HEMISPHERIC TITANIUM POROUS-COATED ACETABULAR COMPONENT WITHOUT SCREWFIXATION

One hundred fifteen hips in 108 patients with primary total hip arthro plasty using the anatomic porous replacement hemispheric acetabular co mponent implanted without adjunctive screw fixation had a mean postope rative followup time of 6 years (range, 5-7.4 years). Clinical evaluat ion was performed using the Harris hip score and patient self assessme nt using a modified Short Form-36 questionnaire. Radiographs were meas ured for radiolucent lines, polyethylene wear, osteolysis, migration, and fractures. No acetabular metal shell had been revised for loosenin g or was radiographically loose with or without migration (more than 3 mm) at final followup, Reoperation was done in nine (8%) hips because of polyethylene insert wear or disassembly. No fracture of the acetab ular bone occurred at the time of surgery or was observed on radiograp h, Fixation of the metal shell was stable, with progressive radiolucen t lines observed at final followup in 2% of the hips. Osteolysis was r ecorded in one patient with two acetabular components. The fixation of noncemented hemispheric porous coated acetabular components is more r elated to the technique of acetabular bone preparation and press fit i mplantation than to whether additional screws or peg fixation are used . Fixation of this acetabular component without screws at an average o f 6 years after surgery is reproducible and predictable in primary hip arthroplasty, The design of modular polyethylene inserts has been imp roved and should reduce the wear rate of reoperations of the polyethyl ene insert.