TOTAL ANKLE PROSTHESIS: RETROSPECTIVE ANALYSIS OF A CONTINUOUS AND HOMOGENEOUS SERIES OF 26 CASES WITH 5–12 YEARS FOLLOW-UP

Abstract

Purpose: The purpose of this work was to evaluate the mid-term clinical and radiological outcome of a homogeneous and continuous series of third-generation total ankle prostheses (resurfacing, cylindric, noncemented, triple-compartment).

Material and methods: From March 1990 to June 1996, 26 patients aged 57 years (32–73) were treated with a New Jersey LCS (n=5) or Buechel-Pappas (n=21) prosthesis. Most of the patients (n=21) had a posttraumatic ankle. Preoperatively, mean ankle motion was 17°. The AOFAS score was used for the clinical assessment. The position of the prosthesis and its stability over time were assessed on the x-rays together with the insert, the bone-prosthesis interface, the bone structure and periprosthetic ossifications.

Results: Intra and postoperative complications were malleolar fracture (n=5), haematoma (n=1), late wound healing (n=1), insert instability (n=2), and medial malleolar conflict (n=1) requiring reoperation with preservation of the implant. At mean follow-up of seven years, two patients had died and one was lost to follow-up. Three had an arthrodesis: failed fixation at two years, secondary talar mobilisation at seven years, and secondary infection at eight years. For the other twenty patients: the AOFAS score was poor for two patients (including one with patent wear), fair in two, and good in 16. Mean joint motion at last follow-up was 24°. Radiographically, there were no significant changes in the position of the tibial and talar elements. Anchorage of the tibial element was fibrous in half of the patients and ossesous in the other half. A macro defect aspect was observed below the talar element in four patients. There were active periprosthetic ossifications in the majority of the patients.

Discussion: The insufficient ancillary for this prosthesis and its old concept explain the frequency of malleolar fractures and the level of the functional outcomes. Improved prostheses should be used. The stability of the results observed in this series of patients followed up to 12 years is an argument favouring indicating prosthesis insertion as an alternative to arthrodesis, particularly since revision of an arthrodesis is not particularly difficult, even with an iliac graft. The radiographic evidence of periprosthetic ossifications or bone resorption, particularly under the implant, emphasises the need for prolonged surveillance.