Internal fixation versus total hip arthroplasty in the treatment of displaced femoral neck fractures: a prospective randomized study of 100 hips.

100 patients 75 years or older, with displaced femoral neck fractures, were randomly assigned to osteosynthesis with two parallel and percutaneously inserted screws (Olmed) or total hip arthroplasty (Lubinus IP). Mean age was 84 (75-101) years, 74% were women and 45% had mental dysfunction. General complications were commoner in the arthroplasty group but the mortality rates did not differ. In the osteosynthesis group, fracture complications were seen in 27/50 hips. In the arthroplasty group, dislocation was the main complication and occurred in 11/50 cases. At 3 months and after 1 year, the Harris Hip Scores were significantly better in the arthroplasty group. When mental dysfunction was present, the dislocation rate after arthroplasty was 32%, whereas the reoperation rate after osteosynthesis was 5%. The opposite pattern of complications was found in patients with normal mental function, 12% versus 60%. The 2-year mortality rate among those with mental dysfunction was 26/45, compared to 7/55 of those with normal function (p < 0.001). We conclude that total hip arthroplasty should be considered for a displaced femoral neck fracture in old patients with normal mental function and high functional demands.