Understanding Hip Xrays
Here are a series of xrays that are illustrated and annotated to identify the anatomic landmarks and concepts that are used during total hip arthroplasty. Please click on the thumbnail image to launch a full sized image that is annotated with the correct landmarks.
normal male pelvic anatomy xray female pelvis xray with osteopenia
The first Xray is of a 35 year old male with no arthritis of the hip. The second Xray is of the pelvis in a 53 year old female with osteopenia. She is post-menopausal and has a borderline osteoporosis of the hips. Notice that the bone in the area of the calcar is much thinner and the cortex of the femoral shaft is much thinner as well. The third Xray is of an elderly female with severe osteoarthritis of the left hip. The first thing to notice about this film is that in contras to the 1st two films which have equal leg lengths, this Xray demonstrates apparently unequal leg lengths. Often the legs are in truth exactly the same length, but they appear different because the arthritic process causes a contraction of the muscles and tendons about the hip. In my practice it is of paramount importance that the xray is taken in the standing position and the patient and I agree on what will be our criteria for deciding on equal leg lengths.
In the next Xray I illustrate how leg lengths are most commonly determined and also illustrate femoral offset — the distance between the longitudinal axis of the femur and the center of acetabulum. This is also an important measurement because increased offset is often associated with persistent post-operative thigh pain, whereas insufficient offset is often associated with a sense that the hip is weak, or unstable.