HYPERSENSITIVITY IN ASEPTIC LOOSENING OF TOTAL HIP REPLACEMENTS - THEROLE OF CONSTITUENTS OF BONE-CEMENT

Aseptic loosening is seen in a significant proportion of cemented tota l hip replacements (THR), In a small subgroup of patients who suffer e arly loosening polyethylene debris is unlikely to be responsible, We r ecently reported one case of allergic contact dermatitis to N,N-dimeth ylparatoluidine (DMT), an accelerator used in bone cement, We have the refore investigated this using skin-patch tests to a variety of substa nces including metals, polyethylene and the separated individual compo nents of Simplex cement, We studied 70 patients, 15 with aseptic loose ning less than two years after THR, 25 with satisfactory long-term cem ented fixation, five with infected loosening of cemented THRs and 25 a waiting hip arthroplasty. We found seven positive reactions to DMT, al of them in patients with the rapid onset of aseptic loosening, Allerg y to DMT is recognised in the dental profession in respect of the 'den ture sore mouth' syndrome, and could also be an occupational hazard si nce some industrial glues contain DMT, Our results suggest the need fo r awareness of possible previous dental or occupational exposure to th e constituents of bone cement, We recommend the use of skin-patch test ing in high-risk cases.