Sensibilizzazione ai metalli delle protesi ortopediche: uno studio su 50 pazienti

Background: currently, about 5% of operations of prosthesis implantation fail, but only a small part of these failures can be attributed to allergic reactions that result in dermatosis such as eczemas, eritrodermia, urticaria and prurigo. Objective: to understand the relevance of the sensitization to the materials used in orthopedic prostheses and the kind of allergic reactions that they can cause. Materials and Methods: the study group consisted of 50 patients (20 women and 30 men), whose ages ranged from 12 to 76 (the average age was 52.26 and the median 59) and who were attending at hospital specialized in orthopedics. All the patients underwent patch tests for metals and orthopedic metals. Ten of them were tested also for SIDAPA (Italian Society of Allergological, Occupational and Environmental Dermatology) integrated standard series and nine for polylactic acid 10% in vaseline. Thirty patients were patch tested before the orthopedic operation and 20 patients were tested after. Results and discussion: fourteen patients tested positive to one or more substances: nickel (14), potassium dichromate (2), palladium (2), cobalt chloride (1) and tin (1). It is difficult to determine if the patients who tested positive after the operation were also positive before, or if they became positive after contact with the metals in the prosthesis. Their case histories did not indicate if they underwent patch-tests for these substances prior to their operations. Moreover, we can not predict if a patient who had a negative patch-test before the operation can develop sensitivity to some metals after the implantation of a prosthesis. Allergy to metals is rather frequent in the general population, and for this reason a patient who must receive a prosthesis can be sensitive before the intervention or they can develop an allergy over time. As a matter of fact the implanted alloy can cause sensitization in a time window ranging from a few days to some years. More and more patients should undergo these tests before being operated for the implantation of a prosthesis and not only when potential sensitization to metals is suspected or when dermatological or orthopedic complications occur.