Nomenclature

Review of Research

To inform the design of new features to address problems with current implants, some clinical research was conducted by searching for peer-reviewed biomedical papers on PubMed.gov. Atlas Spine is additionally interested in the findings from articles that are easily accessible thanks to UCFs subscriptions to numerous journals, and this project includes submitting a review of this research to Atlas Spine to further provide them with resources for future development. Articles discussing ACDF surgeries, performance of implanted devices, and causes of morbidity were sought out. Some key articles from this search provided useful insight how we approached problems of dysphagia and securement, leading to some recommendations made to Atlas Spine. Some of the most significant findings will be discussed in this brief review.

A commentary by Yoo [1] on an article through The Spine Journal provided some insight on dysphagia. While dysphagia is commonly purported to be caused by the presence of an anterior plate, as claimed by the author of the primary work, Yoo disputes this being the sole cause by pointing out a claim made by a study which found a significant association between dysphagia and the retraction of the larynx and pressure during surgery to access the anterior cervical spine. By pointing out such studies, Yoo demonstrates the lack of consensus on the topic which the primary author writes about. Yoo also points out evidence to suggest that soft scar tissue connections to rough-surfaced implants (surfaces such as screw heads) is another cause of dysphagia. An important conclusion from this work was that dysphagia is likely multifactorial, and changing one variable will be unlikely to have significant effects on the rate of dysphagia. For the team, this meant that a zero-profile implant may not achieve its goal of reducing dysphagia after all, as Atlas Spine had hoped. This finding led the team to recommend other novel features such as smooth anterior surfaces, however consideration had to be given to perceptions of surgeons within the field of surgery, and how unlikely this finding would be to change a prevalent interest in zero-profile implants among many.

An article by Wang et. al [2] studies the stability of zero profile implants versus plate and cage implants, which was an important concern for our method of fixation. The study found that there was no significance between stand-alone cages and plate and cage combinations in terms of fusion rate and stability, meaning that the team would not be sacrificing performance by using screws for a zero profile cage design. Additional findings concluded the operation time and blood loss were decreased with zero profile implants within the study, giving the team confidence in advantages of our designs.

Screw design was another variable introduced with findings from a study done by Shea et. al [3], which assessed the performance of medical screws, comparing pullout strength and screw type. Various types of screws were studied, and the primary insight this article provided were that for cortical bone tests, V shaped screw threads were 14-16% more resistant to pullout forces than buttress threading, which is the type of thread that Atlas Spines current medical screw has. In addition to designing the implant, the team has proposed revising the model for Atlass screw and performing some simple tests to assess if the revisions are beneficial.

Other research informed the team on topics such as subsidence, migration, implant strength and failure analysis, which adds to the body of knowledge used to develop each implant. While some of these topics may be cursory to Atlas Spine, they are valuable to the team in building general knowledge but are not included in summaries submitted to Atlas Spine.