Overview of Ankle Arthroplasty
Total ankle arthroplasty (TAA), also known as total ankle replacement, is a type of surgery where a worn-out or damaged ankle joint is replaced with an artificial one. The whole aim of this operation is to get rid of the pain, improve the ability to do regular activities, and keep or bring back movement in the ankle for people with severe ankle arthritis.
In the past, a treatment called ankle arthrodesis (the fusing together of bones in your ankle) was the main approach for treating severe ankle arthritis. However, recent studies reveal that more and more people are opting for TAA.[1][2]
TAA was first created in the 1970s in an effort to retain movement in the ankle when treating severe osteoarthritis (a condition that causes joints to become painful and stiff). Before TAA, the main treatment, arthrodesis, significantly reduced movement in the joint.[4]
Having surgery to replace rather than fuse your ankle, known as arthroplasty, allows the preservation of other joints by making your walking pattern normal and as a result, evening out the pressure on the rest of your lower leg. Now, this procedure is becoming more common as a way to treat severe ankle arthritis.
Anatomy and Physiology of Ankle Arthroplasty
Understanding the structure and function of the ankle joint is very important for doctors to select the right treatment and to ensure successful results. The ankle joint acts like a hinge that allows your foot to move up and down. It is made up of several bones: the bottom of the tibia (the thicker, inner bone of your lower leg), the medial malleolus (the bony bump on the inside of your ankle), the lateral malleolus (the bony bump on the outside of your ankle), and the talus (a bone in the foot that the leg bones connect to).
All these bones work together to form the ankle joint. The ankle stays stable thanks to static and dynamic stabilizers. Dynamic stabilizers are the tendons (tough cords that connect muscles to bones) around the joint, which include the peroneal tendons (on the outside of the ankle). Static stabilizers include the ligaments (tissues that connect bones to each other) and the bony structure of the ankle itself.
Why do People Need Ankle Arthroplasty
Total ankle arthroplasty (TAA), also known as ankle replacement surgery, is a procedure recommended for individuals suffering from severe ankle osteoarthritis. Osteoarthritis is a condition where the protective cartilage that cushions the ends of your joints wears down, causing pain and difficulty in movement.
An ideal candidate for this surgery is generally healthy, not extremely active, and has a normal or low body mass index. It’s also important that they have a well-aligned and stable hindfoot (back part of the foot), as well as strong, healthy surrounding tissues.
According to a study cited, it’s optimal if the patient’s ankle can still move to a certain degree. A flexible ankle that can bend upward at least 5 degrees is ideal for this surgery. This range of motion helps in the successful outcome of the replacement surgery, making recovery easier.
When a Person Should Avoid Ankle Arthroplasty
TAA, which is a type of ankle replacement surgery, is not usually recommended for people with certain medical conditions. These include:
Active infection – if a person is currently fighting an infection, the surgery could make it worse.
Peripheral vascular disease – this is a circulation disorder that can cause poor blood flow to the legs and feet.
Charcot arthropathy – a condition that can cause the foot bones to break down, making surgery more challenging.
Severe osteoporosis – a disease that makes your bones weak and more likely to break.
Osteonecrosis of the talus – a condition where the bone in the ankle, the talus, dies due to lack of blood supply.
Peripheral neuropathy – nerve damage often in your feet and hands that can cause weakness and pain, affecting your balance.
Inadequate soft tissue envelope – this means the area around your ankle doesn’t have enough healthy skin and tissue for a successful surgery.
These conditions can make the TAA surgery more risky because they can lead to the failure of the implanted ankle joint or cause an infection after the surgery.
Equipment used for Ankle Arthroplasty
Total Ankle Arthroplasty (TAA) implants, which are used in ankle replacement surgery, have gone through several changes in design since they were first used. The original designs, or first-generation implants, were heavily reliant but required removal of significant portions of bone for proper fit. These consisted of two primary parts: one part fit onto the shinbone (tibia) and the other onto the ankle bone (talar). These components were attached using a special medical-grade glue known as cement. They were designed in such a way that one was bowl-shaped (concave) and usually made of a type of plastic (polyethylene); the other was dome-shaped (convex) and commonly made from a metal such as a cobalt-chrome alloy. However, these initial implants came with high rates of problems such as loosening of the implant and wearing away of bone around the implant (osteolysis and subsidence), and mechanism failure.
