Radiological and Clinical Outcomes of a Disc-Limited Intervertebral Distraction Technique Applied in Anterior Cervical Discectomy and Fusion–A Proposed Method to Assist Cage Selection

OBJECTIVE: Inappropriate intervertebral height restoration caused by nonoptimal choice of cage size is common in anterior cervical discectomy and fusion. The purpose of this study was to evaluate the radiological and clinical outcomes of cervical intervertebral distraction performed in prediscectomy under the strain limitation of the intact disc in a procedure defined as disc-limited intervertebral distraction. METHODS: A total of 61 patients were enrolled. Japanese Orthopaedic Association score, Neck Disability Index, and visual analog scale score for neck pain were evaluated. The parameters of the degenerative intervertebral space height, mean value of the adjacent intervertebral space heights, preoperative and postoperative day 3 segmental height, regional sagittal alignment and global sagittal alignment were measured on plain radiographs. The change in the degenerative intervertebral space height, postoperative day 3 degenerative intervertebral space height, and intervertebral distraction ratio were calculated according to the parameters measured on radiographs. RESULTS: The change in the degenerative intervertebral space height and distraction ratio in the study group were both significantly lower than those in the control group (both P < 0.001). In the study group, there was no significant difference between postoperative day 3 degenerative intervertebral space height and mean value of the adjacent intervertebral space heights (P = 0.752). The Japanese Orthopaedic Association score improved significantly in both groups, with similar recovery rates. There were significant differences in neck pain score and Neck Disability Index between the groups at the 3 days and 1 month follow-ups (P < 0.001). CONCLUSIONS: Disc-limited intervertebral distraction is beneficial in avoiding overestimation of the cage size when performing anterior cervical discectomy and fusion and physiologically restoring intervertebral space height.