A study published in the June 2024 issue of The Spine Journal found cervical disc implant design can affect the patient’s range of motion postoperatively.

Researchers analyzed flexion-extension range of motion histograms from 1,173 patients in single-level disc replacement clinical trials for seven implants. Implants with built-in stiffness from its nucleus-annulus design saw the highest proportion of implanted segments in the physiological mobility range. Sixty-five of the discs with the two mobile-core implant designs saw a range of motion of 17 degrees or more. 

The study concluded that “prosthesis design significantly influenced the likelihood of achieving FE-ROM in the physiological mobility range, while avoiding hypomobility or hypermobility. Postoperative ROM averaged over all study subjects provides incomplete information about the prosthesis performance — it does not tell us how many implanted segments achieve physiological mobility and how many end up with hypomobility or hypermobility. We conclude that the proportion of index levels achieving postCDA motions in the physiological mobility range is a more useful outcome measure for future clinical trials.”