Dislocation of hip prostheses.

BACKGROUND: In the literature, the dislocation rate for hip prostheses is stated to be 2-3%. Dislocation may have several causes, such as aspects of the patient, the surgeon, the type of prosthesis or the operation. The objective of this study was to identify the frequency, causes and treatment of dislocation in our department.

MATERIAL AND METHODS: The material encompasses all patients operated on with a hip prosthesis at the Department of Orthopaedics, Haugesund Hospital, from 1987 through 2011. Information has been collected retrospectively from databases and patient records after an average of 6.1 years.

RESULTS: During this period, altogether 2,236 patients underwent total hip arthroplasty. Of these, 548 received an ITH prosthesis with a large caput (32 or 28 mm in diameter), while 1,290 received a 22 mm Charnley prosthesis. Lubinus Spll was used in 299 and Landos Corail in 99 patients, all with a caput diameter of 28 mm. In 75 patients (3.4%) the prosthesis had become dislocated. There was no significant difference in dislocation frequency among the four types of prosthesis. Prostheses with a caput diameter of 32 mm were dislocated significantly less frequently than the others (2.0% and 3.6%, p = 0.03) INTERPRETATION: Overall, our results correspond to findings made by others. In this retrospective material, approximately one-third of the patients with dislocated hip prostheses experienced multiple dislocations.