Sometimes surgeons will try conservative care. This can include anti-inflammatory drugs, physical therapy, or a neck brace. This type of treatment doesn't change the failed fusion but it can help the patient manage the painful symptoms.
A second option is revision surgery. Some surgeons advise doing a posterior fusion. They say that going back through the front of the neck requires cutting through scar tissue. This can cause further problems. Others suggest a posterior fusion makes the patient stiffer afterwards because of all the neck muscles cut.
A recent report from UCLA School of Medicine reported mixed results using the posterior approach. Although everyone in the study had a good fusion, about half still had pain. Some patients had severe pain and didn't think the second operation was worth it.
Ask your surgeon for his or her opinion. There may be some things about your situation that lend guidance to a decision of this type. Smoking and overall health make a difference after fusion, too. Your doctor will know what might work best for you.