Avoid Arthroscopic Ankle Fusion in This High-risk Group

What’s the Claim?

A large case series of patients undergoing arthroscopic ankle arthrodesis found:

• 8% developed nonunion, 77% of whom opted for further surgery to try to treat it
• The odds of nonunion were vastly higher among patients with a previous triple arthrodesis in the same foot (70% of them did not fuse; odds ratio 18 [95% CI 4 to 100] compared to those without a previous triple)
• In addition to reoperations for nonunion, nearly 20% of patients underwent surgery to remove bothersome hardware
• Among those who did not have a prior subtalar joint fusion, survivorship of the subtalar joint was 85% at 5 years and 74% at 9 years, though the confidence intervals around those estimates suggest that the survivorship of that joint could have been much lower

How’s It Stack Up?

This is the largest series of arthroscopic ankle fusions by far. It was large enough to perform reasonable multivariable analyses — leading to the important finding about performing these fusions in patients with prior triple arthrodeses, which is a finding we’d not seen before, though it’s biomechanically sensible. There have been other studies of arthroscopic ankle arthrodesis that were of the “this is a tough operation, complications are going to happen” genre, but none of them were large enough to uncover what this study did. Another strength of this study was that it had follow-up on 98% of patients through to an endpoint (union or nonunion).

What’s Our Take?

Converting a triple arthrodesis to a pantalar arthrodesis involves a large load — one that is normally shared by several joints — to pass through just one, even as that joint is trying to fuse. This is a twist on the well-known increased risk of subtalar nonunion in patients with a pre-existing ankle fusion. The fusion construct these authors used was reasonable (two or three large, cannulated compression screws placed in parallel under fluoroscopic guidance through a separate medial incision), but seemingly not enough for that demanding task. CORRelations’ advisor in Foot & Ankle, Greg Guyton, MD, gets the last word:

“This article makes a strong case for performing an open procedure with a strong hardware construct (such as a tibio-talar-calcaneal nail) in this circumstance.”

Source

Woods A, Kendal A, Henari S, et al. Association of Preexisting Triple Fusion and Arthroscopic Ankle Arthrodesis Nonunion. Foot Ankle Int. 2023;44:579-586.