Metal on metal hip arthroplasty surveillance at a tertiary centre: design, patients' adherence, and cost analysis.

PURPOSE Metal-on-metal (MOM) bearings may carry higher than expected revision rates and serious complications: an appropriate surveillance may be advocated. Aims of this paper were to (1) present the biennial experience of MOM surveillance in a tertiary centre, (2) describe the patients' adherence to monitoring, and (3) analyze the costs of the surveillance METHODS: The design of MOM surveillance was developed according to the guidelines of the Italian Society of Orthopaedics and Traumatology. The adherence to every follow-up was expressed as raw numbers and percentages. A cost analysis (direct and indirect costs) was conducted and projected in a five year time span. RESULTS About 61.1% of patients adhered to the first step of the surveillance, and 13.5% answered to a specific questionnaire about MOM implant. About 36.2% of the patients participated for the annual follow-up, and 18.1% entered the six month follow-up program. Of the implants, 2.5% required a revision. A two year surveillance costs €45,520.30, €236,443.98 (57.7%) including revisions. Five-year projected costs will be €23.113,64 (5.6%). Hospital indirect costs, including personnel working days, were €150,392.30 (36.7%). The estimated economic burden for seven years will be €409,949.92 (direct € 259,557.62, indirect €150,392.30). CONCLUSION Patients' adherence to MOM surveillance is modest and the rate of dropouts seems not to stop over the time. Most of the expenses are due to revision surgeries, as well as indirect costs. Economy of scale may be suggested to reduce the costs, involving as much MOM population as possible.