Aims: To compare total hip arthroplasty (THA) and internal fixation in the treatment of displaced femoral neck fractures. Methods: Patients, 75 years or older, including those with mental impairment, were randomized to either internal fixation or cemented primary total THA. A total of 146 hips in 143 patients were followed for two years. After one year 23% had died, and after two years 29%. Mortality was about the same in both groups. The accumulated mortality was pronounced among the mentally impaired patients. Results: In the internal fixation group, 44% underwent further surgery. In the THA group, 18% dislocated. The dislocation rate was higher for the mentally impaired patients. The Harris hip scores were higher in the THA group. Pain was more common in the internal fixation group.

A subgroup of 100 patients was included in a study concerning nutritional status and functional capacity. The THA group fared better concerning weight change over time, locomotion and pain. The nutritional intervention did not show any measurable effects.

All patients were followed until two years postoperatively and all fracture-related hospital costs, including reoperations, were calculated. We found no difference in total costs between the treatment groups. Costs to the municipality were calculated comparing the baseline cost before surgery with the average cost per month during the first postoperative year. No difference was found between the treatment groups. Conclusions: On the basis of these results, we recommend arthroplasty for patients in this age group with normal mental function and high functional demands. When in doubt, an arthroplasty should be generously considered.