Ankle Fusion vs. Ankle Replacement: How to Choose

If nonsurgical care has stopped working for your ankle arthritis, you may be told that the two main options are fusion and replacement. The names sound alike and the goals overlap, but the trade-offs are different, and there is no single right answer for everyone. This article compares them plainly. For the operations and their techniques, see foot and ankle joint fusion and replacement; for the condition, ankle arthritis.

First, is it time for either?

Ankle arthritis is most often the result of an earlier injury, such as a fracture or repeated sprains.^[4] Non-surgical care is the starting point: activity changes, weight management, physical therapy, braces or orthotics, medicine and injections.^[1] Surgery is considered when pain and disability persist despite it, and the choice depends on how far the arthritis has progressed, the alignment of the leg and foot, your age, your activity level, your general health and your goals.^[1,4] Earlier or milder cases sometimes have options that preserve the joint, such as arthroscopic cleaning or realignment procedures, and these are worth asking about before deciding on a fusion or replacement.^[4] See non-surgical treatment.

What each operation does

Ankle fusion (arthrodesis) removes the damaged cartilage, positions the bones in a corrected alignment and holds them together with screws, plates or a rod until they knit. The joint no longer moves, so the pain from bone rubbing on bone is relieved. The neighboring joints take on some of the work.^[1]

Total ankle replacement (arthroplasty) removes the damaged surfaces and puts metal and plastic components in their place, aiming to relieve pain, improve function and maintain motion. Fusion was historically the mainstay of treatment for this problem, and the use of replacement has been increasing.^[2]

What the research shows

• Pain and alignment. A meta-analysis of recent studies found no significant difference between the two.^[3]
• Function and motion. Replacement was associated with better function scores and range of motion.^[3]
• Complications and reoperations. In the same analysis, replacement had more complications and reoperations.^[3] A later meta-analysis that pooled trials and matched studies, including large registry-based ones, found no significant difference in the total complication rate (moderate-certainty evidence).^[5] The two analyses drew on different sets of studies.
• Long-term results of replacement. Uncemented replacements followed for an average of ten years showed sustained improvement in pain and function scores.^[6]
• Neighboring joints. A concern is that fusing the ankle overloads the joints below it. A systematic review found no consensus on whether ankle fusion causes arthritis in adjacent joints, and imaging changes did not always match symptoms.^[7]

What tends to favor one or the other

There are no fixed rules, and the trials do not settle who should have which. Surgeons weigh the following, largely from clinical experience:

• Factors that can favor fusion: a younger, heavier or more active person; significant deformity or bone loss; poor bone quality or unstable ligaments; previous infection; nerve or circulation problems; and a preference for a single, durable operation.
• Factors that can favor replacement: an ankle with good alignment and bone; stiff or arthritic neighboring joints; and a strong wish to maintain motion.

Weight-bearing CT, which scans the foot and ankle while you stand, can show alignment and joint spaces under load and is increasingly used to plan these operations, although access varies.^[8]

Your health matters as well. Smoking increases the risk of nonunion and wound infection after foot and ankle surgery, and it is discussed and addressed before either operation.^[9] See smoking, diabetes and foot surgery healing.

Recovery

Recovery from surgery for arthritis of the foot and ankle can take four to nine months for full recovery.^[1] A fusion depends on the bone healing, and that determines how long you protect the foot. A replacement has its own restrictions, which your surgeon will set out.

Driving is one of the practical questions. In a study of 60 people after right total ankle replacement, 92% had a safe brake response time at six weeks and all who completed the study had one by nine weeks. Those who had not passed at six weeks had more pain and less ankle motion.^[10] See when can I drive after foot or ankle surgery? and recovery after foot and ankle surgery.

Questions to ask your surgeon

• Are joint-preserving options still worth trying in my ankle?
• Which of the two do you recommend for me, and what tipped the decision?
• What is the implant’s record, and what are my chances of needing another operation?
• If I choose fusion, how will my walking, and my neighboring joints, be affected over time?
• How do my smoking status, diabetes, weight and bone quality change the risks?
• How long will I be off the foot, and when can I drive and go back to work?

A second opinion is reasonable before any major operation; see second opinions before foot or ankle surgery.

Common questions

Which is better, fusion or replacement?

Neither is better for everyone. Pain relief and alignment were similar in a meta-analysis, replacement gave better function and motion, and it was associated with more reoperations in one analysis.^[3] Total complications were similar in a later one.^[5]

Will fusion cause arthritis in the joints next to it?

It is a recognized concern, but a systematic review found no consensus, and imaging changes did not always match symptoms.^[7]

Is total ankle replacement a newer operation?

Fusion was historically the mainstay of treatment for end-stage ankle arthritis, and replacement has been used increasingly.^[2]

How long do ankle replacements last?

A study of uncemented implants followed for an average of ten years showed sustained improvement in pain and function scores. Implants can loosen or wear, and some need revision.^[6,3]

Do I need a CT scan first?

Not always. Weight-bearing X-rays are the basic test, and CT or MRI can add detail about the cartilage, the neighboring joints and alignment when surgery is being planned.^[1,8]

The bottom line

Fusion and replacement are both established, and both have real trade-offs: motion against a single, durable solution, and different risks. The choice depends on your ankle, your other joints, your health and your priorities. Ask which you are being offered and why, and what the alternatives were.