An Objective Examination for Painful Hip After Total Hip Arthroplasty

An objective method for evaluating the cause of pain in hip arthroplasty was investigated in patients with a radiolucent zone of less than 2 mm at the cement-bone interface or the cement-stem or socket interface. Eight patients with a McKee-Farrar total hip prosthesis followed up for an average of 102 months and 20 patients with a Charnley total hip prosthesis observed for an average of 43 months were studied. Different components of the implant materials, such as cement monomer, BaSO₄, ceramic, acrylic cement, stainless steel and high-density polyethylene, (HDP) were exposed to normal plasma. Contact activation of plasma was found to occur for all materials, except for HDP, yielding plasma kallikrein. The induced prekallikrein activation was markedly reduced in vitro by Trasylol. There was a significant increase in plasma kallikrein activity in the patients with discomfort and/or pain without gross loosening compared with the patients with pain-free hip arthroplasties. Furthermore, statistically significant enhancement of the kallikrein activity was observed in plasma from the femoral vein at the site of operation compared with that from the cubital vein of the same subject. The enhanced plasma kallikrein activity in the patients gradually decreased, as did the clinical symptoms, when Trasylol was administered. It is concluded that measurement of plasma kallikrein activity may produce useful information about the process of total hip arthroplasty and provide an objective evaluation of pain.