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A new study published in Foot and Ankle International reviews the use of ankle replacements across 6 countries to predict why there is a variance in their use, and to determine how far current demands are being met.

Ankle bones and joint © SHUTTERSTOCK

Total ankle replacement is one of the less commonly known joint replacement surgeries compared to hip or knee replacement. It was first introduced in the early 1970s for the surgical management of ankle trauma and end-stage osteoarthritis (OA). But early outcomes for OA were poor and clinicians continued to use an established technique called ankle arthrodesis, where the bones of the ankle were fused together. This technique wasn't without its difficulties and patients would often experience the loss of mobility, pain, disability, and the potential for OA at adjacent joints.

It wasn't until the 1980s-90s that total ankle arthroplasty, or more commonly called total ankle replacement (TAR), became more widely used following improved postoperative outcomes. Despite evidence supporting improvement following ankle replacement, it remained unclear as to how much TAR has been adopted globally for the treatment of ankle trauma and primary or secondary arthritis.

Dr Thomas Perry, co-lead author and postdoctoral researcher at the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford said: "In the fields of rheumatology and orthopaedics, very rarely do you hear of total ankle replacements. More so, in the context of osteoarthritis, you only typically hear of hip and knee replacements. Why is this the case? Well, currently, there are no clear guidelines for the management of ankle OA, there are several indications for ankle replacement outside of OA including trauma and rheumatoid arthritis and, it takes time to introduce new surgical procedures at a national level. The aims of the study were to better understand why people are having ankle replacements, to examine potential barriers to adoption of ankle replacements and to help predict future requirements."

A collaboration between researchers from Australia, Finland, New Zealand, Norway, Sweden and the UK, the study has been published in the Foot and Ankle International journal. It recorded and compared annual rates of primary ankle replacements between national joint registries for the period 1993 to 2019, and examined sources of variation. Globally, there are just six arthroplasty registries collecting national data on primary ankle replacements and this study utilised all available data from these registries.

The study found that:

  • For the period with data from all 6 countries (2010-2015), New Zealand had the largest annual incidence of ankle replacement procedures per 100,000 population, whereas Finland had the lowest incidence.
  • OA was the predominant diagnosis for ankle replacement in the UK, Australia and New Zealand.
  • RA was the most common indication in Scandinavia.
  • There were no common temporal trends in the utilisation of ankle replacements but there were marked differences with their utilisation.

"The majority of the six registries initially showed an exponential growth in ankle replacements from registry inception. We explored potential reasons for this growth including data completeness, speed of national adoption, whether data collection was voluntary/mandatory etc. Of the 6 registries, 5 showed a year of peak incidence and from this point, we then saw varying rates of decline. Understanding the reasons for such divergence is critical to understanding whether the current surgical demands for ankle replacement are being met," said Thomas.

Annual incidence of primary ankle replacement (all diagnoses) for six countries.        5-year moving averages for the annual incidence rates of ankle replacements per 100,000 population for entire registry period.Annual incidence of primary ankle replacement (all diagnoses) for six countries. 5-year moving averages for the annual incidence rates of ankle replacements per 100,000 population for entire registry period.

Professor Alan Silman, co-author and Professor of Musculoskeletal Health at NDORMS said: "It's fascinating that it has been so variable between countries. It's now important to explore the cause of the decline. The incidence of RA is going down globally with better treatments, but osteoarthritis and trauma are becoming more common. Or could the decline be something more to do with policy or funding? The challenge is to ensure there is enough capacity in a country to perform this surgery."

Rates for primary ankle replacement by OA disease in 6 countriesRates for primary ankle replacement by OA disease in 6 countries

Primary ankle replacement by RA disease in 6 countriesPrimary ankle replacement by RA disease in 6 countries