Study design: A systematic review.
Objective: To critically review and summarize the literature comparing motion preservation devices to fusion in the cervical spine to determine whether the use of these devices decreases the development of radiographical (RASP) or clinical adjacent segment pathology (CASP) compared with fusion.
Summary of background data: Historically, surgical treatment of symptomatic cervical disc disease presenting as radiculopathy and/or myelopathy with anterior cervical decompression and fusion has yielded excellent results. Controversy remains whether RASP and CASP requiring treatment is due to fusion-altered biomechanics and kinematics versus natural history.
Methods: We conducted a systematic search in MEDLINE and the Cochrane Collaboration Library for literature published through February 2012 on human randomized control trials or cohort studies published in the English language containing abstracts to answer the following key questions: (1) Is there evidence that total disc replacement (TDR) is associated with a lower risk of RASP or CASP compared with fusion? (2) Is there evidence that other procedures that do not involve arthrodesis or other motion-sparing devices are associated with a lower risk of RASP or CASP compared with fusion? (3)Is one type of motion preservation device or procedure associated with a lower risk of RASP or CASP compared with others?
Results: The initial literature search yielded 276 citations, of which 73 unique, potentially relevant citations that were evaluated against the inclusion/exclusion criteria set a priori. A total of 14 studies were selected for inclusion. For question 1, RASP was variably reported in studies that compared total disc replacement (TDR) to anterior cervical decompression and fusion (ACDF), and risk differences for reoperation due to CASP ranged from 1.0% to 4.8%, with no statistically significant differences between groups. For question 2, no studies comparing motion preservation devices to ACDF met our inclusion criteria. For question 3, one study comparing motion-sparing devices found the risk of RASP to be similar between groups.
Conclusion: A paucity of high-quality literature comparing motion-preserving devices or treatment methods to fusion or other motion-preserving techniques or devices (with RASP and/or CASP as an outcome using consistent definitions) exists. Independently funded, blinded long-term follow-up prospective studies would be able to delineate the true effects regarding incidence of RASP and CASP and treatment of CASP.
Consensus statement: 1. There is no significant difference in development of RASP and CASP after C-TDR versus ACDF at short- to mid-term follow-up.
Level of evidence: Moderate. Strength of Statement: Strong. Recommendation 1: No recommendation can be made from comparative literature of nonarthroplasty motion preservation device or techniques compared with fusion regarding the risk of RASP or CASP.
Level of evidence: Insufficient. Strength of Statement: Strong. Recommendation 2: No recommendation can be made from direct comparative literature of various motion preservation devices or techniques regarding the risk of RASP or CASP.
Level of evidence: Insufficient. Strength of Statement: Strong.