Chapter 7: Femur/Pelvis/Hip Flashcards

Question

Radiographic Positioning Considerations (Pelvis) Method

Answer 1

1”-2” medial and 3”-4” distal from ASIS

Answer 2

Anatomical position

Answer 3

Medial rotation

Answer 4

External rotation (neutral)

Answer 5

**Typical rotation with fracture** Do not attempt to rotate a fractured hip, could cause displacement or severe the femoral artery

Answer 6

- IR 14x17 lengthwise (portrait), 40 SID 75-80 kVp, 70 kvp- distal 75 kvp- proximal (if on table use table bucky!) - Pt supine with femur centered to midline of table or stretcher. Rotate leg internal **5º for distal femur** and **15-20º for proximal femur**. Condyles should be parallel to IR even if proximal or distal. Ensure knee joint is included on IR (2” of knee joint). - CR perpendicular to IR and femur, direct to midpoint of IR. Include area of interest on larger IR, overlap 2-3” of shaft. Marker placed lateral, in thinnest area of ST shadow - Anatomy: Distal 2/3 of femur including knee joint is shown. Knee joint space won't appear fully open. because of divergent beam. - Position: No rotation, femoral and tibial condyles should appear symmetric, patella towards medial side of femur. Medial half of fibular head superimposed by tibia. Femur centered with minimum of 1” knee included, collimate to ST margins. - Exposure: No motion- clear bony trabeculae, even density (brightness) of entire femur. Fine trabecular markings are clear and sharp throughout lenth of femur.

Answer 7

- IR 14x17 portrait, 40 SID, 75-80 kVp - Pt in lateral recumbent on affected side (supine if x-table is performed). Flex knee 45º. Align femur to midline of table or IR. Place unaffected leg behind patient. - X-table: place support under the affected leg and knee, support foot & ankle in true AP position (unless severe trauma). Place IR along medial aspect of femur - CR perpendicular to femur and directed to midpoint of IR Adjust IR to include 2” of knee joint. Collimate on both sides. MARKER ANTERIOR FOR LATERAL - Anatomy: Distal 2/3 of femur including minimum of 1” knee joint. Knee joint not open, distal femoral condyles won't be superimposed due to divergent rays. - Position: True lateral demonstrated by anterior and posterior margins of femoral condyles superimposed and aligned with open patellofemoral joint space. Femur centered to collimation field with knee joint space minimum of 1” from distal IR margin. Collimation to include ST margins - Optimal exposure, near-uniform density of distal and prox femur. No motion-bony trabecular detail

Answer 8

- IR 14x17 portrait, 40 SID, 75-80 kVp - Patient in lateral recumbent position with affected side down. Flex affected knee 45º, align femur to midline of table/IR. Extend unaffected leg behind patient, have patient rotate posteriorly 10-15º to prevent superimposition of proximal femur and hip joint. - Adjust IR to include hip joint (upper IR at level of ASIS) **Suspend respiration** - CR perpendicular to femur, directed to midpoint of IR. Collimate to include minimum 1” of hip joint and to ST margins. - Anatomy: Prox ½ to 2/3 of proximal femur, including hip joint. Prox femur and hip joint **should not** be superimposed by opposite leg. - Position: Superimposition of greater and lesser trochanters by femur, with only a small part of the trochanters visible on medial side. Most of greater trochanter superimposed by the neck of the femur. - Exposure: Uniform density of entire femur, no motion, sharp bony trabecular detail

Answer 9

- IR 10x12 (14x17 for prosthesis), 40 SID, 75-80 kVp - **Do not rotate leg if fracture is obvious or suspected**. Pt supine, arms by side or on chest (pt. with fx. will often hold affected hip). Locate femoral neck and align to CR and midline of table/IR. Ensure no rotation of pelvis (palpate ASIS). Rotate affected leg 15-20º. **Suspend respiration**. - CR perpendicular to femoral neck (femoral neck 1-2” medial & 3-4” distal to ASIS). 2 sided collimation at least. - Anatomy: Evidence of proper collimation. Most of the femur and the joint nearest to the pathologic site (a 2nd projection of the other joint is recommended.) - Position: Femoral neck not foreshortened on the proximal femur. Lesser trochanter not seen beyond the medial border of the femur or only a very small portion seen on the proximal femur. Prosthesis included in it’s entirety. - Exposure: Sharp cortical and trabecular markings-no motion

