Essential Insights On Treating End-Stage Ankle Arthritis
The failure rate of ankle implants may be related to the intrinsic design as well as surgeons’ incomplete restoration of the critical stabilizing role of the ligaments, triplanar motion and the lack of involvement of the underlying subtalar joint in the coupled motion of the joint complex.8,19-21 While SooHoo and colleagues found that total ankle arthroplasty had a greater risk than ankle arthrodesis for implant-related infections requiring revisional surgery, there was a decreased risk of the patient requiring a subsequent subtalar joint fusion.22 This suggests that ankle fusion increases the risk of adaptive arthritis on adjacent joints. An isolated ankle fusion, especially in a younger patient, could therefore eventually progress into a pantalar fusion, further increasing limitations instead of preserving the patient’s existing movement and function.18
In an intermediate and long-term meta-analysis, Haddad and coworkers concluded that the data suggests a minimum equivalence between an ankle arthrodesis and ankle replacement once the poor connotations associated with first-generation ankle implants are negated.5
According to Easley and colleagues, “Comparative studies with a fair to good quality level of evidence suggest that total ankle arthroplasty provides equal pain relief and possibly improved function compared with ankle arthrodesis.”12 They also found that the literature supports a return to an active lifestyle of recreational sporting activities and low-impact exercise after patients have had a total ankle implant procedure.12
Anecdotally, the lead author has had patients who ran marathons and participated in team sports after a successful ankle implant (of course, this was totally against advice). There is no universal list of indications for this procedure as the increasing familiarity and experience of surgeons have expanded the application. Surgeons had considered deformity and angulation as contraindications but more surgeons have performed total ankle implants while concurrently or previously addressing some of these deformities. As ankle implants increase in popularity with the development of this new generation of implants, this procedure is an excellent option for an experienced surgeon to help patients maintain function and mobility in the setting of advanced end stage arthritis.
Three Factors To Keep In Mind When Comparing Reported Outcomes Of Ankle Arthroplasty And Ankle Arthrodesis
The literature is relatively sparse when it comes to a true comparison of the results of ankle replacements as opposed to arthrodesis results for three reasons.
1. Scoring systems that try to judge function, such as the AOFAS score, are partially based on range of motion, making them skewed as far as the evaluation of these two techniques goes (favoring replacement).
2. In most cases of reporting data on ankle replacement, the authors have reported relatively short-term data (five years or less) on their first 100 cases of ankle replacement whereas ankle arthrodesis data might offer more long-term results and be based on better technical skills of the surgeon. Typically, we then have a problem with the evaluation of cases when the surgeon who is excellent at ankle arthrodesis and has been doing the procedure for years suddenly begins to do ankle arthroplasties and reports the data before gaining comparative experience. These naturally have a large learning curve associated with them and it is in the period of this learning curve (the first 100 procedures) when cases are being reported. We would be better served if a highly skilled and experienced surgeon who is excellent at ankle arthroplasty was reporting on these procedures.
3. We are also changing the technology associated with ankle arthroplasty but not reporting on this as quickly in our literature. In other words, studies that take place over the course of years are actually studying older technology. Current technology is available but it has not been studied long enough to give it validity. Accordingly, our data is even less significant.
Given these reasons, the lead author thinks we have stifled what should have been a more aggressive switch to ankle arthroplasty when comparing it to ankle arthrodesis.