A failed cervical fusion, known medically as pseudarthrosis, means the bone never fully healed across the fused segment after surgery. Fixing it typically requires revision surgery, though the specific approach depends on what went wrong and whether neighboring spinal levels have also developed problems. The good news: revision techniques have advanced significantly, and several surgical strategies can address the failed segment effectively.
How a Failed Fusion Is Confirmed
Returning neck pain, arm pain, or neurological symptoms like numbness and weakness after a cervical fusion should raise suspicion that the fusion didn’t take. But symptoms alone aren’t enough to confirm pseudarthrosis. A CT scan is the most reliable way to check, because thin-cut images can show whether bridging bone actually formed between the vertebral bodies, facet joints, or posterior elements. Plain X-rays can sometimes reveal problems, but they’re not highly reproducible for confirming fusion status, especially for the small posterior facet joints.
For more severe cases, the signs are harder to miss. Loose or displaced screws and plates, a cage that has sunk into the vertebral body (called subsidence), or visible motion on flexion-extension X-rays all point to a fusion that has failed. Flexion-extension films specifically look for more than 2 millimeters of motion at the fused segment, which shouldn’t move at all if the bones have grown together.
Pseudarthrosis vs. Adjacent Segment Disease
One of the trickier parts of diagnosing a failed fusion is figuring out exactly where your symptoms are coming from. Adjacent segment disease (ASD) is a separate problem: new degeneration at the spinal levels directly above or below the original fusion. It produces its own neck and arm pain, and it can develop alongside pseudarthrosis. In fact, many patients have both at the same time, and it can be genuinely difficult to determine which condition is driving the symptoms. When both are present, surgeons often extend the fusion to address the failed segment and the degenerated neighbor in a single revision procedure.
What Causes the Fusion to Fail
Hardware problems are a major contributor. In a large review of over 2,200 anterior cervical plating cases, about 10.7% developed some form of hardware complication. Plate loosening was the most common issue at 3.2% of cases, followed by screws penetrating through the endplate (1.9%) and screws pulling out (1.7%). Plates and screws that break, while less common, tend to fracture at the base due to metal fatigue, and this almost always happens in the setting of pseudarthrosis. When the bone hasn’t healed, the hardware bears all the mechanical load and eventually gives way.
Plates that were cut too long during the original surgery create a different problem: they can impinge on the disc above or below the fusion, accelerating degeneration at that level and eventually requiring additional surgery. Multilevel fusions carry higher risk overall. In one study of multilevel anterior cervical fusions, 26% of patients needed reoperation specifically for pseudarthrosis and another 6% for adjacent segment disease, for a total reoperation rate of 35% within two years.
Revision Surgery From the Front
The most common fix is a revision anterior approach, essentially going back in through the front of the neck. The surgeon removes the old hardware, clears out any scar tissue or fibrous material at the fusion site, and prepares the bone surfaces fresh. A new cage or bone graft is placed, and new plates and screws stabilize the segment.
One option gaining traction is converting the failed fusion to an artificial disc replacement instead of re-fusing it. In a series of five patients whose original fusions developed pseudarthrosis, the failed hardware was removed, a thorough discectomy was performed, and an artificial disc was implanted. All five achieved successful outcomes without complications, and their postoperative range of motion matched what you’d expect from a first-time disc replacement on a segment that was never fused. This approach has the potential advantage of restoring motion rather than trying to get the same segment to fuse a second time.
Revision Surgery From the Back
When a front-only approach has already failed, or when the anatomy makes another anterior surgery too risky, surgeons can approach from the back of the neck (a posterior approach). Posterior cervical fusion uses screws placed into the lateral masses or pedicles of the vertebrae, connected by rods. This can be done as a standalone procedure or combined with an anterior revision for a 360-degree fusion, where both the front and back of the spine are stabilized. The 360-degree approach is typically reserved for the most challenging cases, such as multilevel failures or significant instability.
Risks of Revision Surgery
Revision cervical surgery carries higher complication rates than the original procedure, particularly for nerve and swallowing issues. Recurrent laryngeal nerve palsy, which causes hoarseness and difficulty swallowing, occurs in about 2% of first-time anterior cervical surgeries. In revision cases, that rate jumps to 8-10%, and for patients specifically undergoing revision for pseudarthrosis, it can reach as high as 20%. The scar tissue from the first surgery makes the nerve harder to identify and protect.
Postoperative dysphagia (difficulty swallowing) is also more common in revision procedures. Female sex, revision status, and operations spanning more than two levels are all independent risk factors. Most swallowing difficulty improves over weeks to months, but it’s worth knowing it’s more likely the second time around.
Bone Grafting and Growth Factors
Because the fusion already failed once, surgeons often turn to more aggressive biological strategies to encourage bone healing the second time. Autograft, bone harvested from your own body (usually the hip), remains a gold standard because it contains living bone cells. The tradeoff is donor site pain and a second surgical wound.
Bone morphogenetic protein (BMP-2), a lab-made growth factor that powerfully stimulates new bone formation, is another option. It has shown the ability to achieve robust fusion rates in revision cervical cases, and in one early study comparing it to hip bone graft in single-level fusions, both groups achieved 100% fusion. However, BMP-2 use in the front of the cervical spine is off-label, and it has been linked to complications including swelling that can compromise the airway. The right dose and delivery method matter significantly in this area, and its use in revision cases requires careful judgment about whether the benefits outweigh the risks for your specific situation.
Non-Surgical Options
Not every pseudarthrosis needs a second surgery. Some patients have a failed fusion on imaging but manageable symptoms, and for them, conservative management may be reasonable. External bone growth stimulators, which deliver low-level electrical or ultrasound energy to the neck, are sometimes prescribed to encourage bone healing across a fusion site that hasn’t fully consolidated. Physical therapy focused on strengthening the neck and shoulder muscles can help stabilize the area and reduce pain. Pain management through anti-inflammatory medications, nerve blocks, or other targeted injections can also bridge the gap for patients who want to avoid or delay another operation.
The key distinction is whether the failed fusion is causing progressive neurological symptoms like worsening weakness, numbness, or coordination problems. Stable pain without neurological decline gives you time to try conservative approaches. Progressive nerve compression typically pushes the decision toward revision surgery.