Introduction

Total ankle arthroplasty (TAA) is an increasingly popular treatment option for patients with end-stage ankle arthritis. However, for most implant systems, failure rates of 10–20% have been reported within the first 10 years after primary TAA. Pain is the primary symptom that indicates failure of TAA but cause of it can be difficult to establish.

Introduction

Total ankle replacement as a valid treatment for end stage ankle arthritis, is gaining popularity and every year there is an increasing number of procedures. With revision rates as high as 21% at 5 years and 43% at 10 years there is a need for understanding and reporting the outcome of revision ankle replacement. Our aim was to study the patient reported outcomes following revision TAR with a minimum of 2 year follow up.

Mechanical ankle instability is elicited through examination and imaging. A subset of patients however report “functional” instability ie/ instability without objective radiological evidence. Little research compares operative outcomes between these groups. We hypothesised patients with “mechanical instability” were more likely to benefit from operative intervention than those with “functional instability”.

This was a single centre, retrospective case note review of prospectively collected data. Inclusion criteria: over six months of symptoms, failed conservative management, surgical stabilisation between 2016–2018. Data collected: demographics, operative procedure, preoperative and postoperative PROMs.

Nineteen patients were included. All had preoperative MRIs determining ligamentous involvement. Nine had radiological evidence of instability, eight had negative radiographs. Two were excluded due to no intraoperative radiographs.

There was no statistical difference in preoperative MOxFQ scores between the groups (p=0.2039). Preoperative EQ5D-TTO scores were statistically different (mean mechanical 0.58 vs functional 0.26, p=0.0162) but not EQ5D-VAS scores (mean mechanical 77 vs functional 53, p=0.0806).

Mechanical group's preoperative, 26 and 52 week scores respectively: Mean MOxFQ= 57.88, 22.13, 18.5. Mean EQ5D-TTO= 0.58, 0.78, 0.84. EQ5D-VAS= 77, 82, 82.5.

Functional group's preoperative, 26 and 52 week scores respectively: Mean MOxFQ= 71.87, 37.75, 23. Mean EQ5D-TTO 0.26, 0.63, 0.76. EQ5D-VAS 53, 80, 88.

This trend of improvement in PROMs was not reflected in patient satisfaction scores. 75% of respondents in the functional group reported dissatisfaction at 26 weeks versus no dissatisfaction in the mechanical group. We should consider counselling patients accordingly when offering surgery.

Background

MRI is the preferred modality for the diagnosis of ankle joint pathology. Musculoskeletal radiologists aim to determine and report both chondral and/or osseous stability/instability of each lesion. The aim of this study was to specifically analyse the reliability of MRI reported findings in predicting the stability of OCL's in symptomatic patients.