General Information
Allergy to Joint Replacements
Occasional reports of joint replacement implant failure because of an apparent allergy to one of the metals in the device have appeared in the orthopaedic literature ever since metal implants were used. 1-3 It is now recognized that a small number of patients will suffer from a form of allergy or hypersensitivity to constituents of the metal-on-metal bearings even in the absence of high wear 4-6. The histological features of the reaction characterizing the joint tissues from these hypersensitive patients are different from the classical text-book form of Type 4 delayed type hypersensitivity. 7 For this reason, the term ALVAL (aseptic lymphocytic vasculitis associated lesions) has been coined to describe the histological features associated with an allergy-like reaction in the joint tissues. 8 It should be noted that some pathologists object to the inclusion of the "vasculitis" part of this new name and vasculitis in the strict sense of the word is not a prominent feature of the lesions.
This website provides case examples to help surgeons and pathologists who may be faced with a case of suspected metal sensitivity associated with a joint replacement. The characteristic histological features in the periprosthetic tissues are infiltrates of lymphocytes, often with plasma cells, arranged perivascularly or in dense aggregates. In severe cases, there may be a wide necrotic tidemark between the tissue edge and the lymphocytes which are then arranged in a broad band at the back of the tissue section. These infiltrates appear in the absence of infection or mechanical causes for pain. It is important to note that lymphocytes can be present in relatively large numbers in response to excessive wear debris and the reason for their presence is unclear 9,10.
Diagnosing metal sensitivity can be difficult, and it may be hard to differentiate it from a reaction to excessive wear debris, the diagnostic table is provided to help pinpoint the cause of pain. There is a wide variety of clinical presentations of metal sensitivity, typically the patients report ongoing pain or discomfort, typically in the groin, often accompanied over time with an effusion which may progress to form an enlarged fluid hernia or a groin mass. If all possible causes for the patient’s pain can be eliminated by imaging or hematological testing, a diagnosis of metal sensitivity should be entertained and if confirmed, the cobalt chromium bearings should be removed to avoid ongoing soft tissue damage. 11
Skin Sensitivity and Hip Sensitivity
Approximately 10-15% of the general population has a skin sensitivity to metal, nickel being the most common sensitizer, followed by cobalt and chromium. 5 There is concern, therefore, that patients with a skin sensitivity will also have an adverse reaction to a cobalt chromium hip replacement although there is little actual evidence to support this concern. It should be noted that the FDA lists skin sensitivity as a contraindication to metal-on-metal hip resurfacing.
A small retrospective survey of patients with a metal-on-metal hip resurfacing was carried out at one center which performs a large number of hip resurfacings (the Joint Replacement Institute, St Vincent's Hospital Los Angeles). Patients were asked about reactivity to jewelry (type of jewelry involved, the metal involved, and the nature of the reaction). One hundred seventy-eight patients responded (142 male 35 female) and 21 (5.6%) reported they had a skin problem, mostly to stainless steel (which contains a small amount of nickel) or "cheap" jewelry in the form of rashes, redness and itching. Of those 21, 11 were male and 13 were female, but since most of the overall patient cohort was male, the proportion of females with skin reactions was relatively higher. However, regardless of their problems with jewelry, none of these patients had any problems with their hip replacement.