Total Ankle Replacement

The association of significant ankle trauma has been linked to the development of ankle arthritis for a very long time. It has been long known that ankle fractures frequently progress to post traumatic arthritis. It is very common to hear about someone that has broken their ankle and then consistently refer to it as their bad ankle. The more significant the energy and the type of ankle fracture the higher the likelihood of developing significant symptomatic ankle arthritis. Simple non displaced rotational fibular fractures have a low likelihood of going on to symptomatic arthritis while high energy pilon type fractures will progress to ankle arthritis almost 100% of the time. Over the past 20 years many studies have looked at the effect of minimal ankle trauma and have found that recurrent low energy trauma also can lead to the development of significant and symptomatic post traumatic arthritis at the ankle. Patients with recurrent ankle sprains in their teens, twenties and thirties have been shown to develop ankle arthritis in their 40s and 50s if the instability is not treated. Additionally, the inflammatory arthropathies like rheumatoid arthritis and lupus occur in the ankle frequently as well.  All of these conditions tend to occur in a younger patient population than hip and knee arthritis.

Historically, treatment for ankle arthritis has not been great; however, there has been significant progress and evolution with significantly more options and better outcomes. For early stage arthritis treatment consists of physical therapy, bracing, and medical management with anti inflammatories either oral or topical. Corticosteroid injection under ultrasound or fluoroscopic guidance can also be used to treat symptomatic arthritis and can produce 3 to 6 months worth of meaningful pain relief. Viscosupplementation has not been found to be particularly helpful in ankle arthritis and has been shown to cause a significant flare reaction, unlike in the hip, knee, and shoulder. Newer injection modalities have been found to be promising for use in ankle arthritis.  Amniotic allograft, platelet rich plasma, and stem cell therapy (either from iliac crest aspirate or from abdominal fat) have all had very encouraging results. These modalities all work thru a different mechanism of action but have been shown to decrease symptoms in arthritis, and constitute Regenerative Medicine treatment for Osteoarthritis of the ankle.

End stage ankle arthritis, that is arthritis which is unresponsive to all of the treatment modalities previously mentioned is generally treated with surgery. Historically, the only treatment available for ankle arthritis was an arthrodeisis which fused the ankle.  By eliminating the joint pain is eliminated, but motion is also eliminated as well. This leads to a limp, but more importantly, it causes joints adjacent to the ankle to increase the amount that they move to compensate for the motion lost at the level of the ankle. Multiple studies have shown that over time this leads these adjacent joints to become arthritic. On average these joints become significantly arthritis about ten years after an ankle fusion and this the progresses on to further significant surgery. Unfortunately, these joints also need to be fused or replaced and the ultimate result is a very stiff and not very functional leg, i.e. a peg leg.

Another technique, distraction arthroplasty of the ankle has been used to treat ankle arthritis. This technique involves placing and external fixator, like a scaffold, on the outside ankle and distracting the ankle to create more joint space. Although this technique initially had good results in the literature, mid to long term outcomes have not been as promising and there tends to be continued pain and disability at the level of the ankle post treatment.

Ankle arthroplasty, or total ankle replacement has been an emerging orthopaedic technology. Just like the ability to replace shoulders, hips and knees, we have the ability to replace the ankle with a prosthesis. First attempted in the 1960s, the first prosthesis available in the United States was approved by the FDA in 1997. This prosthesis underwent several design changes thru its lifespan and results progressively improved. Several more implants were approved in 2007 and have gone thru progressive improvements and updates. With each generation of implants results continue to improve in the short, mid and long term. Ankle replacement is a joint sparing procedure that allows for the removal of the arthritis in the joint and that joint is replaced by two metal components with a plastic polyethylene liner in between the two metal components. This is exactly the same as your hip and knee replacements. Each generation of total ankle and each new implant introduces exponential improvements in ease of use and improved outcomes, durability and longevity. Newer systems also have instrumentation that allows for easier and more accurate placement and take the patients anatomy into account with custom made tools for a personalized and bespoke surgery. These improvements also allow for more reproducible surgeries with improved outcomes and longevity of the implant. Newer systems have also taken polyethylene technology into account and are using more durable plastic pieces as a bearing surface leading to increased survival and decrease need for revision surgery. The newest FDA approved and cleared total ankle is the Kinos Axiom total ankle. It introduces significant improvements over previous generation total ankles. This ankle replacement was designed to have a natural articulating geometry that is biomechanically accurate to a normal intact native ankle with continuous surface contact that will mimic and restore normal motion and function. The Kinos ankle provides motion in all three anatomic planes providing significantly more range of motion than all competitors in internal and external rotation as well as inversion and eversion at the level of the ankle. Most importantly the Kinos ankle significantly decreases stresses at the level of the articular surface. Studies have shown that there is and 80% reduction in contact stress and greater than 50% reduction in wear potential of the polyethylene liner because of this. This will ensuree that the Kinos Axion has a longer survivorship than its competitors do. The novel design of the Kinos has lead to significant improvements in implant to bone stability that is substantially better than all of the competitors.