In an attempt to tackle the issues that arose with the large bone removal required by the original designs, newer (second-generation) models were introduced. These implants included innovations like the Buechel-Pappas Total Ankle Replacement used in the U.S. and the Scandinavian Total Ankle Replacement (STAR) used in Europe. These models retained the bone much better by not requiring as much bone to be removed. Additionally, they simply required pressure to fit into place (press fit). Despite these improvements, the second-generation models had a significant number of failures due to the wearing down of the plastic part of the implant.
Modern upgrades or third-generation implants were designed to address these failure issues. Some models of these upgraded implants are the Salto, Hintegra, Mobility, and Bologna-Oxford (BOX). They have a separate plastic part which is not built into the bone components. They require less bone removal but need careful tuning (balancing) for them to work successfully. This generation of implants relies heavily on the health and stability of the ligaments around the ankle. The surgical tools used to implant them have also improved, often making use of cutting templates (cutting jigs). Surgeons now also make use of an advanced imaging technique in 3D and patient-specific guides during surgery. This reduces surgery time and patient exposure to x-rays without affecting the correct placement of the implant.
Who is needed to perform Ankle Arthroplasty?
In order for a TAA (or total ankle arthroplasty – a surgery used to replace a damaged ankle joint with an artificial one) to be done with full safety, certain medical experts need to be involved:
1. An anesthesiologist, or anesthetist, who is a doctor specializing in making sure you don’t feel any pain during surgery by administering medications.
2. A surgical or scrub technician who assists the surgeon during the operation, helping prepare the surgical instruments and maintaining sterility in the operating room.
3. An operating room circulating nurse: they don’t directly participate in the surgery, but they manage the overall environment in the operating room to ensure safety and efficiency.
4. A foot and ankle surgeon is a doctor who specializes in surgeries of the foot and ankle, including the TAA procedure. This is the person who actually performs the operation.
5. A surgical assistant helps the surgeon during the operation. This could be either a physician’s associate or a first assist.
6. A recovery nurse who takes care of you after the surgery, monitoring you as you wake up from anesthesia and helping manage any pain or discomfort.
7. Lastly, an implant device representative might also be present; they provide the necessary artificial components being implanted and serve as a guide when those parts are being used.
Preparing for Ankle Arthroplasty
Before someone gets a Total Ankle Arthroplasty (TAA), a type of surgery for severe ankle arthritis, the doctor needs to understand their full medical history. This includes any previous surgery on the affected ankle, current medications, any allergies, history of injuries to their ankle, and past treatments for the ankle.
The doctor also needs to evaluate the patient’s health properly, including checking how the patient walks, how well the ankle moves, blood circulation in the leg, ankle stability, and the condition of the skin.
Then, the doctor uses pictures taken by machines to look at the ankle’s structure. These pictures help the doctor plan for the surgery.
They may use a standard x-ray which is done when the person is standing. This gives clear images of the bones in the ankle to help plan for the surgery.
Computed Tomography (CT) scans could be used to understand the quality of the bone before doing the surgery. The technology has advanced to a point where the scans can be used to create tailored guides for cutting the bone during surgery. These guides are 3-dimensional printed and require that a CT scan be done before the surgery and sent to the maker of the implants.
Pictures from Magnetic Resonance Imaging (MRI) could possibly be used to see how severe the arthritis is, the extent of any bone loss, if there are any bone cysts or areas of dead bone tissue. All of these factors help the doctor plan for the surgery and anticipate possible problems.
How is Ankle Arthroplasty performed
Your doctor will be using a common medical procedure called ankle arthroplasty, also known as Total Ankle Replacement (TAA) to treat your condition. This might sound complex, but let’s break the process down into simpler terms.
Before the procedure starts, an anesthesiologist will make sure you’re fully asleep and not feeling any pain. They use a method called general anesthesia, which is usually paired with a regional nerve block. An antibiotic is given to you to ward off any potential infections during the procedure, once they’ve put you to sleep.
Next, you’ll be set up for the procedure. You’ll be lying down flat on our back on a special operating table that allows the doctors to see all of the area where they’ll be working. They’ll use a special instrument, called a tourniquet, to prevent excessive bleeding, by applying it high up on the leg that’s being operated on. Then, they’ll cover you with sterile drapes to keep everything clean.
