Chapter objectives
Chapter objectives
2. Identify the location of the major landmarks of the pelvis and hip and describe two methods of locating the femoral head and neck on an AP hip and pelvis radiograph.
The crests of the ilium and ASIS are important positioning landmarks. The superior margin of the symphysis pubis is a possible landmark for pelvis and hip positioning and for positioning of the abdomen because it defines the inferior margin of the abdomen. However, if other associated landmarks are available, the symphysis pubis is generally not used as a palpated landmark because of patient modesty and potential embarrassment. The greater trochanter can be located by firm palpation of the soft tissues of the upper thigh. The prominence of the greater trochanter is about the same level as the superior border of the symphysis pubis whereas the ischial tuberosity is 1 1/2 to 2 inches below the symphysis pubis. Determine the midpoint of a line between the ASIS and the symphysis pubis. The neck is approximately 2 1/2 inches and the head 1 1/2 inches distal and at right angles to the midpoint of this line.
3. List the structural and functional differences of the greater and lesser pelvis and the structural difference between the male and female pelvis.
The general area above or superior to the oblique plane through the pelvic brim is termed the greater or false pelvis. The flared portion of the pelvis that is formed by the wings of the ilia forms the lateral and posterior limits of the false pelvis whereas the abdominal muscles of the anterior wall define the anterior limits. The inferior portion is termed the lesser or true pelvis. It is a cavity that is completely surrounded by bony structures, and it forms the actual birth canal.
The general shape of the female pelvis is wider with the ilia more flared and shallower from front to back. The male pelvis is narrower, deeper or less flared with a heart shaped pelvic inlet.
4. List the correct classification and movement type for the pelvic joints.
Sacroiliac joint- synovial, limited movement, irregular gliding.
Symphysis pubis- cartilaginous- amphiarthrodial.
Union of acetabulum- cartilaginous- synarthrodial, non-moveable.
Hip joint- synovial- diarthrodial, ball and socket.
8. Determine whether a pelvis of hip is in a true AP position based on the established radiographic criteria.
Lesser trochanters should not be visible at all. Great trochanters should appear equal in size and shape. No rotation is evidenced by symmetric appearance of the iliac alae or wings, the ischial spines and the two obturator foramina. A foreshortened or closed obturator foramen indicates rotation in that direction. The right and left ischial spines should appear equal in size. Correct centering evidenced by demonstration of entire pelvis and superior femora without foreshortening in collimated field.