Radiographic severity of arthritis predicts outcome following total ankle replacement

S. Chambers, J. Ramaskhandan, M. Siddique

Introduction: It has been previously demonstrated that radiographic severity of osteoarthritis (OA) predicts outcome following knee and hip replacement. In certain circumstances patients may undergo arthroplasty without severe radiographic disease. An example may be the patient with significant chondral damage unsuccessfully treated with arthroscopy. This patient may proceed to joint replacement when their radiographs would not normally merit such intervention.

Methods: We investigated whether these findings were also applicable to total ankle replacements (TAR). We retrospectively reviewed a single-surgeon, single-implant series of 124 TAR with minimum 2 year follow up. Pre-op X-rays were graded using the Kellgren-Lawrence classification. Outcome was measured using the FAOS, SF-36 Score and validated Patient Satisfaction Score.

Results: 96 patients with Grade 4 OA had the biggest improvement in FAOS (p< 0.047). Only half of 28 patients with Grade 3 or less were satisfied at 2 yrs, compared to 91.1% of Grade 4 patients (p< 0.001). 93.9% of patients with Grade 4 disease felt that their quality of life was improved by surgery, versus 47% of patients with grade 3 or less (p< 0.001). 77.3% of Grade 4 patients said they would have the operation again, versus just 52.2% of patients with grade 3 or less (p=0.014). Satisfied patients had an average grade of 3.9, while dissatisfied patients had an average grade of 2.9 (p< 0.05).

Conclusions: While this study does not explain all of the dissatisfaction in TAR, radiological severity is an important factor that the surgeon must consider when planning how best to treat their patients. This study does not allow us to answer the question of how to manage with patients who have significant chondral lesions and MRI findings of subchondral bone oedema, but it does highlight the fact that caution must be used when considering patients for arthroplasty who have low radiographic severity of OA.