MIGRATION OF POLYETHYLENE WEAR DEBRIS IN ARTHROPLASTIES - A CANINE MODEL

The distal migration of polyethylene wear debris appears to be a major cause of loosening and osteolysis of cementless total hip arthroplast ies. The use of modern cementing techniques, circumferential porous or hydroxyapatite (HA) coating has been advocated as a means of preventi ng access of the particles to the bone-implant interface. The purpose of this study was to compare the ability of different methods of impla nt fixation to prevent wear debris migration. Three each of smooth, po rous-coated, HA-coated, and cemented hemiarthroplasties were implanted in the right hip of 12 dogs. Polyethylene particles were injected int o the hip once a month for 4 months and then the femurs were sectioned . The percentage bone ingrowth was 8% for the smooth, 38% for the poro us, and 83% for the HA-coated sections, Infiltration of the interface membrane by histiocytes containing polyethylene particles, and endoste al scalloping or osteolysis were found on all sections of the smooth p rostheses. No particles or osteolysis were found on any sections of th e other three types of prostheses. Capsular and lymph node sections fr om all dogs revealed histiocytic infiltration with numerous polyethyle ne particles present. It is concluded that the use of cement, porous, or HA coating prevents or delays access of the polyethylene wear debri s to the bone-implant interface. No one of these methods of fixation p roved more advantageous in the 5-month limit of this study. (C) 1995 J ohn Wiley & Sons, Inc.