Advances in Ankle Replacement Surgery
Total ankle replacements seem to be an increasingly popular procedure
Perhaps you know someone who has had a hip or knee replacement, probably due to osteoarthritis, one of the unwelcome perks of getting older. You may have heard a joint replacement referred to as arthroplasty, which comes from two Greek words – ortho meaning joint, and plasty being the process of molding or forming.
The damaged joint is removed and replaced with an artificial prosthetic device in this procedure.
It's less likely that you've heard of an ankle arthroplasty, also known as a total ankle replacement. The damaged joint is removed and replaced with an artificial prosthetic device in this procedure, first attempted in the '60s and '70s.
Initially, poor results led to continued research and experimentation until 1992, when the Agility Total Ankle System Prothesis became the first device to receive FDA approval. Fast forward to today, with continued technological improvements and excellent success rates, ankle replacement is becoming an increasingly viable procedure for active boomers who don't want to exchange their tennis racquets for rocking chairs.
Understanding Ankle Arthritis
Unlike arthritis of the hips and knees, generally a result of "wear and tear," posttraumatic ankle arthritis is a condition that results from old injuries such as fractures or repeated or severe sprains that may have happened in your twenties or thirties.
Even decades later, the injury to the ankle's robust and slippery cartilage (which covers the bones' surfaces where they meet) or to the bones themselves causes the wearing away of the cartilage. Due to the reduced cushioning from the damaged cartilage, patients experience pain, often over the outer aspect of the ankle joint.
This is accompanied by inflammation, swelling, stiffness, restricted ankle motion and difficulty walking. Even if the body can produce new cartilage, it grows in irregular, bumpy patterns rather than the original smooth cartilage, formerly allowing for the ankle joints' gliding motions.
Bone grafting may help the bones heal together, creating an immovable, unbending joint.
The bumpiness results in the ends of the ankle bones rubbing and grinding against each other. The bones may also sprout small growths called osteophytes, or bone spurs, which cause increased friction and pain in the joint.
The ankle joint is typically surrounded by synovial fluid, which provides lubrication. In an arthritic ankle, the amount of joint fluid can change, reducing the cushioning or creating swelling.
As the body attempts to compensate for changes in the ankle, the surrounding soft tissues are stressed, with tendons and ligaments being stretched and losing function, causing more ankle pain and instability.
Conservative methods of nonsurgical treatment such as physical therapy, ankle braces, compression socks, corticosteroid injections, activity modification, and nonsteroidal anti-inflammatory drugs (NSAIDs) can often help to reduce the pain and swelling of ankle arthritis, keeping you mobile and relatively comfortable for years.
A surgical procedure may be recommended when these no longer provide adequate pain relief. Two surgeries have proven to be effective in alleviating the pain and discomfort of advanced ankle arthritis. Ankle arthrodesis, also known as ankle fusion, was the gold standard of treatment until technology made total ankle replacement a more feasible and successful procedure.
Internal or external fixation devices such as plates or screws are used to fuse the joint in ankle fusion. Bone grafting may be done to help the bones heal together, creating an immovable, unbending joint.
Total ankle arthroplasty involves the removal of the ankle joint, which is replaced with an artificial implant made of titanium, cobalt chromium alloy or other materials.
According to the Cleveland Clinic, about 90% of fusions are successful, leading to fully fused and relatively painless ankles. Unfortunately, fusion can cause the adjacent joints to work harder than previously, and eventually, neighboring joints can develop arthritis.
Total ankle arthroplasty involves the removal of the ankle joint, which is replaced with an artificial implant made of titanium, cobalt chromium alloy or other materials. This allows pain relief while supporting ankle motion so that most patients can safely engage in activities such as skiing, cycling, tennis, bowling and dancing.
Certain contact sports like running and football are not recommended since they could increase the chance of injury and cause more rapid wear and tear of the device. The procedure allows for joint flexibility with accurate anatomical motion, such as dorsiflexion, plantar flexion and rotation, all being preserved.
According to David Matthew Walton, MD, an Assistant Professor of Orthopedic Surgery at the University of Michigan in Ann Arbor, "If things go well in an ankle replacement procedure, 85% of devices are in and functioning well in ten to twelve years."
He added, "Unlike fusion surgery, arthroplasty protects the joints and surrounding tissues around the device, limiting the likelihood of problems and future arthritis in adjacent structures."
Two other lesser-used procedures - ankle joint distraction and supra malleolar osteotomy – are other possibilities for treating the arthritic ankle.
The Ins and Outs of Ankle Replacements
Arthroplasties are not appropriate for all patients, and you and your surgeon will discuss the pros and cons of each procedure and your hopes and expectations for the surgery.
Generally, says Walton, ankle replacement is reserved for patients 60 and older because, in younger persons, there might be a need for too many replacements of the device or revision surgeries. "How long ankle replacements last is the million-dollar question," he says.
Material advancements in how the bone heals and grows into the implant allows for a more rock-solid fit into the bone.
Contraindications may include bone that is too damaged due to avascular necrosis, peripheral neuropathy, osteoporosis, morbid obesity or a history of deep ankle infections.
Because the significant complication of total ankle replacement is delayed or poor wound healing, patients with systemic medical conditions such as diabetes or circulatory disorders may not be appropriate candidates.
Individuals with manual labor or jobs with other high physical demands may be better suited to a fusion procedure. Ankle replacement surgery has a lengthy recovery period, as does ankle fusion. After an arthroplasty, a cast is applied, and the leg must be kept elevated, with no weight placed on the foot.
After two to four weeks, you can start walking in a boot, and physical therapy begins. At eight weeks, most people start wearing normal shoes, driving and engaging in limited activity. While everyone is different, by six months, most people are typically 75% recovered, with complete healing and maximal function achieved in one year.
Current State of the Art
Technological advances in the last 10-15 years, coupled with more precise knowledge of ankle biomechanics and awareness of soft tissue balance and component alignment, have increased the sophistication and success of total ankle replacements.
The device design of implants has moved from a two-component to a three-component model. 3D printing technology has led to the development of customized prosthetics that fit the patient's anatomy based on size, gender and unique characteristics of their arthritis.
Walton says, "Patient specific instrumentation, in which a mold is made using specific cutting guides and blocks, significantly improves placement accuracy and allows for a faster surgical procedure." He adds, "Material advancements in how the bone heals and grows into the implant allows for a more rock-solid fit into the bone."
A multisite cohort study in the Journal of Bone and Joint Surgery surveyed 517 participants who underwent either total ankle replacement or ankle fusion surgery. It found that there was a significant improvement in activities of daily living in the total replacement group, and that satisfaction in several patient-reported outcomes was greater after total ankle arthroplasty than after ankle fusion.
"With advances in accuracy and use of newer materials, people are more confident of their ability to get a consistently good outcome," says Walton. And as the population grows older, still yearning to stay happy, healthy and active, total ankle replacements seem to be an increasingly popular procedure.