HYDROXYAPATITE-COATED TOTAL HIP FEMORAL COMPONENTS IN PATIENTS LESS-THAN 50-YEAR-OLD - CLINICAL AND RADIOGRAPHIC RESULTS AFTER 5 TO 8 YEARSOF FOLLOW-UP

One hundred and thirty-three patients (152 hips) who were an average o f thirty-nine years old (range, sixteen to forty-nine years old) recei ved a proximally hydroxyapatite-coated femoral prosthesis as part of a total hip arthroplasty and were followed for a minimum of five years (average, 6.4 years; range, five to 8.3 Sears) or until revision, The average Harris hip score was 47 points (range, 22 to 77 points) preope ratively and 93 points (range, 49 to 100 points) at the time of the la test clinical evaluation, Two patients who had a well. fixed femoral i mplant had activity-limiting pain in the thigh at the time of the most recent examination, Radiographic changes consistent with bone-remodel ing (cortical hypertrophy and bone condensation) typically were seen a round the mid-part of the shaft of the prosthesis, Forty-eight (32 per cent) of the 148 hips that were included in the radiographic analysis demonstrated a small amount of erosive scalloping in either zone 1 or zone 7 of Gruen et al., and intramedullary osteolysis was suspected i n only one hip, All stems were radiographically osseointegrated accord ing to a modification of the criteria described by Engh et al, Four st ems were revised, but none of the revisions were performed because of mechanical failure (two stems were revised in conjunction with a revis ion of the cup because of pain; one, because of an infection; and one, after a traumatic femoral fracture that occurred six years postoperat ively). Thus, the rates of aseptic and mechanical failure were both 0 per cent, The combined rate of failure, which included the two stems t hat were revised because of pain and the two stems that were associate d with pain that limited activity, was 2.6 per cent (four of 152 stems ), The over-all clinical results associated with hydroxyapatite-coated femoral components were excellent in this group of young patients aft er intermediate-term follow-up, A review of serial radiographs showed mechanically stable implants with osseous ingrowth, evidence of stress transmission at the middle part of the stem, and minimum endosteal os teolysis.