Abstract
Metal-on-metal bearing surfaces were reintroduced to take advantage of the reduction in volumetric wear afforded by these bearings and reduce the complications of osteolysis and aseptic loosening. In addition, metal-on-metal hip resurfacing and many metal-on-metal total hip replacement systems employed large diameter femoral heads, thereby reducing the risk of dislocations. Unfortunately, many metal-on-metal systems demonstrated poor survivorship and were associated with adverse local tissue reactions (ALTRs) related to metal debris generated from the bearings and/or modular connections.
Careful clinical surveillance of patients with metal-on-metal bearings is warranted to identify patients with ALTR at an early stage in order to intervene prior to the development of extensive peri-articular soft tissue damage. Monitoring may include serum or whole blood metal levels and metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) depending on the patient's signs and symptoms and the track record of the implanted device. While there currently is a lack of high quality evidence-based guidelines on the management of patients with either symptomatic or asymptomatic metal-on-metal total hip replacements, professional organizations have issued consensus-based algorithms to guide the practitioner in management. Ultimately, the decision for revision surgery should not be based on a single diagnostic test but on the entire clinical scenario.
