PROSPECTIVE FOLLOW-UP OF A HOMOGENEOUS AND CONTINUOUS SERIES OF 42 TOTAL ANKLE ARTHROPLASTIES

Abstract

Purpose: Prosthetic replacement of the ankle joint is a controversial issue. Minimally invasive noncemented third-generation implants with a third component have enabled improved clinical results and prolonged mid-term implant survival. These results authorise prosthetic implantation as an alternative to arthrodesis in selected patients. New developments in prosthesis concepts and design, aimed at overcoming the insufficient results of earlier implants, require early validation with a prospective clinical and radiological follow-up. The objective of this work was to present the mid-term results with the SALTO prosthesis implanted in 42 patients.

Material and methods: Forty-two SALTO prostheses implanted between February 1997 and December 2000 were followed prospectively for two to six years. The implant design, which mimics the anatomic asymmetry of the talar dome, uses a mobile polyethylene insert and optional fibular resurfacing for optimal primary and long-term stabilisation. Data were collected prospectively using a computer database which provides the AOFAS score. Metrological analysis of the digitalized x-rays (AP, lateral and stress) were used to study the precision of the insertion, implant stability, and prosthesis kinematics. Posttraumatic osteoarthritis predominated (n=29) in this series. Mean age was 54 years (30–79).

Results: None of the patients were lost to follow-up. Three patients had a revision procedure for arthrodesis (persistent pain in two and sepsis in one). The clinical score was excellent or good in 88% of patients. The mean clinical score was 20.5 points preoperatively and 70 points at last follow-up. The radiological analysis demonstrated the precision of the insertion technique and did not disclose any evidence of significant implant mobilisation with time. There were no failures related to the lateral malleolar implant (n=12). Radiographically, mean ankle movement was 15.2–23°. Changes in the periprosthetic bone were noted.

Discussion: The quality of the results with the prosthesis under study and the short- and mid-term stability enable envisaging implantation when the local or regional anatomic conditions suggest arthrodesis would produce unsatisfactory results. The improvement in function (exceptionally total recovery) remains difficult to predict. Further follow-up of these patients is needed.