-2.99% in group II. The height of the neural foramen was increased by a mean of 18.7+/-4.21% in I and 1.0+/-2.34% in II. The area of neural foramen was increased by a mean of 21.5+/-3.50% in I and -2.1+/-4.39% in II, with significant differences between groups in all parameters. CONCLUSION: The minimal anterior lumbar interbody fusion with pedicle screw fixation was superior to posterolateral fusion with pedicle screw fixation for increasing disc height and the height and area of neural foramen.

The Changes in the Dimensions of Neural Foramen After Anterior Interbody Fusion in the Spondylolisthesis / 대한척추외과학회지

STUDY DESIGN: A prospective radiological assessment was performed using computerized tomography measurements. OBJECTIVES: The aim of this study was to assess the changes in the dimensions of the neural foramen after anterior interbody fusion with posterior fixation in spondylolisthesis. SUMMARY OF LITERATURE REVIEW: Anterior lumbar interbody fusion distracts the height and width of the neural foramen. MATERIALS AND METHODS: Anterior interboody fusion with posterior fixation was performed in twenty-five patients. The sagittal parameters were the height and area of the neural foramen. The fused lumbar segments was imaged in the direct sagittal projections in a CT (SOMATOM Senstaion; SIMENS, Germany) and 1-mm slice thickness before surgery and after solid fusion. Computer digitation was used for the measurements independently by three different observers. Statistical analysis was performed using a Wilcoxon signed test and a paired T-test to determine the correlation between the measurements, and Pearson correlation to determine the level of interobserver and intraobserver agreement. RESULTS: After anterior interbody fusion and posterior fixation, the height and the area of the neural foramen had increased significantly by 15.5+/-14.0%(p.0.001) and 23.2+/-17.7%(p.0.001). There was a significant confidence in interobserver (0.9466~0.9996) and intraobserver(0.8896~0.9991) agreement. CONCLUSIONS: Anterior interbody fusion significantly increased the changes in the dimensions of the neural foramen. Anterior distraction and decompression with anterior interbody fusion increased the area of the neural foramen This study shows that anterior interbody fusion can be used to decompress the neural foramen in the spondylolisthesis.

Height Changes of Intervertebral Disc and Neural Foramen after Anterior Lumbar Interbody Fusion in the Lumbar Spine / 대한척추외과학회지

STUDY DESIGN: A prospective clinical study with radiologic assessment was conducted. OBJECTIVES: To analyze the height changes of the intervertebral disc and neural foramen and width changes of the neural foramen after anterior lumbar interbody fusion and posterior fixation in the lumbar spine. SUMMARY OF LITERATURE REVIEW : Anterior lumbar interbody fusion distracts the height of the intervertebral disc and neural foramen and the width of the neural foramen. MATERIALS AND METHODS: Minimal anterior lumbar interbody fusion and posterior fixation were performed in 20 cases from January 1999 to January 2001. The measuring factors were the height of the anterior and posterior discs, and the height and width of the neural foramen, measured with a caliper in 1mm reconstructive, computed tomography, sagittal images before and 6 months after anterior lumbar interbody fusion. The factors were independently measured by three different persons. RESULTS: The height of the anterior and posterior discs was increased by mean 32.2% and 40.5%, respectively. The height of the right and left neural foramen was increased by mean 15.7% and 18.3%, respectively. The width of the superior, middle and inferior neural foramen was increased by mean 20.6%, 30.3% and 38.6%, respectively. There were significant increases in all measuring factors after minimal anterior lumbar interbody fusion. CONCLUSIONS: Minimal anterior lumbar interbody fusion significantly increased the height of the anterior and posterior intervertebral discs, and the height and width of the neural foramen, and produced neural decompression.