Dual mobility cups hip arthroplasty as a treatment for displaced fracture of the femoral neck in the elderly. A prospective, systematic, multicenter study with specific focus on postoperative dislocation.

INTRODUCTION: Displaced fractures of the femoral neck in the elderly are best treated with arthroplasty. The type of arthroplasty to be used, either hemi- or total hip arthroplasty, remains controversial as total hip replacements potentially have a higher rate of dislocation.

HYPOTHESIS: Dual mobility cups have a low dislocation rate when used to manage acute fractures of the femoral neck.

PATIENTS AND METHODS: In a multicenter prospective study conducted in France over an inclusion time of 3 months, all displaced fractures of the femoral neck treated with arthroplasty were operated on with insertion of a dual mobility cup. Patients had clinical and radiological assessment at 3, 6, and 9 months postoperative.

RESULTS: Two hundred and fourteen hips in 214 patients with a mean age of 83 years (range, 70-103 years) were included. None of the patients was lost to follow-up. The mortality rate after 9 months was 19%. Two patients (1%) had early postoperative infection successfully treated with lavage and antibiotics. Three patients (1.4%), operated through a posterior approach, presented one postoperative dislocation, all of which were posterior. Reduction was performed through closed external manipulation under general anesthesia. There was no recurrence of dislocation.

DISCUSSION: This low rate of dislocation after acute total hip replacement using dual mobility design cups favorably compares with hemiarthroplasties. Dual mobility cups might therefore be considered a valuable option to prevent postoperative dislocation when treating displaced intracapsular fractures of the proximal femur in elderly patients if a total hip replacement is recommended. Further study is needed before extending the indications for total hip arthroplasty following a fracture of the femoral neck, to assess the potential cost and complications of a longer procedure with its potential acetabular complication, and weigh them against the potential benefits.