Have you ever heard the expression What’s good for the goose is good for the gander? It’s an English idiom (figure of speech) that suggests if something is good for one thing, it can be useful for something else as well. In the world of spine surgery, bone substitutes called bone-morphogenetic proteins (BMPs) have been used successfully in lumbar spinal fusions. That’s what they’ve been approved for by the Food and Drug Administration. They replace human bone grafts that are hard to come by, don’t always take, and can leave the donor site more painful than the fusion site when the patient donates his or her own bone for the procedure.
The problem with BMPs is that some surgeons have extended their use to fusions of the cervical spine (neck). This practice is referred to as an off-label use (i.e., not for what it was intended). And suddenly, what was good for the goose (lumbar spine) was no longer good for the gander (cervical spine). Unexpected complications arose — too much bone growth resulted in swelling of the airway, compression of the airway, difficulty swallowing, hoarseness, and poor wound healing. These complications are not minor, but serious enough to potentially be life-threatening.
Not to be an I-told-you-so kind of guy, but the surgeon who originally researched the use of BMPs and eventually got them FDA approved has said all along that these bone substitutes have only been tested in the lumbar spine and that’s the only place they should be used. Using new technologies like bone growth factors in similar but not exactly the same ways is legal, just not always advised.
At least one study showed that BMP is safe for use in the thoracic spine and posterior cervical spine. The real problem appears to be use of BMPs in the anterior cervical spine. Anterior means the fusion is done from the front of the neck. That approach avoids contact with the spinal cord and reduces the potential for neurologic damage. Clearly, the complication rate was much higher (50 per cent higher) when BMP was used in the anterior cervical spine compared with posterior cervical spine or the lumbar spine.
So why isn’t the FDA protecting the public on this issue? Well, again, as mentioned — it’s not illegal to use products off-label. Drug companies can’t advertise or promote off-label use without adequate trials and safety studies. But there’s nothing stopping a surgeon from seeing that something works well in one situation and giving it a try in another different, but similar application. And that’s what happened with BMPs in anterior cervical spine fusions.
Only what worked well for the lumbar spine didn’t pan out for the cervical spine. The natural question is Why not? It’s not entirely clear just yet. There’s some speculation that when the surgeon took the product (packaged for the lumbar spine procedure) and used it in the cervical spine, rather than throw half of the expensive BMP away, he or she used it all. That resulted in overgrowth of bone in an area with little room for additional bone with the trachea, esophagus, nerve supply, and soft tissues contained in a small, limited space of the throat and neck.
As a result of these unexpected complications, there’s been a call for closer supervision of new technologies like BMPs. Surgeons are pointing fingers at the FDA and saying safety should be under their umbrella and products shouldn’t be released without full and satisfactory testing. Others are suggesting the FDA has a role in close surveillance in after market results but that medical societies and surgeons themselves must be responsible for follow-up reporting.
Actually, for those surgeons who attended annual spine meetings and conferences, there was plenty of discussion about the early results of BMPs for anterior cervical spine fusion. But those who didn’t attend the meeting didn’t get the memo, so-to-speak. So this off-label use of BMPs continued with some devastating results that went otherwise unreported. Now, those who are in the know say that at the very least the use of BMPs in anterior cervical spine fusions should be halted until further studies deem it is safe to use and guidelines are provided for how best to use it for that purpose.