Incidence of Pseudotumor and Acute Lymphocytic Vasculitis Associated Lesion (ALVAL) Reactions in Metal-On-Metal Hip Articulations: A Meta-Analysis
ABSTRACT We systematically reviewed the peer-reviewed literature to determine a pooled estimate of the incidence of pseudotumor and acute lymphocytic vasculitis associated lesions (ALVAL) in adult patients with primary metal-on-metal (MoM) total hip arthroplasty or resurfacing. Fourteen eligible articles were identified, with a total of 13,898 MoM hips. The incidence of pseudotumor/ALVAL ranged from 0% to 6.5% of hips with a mean follow-up ranging from 1.7 to 12.3years across the studies. The pooled estimated incidence of pseudotumor/ALVAL is 0.6% (95% CI: 0.3% to 1.2%). The rate of revision for any reason ranged from 0% to 14.3% of hips, with a pooled estimate of 3.9% (95% CI: 2.7% to 5.3%).
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ABSTRACT: Abnormal wear of cobalt-containing metal-on-metal joints is associated with inflammatory pseudotumours. Cobalt ions activate human toll-like receptor 4 (TLR4), which normally responds to bacterial lipopolysaccharide (LPS) in sepsis. Activation of TLR4 by LPS increases the expression of chemokines IL-8 and CXCL10, which recruit leukocytes and activated T-cells, respectively. This study was designed to determine whether cobalt induces a similar inflammatory response to LPS by promoting the expression of IL-8 and CXCL10. A human monocytic cell line, derived from acute monocytic leukaemia, was treated with cobalt ions and expression of IL-8 and CXCL10 measured at mRNA and protein levels. Cobalt-treated macrophages showed a 60-fold increase in IL-8 mRNA, and an eightfold increase in production of the mature chemokine (both p < 0.001); expression of the CXCL10 gene and protein was also significantly increased by cobalt (both p < 0.001). Experiments were also performed in the presence of CLI-095, a TLR4-specific antagonist which abrogated the cobalt-mediated increase in IL-8 and CXCL10 expression. These findings suggest that cobalt ions induce inflammation similar to that observed during sepsis by the simultaneous activation of two TLR4-mediated signalling pathways. These pathways result in increased production of IL-8 and CXCL10, and may be implicated in pseudotumour formation following metal-on-metal replacement. Cite this article: Bone Joint J 2014; 96-B:1172-7.09/2014; 96-B(9):1172-7. DOI:10.1302/0301-620X.96B9.33476
Journal of Orthopaedic Science 10/2014; DOI:10.1007/s00776-014-0623-2 · 1.01 Impact Factor
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ABSTRACT: Total hip arthroplasty (THA) is the gold standard in the treatment of degenerative hip disease, especially in the older patient. Concerns regarding the higher levels of failure of traditional implants in younger, more active patients have led to a search for alternative arthroplasty techniques. Hip resurfacing (HR) is one of these alternatives. When compared with THA, HR has some theoretical advantages that stem from preservation of the patient’s normal proximal femoral anatomy and the use of a large diameter metal on metal bearing. This has the potential to more accurately replicate physiological hip function, reduce the risk of dislocation and allow higher levels of activity with minimal wear of the articulating surface. In addition, the preservation of proximal femoral bone stock offers the potential for easier revision options as would inevitably be required in younger patients. In order to be considered a suitable alternative, HR would need to demonstrate improvements or at least equivalence in functional outcomes and survivorship along with evidence of successful preservation of bone stock leading to good outcomes from future revision surgery. Whilst the recent expansion of data both in the orthopaedic literature and the mainstream media concerning the potentially devastating problems from large metal-on-metal (MoM) bearings in some settings carries some salient lessons for both the development, marketing and uptake of new orthopaedic implants, it should be put in the context of the resurfacing literature as a whole. In this review we aim to review the current evidence base for HR compared with THA and examine the current indications for the procedure.