Long term consequences of Total Ankle Replacement versus Ankle Fusion; a 25 year national population study of 41,000 patients

C Hennessy, S Abram, C Loizou, R Brown, B Sharp, A Kendal

Introduction: Definitive treatment for ankle arthritis is either Total Ankle Replacement (TAR) or Ankle Fusion (AF). AF may pre-dispose to hindfoot fusion resulting in a debilitatingly rigid ankle-hindfoot complex. In comparison, TAR may protect against adjacent joint disease but is associated with high revision rates. We do not know the life-time risks of further surgery, adjacent joint disease progression and rare but serious complications of TAR versus AF.

Methods: An England population cohort study was performed using the ONS mortality linked Hospital Episode Statistics database (1998-2023). The primary outcome was Kaplan-Meier curve analysis of revision surgery free survival of TAR versus AF. Secondary outcome measures were the rates of any re-operation to the ankle/hindfoot, including hindfoot fusion rate, 90-day complications, and peri-operative mortality.

Results: 10,335 TAR and 30,704 AF were analysed. The revision rate of TAR was significantly higher than AF at all time points, including 5 years (6.7% vs 2.1%), 10 years (11.1% vs 2.9%) and 20 years (13.1% vs 3.1%). There was no significant difference in 20-year risk of hindfoot fusion following AF (5.94%, 95% CI 5.15 to 6.8%) versus TAR (4.80%, 95% CI 3.4% to 6.6%). TAR was associated with higher risks of intra-operative fracture (0.42% vs 0.10%, RR = 4.35) and re-operation for wound infection (0.26% vs 0.15%, RR 1.74) but fewer pulmonary emboli (0.23% vs 0.58%, RR = 0.40).28.9% of TAR
resulted in a further operation; 60% of which were for exploration/debridement, infection, aspiration and/or revision.

Conclusions: Both TAR and AF are safe definitive treatments of ankle arthritis with low peri-operative risk. The risk of subsequent hindfoot fusion after AF is very low and not significantly higher than after TAR. England TAR revision rates are lower than reported globally with many smaller operations performed before the more complex revision surgery.