Pelvis and Hips

Evaluation Criteria Structures shown Position/projection Collimation/central ray Exposure criteria Acceptable and unacceptable pelvis and hip images based on errors i.e.: Motion Collimation Positioning Exposure factors Side markers and patient demographic information Every time a radiographer completes an image, an evaluation must be made to determine whether the image is diagnostically optimal for the radiologist to provide an accurate diagnosis. A radiologist should NEVER have to return an image for repeat if proper evaluation of the image is done by the radiographer. Here are five basic criteria for radiographic evaluations and critique. These should be used every time a radiographic image is performed.

Introduction <Image 1> The pelvic girdle is divided into three parts which are connected by cartilage in the youth and fused in the adult: ilium, pubis, and ischium. The hip is a diarthrodial, ball-and-socket joint located between the proximal extremity of the femur and the pelvic girdle. The joint is capable of a wide range of movements including flexion, extension, abduction, adduction, lateral rotation and medial rotation. The term pelvis means basin, used to describe the irregularly shaped opening created by the two hip bones, the sacrum, and coccyx. The opening within the pelvis is often separated into the greater and lesser segments, sometimes referred to as the true and false pelvis, by an oblique plane at the pelvic inlet. The pelvis transmits the weight of the upper body to the lower limbs and forms the lower part of the abdominal cavity.

AP Pelvis Basics <Images 2, 3> The AP projection of the pelvis provides a general survey of the bones of the pelvis and the head, neck, and greater trochanter of each of the femora.

AP Pelvis Imaging Criteria Technical Considerations Regular IR Grid kVp range: 85-90 SID: 40 inches (100 cm) IR size 14 x 17 inch (35 x45) Patient Position Supine on the table Patient should be dressed in a gown with clothing from the waist down removed Part Position Midsagittal plane of the body should be centered to the midline of the table Shoulder should be adjusted to lie in the same transverse plane Elbows should be flexed with the hands resting on the upper chest Pelvis should be adjusted so that it is not rotated (distance from the ASIS and table top is the same on both sides) Feet should be internally rotated approximately 15 degrees IR is positioned so that its upper border is 1 to 1 ½ inches (3-4 cm) above the iliac crest Central Ray (CR) CR perpendicular to the mid point of the IR (approximately 2 inches superior to the symphysis pubis) Patient Instructions “Take a breath and hold it, don’t breathe or move.” Evaluation Criteria Entire pelvis and proximal femora should be visualized Pelvis should not be rotated as evidenced by: Symmetrical iliac alae Symmetrical obturator foramina Visualization of ischial spines equally on both sides Sacrum and coccyx aligned with the symphysis pubis Little or none of the lesser trochanters should be visible beyond the medical edges of the femora Greater trochanters should be fully visualized Density should be sufficient for femoral heads to be demonstrated through the acetabula Click each button for more information about imaging the AP pelvis. Technical Considerations Evaluation Criteria Additional Information

Knowledge Check <Image #3> With the legs turned in 15 degrees for an AP pelvis, what happens to the visualization of the lesser trochanter? It is almost invisible It is in profile About 2/3 of the lesser trochanter is visible It stays the same

AP Frog Lateral Pelvis Basics <Images 6, 18> The AP frog lateral pelvis (modified Cleaves method) is performed for the investigation of congenital hip disease. It is contraindicated in patients with suspected fractures or pathologic hip disease.

AP Frog Lateral Pelvis Imaging Criteria Technical Considerations Regular IR Grid kVp range: 85-90 SID: 40 inches (100 cm) IR size 14 x 17 inch (35 x45) Patient Position Supine on the table Patient should be dressed in a gown with clothing from the waist down removed Part Position Midsagittal plane of the body should be centered to the midline of the table Shoulder should be adjusted to lie in the same transverse plane Elbows should be flexed with the hands resting on the upper chest Pelvis should be adjusted so that it is not rotated (distance from the ASIS and table top is the same on both sides) Knees should be flexed and the feet drawn up as much as possible This will place the femora to be abducted to approximately a 40 degree angle from the vertical Central Ray (CR) CR perpendicular to a point 1 inch (2.5 cm) superior to the symphysis pubis Patient Instructions “Take a breath and hold it, don’t breathe or move.” Evaluation Criteria Image should include acetabula, femoral heads, and necks Pelvis should not be rotate as evidenced by: Symmetrical iliac alae Symmetrical obturator foramina Visualization of ischial spines equally on both sides Sacrum and coccyx aligned with the symphysis pubis Lesser trochanter should be projected on the medial side of the femur Additional Information This is a modification of the original Cleaves method, which called for a cephalic angulation to parallel the long axis of the femora Click each button for more information about imaging the AP frog lateral pelvis. Technical Considerations Evaluation Criteria Additional Information

Knowledge Check <Image 18 and 20> Label the following anatomy: Femoral head, Femoral head within acetabulum, Femoral neck, Greater trochanter, Lesser trochanter

AP Hip Basics <Images 8 and 13> The AP hip is performed to visualize the head, neck, trochanter and proximal third of the femoral shaft. The AP hip is usually performed unilaterally when there is a follow up evaluation of a hip prosthesis or other orthopedic hardware and/or follow up on pathology and trauma.

