Symptomatic Adjacent Segment Disease After Anterior Cervical Discectomy for Single-level Degenerative Disk Disease.

STUDY DESIGN: A prospective cohort of 142 patients underwent either anterior cervical discectomy alone, anterior cervical discectomy with fusion by cage stand-alone, or anterior cervical discectomy with arthroplasty. We then followed up on their condition for a mean of 9.1±1.9 years (5.6-12.2 y) later.

OBJECTIVE: We aimed to evaluate the annual rate of clinically symptomatic adjacent segment disease (ASD) and to analyze predictive factors.

SUMMARY OF BACKGROUND DATA: Until recent, ASD has been predominantly evaluated radiologically. It is not known whether all patients had complaints. A frequent cited annual rate of ASD is 2.9%, but a growing number of studies report a lower annual rate. Furthermore, maintaining motion to prevent ASD is one reason for implanting a cervical disk prosthesis. However, the results of studies contradict one another.

METHODS: Participants took part in a randomized controlled trial that ended prematurely because of the publication of evidence that did not justify continuation of the trial. The patients were randomly allocated to 3 groups, each of which received one of the abovementioned treatments. We defined symptomatic ASD as signs and symptoms caused by degeneration of an intervertebral disk adjacent to a level of previous anterior cervical disk surgery. At the last follow-up, we were able to ascertain whether clinically symptomatic ASD was present in any of the participants.

RESULTS: The overall annual rate of symptomatic ASD was 0.7%. We found no statistically significant correlations between any of the investigated factors and symptomatic ASD except for the surgical method used. Symptomatic ASD was seen less often in anterior cervical discectomy solely or anterior cervical discectomy with arthroplasty than in anterior cervical discectomy with fusion by plate fixation.

CONCLUSIONS: The annual rate of symptomatic ASD after an anterior cervical discectomy procedure was estimated to be 0.7%. This seems to be related to the procedure, although firm conclusions cannot be drawn.

LEVEL OF EVIDENCE: Level 2-prospective cohort.