Incidence and risk factors of dislocation after total hip replacement with a ceramic acetabular system

Abstract Objectives This study retrospectively analysed the incidence of dislocation and its risk factors in a multicentre series of total hip replacement with a Trident ® ceramic acetabular system. Material and method Cases of dislocation in a series of 401 total hip replacements performed using a Trident ® ceramic acetabular system in 10 Spanish hospitals between the years 1998 and 2004, with a mean follow-up of 5.08 years, were analysed and compared to a control group. The influence of different variables, general, clinical and surgical was evaluated and a computer-assisted analysis was made of the radiographic variables possibly involved in the risk of dislocation. Results The incidence of dislocation in the whole series was 1.75%, lower than incidence rates in series analysed that used other types of artificial joints. The most important dislocation risk factors found were the abduction angles and acetabular inclination ( P  = 0.016), although there was also tendency to dislocation as the patient age and the ASA level increased. Conclusion When performing a ceramic-ceramic joint total hip replacement, the angle of acetabular abduction appears to be the most important factor to take into account to prevent dislocation. Femur head sizes greater than 32 mm could act as a limiting factor of the risk of artificial joint dislocation. Clinical variables, such as the age of the subject or ASA level show a tendency as a risk of artificial joint dislocation.