Evaluation and treatment of the painful hip resurfacing
Hip resurfacing arthroplasty (HRA) can have unique failure mechanisms not commonly seen with traditional metal on polyethylene total hip replacements (THRs) due to the shape and fixation of the implants, interaction of the bone with the implants, biomechanics of the joint, and the metal-on-metal (MOM) articulation. As such, one should be aware of the most common mechanisms for pain in a hip resurfacing to be able to evaluate the problem with the proper imaging and laboratory studies. Besides the usual causes of pain in a hip arthroplasty such as infection, hip flexor tendonitis, and implant loosening, there can also be bone-to-implant impingement, synovitis from metal debris, and immunologic reaction to metal debris. Thus, the diagnosis of problems in a metal on metal hip resurfacing is aided by the use of diagnostic modalities such as metal ion measurement and metal artifact reduction imaging techniques. The treatment of such problems can consist of a revision to a stemmed THR, either by revising the femoral component only, or performing a revision of both components.