Comparison of bipolar hemiarthroplasty and total hip arthroplasty with dual mobility cup in the treatment of old active patients with displaced neck of femur fracture: A retrospective cohort study

BACKGROUND: The standard treatment of displaced femoral neck fracture is arthroplasty. THA is reportedly superior to BHA in terms of hip pain, function and reoperation rate. On the other hand THA has a higher rate of dislocation. Total hip replacement with dual mobility cup increases the range of motion and reduces the chances of dislocation. The aim of this study is to compare the functional outcome, rate of dislocation, complications and mortality between BHA and THA with dual mobility cuff for the treatment of displaced neck of femur fracture. PATIENTS AND METHOD: This is a non-commercialized retrospective cohort study conducted at our tertiary care level 1 trauma centre. Patients of age group 60 years and above who underwent hip arthroplasty (BHA or THA with dual mobility implant) between 2015 and 2017 for displaced neck of femur fracture with a complete follow up for one year were included. Both groups were assessed for postoperative surgical complications including dislocation, fracture, surgical site infection, and medical complications, one-year mortality and functional outcome were analysed via Harris Hip Score (HHS) at the latest follow up. RESULTS: Overall 104 patients were included in the study out of which 77 patients underwent BHA while 27 underwent THA with dual mobility cup. Baseline characteristics were found to be similar in both groups. Mean pre-op HHS for bipolar group was found to be 71.01 while for THA with dual mobility cup group it was 73.52 with the difference being statistically insignificant (P = 0.12). Mean post-op HHS for bipolar group was noted to be 68.82 whereas for THA with dual mobility cup group it was 76.81. The difference was found to be statistically significant with a P-value of <0.01. With regards to post-operative complications and one-year post-operative mortality, no significant difference was noted between both groups. CONCLUSION: In relatively young and active elderly patients with displaced neck of femur fracture, a THA with dual mobility cuff provides better hip functional outcome, does not increase mortality or morbidity as compared to BHA and can be considered as primary treatment modality.