We evaluated 6 cases of total hip arthroplasty using a constrained acetabular component (constrained THA) . The mean age of patients at operation was 75 years (range, 68 to 83 years) . Patients' original diseases were coxarthrosis (2), rapidly destructive coxarthropathy (2), osteonecrosis of femoral head (1) and rheumatoid arthritis (1) . All hips were followed up from one year 2 months to 3 years (mean, 2 years 2 months) . The average Japanese Orthopaedic Association score (JOA score) improved from 22.8 to 72.5 points. No dislocation and loosening were observed in the cases except for that of an 83-year-old woman who had marked obesity and dementia. Constrained THA can decrease the incidence of recurrent dislocation and provide good stability for the hip joint, although the indications must be carefully assessed.
