Medium term follow-up of the AES ankle prosthesis: High rate of asymptomatic osteolysis

Rodriguez, Dante; Bevernage, Bernhard Devos; Maldague, Pierre; Deleu, Paul-André; Tribak, Karim; Leemrijse, Thibaut

doi:10.1016/j.fas.2009.05.013

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Volume 16, Issue 2 , Pages 54-60, June 2010

Medium term follow-up of the AES ankle prosthesis: High rate of asymptomatic osteolysis☆

Dante Rodriguez, MD
- Andres Caceres Avenue, 96B, Chiclayo City, Peru
- Corresponding author.
Bernhard Devos Bevernage, MD
- Department of Orthopaedic Surgery, Cliniques Universitaires St-Luc 10, Avenue Hippocrate, B1200 Bruxelles, Belgium
Pierre Maldague, MD
- Department of Orthopaedic Surgery, Cliniques Universitaires St-Luc 10, Avenue Hippocrate, B1200 Bruxelles, Belgium
Paul-André Deleu
- Department of Orthopaedic Surgery, Cliniques Universitaires St-Luc 10, Avenue Hippocrate, B1200 Bruxelles, Belgium
Karim Tribak, MD
- Department of Orthopaedic Surgery, Cliniques Universitaires St-Luc 10, Avenue Hippocrate, B1200 Bruxelles, Belgium
Thibaut Leemrijse, MD
- Department of Orthopaedic Surgery, Cliniques Universitaires St-Luc 10, Avenue Hippocrate, B1200 Bruxelles, Belgium

Received 11 March 2009; received in revised form 29 May 2009; accepted 31 May 2009. published online 10 July 2009.

Abstract

Background

The AES^® (Ankle Evolutive System) is a cobalt–chromium three-component ankle prosthesis with a hydroxyapatite coating, similar to the Buechel-Pappas™ ankle prosthesis, but with some modifications. Our objective was to assess its medium term follow-up results as well as its complications.

Methods

21 patients (mean age of 57.6 years) were operated by a total ankle arthroplasty (TAA), using the AES^® implant, according to the standard technique. Only 18 patients were included. The other three patients were excluded from the study: two had been revised for avascular talar necrosis and one patient was happy with her outcome but could not present for logistic reasons at the last follow-up. Indications for surgery included posttraumatic osteoarthritis, primary osteoarthritis, hemochromatosis, rheumatic arthritis and osteoarthritis as a sequel of ankle instability. All patients were analyzed clinically and radiologically. Special attention was given to the presence or not of areas of osteolysis around the implants as well on conventional radiography as on CT-scan imaging, according to a specific protocol.

Results

The mean follow-up was 39.4 months. Average American Orthopaedic Foot and Ankle Society (AOFAS) ankle–hindfoot score improved from 52.2 preoperatively to 86.6 postoperatively. No intra-operative complications or early complications have been noted. Delayed complications were the following: one valgus malalignment, one recurrent painful anterior heterotrophic bone formation. Above all, we noted on conventional X-ray the presence of osteolysis in 77% (14) of our patients, with a size of 0.5–1cm or greater on conventional X-ray. The most vulnerable area seemed to be the posterior tibial plafond. The four remaining patients did not show any cyst formation on X-ray but did also, just as the other 14 patients, on the CT-scan. CT-scan, on the contrary, found more osteolysis in the body of the talus, underneath the implant, an area masked on conventional X-ray. Only one patient was revised with allograft bone filling of a symptomatic osteolysis, without the need for implant removal.

Conclusions

This retrospective study shows a high frequency of delayed appearance of osteolysis (77%) in 18 AES total ankle arthroplasties. Fortunately at this moment and considering one revision, this considerable amount of asymptomatic osteolysis could not warrant a durable uncomplicated outcome.

Keywords: Ankle prosthesis, Osteolysis