Introduction A review of hip replacements performed in our hospital between 1991 and 2000 has identified a group of post-operative patients in whom recurrent dislocation has been deemed untreatable because of medical comorbidity. We tried to identify a group of patients at risk of recurrent dislocations. This paper presents our experience with the Kasselt cup in these patients

Methods We have used the Kasselt cup with indications being: a) prophylaxis, in patients with perceived greater risk of recurrent dislocation and b) treatment of recurrent (three or more) dislocations following THR. Patients were identified from clinical records and a National Joint Register. From 1998 to 2002, 51 patients underwent THR utilizing semi-constrained Kasselt cup. All living patients were invited for clinical and radiographic examination. Forty-eight patients (51 hips) were available for study. Thirty-nine patients were able to attend clinic and nine were interviewed by telephone. Average follow-up was 18.6 months (range 6 to 36 months). Average age was 75.6 years (range 56 to 92 years). Twenty-nine operations were done prophylactically and 22 for recurrent dislocations.

Results Three patients suffered further dislocations, from the recurrent dislocation group. One suffered a single dislocation post-operatively which was reduced by close manipulation and to-date has not re-dislocated. The second continued to dislocate. The third was revised with a Kasselt cup for recurrent dislocation and suffered three further dislocations. This patient was re-revised and to-date (six months) has had no further dislocation. The mean Harris Hip Score in the whole group was 79 (range 49 to 100). We have seen no dislocation in patients in the ‘at risk’ group in this short term

Conclusion The value of this prosthesis remains uncertain.

A review of total hip replacements (THR) performed in Palmerston North between 1991–2000 has identified a group of postoperative patients in whom recurrent dislocation has been previously deemed untreatable because of medical co-morbidity. From 1998 to 2001, 47 patients underwent THR utilizing a semi-constrained “Kasselt” cup to reduce the risk of dislocation. Indications for use of this cup were: Recurrent dislocation following primary or revision THR (3 or more dislocations) or perceived greater risk of recurrent dislocation eg. elderly, mental confusion, neurological compromise or fracture neck of femur.

This paper presents the early results in these 47 patients (49 hips). Clinical records and radiographs of all hip replacement patients were retrospectively reviewed to identify the “Kasselt” group and telephone contact was made for permission to participate in the study. All living patients were sent a self-evaluation questionnaire and invitation to attend clinic for physical examination and radiographs of the hip joint. Twenty-one patients were recurrent dislocators and 24 were at risk patients. Out of 45 living patients 36 were physically examined between 6 and 36 months following surgery. All collected data was statistically analysed using StatWave software.

Results: Forty-three of the 45 living patients (47 hips) had no dislocations following surgery. Two patients suffered further dislocation, both of whom were previously recurrent dislocators. One suffered a single dislocation postoperatively which was reduced closed and to date has not re-dislocated. The second continues to dislocate. The mean postoperative Harris Hip Score in the whole group is 79 (range 49–100). Early results reveal no dislocations in the “at risk” primary group.