Late Nontraumatic Dissociation of the Femoral Head and Trunnion in a Total Hip Arthroplasty

Abstract

Background. Modular total hip arthroplasties are increasingly popular because customisation allows optimal restoration of patient biomechanics. However, the introduction of component interfaces provides greater opportunities for failure. We present a case of late nontraumatic dissociation of the head-neck interface, more than 10 years after insertion. Case Description. A 58-year-old woman had a left metal-on-metal total hip arthroplasty in 2002 for hip dysplasia. Following an uneventful 10-year period, she presented to hospital in severe pain after standing from a seated position, and radiographs demonstrated complete dissociation of the modular femoral head from the stem, with the femoral head remaining in its cup. There was no prior trauma or infection. Mild wear and metallosis were present on the articulating surface between the femoral head and trunnion. Soft tissues were unaffected. Discussion and Conclusions. This is the latest occurrence reported to date for nontraumatic component failure in such an implant by more than 7 years. The majority of cases occur in the context of dislocation and attempted closed reduction. We analyse and discuss possible mechanisms for failure, aiming to raise awareness of this potential complication and encouraging utmost care in component handling and insertion, as well as the long term follow-up of such patients.

In Vivo Damage of the Head-Neck Junction in Hard-on-Hard Total Hip Replacements: Effect of Femoral Head Size, Metal Combination, and 12/14 Taper Design

“…However, HNJ, like all self-locking taper junctions, is at risk of disassembly, mechanical failure, or junction surface damage [ 3 ]. Clinical studies have shown that the occurrence of head disassembly—often secondary to hip dislocation or accidents—or of mechanical failure of the male taper is rare [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Therefore, the major concern is about HNJ damage occurring in vivo.…”

Impending Trunnion Failure: An Uncommon Radiographic Presentation of Total Hip Arthroplasty Failure

“…Of these, 24 cases had no radiographic findings of trunnionosis [ 17 , [24] , [25] , [26] , [27] , [28] ]. Almost two-third of the cases had complete dissociation, gross trunnion failure, or femoral neck fracture evident on a radiograph [ 17 , 25 , 26 , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] ]. Figure 4 represents this more common radiographic presentation of gross trunnion failure seen at the same medical center as the patient in our case report.…”

Early Disassembly of Femoral Head and Neck Components After Total Hip Arthroplasty Revision

“…Disassociation between components can occur during closed reduction attempts following dislocations [6]. Sufficient impaction between the femoral head and neck is achieved following a strong blow with a 0.5 kg hammer, and the load exerted during activities of daily living may also strengthen the impaction [7]. Nontraumatic dislocation in which the femoral head remained in the acetabular cup is rarely reported [8].…”