In Vivo Dissociation Of A Dual Articulation Bearing In Revision THA - Case Report

Abstract

Revision total hip arthroplasty (THA) can be a difficult reconstructive procedure that challenges the skills of even the adroit orthopaedic surgeon. Revision THA for aseptic failure after acetabular/pelvic fracture is one of the more difficult challenges in the realm of hip reconstruction. The high complication rate associated with this complex reconstruction remains the dominant obstacle for obtaining consistent satisfactory outcomes. The specific problems of boney defects, pelvic malalignment, heterotopic ossification, soft tissue scarring, and muscle atrophy compromise the goals of revision THA, which include osteointegration of implant to host bone, restoration of hip joint biomechanics, and joint stability12. Recurrent dislocation in revision THA is one of the more frustrating complications for both the patient and the surgeon, and it remains so even today. Despite this, there continues to be developments in surgical technique and prosthetic design to enhance prosthetic hip stability. One prosthetic design, the dual articulation hip bearing, was developed to enhance THA stability. The dual articulation concept was developed by professor Gilles Bousquet and engineer André Rambert in the late 1970’s14. The dual mobility design incorporates two articular surfaces within the THA bearing. The acetabular cup is composed of a metallic bearing that articulates with an ultra high molecular weight polyethylene (UHMWPE) ball. Within the UHMWPE head is an inner ball that is enclosed within the polyethylene (figure 1). This design concept increases hip primary arc range before impingement.The Bousquet dual mobility concept has been used over the last 20 years in Europe with successful clinical outcomes6,7,9,11. In the United States, the dual articulation bearing design received FDA clearance in 2011. However, as with the addition of any modular part, there is the potential for new in-vivo failure mechanisms. With the dual mobility construct, the new failure mechanism is dissociation of the inner head1,10. We report in this case an early traumatic dissociation of a dual mobility bearing utilized in a complex revision THA. To our knowledge, this is the first reported case of a traumatic in-vivo disassembly of a dual articulation bearing THA.Key Words: Dual Articulation, Dual Mobility, Active Articulation, THA, Revision, Dissociation, Dislocation