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Background
Total hip arthroplasties (THAs) are one of the most successful orthopedic procedures, with greater than 95% of patients experiencing relief and a nearly 90 - 95% success rate 10 years after the procedure. In general, the THA prostheses are modular with a femoral component, an acetabular component, and a bearing surface. Some hardware are extensively modular with a separate femoral head and stem, and a separate acetabular liner and shell. In this exhibit, various types of THA components will be explored with radiography, and common complications visualized on radiography and CT according to the type of hardware used.

Educational Goals / Teaching Points
The educational goals of this exhibit are to provide an overview of commonly seen components of THA hardware with corresponding imaging correlations. The presentation will explore the different varieties of THAs seen on radiographs and CTs and explore the common complications depending on the type of hardware, material. and technique used.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Common fixation techniques identifiable on radiographs are cemented and uncemented techniques. One of the preferred techniques is the "press-fitting" of the femoral stem to the surrounding bone, which relies on bony growth into the porous surfaces of the prosthetic. The common cement is a methylmethacrylate cement, which is used in patients with poor bone mineralization. The acetabular and femoral components are identifiable on radiographs with attention to density, shape, and surface pattern. Acetabular components can be a single piece (monoblock) or two pieces (modular). In modern THAs, the bearing surface is a ceramic femoral head with an acetabular liner made of highly crosslinked polyethylene. Femoral stems can be monolithic (both head and stem) or modular (separate head, stem and sometimes collar). There are two types of stems that are used in cemented applications which are the loaded/sliding-taper and composite-beam. Evaluation of a hip prosthesis may be described in Dee and Charney zones for the acetabular cup and Gruen zones for the femoral stem. Common hip prosthesis complications include periprosthetic loosening and component migration. Other complications are secondary effects of metal debris, bone resorption, and remodeling.

Conclusion
THA is a common procedure widely employed around the world today. A simple radiograph can provide significant insight into the material and components used in THA, which may be often overlooked on imaging. This exhibit will identify clinically relevant information identifiable on imaging to aid in diagnostic interpretation of potential complications.