There is a curious observation about patients who have a cervical spine fusion procedure when those patients are part of a Food and Drug Administration (FDA) study. They have a higher reoperation rate compared with people who have a cervical fusion outside of an FDA study.
Cervical fusion patients in two groups studied (private investigation versus FDA study) received the standard anterior cervical discectomy and fusion (ACDF) procedure you mentioned. One group was part of the FDA investigational studies comparing results of ACDF (the control group) with disc replacement. The second group was patients who had the same ACDF procedure as part of their regular clinical treatment (not as a control group or experimental group).
It is suspected that just being part of an investigational study comparing disc replacement to cervical fusion is enough to produce the difference in results. In other words, being a patient in an FDA study is a risk factor for a second surgery.
Why is that? There are several theories to help explain these differences. First, surgeons working within an FDA study may be quicker to intervene when the results aren’t satisfactory. A second surgery is scheduled sooner than it would be out in a private orthopedic practice.
Second, in the FDA study, the surgeons were only allowed to make corrections at one level, whereas fusion surgeries in real clinical practice could have two or more spinal levels fused. The result is a more stable spine for the group outside the FDA and higher reoperation rates for the FDA participants.
The FDA patients who needed a multi-level fusion but only got a single-level fusion went into the procedure (and came out of the surgery) with greater instability compared with those individuals who only needed a single-level fusion and got it.
The higher reoperation rate in the FDA fusion group doesn’t reflect or match the reoperation rate after fusion in usual clinical practices. Just being in the control group could be the trigger for poor results. We don’t know for sure yet.
Where do we go from here? There is a need to establish some basic guidelines (“criteria”) for when someone should have a reoperation following spinal fusion. Right now, there are multiple factors that influence the decision to reoperate after the first fusion procedure. For example, the surgeon may respond more to the patient’s complaints of pain and disability than to the results seen on X-rays.
Finding a way to describe a “failed” first fusion procedure that could be used in all studies would be very helpful. If each surgeon identifies what he or she views as a “failure” but it’s not routinely the same from study to study, then the results measured in terms of reoperation rates isn’t possible. Studies are needed to establish “thresholds” for reoperation (i.e., at what point would reoperation always be recommended no matter what study the person is in?).
Although this study does not have all the answers yet, it does raise some interesting observations and suggestions about the use of anterior cervical discectomy and fusion inside and out of the FDA. Further evaluation of these differences are needed.