Dual mobility THR: Resolving instability and providing near normal range of movement

Dislocation is a common complication of Total Hip Replacement (THR), particularly when performed in primary (indications with increased risk of instability) and in revision scenarios. Dual mobility THR (DMTHR) minimizes the risk of instability in such scenarios, however most of the evidence is from western literature. Results of DMTHR in Indian scenarios where patient want to go back to their normal routine activities of squatting and sitting cross-legged is lacking. The aim of our study was to evaluate the short to mid-term results of DMTHR for varied indications (both primary and revision) in Indian scenario. To evaluate the outcome of the DMTHR in terms of functional range of motion and the ability to go back to their pre-injury level of activity.

This is a retrospective study of 150 patients operated with DMTHR between January 2015 to February 2019 with a minimum follow-up of 12 months. Patients were evaluated clinically using Modified Harris Hip Score (HHS), Range of Motion (ROM), and Patient Reported Outcome Measures (PROM) like ability to squat and sit cross legged. Radiological evaluation was done using radiographs to assess loosening, stress shielding, osteolysis.

Mean follow up in our study was 25.2 months (Range 12-46 months). Mean Modified HHS was 71.8 ± 8.11 at 6 weeks post-op and 85.8 ± 7.62 at last follow-up. HHS showed excellent outcome in 36 hips (26.7%), good outcome in 76 hips (56.7%), fair outcome in 20 hips (14.6%), poor outcome in 3 hips (2%). All our patients were allowed to squat and sit cross-legged at a mean follow-up period of 13 weeks (8 weeks-20 weeks) except 10 cases of Revision THR where patients were advised not to squat or sit cross-legged. All patients were able to resume their activities of daily living.

DMTHR in patients of all ages has shown a good short to midterm clinical outcome which is comparable to conventional THR. It confers the benefit of stability allowing our patients to squat and sit cross legged which is often one of the expectation and requirement of a patient undergoing THR in India. DMTHR in both primary and revision scenarios exhibit a low risk of dislocation, complications and revision surgery.