286. SALTO™ TOTAL ANKLE ARTHROPLASTY: INFLUENCE OF THE TIBIAL STEM DESIGN ON SUSTAINED ANCHORAGE IN THE PERIPROSTHETIC BONE: 120 CASES

Abstract

Purpose of the study: The purpose of this prospective controlled trial was to evaluate the influence of the tibial stem design on the primary fixation of the tibial base of a total ankle arthroplasty (TAA) and on radiographic remodelling of adjacent bone.

Material and methods: Sixty Salto™ TAA with a short stem were studied with one to three years follow-up. This series was mated with a control series of 60 TAA using conventional ‘cannon’ implants. All patients were assessed clinically with the AOFAS score and radiographically on the loaded ankle.

Results: The two consecutive series were reviewed a mean 23 months. The mean AOFAS score at review was 83.6 points (mean gain 45 points). The functional analysis did not disclose any difference between the two series. There was no evidence of tibial piece migration. The incidence of lucent lines, all partial (32.5%) and bone remodelling was higher in the cannon TAA series than in our short-stem TAA series, but the difference did not reach statistical significance. Considering all prostheses together, the incidence of bone condensation was 39.3%; and bone defects 16%. Young age appeared to be the only factor correlated with the development of defects (p=0.01). One progressive defect was grafted. Two prostheses were removed (one talar necrosis and one malposition).

Discussion: Primary fixation of the tibial base of the Salto™ prosthesis is excellent, irrespective of the design of the anchor stem. Suppression of the cannon did not reduce statistically the phenomena of osteolysis. The mechanism of the periprosthetic osteolysis is probably plurifactorial, associating biochemical and mechanical factors.