Abstract
Ninety-five hip joints in 8 8 patients suffering from osteoarthritis have been treated by bipolar hip prosthesis over the past 9 years. Out of them, 26 joints in 23 patients were followed up clinically and roentgenographically for more than 5 years, with a mean of 5 years, 7 months. The age at operation ranged from 35 to 75, averaging 59.7 years. The Bateman UPF ll with curved Moore stem was used as the component in all cases. Good results were obtained. In a clinical evaluation done by the criteria for JOA hip score, the averag total score of 45.8±11.0 at preoperation changed to 83.2±9.1 postoperatively. On roentgenograms the medial migrated distance of the outer head was 0.04±1.8mm on an average. Apparent medial migration was recognized in 2 (7.7 %) out of the 26 and their migrated distances were 5mm and 4mm. On the other hand, greater upward migration was seen 2.3±1. 7mm on an average. This outer head migration showed a tendency to move upward and outward. The average distal migration of the stem was 4.8±4.3mm. One case had a distal migration of 2 0.5 mm and there was some trouble achieving fixation on the femoral site. Functional roentgenograms showed that the movability between the stem head and the inner bearing was much more dominant than that between the outer head and the acetabulum.
