Ankle

Can mal-aligned ankles be successfully replaced?

Following a theme, researchers in Durham (USA) have looked again at the importance of pre-operative tibio-talar alignment in total ankle replacement. The conventional wisdom is that excessive coronal tibiotalar mal-alignment is a contraindication to total ankle replacement. This research team, however, didn’t take this at face value and set out to re-examine the effect of coronal alignment on outcomes in total ankle replacement. They set out to compare clinical outcomes and clinical performance scores between patients with different levels of coronal mal-alignment. This study cohort, similar in size to the previous one, contained 103 patients and was subdivided into groups according to pre-operative deformity. Excessive deformity (> 15°) in either plane was seen in 17, moderate valgus (5° to 15°) in 21, and moderate varus alignment (5° to 15°) in 27. The remaining 38 patients were neutrally aligned. Outcomes were assessed with clinical measures (American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score, the Foot and Ankle Disability Index (FADI)), quality of life assessment (SF-36), and clinical assessment (timed up and go test (TUG), the four square step test (4SST), and walking speed). All of these assessments were carried out prospectively pre- and post-operatively. The most marked finding was the improvement of coronal plane alignment, with 95% of patients achieving normal post-operative alignment. The surgical team used the now standard arthroplasty and balancing procedures with deltoid ligament release, lateral ligament reconstruction, and posterior soft-tissue release performed in addition to arthroplasty were necessary. As a whole there were significant improvements in all measured scores including AOFAS (pain, function, alignment, and hindfoot scores) and the SF-36 (body pain, physical function), and there were marked and significant improvements in walking speed, TUG and 4SST scores. This is all in line with what other reports have shown. What differs here is that the authors had a large proportion of mal-aligned ankles. They demonstrated no differences between the subgroups in these outcome measures.⁴ This paper conclusively demonstrates that coronal plane mal-alignment is not necessarily a contraindication for total ankle replacement. The authors report an impressive correction of bony and soft-tissue deformity in their series with little residual post-operative deformity. It stands to reason that if the deformity can be corrected, then it should not compromise outcome.