Extra-articular deformities and the role of hip resurfacing - a proposed classification system.

There has been an increasing demand for hip resurfacing as an alternative to total hip arthroplasty. A number of reports have been published recently detailing the technique and role of resurfacing in a variety of extra-articular deformities, dysplastic conditions, and settings of retained intramedullary hardware and other impediments. The following report proposes a classification system that recognizes intramedullary and extramedullary deformities. With the long-term expectation for resurfacing, these complex situations may require categorization to segregate risk factors in order to allow for better planning and prognostication.