Adverse Local Tissue Reaction in Total Hip Replacement

Abstract

<p>Total hip replacement (THR) utilizing metal-on-polyethylene articulations was successful for many years. Modifications in materials and implant designs were created to improve wear and allow greater ability to adjust the implant position, optimizing joint mechanics. Three recent cobalt-chromium designs that involve metal to metal contact (metal-on-metal or MoM, modular neck-stems, large metal femoral heads) have produced metal debris through corrosion, releasing cobalt ions around the implant. Unfortunately, these metal nanoparticles have led to a wide spectrum of soft tissue destruction called adverse local tissue reaction (ALTR). This review article assesses ALTR following THR using MoM cobalt-chromium designs, as well as the diagnostic testing used to identify at risk hips. Findings revealed that a possible explanation for ALTR is hypersensitivity to cobalt with lymphocytic perivascular infiltration, known as aseptic lymphocytic vasculitis associated lesion (ALVAL). Solid or cystic masses called “pseudotumors” may also form around the implant. Given the destructive nature of ALTR to the surrounding capsule, muscle, and bone, surgical revision of the MoM junction is generally required. In addition to physical examination and x-rays, diagnosis now depends on drawing serum cobalt and chromium levels, as well as the use of a metal artifact reduction suppression (MARS) MRI.</p><p>The authors believe that the optimal design and bearing surface for THR is a titanium femoral stem and acetabulum with a ceramic femoral head (32 or 36 mm) articulating on a polyethylene acetabular insert. Manufacturers have now produced a polyethylene with superior bearing characteristics, as evidenced by minimal wear after five to ten years of implantation. </p>