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

Cage Augmentation of the Retained Acetabular Shell with a Dual Mobility Cup using the Double Socket Technique

Introduction

Prevention of dislocation after total hip arthroplasty (THA) remains a topic of debate. There are various surgical options to manage hip instability such as large femoral heads, and constrained liners, although the best option to tackle this is still controversial. In revision scenarios with previous well-fixed acetabulum shells, the cementation of polyethylene liners or the cementation of dual mobility (DM) into a well-fixed acetabulum shell (Double Socket Technique) has been documented before.Here, we report a case of re-revision THA, where we have used the Double Socket Technique of retaining the previous well-fixed acetabular shell with the cementation of the DM cup along with an anti-protrusio cage inside the socket. To the best of our knowledge, this is the first such a case to be reported worldwide.

Case Report

A 54-year-old male who underwent THA in 1990 and an acetabulum cup revision in 2003 presented to us with right hip pain. Radiographs showed Paprosky Type 3A femoral bone loss and polyethylene wear. Intraoperatively after removing the polyethylene liner, the acetabulum shell was found to be well fixed and therefore retained. To increase stability, an anti-protrusio cage was inserted over it and a DM cup was cemented onto it (double socket). The femoral stem was revised using Wagner stem and encerclage wires and a hook plate was used to stabilize the osteotomy site.

Conclusion

This technique is a reliable option and helps shorten the surgical time and reduce the bone loss that can occur in extracting a well-fixed acetabulum shell. The use of a DM cup decreases the chances of instability compared to the cementation of polyethylene liners and decreases the high failure rate associated with the use of cementation of constrained liners. The addition of an anti-protrusio cage in addition to the Double Socket Technique increases the stability of the construct.

An early experience of the use of dual mobility cup uncemented total hip arhroplasty in young patients with avascular necrosis of the femoral head

Introduction

THA (Total hip arthroplasty) in advanced grade (grade 4) avascular necrosis (AVN) is a challenge to the treating surgeon as it affects young patients who have high functional demands and increased dislocation risk. The aim of the study was to evaluate the efficacy, survivorship, and dislocation rate of uncemented dual mobility cups (DMC) in advanced grade IV AVN young patients.

Methods

Retrospective cohort study involving 204 DMC THA for advanced grade IV AVN from January 2013 to December 2015. The sample size of the study was estimated to be 188 hips with an α error of 0.05 and β error of 0.2. Inclusion criterion was patients less than 55 years of age with advanced grade IV AVN. Patients >55 years of age, patients diagnosed with primary osteoarthritis of the hip and hip fracture were excluded from the study. 172 patients (32 with bilateral & 140 with unilateral affection) with 204 DMC THA were evaluated clinically by Harris Hip Score (HHS) and radiologically at a follow up of 60 months. P value < 0.05 was considered significant.

Results

Mean age of the patients was 42.5 ± 5.3. Preoperative HHS was 50.6 ± 10.5. Postoperative HHS at 5 years follow up was 96.4 ± 2.6. None of the operated patient had any dislocation episode or had undergone hip revision surgery (statistically significant against historical control of 2%, p value = 0.042). The radiological evaluation at 5 years showed no signs of radiolucent lines, periprosthetic osteolysis, polyethylene wear and signs of displacement or migration of the DMC. Cumulative survivorship rate at 5 years follow up was 100% without any revision/dislocation.

Conclusion

Use of DMC THA in young, advanced grade IV AVN patients was found to be a reliable option showing excellent early functional results with no dislocation. Ongoing follow up of this cohort is required to confirm the maintenance of these excellent functional results at follow up in the long term.

Superior functional outcome with dual mobility THR as compared to conventional THR in fracture neck femur: a prospective cohort study

Introduction: Total Hip Replacement (THR) in displaced Fracture Neck of Femur (FNOF) is associated with higher dislocation rates. Conventional THR with a large femoral head and anterior approach has reduced the instability, but it remains higher than THR done for other aetiology. Recent studies have shown reduced dislocation rates with dual mobility THR (DMTHR) for FNOF; however, there is a lack of comparative research to show its superiority over conventional THR. Further, its role in the Asian subcontinent, where the patient requires sitting cross-legged or squatting, has not been studied. Methods: A prospective cohort study of 103 elderly patients with displaced FNOF with a minimum follow-up of 1-year. Fifty-two patients were operated on with DMTHR and fifty-one patients with conventional THR. Both the groups were matched in terms of demographic data, surgical approach, and postoperative protocol. Radiological and functional outcomes in terms of Harris Hip Score (HHS), Range of motion, Patient Reported Outcome Measures (PROM), and Dislocation rate were compared between the two groups. Results: Mean HHS of the DMTHR group was 76.37 at three months and 87.02 at the end of the 1-year postoperatively, which was significantly better than the conventional THR group 65.65 at three months and 72.96 at 1-year. The range of motion was significantly better in the DMTHR group than the conventional THR group. There was no significant difference in radiological outcomes and postoperative dislocation rate between the two groups. Conclusion: Dual mobility implants give better results than conventional implants for primary THA in elderly patients of displaced FNOF regarding better function and greater range of motion.