Low dislocation rates achieved when using dual mobility cup hip implants for femur neck fractures

Background: Total hip replacements done for intracapsular neck of femur fractures (NOF) have a dislocation rate of up to 14%. This is seven times higher than in total hip arthroplasty (THA) done for osteoarthritis. Using a dual mobility cup (DMC) has been shown to be effective in addressing dislocation in elective THA. Our hypothesis is that the use of DMC in NOF will do the same. This study aims to determine the incidence proportion of dislocation of DMCs one year after surgery in patients who received THA for NOF and to compare it to dislocation rates as documented in existing studies. Methods: A retrospective study was done on 86 patients treated with DMC THA for an intracapsular NOF fracture from 2012 until 2016. A minimum one-year follow-up period was required for inclusion into the study. The number of dislocations at one year after surgery was noted. Results: Forty-one patients with a mean age of 60.7 years were included (26 females and 15 males). All patients were operated via the posterior approach. None of the patients had dislocated after one year. Conclusion: Low dislocation rates can be achieved using DMC THA in the management of intracapsular NOF fractures. Our one-year dislocation rate of 0% compares favourably to conventional THA and is comparable to similar DMC studies done outside of South Africa. Level of evidence: Level 4