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

Purpose: 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 determine whether the height of the implants was associated with postoperative foraminal height and volume, and with clinical improvement in patients suffering from cervico-brachial neuralgias due to degenerative foraminal stenosis. Methods We conducted a prospective follow-up of patients who underwent ACDF for cervicobrachial neuralgias due to degenerative foraminal stenosis. Patient had filled auto questionnaires (Neck Disability Index (NDI), Visual Analog Scales (VAS) for cervical and radicular pain) and performed a CT-scan pre and post-operatively. Disc height, foraminal height 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. A significant improvement in the 3 scores was observed at 3 months postoperatively (p < 0.001). We found a significant improvement in every radiological parameter, with a significant increase in disc height, foraminal height and foraminal volume being respectively + 3,22mm (p < 0,001), + 2,12mm (p < 0,001) and + 54mm 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). Increase in foraminal height was significantly correlated with foraminal volume (p < 0,001) and with improvement in NDI score (p:0,037). Considering all those findings, our study suggests that indirect decompression helps in clinical improvement after ACDF. Conclusion This study provides interesting data regarding the clinical benefit of indirect decompression in ACDF performed for cervicobrachial neuralgias.