Dual Mobility Cup in Fractures of the Femoral Neck in Neuromuscular Disorders and Cognitive Dysfunction Patients above 60 years-old.

Objectives: Dislocation rate of total hip arthroplasty (THA) can be as high as 20% for patients with fracture neck of femur, which is a disastrous complication in these vulnerable patients. Numerous techniques, including bipolar arthroplasty and constrained liner, have been adopted to minimize the risk of dislocation. We aimed to evaluate the role of dual mobility Cups in treating patients with fractures of the femoral neck with high risk of postoperative dislocation due to neuromuscular instability disorders. Methods: A prospective cohort study was conducted (place is blinded as asked during submission), between 2016 and 2019, with a post-operative follow up period of two years. We included skeletally mature patients with femoral neck fractures having neuromuscular disorders and cognitive dysfunction who are candidates for THA above 60 years. Patients were then followed up clinically and radiographically at the clinic using Harris Hip Score (HHS) and x-rays at six weeks, six months, one year and two years postoperatively. Results: Twenty patients (20 hips) with femoral neck fractures with high risk of postoperative dislocation due to neuromuscular instability disorders undergoing dual mobility cup were included. The mean age of patients was 70.5 ±6.42 years. There is highly significant difference between HHS preoperatively and postoperatively (six weeks, six months and one, two years) p<0.001.Infection occurred in one case (5 %), sciatic nerve injury occurred in one case (5%), and none of the patients had postoperative dislocation. Conclusion: Dual mobility cup is effective in preventing early dislocation in patients suffered from fracture neck of femur with muscle weakness due to neurologic disorders.