Motion analysis of single-level cervical total disc arthroplasty: a meta-analysis

The purpose of this review was to investigate whether cervical total disc arthroplasty (CTDA) preserves motion of the treated level and what its effect is on adjacent segments.

Relevant published reports were collected from PubMed, Medline and Cochrane library. The original studies were considered eligible only if the range of motion (ROM) of the index or adjacent level had been investigated. A meta-analysis was then performed on the collected data. Statistical heterogeneity across the various trials was tested using Cochran's Q statistic and I (2) ; in the case of heterogeneity, a random effect model was used.

The weighted mean differences (WMDs) of the index level were 0.34 (95% confidence interval [CI], -0.53∼1.21, P = 0.440) and 0.23 (95% CI, -1.92∼2.38, P = 0.834) in all included studies and randomized control trials (RCTs), respectively. The WMDs of the cranial adjacent levels, caudal adjacent levels and whole cervical spines were 1.01 (95% CI, 0.55∼1.47, P = 0.000), 1.10 (95% CI, 0.61∼1.59, P = 0.000) and 3.40 (95% CI, -6.02∼12.82, P = 0.479), respectively.

These findings suggest that the protective effect against adjacent segment degeneration provided by cervical arthroplasty might not be as good as has been believed. Long-term supporting evidence is still needed.