Roentgenographic features of digitized clinical orthopaedic radiographs of follow-up after total hip arthroplasty

When a patient undergoes an arthroprosthesis implant, the stresses acting on the bone are redistributed, and correspondingly, the bone density adjacent to the entire prosthesis changes its pattern. In order to study these phenomena an automatic methodology has been developed: this methodology is based on the bone density measured on X-ray. The method is compared to other bone densitometry methods and to more recent hone remodeling pattern recognition methods; it turns out to be cost-effective and it has the advantage of allowing back-dated investigation exploiting the numerous existing radiograph records relative to arthroplastic followup. The results of the set-up videodensitometric analysis show the method not only has diagnostic capability, but also can effectively support prostheses designers; moreover, the results obtained offer a capable support to real-time observation of remodeling processes and to the biomechanical assessment of the behavior of bone implant systems. For the clinical practice a risk index has been set up in order to systematize the numerous data collected from the measuring mesh grids and to monitor dangerous situations, which can end in implant failure. (C) 1997 Academic Press Limited.