Bias in cervical total disc replacement trials.

Overview

PURPOSE OF REVIEW: Cervical disc replacement (CDR) has emerged as a motion-preserving alternative to anterior cervical discectomy and fusion in selected cases. Despite favorable literature, CDR is not universally accepted because of concerns regarding bias in the existing literature. The purpose of this review is to identify the possible biases in the disc replacement literature. RECENT FINDINGS: Recent studies that compare CDR and ACDF have demonstrated equivalent or superior outcomes, lower rates of secondary surgery, and equivalent safety at medium- and long-term follow-up. In our review, we identified four types of bias that may affect the CDR literature: publication bias, external validity, confounding bias, and financial conflicts of interest. Bias, whether intentional or unintentional, can impact the interpretation and outcome of CDR studies. Recognition of this issue is critical when utilizing the existing literature to determine the efficacy of CDR and designing future studies.