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.