Two of commonest types of hemiarthroplasty used for the treatment of a displaced intracapsular fracture are the uncemented Austin Moore Prosthesis and cemented Thompson hemiarthroplasty. We performed this trial to determine if any difference in outcome exist between these implants. We undertook a prospective randomised controlled trial of four hundred patients with a displaced intra-capsular hip fracture. All operations were performed or supervised by one orthopaedic surgeon and all by a standard anterolateral approach. Patients were followed by a nurse blinded in the type of prosthesis to assess residual pain and mobility. The average age of the patients was eighty-three years and 23% were male. 73% came from their own home with the remainder from institutional care. There was no statistically significant difference in mortality between groups. Pain scores were less for those treated by a cemented prosthesis (p value <
0.00001). Mobility change was also less for those treated with a cemented implant (p=0002). No difference was found in hospital stay, implant related complications, re-operations or post-operative medical complications between the two groups. One case of non-fatal intraoperative cardiac arrest occurred in the cemented group. In summary a cemented Thompson Hemiarthroplasty causes less pain and less deterioration in mobility compared to the uncemented Austin Moore hemiarthroplasty, without any increase in complications. The continued use of an uncemented Austin Moore cannot be recommended.