CORR Insights^®: Acetate Templating on Digital Images Is More Accurate Than Computer-based Templating for Total Hip Arthroplasty

Excerpt

Preoperative templating is an important step in planning for THA. The goals of templating are to predict the femoral and acetabular implant size, orientation, position, and any expected change in leg length and offset. Since the radiograph cassette is positioned adjacent to the soft tissues posterior to the hip, the anteroposterior radiograph image of the hip is magnified by approximately 20% depending primarily on the distance from the hip joint to the radiograph cassette [1]. Although radiographic magnification can vary, it can also be more-accurately quantitated with use of a radiographic magnification marker placed at the level of the femur [6]. Since translucent acetate templates generally only came in one size (adjusting for enlargement by approximately 20%), this approach could introduce inaccuracy in preoperative templating. However, the implementation of digital radiographic systems in many hospitals and health care facilities has essentially eliminated the use of printed radiograph films. This has resulted in considerable cost savings due to elimination of printed radiograph films and storage, easy access to images by multiple health care providers, and availability of radiographs in the electronic record. …