How Center of Rotation Changes and What Affects These After Cervical Arthroplasty: A Systematic Review and Meta-analysis

Abstract

Purpose: To determine how center of rotation (COR) changes and what affects changes in COR after cervical arthroplasty.

Methods: A systematic literature review of in vivo clinical studies comparing the location of the COR before and after cervical arthroplasty with different artificial prostheses was performed. Meta-analysis was performed using a fixed effects model where appropriate.

Results: A systematic review of the PubMed, EMBASE, and Cochrane Library databases was conducted. We initially identified 267 studies, of which 14 involved in vivo kinematics studies evaluating COR following cervical arthroplasty. We found that at the last follow-up, the COR location shifted anteriorly in patients from 4 studies including 85 segments, superiorly in patients from 4 studies including 98 segments, anterior-superiorly in patients from 4 studies including 290 segments, and anterior-inferiorly in patients from 1 study including 272 segments after cervical arthroplasty. The COR location showed no significant change in patients from 5 studies including 106 segments after cervical arthroplasty. Changes in COR showed a certain trend after cervical arthroplasty with different types of prostheses.

Conclusions: Prosthesis design affects changes in COR after cervical arthroplasty. If a constrained or semiconstrained prosthesis is chosen (2-piece implant, ball-and-socket, or ball-in-trough design), the COR location tends to shift anteriorly and/or superiorly, whereas if a nonconstrained prosthesis is chosen (3-piece implant, mobile nucleus design), the COR tends to keep the same location as preoperation. In addition, the position of the prosthesis in the intervertebral space also can affect changes in COR after cervical arthroplasty.

Keywords: Center of rotation; Cervical arthroplasty; Clinical study; In vivo.