Arthrodesis is a surgical procedure that permanently fuses two bones in a joint together, eliminating movement at that joint to relieve pain. It’s most commonly performed on the ankle, wrist, spine, and smaller joints of the hands and feet. The goal is straightforward: if a damaged joint causes severe pain every time it moves, removing that movement removes the pain.
Why Joint Fusion Is Performed
The most common reason for arthrodesis is advanced arthritis that hasn’t responded to nonsurgical treatments like anti-inflammatory medications, injections, or braces. This includes both age-related wear-and-tear arthritis and inflammatory conditions like rheumatoid arthritis. When cartilage breaks down completely, bone grinds against bone with every movement, creating pain that can be debilitating.
Joint fusion is also used after severe fractures that leave a joint too damaged to function, after ligament injuries that cause chronic instability, and in cases where the blood supply to a bone has been lost (causing the bone to slowly collapse). In the spine, fusion is performed to stabilize segments that have become unstable due to disc degeneration, fractures, or deformity. In every case, the underlying logic is the same: the joint is too damaged to preserve, so it’s locked in place permanently.
What Happens During Surgery
The surgeon removes any remaining cartilage from the joint surfaces and roughens the exposed bone, a process called decortication. This raw bone-on-bone contact is essential because it triggers the body’s natural healing response, encouraging new bone to grow across the gap and weld the two sides together. In many cases, a bone graft is packed into the joint space to speed this process along.
To hold everything in position while the bones fuse, the surgeon uses internal hardware. Depending on the joint and the surgeon’s preference, this might be screws, metal plates, wires, or staples. These stay in the body permanently in most cases, though they can be removed later if they cause irritation. The joint is positioned at a functional angle before being locked down. For an ankle, that means a position that allows a natural walking gait. For a wrist, it’s typically a slight extension that allows grip strength.
Recovery and Bone Healing
Most people return to typical activities about 3 to 4 months after surgery, though the full timeline varies by joint and individual health. Bone fusion is a biological process that can’t be rushed. Your body needs to grow new bone across the joint, and surgeons confirm this is happening through regular X-rays during follow-up visits.
A large review of over 2,400 ankle fusions found that bone union occurs in roughly 93% to 96% of cases, with average time to union ranging from about 10 to 15 weeks depending on the rehab protocol. There’s been debate about how long patients should stay off their feet after ankle fusion, but that same review found similar union rates whether patients began bearing weight within the first week or waited six weeks or longer. Your surgeon will tailor weight-bearing restrictions based on how stable the fixation feels and how your healing progresses.
Physical therapy plays a central role in recovery. Even though the fused joint no longer moves, the surrounding joints and muscles need to be strengthened and retrained to compensate.
How Well It Works for Pain
For most patients, the pain relief is dramatic. A study of 40 patients who underwent fusion of the sacroiliac joint (where the spine meets the pelvis) found that average pain scores dropped from 8.7 out of 10 before surgery to 0.9 at one year. That improvement appeared as early as six weeks and held steady through the 12-month follow-up. Every single patient in the study said they would have the surgery again. Ninety-eight percent experienced what researchers classified as a clinically meaningful benefit.
These results reflect a best-case scenario at a single joint, but the overall principle holds across fusion sites: when the right patient gets the procedure for the right reason, pain relief is typically substantial and lasting.
Fusion vs. Joint Replacement
For some joints, particularly the ankle and certain finger joints, patients face a choice between fusion and joint replacement (arthroplasty). The two approaches solve the same problem differently. Fusion eliminates pain by eliminating movement. Replacement preserves some movement by installing an artificial joint.
A study comparing the two approaches for end-stage ankle arthritis found remarkably similar results in overall function. Both groups scored identically on a standard hindfoot assessment (75.6 out of 100). The fusion group had slightly better pain relief, while the replacement group scored higher on functional movement. About 75% to 76% of patients in both groups remained active in sports after surgery, though activity levels declined somewhat in both.
The traditional recommendation has been fusion for younger, more active patients (since artificial joints can wear out and need revision) and replacement for older patients with lower physical demands. In practice, the decision depends on which joints are involved, how much deformity is present, and what activities matter most to you.
Long-Term Effects on Neighboring Joints
The most significant long-term trade-off of fusion is its effect on adjacent joints. When one joint is locked, the joints above and below it have to pick up the slack, absorbing forces and ranges of motion they weren’t designed to handle alone. Over time, this extra stress can accelerate wear and tear in those neighboring joints.
This phenomenon is best documented in the spine. Biomechanical studies show increased pressure on the discs next to a fused segment. In the lumbar spine, the annual rate of developing symptoms from adjacent segment degeneration is about 2% to 3%. Over the long haul, a systematic review found that 34% of lumbar fusion patients showed radiographic signs of degeneration at neighboring levels, though only about 14% developed symptoms significant enough to be classified as disease. A study following patients for over 20 years after lumbar fusion found that 6% eventually needed surgery at an adjacent level.
In the cervical spine, the annual rate of symptomatic adjacent segment disease is around 3%. These numbers don’t mean fusion inevitably destroys nearby joints. Some of this degeneration would have happened naturally with aging, as imaging studies of people who never had surgery show disc abnormalities in 14% of those under 40 and 28% of those over 40. But fusion does appear to accelerate the process, and this is one reason surgeons try to fuse as few levels as possible.
What Increases the Risk of Failure
The primary way arthrodesis fails is through nonunion, meaning the bones never fully fuse together. This leaves the joint unstable and still painful, often requiring revision surgery.
Smoking is the single biggest modifiable risk factor. Nicotine interferes with bone healing on multiple levels: it reduces the activity of proteins that drive new bone formation, and it weakens the structural proteins that give the fusion mass its strength. In a large study of single-level spinal fusions, the nonunion rate for nonsmokers was 14.2%, compared to 26.5% for patients who continued smoking after surgery. Patients who smoked more than 10 cigarettes a day and had multi-level fusions had roughly double the odds of nonunion. Even quitting after surgery helps, though former smokers who quit for at least six months still had a slightly elevated nonunion rate of 17.1%.
Other factors that increase risk include poor blood supply to the area, infection, diabetes, and malnutrition. Misalignment during surgery also matters. If the fused joint isn’t positioned correctly, it creates abnormal stress patterns that can compromise both the fusion itself and the health of surrounding joints.