CAMRT Radiography Practice Exam

What is best demonstrated when conducting a pelvis x-ray with externally rotated legs?

1. Greater trochanter

2. Lesser trochanter

3. Ischial tuberosity

4. Pubic symphysis

The correct answer is: Lesser trochanter

When a pelvis x-ray is performed with the legs externally rotated, the positioning allows for optimal visualization of specific anatomical structures. In this case, the lesser trochanter of the femur is best demonstrated. The external rotation of the legs places the femoral neck in an optimal position relative to the x-ray beam, which provides clearer delineation of the lesser trochanter. This trochanter is located on the medial side of the femur and is typically more pronounced when the legs are externally rotated. As a result, the radiographic projection will show it prominently, making it easier to assess for any abnormalities. The other options pertain to structures that may not be as clearly defined in this particular positioning. For instance, while the greater trochanter can often be visualized, it tends to be more clearly displayed when the legs are in a neutral position. The ischial tuberosity and pubic symphysis, located in different areas of the pelvis, may also not be as distinct under these circumstances compared to other positioning techniques. Thus, the external rotation specifically enhances the visibility of the lesser trochanter.