Effects of indirect foraminal decompression during anterior cervical disc fusion procedure: preliminary results of a prospective study with clinical and radiological outcomes

Introduction: The respective effects of direct and indirect decompression in the clinical outcome after anterior cervical disc fusion (ACDF) is still debated. The main purpose of this study was to analyze the effects of indirect decompression on foraminal volumes during ACDF performed in patients suffering from cervico-brachial neu-ralgias due to degenerative foraminal stenosis, i.e. to determine whether implant height was associated with increased postoperative foraminal height and volume.Methods: A prospective follow-up of patients who underwent ACDF for cervicobrachial neuralgias due to degenerative foraminal stenosis was conducted. Patient had performed a CT-scan pre and post-operatively. Disc height, foraminal heights and foraminal volumes were measured pre and post operatively. Results: 37 cervical disc fusions were successfully performed in 20 patients, with a total of 148 foramina studied. Foraminal height and volume were measured bilaterally on the pre-and post-operative CT scans (148 foramina studied). After univariate analysis, it was found a significant improvement for every radiological parameter, with a significant increase in disc height, foraminal height and foraminal volume being respectively +3,22 mm (p < 0,001), +2,12 mm (p < 0,001) and +54 mm(3) (p < 0,001). Increase in disc height was significantly associated with increase in foraminal height (p < 0,001) and foraminal volume (p < 0,001). At the same time, in-crease in foraminal height was significantly correlated with foraminal volume (p < 0,001), and seems to be the major component affecting increasing in foraminal volume. Conclusion: Indirect decompression plays an important part in the postoperative foraminal volume increase after ACDF performed for cervicobrachial neuralgias.