Modularity of the femoral head-neck junction provides increased intraoperative flexibility to the surgeon. Complications of this modularity include damage to the trunnion, with subsequent bone and/or soft tissue loss from adverse reactions to metal debris.
We describe two cases of severe metal-induced osteolysis and soft tissue damage requiring revision 10 and 13 years following implantation of a unipolar endoprosthesis. Damage to the trunnion resulted in severe acetabular and trochanteric osteolysis and soft tissue loss requiring complex revision surgery.
Several reports have shown the trunnion, the head-neck interface, and the neck-stem couple as the causes of this early failure secondary to metal ion release from mechanical fretting corrosion or from crevice corrosion at these modular interfaces. These reports have been in association with a total hip prosthesis rather than a unipolar endoprosthesis. Revision of a unipolar endoprosthesis is most commonly attributable to stem loosening or acetabular erosion from the large femoral head articulating on the host acetabular cartilage and not owing to failure of the trunnion.
Purposes and clinical relevance:
Trunnion damage resulting in a severe reaction to metal debris with acetabular osteolysis, erosion of the greater trochanter, and loss of the abductor mechanism can occur years after implantation of a cementless unipolar endoprosthesis. This raises questions regarding long-term safety of the modular interface of a contemporary cementless stem and a large-diameter unipolar head. We recommend long-term followup of patients with a unipolar endoprosthesis as early recognition and treatment are required to avoid a potentially complex revision.
"Furthermore, numerous reports suggest corrosion at the head-neck junction or neck-stem junction as a cause [6–8]. Concerning the specific causes after hemiarthroplasty (HA), several case reports have been published describing massive metallosis caused by the abraded outer shell or trunnion corrosion in unipolar HA [9–11]. However, in this case, there was no apparent source of metal release previously described in the literature. "
[Show abstract][Hide abstract] ABSTRACT: A 68-year-old male with failure of bipolar hemiarthroplasty consistent with adverse reaction to metal debris (ARMD) who presented with a painful cystic lesion and lower extremity swelling was encountered. However, revision surgical findings showed no apparent cause of ARMD previously described in the literature, such as corrosion at the head-neck junction and articular abrasion. Therefore, it was difficult to make a definite diagnosis of failure secondary to ARMD, which consequently led to the decision to perform two-stage revision procedure, though the stem was firmly fixed. Postoperative analysis in the retrieval tissues showed that the metal debris mainly originated from the titanium alloy stem itself. Although this is a very rare case, one should be aware that even the well-fixed femoral components themselves have the potential to be the cause of ARMD.
[Show abstract][Hide abstract] ABSTRACT: The diagnosis and treatment of patients with painful total hip arthroplasties secondary to taper corrosion and wear of modular junctions and metal-on-metal bearings represents a major challenge for the orthopaedic clinician. Guidelines are evolving as we analyze the growing body of evidence regarding metal-related failures of orthopaedic implants and adverse reactions to metal debris. In this article 6 case examples are presented to enhance understanding and application of current evidence into practice. Clinical expertise is integrated with the best available evidence from research and national joint registries data into the decision making process relevant for patient care in everyday practice. Issues addressed include understanding taper corrosion and metal failure mechanisms, clinical presentation of adverse soft tissue reactions, utility of specialized tests such as metal ion analysis and cross-sectional imaging studies, the utility of modular components for primary THA, dealing with recalled component, and current recommendations.
The Journal of arthroplasty 04/2014; 29(4):663-7. DOI:10.1016/j.arth.2014.02.003 · 2.67 Impact Factor
[Show abstract][Hide abstract] 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.
06/2015; 2015:1-5. DOI:10.1155/2015/738671
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