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What is ankle and foot fusion surgery?

The human foot is built to move—its bones and joints are designed to walk, run, jump and swivel. But if those bones and joints move too much, lack the proper stability or are misaligned, the result can be cartilage damage, arthritis and persistent pain. In that case, fusion surgery may be required.

The particular fusion procedure will depend on the part of the foot where the excess motion occurs. Some of the most common include ankle arthrodesis, midfoot fusion and subtalar fusion. In all cases the surgeon will remove degenerated cartilage and use surgical hardware to hold bones in a corrected position. The bones grow together during healing, providing increased stability and improved function.

Ankle arthrodesis, also known as ankle fusion, is a procedure done to relieve the pain of an arthritic ankle and maintain or improve its function. Midfoot fusion addresses problems of the bones and joints that make up the arch of the foot: If these joints are not sufficiently stiff or if the bones are misaligned, the result can be arthritis. In a midfoot fusion, some or all of these joints are fused.

A subtalar fusion is done on the joint just below the talus bone, which makes up the lower part of the ankle. (The talus bone is the one that the leg bones rest on.) The subtalar joint is responsible for the foot’s ability to move side-to-side, but if the joint is deformed or unstable, it may cause arthritis or make it difficult to walk on uneven surfaces. A subtalar fusion fuses the talus bone with the bone below it (the calcaneus or heel bone) to make movement easier and relieve pain.

Complications

As with any surgery, fusion surgeries of the foot and ankle carry certain risks, such as infection, bleeding, blood clots, nerve or blood vessel damage, and anesthesia-related problems.

In addition, the bones may fail to heal or fully fuse, or may be misaligned after fusing. In some cases, the surgical hardware may be irritating. If the discomfort is substantial, the hardware may be removed once healing is complete.

Over the long term, ankle arthrodesis may increase the risk of arthritis in other joints in the foot. This can occur because these other structures compensate for the lack of mobility in the fused joint by moving more or differently.

Types of ankle and foot fusion surgery

Surgery is performed differently for each area in the feet and ankles, and each area can have more than one type of fusion surgery. Each individual fusion surgery will often use bone graft material to cover the joint and surrounding bones to augment the fusion process.

Categorized by region, types of ankle and foot fusion surgery include:

  • Ankle fusion surgery
    • Open ankle fusion surgery—The surgeon makes an incision in the ankle, then surgically removes the damaged cartilage surfaces from the joint. This creates a level bone surface to help aid in fusion. The surrounding bones that attach to the joint are then aligned properly and large metal screws are inserted to hold the bones together while they fuse.
    • Arthroscopic ankle fusion surgery—During this procedure, the surgeon uses an instrument called an arthroscope to help with the fusion. An arthroscope is a miniature camera inserted into the ankle joint through a small incision, allowing the surgeon to see within the ankle during the procedure. The surgeon then inserts other instruments into the ankle to remove the cartilage surfaces from the joint. Once the surface of the joint is prepared, screws are then inserted through small incisions in the bones to support them as they fuse together.
  • Foot fusion surgery
    • Hindfoot fusion—This type of foot fusion surgery consists of fusing one or more of the three joints in the hindfoot region. If only the subtalar joint is being fused, then one incision will be made on the outside of the foot below the ankle. Double and triple fusion will require an extra incision to be made on the inside of the foot. After the surgeon removes the damaged cartilage and aligns the joints and bones properly, metal screws are inserted to keep the bones in place while they fuse.
    • Midfoot fusion—This procedure involves fusion of one or more of the joints in the midfoot section. Sometimes all of the joints in the midfoot need to be fused together. The surgeon will remove the damaged cartilage, realign the bones properly and insert metal fixations to keep the bones in place as they heal together.
    • Great toe fusion—This foot fusion surgery aims to properly align and immobilize the joint of the great toe. After the cartilage is removed from the affected joint, the bone is prepared for fusion. The joint is then positioned in order to maximize walking ability and maintain weight bearing position and is fixated with screws or a plate to maintain proper placement as the bone fuses.

What to expect

Depending on the specific procedure, a fusion surgery of the ankle or foot may be done under general or regional anesthesia, with a nerve block to prevent pain.

The surgeon will make an incision to gain access to the area under repair. In most cases, after removing the cartilage from the bones of the joint, the surgeon will use surgical tools to roughen the surface of the bones; this helps them grow together as they heal. Bone graft material may be added to encourage a stronger and more stable fusion. The surgical team may use X-rays during the procedure to ensure proper positioning, and will secure the bones with surgical hardware.

Recovery

In the days after surgery, it is important to keep your foot elevated as much as possible in order to reduce swelling. Your foot may be in a cast or padded splint to prevent movement and reduce the risk of the bones being jostled out of position.

You will need to avoid putting weight on the affected foot for up to 12 weeks after the surgery. During this time, you may find it helpful to use crutches or a walker or knee scooter. Your doctor will get periodic X-rays to confirm proper alignment and healing. Once the joint or joints have healed sufficiently, you can gradually introduce weight-bearing activities. If necessary, your doctor will prescribe physical therapy.

Generally, any plates or screws used in the fusion procedure can remain in the foot, unless they cause pain.

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