Bias in cervical total disc replacement trials.
OBJECTIVE
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.


RESULTS
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.
Department of Orthopedic Surgery, Department of Neurological Surgery, Rothman Institute, Thomas Jefferson University, 2500 English Creek Ave, Egg Harbor, NJ, 08234, USA. kris.radcliff@rothmaninstitute.com.
Kristen
K
Radcliff
Robert Wood Johnson Medical School, Rutgers University, Brunswick, NJ, USA.
Sean
S
Siburn
Rothman Institute, Bryn Mawr, PA, USA.
Hamadi
H
Murphy
Department of Orthopedic Surgery, Department of Neurological Surgery, Rothman Institute, Thomas Jefferson University, 2500 English Creek Ave, Egg Harbor, NJ, 08234, USA.
Barrett
B
Woods
Department of Orthopedic Surgery, Carl Icahn School of Medicine, Mt. Sinai University, New York, NY, USA.
Sheeraz
S
Qureshi
Anterior cervical discectomy fusion; Bias; Cervical disc replacement; Cervical radiculopathy