Five cases of early dissociation between the bipolar hip endoprosthesis cup components; either spontaneously or during reduction maneuvers

Abstract

Bipolar hemiarthroplasty is frequently used in the treatment of intracapsular hip fractures. Dissociation of the bipolar components can happen during the hip dislocation, the reduction maneuvers, or spontaneously without any dislocation. Here we report early dissociation between bipolar components in two cases during the attempt of closed reduction maneuvers and three cases with spontaneous dissociation without any trauma. To prevent or minimize this complication; the reduction of dislocated hips must be achieved very gently under general anesthesia with fluoroscopic control. During the initial operation the surgeons must be sure that the bipolar components are locked to each other and after final reduction, especially in osteoarthritic acetabulums, that the cup position is not in varus position.

Early Recurrent Dislocation and Dissociation of Bipolar Cup: Two Intricate Cases and Review of Literature.

“…The most common cause of early dissociation in the reports was manipulation for closed reduction after bipolar cup dislocation. Dissociation during attempted closed reduction is a speci c implant-related complication that can occur even under general anesthesia sometimes [9,21]. The bottle-opener mechanism is the most commonly accepted reason for early bipolar cup dissociation [21], and it may account for 79% of the early dissociation published cases [16].…”

“…No previous studies, except for case reports, have described the strategy to manage early bipolar cup dissociation. Surgery included open reduction of the dissociation, modular components exchange (locking ring or PE liner or bipolar cup), and conversion to a THA, and another BHA (stem and bipolar components) [8,9,18].…”

“…Dislocation after hip hemiarthroplasty is a common complication, but dissociation of a bipolar prosthesis is rare. The bipolar cup dissociation in which the femoral head dissociates from the PE liner may occur late or early postoperatively [8][9][10]. Late dissociations are commonly caused by long-term wear of the PE liner and sometimes fracture of the locking ring.…”

“…Some scholars reported the frequency of early dissociation of the bipolar cup was 13% in patients with dislocations [11]. Dissociation of the bipolar components can happen during the hip dislocation, the reduction maneuvers, or spontaneously without any dislocation [9]. The dissociation between the bipolar components has very devastating results and almost always requires surgical management.…”

Disassembly of bipolar hemiarthroplasty cup causing stem notching: A case report

“…Revision surgery to total hip arthroplasty was performed with acetabulum and bipolar cup component replaced and notched stem retained. While bipolar cup dissociation has been reported in case series, [1][2][3] this associated notching from bipolar cup dissociation onto femoral stem has rarely been reported. 4 We reviewed the current literature on dissociation of bipolar hip hemiarthroplasty regarding the pattern, risk factors, as well as salvage options.…”