I am an assistant in a hospital library. So, although I'm not a fully trained librarian, I have learned how to do searches on the Internet and especially using PubMed to find things. This has been helpful since I am having some neck issues myself and looking at possible surgery to either fuse C56 or replace the disc there. However, when I did a search comparing these two treatments, I found almost 300 studies. I don't have the ability to really figure this out. I'm hoping you can just tell me how to get down to the basic information I'm looking for.
The vast amount of information on the Internet can be very overwhelming. Even with a reputable and trustworthy site like PubMed, it is easy to get lost in the volume of studies and available analysis. Sometimes it seems without a degree in statistics, just understanding the value of each study published can be a challenge.
That's why many folks looking for reliable research information turn to studies that are either systematic reviews or meta-analyses. Each of these types of studies provides conclusions based on a more careful review of the literature.
In the case of outcomes for fusion versus disc replacement, there is one study from medical personnel at three different reputable institutions that might give you some helpful information. They specifically evaluated the results of cervical spine (neck) fusion against disc replacement in terms of a condition known as adjacent segment disease (ASD). This is one of the major potential complications to consider after either one of these surgeries.
Adjacent segment disease (ASD) refers to the degeneration of tissue (disc, joints, vertebra) at the spinal level above or below where the fusion or disc replacement took place. It occurs because of increased load transmitted to the surrounding areas when the primary (first) site of disease is disrupted surgically and treated.
The authors of this review of surgical treatment for painful cervical disc disease describe their work as "structured" and "rigorous." And it was truly both! They did a very thorough review of published studies comparing the results of cervical spine (neck) fusion with total disc replacement and that's what you are looking for.
Their search was for information on radiographic (X-ray) results and clinical pathology after these two treatment approaches. The specific focus was on adjacent segment disease (ASD). Like you, they found hundreds of possible studies (276 to be exact using some criteria for inclusion and exclusion that they describe in their summary article).
They were able to drill down those 276 studies to 14 that were of high enough quality that actually compared radiographic and/or clinical results after these two different procedures. In most of the studies, the information was either not recorded or incomplete.
Their conclusions? First and foremost, studies comparing fusion versus disc replacement for cervical spine degenerative disc disease come up short. There was a moderate amount of evidence that no difference exists in short-term or medium-length follow-up results between fusion and disc replacement. In other words, the development of adjacent segment disease is about the same after either type of treatment. But no specific recommendation could be made to guide the selection of treatment without further studies with stronger evidence.
Likewise, they were unable to offer any firm conclusions about the value or benefit of one disc replacement system over another. There just isn't enough evidence or enough strong evidence to make such a statement.
You are entering an area of medical research that has more unknowns than knowns. Although either treatment is considered safe and effective, each one has its own advantages and disadvantages. Don't give up the search! But take the information you find and talk to your surgeon about his or her opinions, experiences, and recommendations for you. Current evidence in the literature is always helpful but each patient is different and cannot be treated in a cookie cutter approach. Your surgeon will evaluate your specific situation, condition, and circumstances and guide you.