Hemiarthroplasty of the hip and dislocation.

A retrospective study was undertaken on 171 patients who had suffered a subcapital fracture of the neck of the femur between 1982 and 1986. The aim was to compare the dislocation rates in bipolar and monopolar endoprostheses. The basic surgical approaches were utilized: the posterior and direct lateral. Four endoprostheses were employed: Thompson's Moore's (monopolar), Monk's 'hard top', and Charnley-Hastings' (bipolar). There was no significant difference in the dislocation rates between monopolar and bipolar devices. It is concluded that the bipolar devices do not offer any additional protection against dislocation when compared with the traditional monopolar devices.