The MELISA test may be used in two ways for orthopaedic patients. First, prior to surgery, patients whose clinical history suggests metal sensitivity may be pre-tested to ensure that they receive the most suitable implant, more info HERE. Second, post-surgery, MELISA can be used to identify if metal hypersensitivity is responsible for any of the symptoms that have developed.
Patients suffering from metal hypersensitivity may have numerous local symptoms associated with an overactive immune system, such as localised pain, swelling, cutaneous allergic reactions, joint and muscle pain, implant failure, apparent recurrent infections around the operation site, and possible systemic reactions such as fibromyalgia, chronic fatigue and cognitive impairment. MELISA is a scientifically proven and clinically validated blood test that detects type-IV hypersensitivity to multiple metals at the same time.
Metal hypersensitivity and orthopaedics
Metal hypersensitivity is a well-documented factor in the failure of implants, and the need for testing in sensitive patients is well recognized by both implant manufacturers and by surgeons alike. The prevalence of metal hypersensitivity in patients with implants is significantly higher than in the general population, with an even higher rate among patients with failed or failing implanted devices.
An exact breakdown, which includes trace amounts of metals present, is needed prior to testing, but below is a guideline. Metals usually found in common medical grade alloys include:
Cobalt chrome: cobalt, chromium, manganese, molybdenum, nickel, tungsten
Stainless steel: chromium, manganese, molybdenum, nickel, tungsten
Titanium alloy (TiAl6V4): titanium, vanadium, aluminium, traces of nickel
Recently, cases of titanium hypersensitivity have also been described. Titanium is a transition metal and thus may function as a hapten and trigger cellular hypersensitivity. Since titanium, in the form of titanium dioxide (E171), is used as white pigment in toothpaste, cosmetics and medication, the latent sensitization of susceptible individuals is possible. Traces of nickel (0.03%) may be found even in commercially pure titanium due to the production process.
Stents, clips and coils
Both bare metal and drug eluting stents have been occasionally implicated in the developments of various hypersensitivity reactions. More information about the metals commonly contained in stents can be found HERE. It is important to establish which metals are contained in your device prior to testing.