AP Hip Imaging Criteria Technical Considerations Regular IR Grid kVp range: 85-90 SID: 40 inches (100 cm) IR size 10 x12 inch (24 x 30) Patient Position Supine on the table Patient should be dressed in a gown with clothing from the waist down removed Part Position Sagittal plane 2 inches medial to the ASIS of the affected side should be centered to the midline of the table Shoulder should be adjusted to lie in the same transverse plane Elbows should be flexed with the hands resting on the upper chest Pelvis should be adjusted so that it is not rotated (distance from the ASIS and table top is the same on both sides) Foot should be internally rotated approximately 15 degrees IR should be centered to the upper limit of the greater trochanter Central Ray (CR) CR perpendicular to the midpoint of the IR (approximately 2 inches medial to the ASIS of the affected side at the level just above the greater trochanter) Patient Instructions “Take a breath and hold it, don’t breathe or move.” Evaluation Criteria Little or none of the lesser trochanter should be visible beyond the medial edge of the femur Greater trochanters should be full visualized Density should be sufficient for the femoral head to be demonstrated through the acetabulum Additional Information In the initial examination of the hip, an AP pelvis is often done to demonstrate the entire pelvic girdle and both upper femora Follow-up studies are confined to the affected side If an orthopedic appliance is in place, AEC should not be used A larger IR may be required to demonstrate the entire prosthesis Click each button for more information about imaging the AP hip. Technical Considerations Evaluation Criteria Additional Information

Knowledge Check <Images 12-13> Label the following anatomy: Ilium, Acetabulum, Femoral head, Greater trochanter, Pubis symphysis, Femoral neck, Lesser trochanter, Femoral shaft

Lateral Hip Basics <images 7 and 9-1> The lateral hip provides an orthogonal image of the hip joint. Structures demonstrated on the radiograph include the proximal femur and the acetabulum. This position is contraindicated in patients with suspected fractures or pathologic hip disease.

Lateral Hip Imaging Criteria Technical Considerations (image evaluation criteria) Regular IR Grid kVp range: 85-90 SID: 40 inches (100 cm) IR size 10 x12 inch (24 x 30) Patient Position Supine on the table Patient should be dressed in a gown with clothing from the waist down removed Part Position Patient should flex the knee and turn slightly toward the affected side and abduct the leg to place the femur parallel to the IR Center the hip (midway between the ASIS and the symphysis pubis) to the midline of the table Unaffected leg should be extended behind the affected leg Central Ray (CR) CR perpendicular to the hip Patient Instructions “Take a breath and hold it, don’t breathe or move.” Evaluation Criteria Hip joint should be centered to exposed area Any orthopedic appliance should be seen in its entirety Additional Information In the initial examination of the lateral hip, a bilateral frog leg pelvis is often done to demonstrate the entire pelvic girdle and lateral view of both upper femora Follow-up studies are confined to the affected side If an orthopedic appliance is in place, AEC should not be used A larger IR may be required to demonstrate the entire prosthesis This position should not be used when a fracture is suspected because of the possibility of displacing fracture fragments. A superoinferior projection should be done instead Click each button for more information about imaging the lateral hip. Technical Considerations Evaluation Criteria Additional Information

Knowledge Check <Image 9-1> What is the arrow pointing at in this lateral hip image? Femoral neck Acetabulum, Obturator foramen Fractured femoral head

Cross Table Lateral Hip Basics <Images 9, 16> This lateral position of hip is indicated when the patient cannot be positioned for a routine lateral hip position. It is also called the Danelius-Miller Method.

Cross table Lateral Hip Criteria Technical Considerations Regular IR Grid kVp range: 85-90 SID: 40 inches (100 cm) IR size 10 x12 inch (24 x 30) Patient Position Supine on the table Patient should be dressed in a patient gown with clothing from the waist down removed Part Position Knee of the affected leg should be extended unless contraindicated Unless contraindicated, internally rotate the foot to the affected side 15 degrees Flex the knee and hip of the unaffected side and raise the leg using some suitable support for the leg Top of the cassette should be at the top of the iliac crest and should be parallel to the femoral neck and perpendicular to the CR Central Ray (CR) CR horizontal, perpendicular to the hip (about 2 ½ inches or 7 cm below the intersection of the localization points described Patient Instructions “Take a breath and hold it, don’t breathe or move.” Evaluation Criteria Proximal femur, hip joint, and acetabulum should be visualized As much as possible of the femoral neck should be visualized Only a small portion of the lesser trochanter should be seen on anterior and posterior femur Additional Information To localize the long axis of the femoral neck, draw a line between the ASIS and the superior border of the symphysis pubis and note its center point. Palpate the most prominent lateral protrusion of the greater trochanter and note a point 1 inch distal to it. A line drawn between these two point will parallel the long axis of the femoral neck Click each button for more information about XYZ Technical Considerations Evaluation Criteria Additional Information

Knowledge Check <Images 16-17> Label the following anatomy: Acetabulum, Femoral head, Femoral neck, Greater trochanter, Lesser trochanter, Ischial tuberosity, Posterior surface

Summary Imaging of the pelvis and hip is often performed post initial trauma where the survey images are taken to determine the extent of injury. These types of images are used to assess the orthopedic appliance and healing process.