Long-term Radiological Evidence of Affected and Adjacent Segment Disease after Anterior Cervical Foraminotomy

Anterior cervical foraminotomy (ACF) is a surgical procedure for cervical radiculopathy to avoid fusion and adjacent segment disease (ASD), but its long-term outcome has yet to be investigated. It is also unclear whether ACF enables preservation of range of motion (ROM) and decreases ASD compared with anterior cervical discectomy and fusion (ACDF). This study included nine patients who underwent ACF, and 12 who underwent ACDF and with follow-up period of at least 5 years (average follow-up: 8.7 years). Preoperative and postoperative radiological findings were investigated, comparing the changes in ACF versus ACDF. All disc height (DH) levels (C2/3-C7/Th1) were measured preoperatively and postoperatively in all 21 patients to compare with the change due to the natural history. The ACF group experienced significant loss of DH (0.6 mm, 13.5%, p <0.01) and ROM (p <0.01) at the operated level postoperatively. However, loss of DH was not significantly different from natural changes at unaffected levels, and ROM was maintained. The ACDF group experienced a significant increase in the ROM of the cranial adjacent segment from 6.46 to 7.45 mm (p <0.01), and the dislocation in dynamic X-ray was also significantly increased from 1.61 to 2.89 mm (p <0.01), indicating radiological ASD. The ACF group had no significant increase in ROM and dislocation. ACF causes significant loss of DH and ROM, but this change is not significantly different compared with natural changes at unaffected levels. Furthermore, ACF causes less ASD than ACDF in the long term.