The surgeon starts the procedure by making a cut near the ankle, on the side of a tendon called the tibialis anterior tendon. They carefully move the skin and underlying tissues aside to expose the bones and joints they’ll be working on. They’ll also make sure to avoid harming your tendons and nerves during this time.
Once the surgeon has properly exposed the bones, they’ll begin reshaping them to fit the artificial joint. The surgeon uses special techniques to avoid injuring other bones in the area. In some cases, they might use a small pin to prevent potential fractures.
Afterwards, they begin to trial fit the prosthetics into the joint to make sure they’ve found the right size. This may involve adjusting the soft tissues around the joint for a perfect fit. Once they’re sure everything fits perfectly, they insert the final implants into the bones and make sure they’re securely in place.
With the new joint in place, the surgeon cleans the surgical wound thoroughly to ensure there are no foreign materials left inside. They then close up the tissues they moved aside earlier and then stitch up your skin.
Once the procedure is done, your leg will be covered with sterile dressing and a short leg splint. You’ll need to keep this on for a few weeks as your leg heals. After two weeks, they’ll remove the splint and the stitches and you’ll be able to start moving your ankle. However, you’ll need to avoid putting weight on it for a total of four weeks.
To make sure your recovery is going well, your doctor will periodically take x-rays of the leg. This will allow them to check the position of the new joint, ensure no fractures have occurred, and to monitor the condition of the surrounding bones.
In some cases, the surgeon might use a different method known as the lateral approach. While this is less common and has fewer implant options, it could be necessary if your situation requires a special type of surgery called a osteotomy.
Possible Complications of Ankle Arthroplasty
After undergoing a total ankle arthroplasty (TAA), which is a surgical procedure to treat severe forms of ankle arthritis, some complications may arise. These can range from issues with wound healing and infection to fractures that occur during the operation. Let’s break down some of these complications.
Starting with wound healing, after TAA, complications can vary from minor to severe. Minor issues might involve symptoms such as the wound not healing as quickly as expected or becoming infected, which can lead to conditions like cellulitis (a skin infection) or an abscess (a swollen area filled with pus). In order to decrease the chances of these complications occurring, doctors try to handle the soft tissues involved in the surgery with great care. Use of certain stitches that reduce strain and the application of a pressure dressing have been shown to help with this.
In some cases, infection can affect the artificial joint itself. This is called a prosthetic joint infection (PJI) and, although it’s quite rare, it requires aggressive treatment. If the infection occurs soon (within three weeks) after surgery, doctors usually treat it with a thorough cleaning of the wound and antibiotics, and by swapping out the plastic part of the artificial joint. If the infection becomes chronic or long-term, they may need to remove the artificial joint completely, do an extensive cleaning of the ankle and surrounding tissues, and put in a temporary spacer that releases antibiotics. After this, you would undergo an intense course of antibiotics, either taken orally or administered intravenously. In severe cases, the infection might need to be physically cleaned out multiple times and the artificial joint replaced after the infection is cleared.
During the TAA procedure, there’s a small risk of accidentally fracturing the medial malleolus, which is one of the bumps on the ankle. This typically happens when making the cuts for the artificial joint placement, especially if the cuts are closer to the inside of your ankle. To prevent this, doctors can use screw fixation, a technique where screws are placed into the bone to stabilize it, and these screws are usually kept in the ankle after surgery.
There are other complications that could arise after TAA surgery, including nerve damage, loosening of the implant, changes to the talus bone (which is part of the ankle), injury to the tendon, issues with the plastic part of the artificial joint such as displacement, issues with the joint space, and arthrofibrosis which is a stiffness of the ankle joint due to excess scar tissue formation.
What Else Should I Know About Ankle Arthroplasty?
Total Ankle Arthroplasty (TAA) is a rapidly evolving treatment option for severe ankle osteoarthritis. Osteoarthritis is a condition that causes joints to become painful and stiff. In comparison to ankle fusion surgery, this approach keeps the ankle joint mobile, which allows for a more natural and healthy way of treating the ankle.
Arthroplasty is great because it helps prevent weird walking patterns that often come with other treatments. This is especially important because it helps to take care of the other joints in your leg.