Answer 10

- IR 10x12 landscape (can be done portrait, depending on patient), 14x17 for hip prosthesis, 40 SID, 75-80 kVp - Pt supine, align affected hip with CR, midline of table or IR. Flex knee and hip of affected side, sole of foot against inside of opposite leg, as near knee as possible. Abduct femur 45º from vertical (optimal is 20-30 º to prevent foreshortening), angle sponge under knee, sole of foot next to other tib/fib. Center affected femoral neck to midline of CR & IR. 1-2” medial, 3-4” distal. **Suspend respiration** - CR perpendicular to IR, directed to midfemoral neck. Collimate to all 4 sides of interest - Anatomy: Demonstrates lateral view of acetabulum and femoral head & neck, trochanters, prox 1/3 of femur are visible. - Position: Proper abduction (45º) of femur demonstrated by femoral neck seen in profile, superimposed by greater trochanter. Femoral neck in center of collimated field. - Optimal exposure shows margins of femoral head & acetabulum through overlying pelvic structures w/o overexposing prox femur. Sharp bony trabecular details and ST, no motion.

Answer 11

- IR 14x17 landscape, (can use 10x12 for pediatrics). Minimum 40 SID (can use more distance for a larger pelvis to project divergent rays & decrease magnification), 75-85 kVp - Pt supine, arms by side or on chest, can be done upright to evaluate joint spaces. Align MSP of pt to center of bucky/IR. Ensure pelvis is not rotated (ASIS equal). Separate legs and feet, internally rotate WHOLE LOWER EXTREMITY 15-20º. Use support devise if patient can’t hold position (tape/sandbags). **Suspend respiration** - CR perpendicular to IR directed midway between between the level of ASIS & pubic symphysis (2” below ASIS). Ensure top of crest is in light field. Collimate to 4 sides of anatomy - Anatomy: Include pelvic girdle, L5, sacrum & coccyx, femoral head, neck, trochanters visible. - Position: Lesser trochanters should not be visible, or minimally on medial side. Greater trochanters visible & equal in size and shape. No rotation evidenced by symmetric appearance of ilia alae (wings), ischial spines and both obturator foramina (a closed obturator foramina indicates rotation in that direction). Correct centering by entire pelvis and superior femora without foreshortening in collimated field. - Optimal exposure, visualizes L5 and sacrum area, margins of femoral heads and acetabula overlying pelvic structures. No overexposure of ischium and pubic bones. Femora and pelvic structures with sharp bony trabecular detail- no motion

Answer 12

- IR 14x 17 landscape, minimum 40 SID, 75-85 kVp. (Shield if possible. Dont use center cell for AEC if female patient is shielded). - Pt supine, align patient to midline of table/IR. Ensure no rotation of pelis. Flex both knees 90º. Place plantar surfaces of feet together and abduct femora 40-45º from vertical. Center CR at level of femoral heads, top of IR 1” above iliac crests. Ensure both femora are abducted equal amounts. Provide sponge under each knee if necessary. **Suspend respiration.** - CR perpendicular to IR, directed to a point 3" below level of ASIS (1" below symphysis pubis). - Anatomy Demonstrates: femoral heads, necks, acetabulum, and trochanters. - Position: No rotation evidenced by symmetric appearance of pelvic bones (ala of ilium), 2 obturator foramina & ischial spines if visible. Femoral heads, necks, and greater and lesser trochanters equal if thighs are abducted equally. Lesser trochanters equal in size projected beyond medial lower margin of femora. Most of greater trochanters superimposed over femoral necks, which appear foreshortened. Collimate to area of interest. - Optimal exposure visualizes margins of femoral head and acetabulum through overlying pelvic structures without overexposing prox femora. St boney trabecular detail- no motion

Answer 13

- IR 10x12 landscape (lengthwise to long axis of femur) 14x17 for prothesis, 40 SID, 80-90 kVp - Pt supine, table/stretcher/bed. Elevate pelvis 1-2” (towel-sheet etc). Flex & elevate unaffected leg so thigh is near vertical position & outside collimation field. Support foot/ankle on support devise. Ensure no rotation of pelvis. Localize femoral neck- 2” medial” 4” distal to ASIS. Place top of IR in crease above iliac crest of affected side. Adjust IR to be parallel with femoral neck & perpendicular to CR. Internally rotate affected leg 15-20º unless contraindicated. **Suspend respiration ** - CR perpendicular to IR and femoral neck. Collimate to 4 sides, close collimation important for detail and reducing pt dose. - Anatomy: Entire femoral head, neck, trochanter & acetabulum visualized w/ prosthetic devise. Only small part-if any of lesser trochanter visualized with medial rotation of leg. - Distal portion of femoral neck superimposed by greater trochanter. ST of elevated leg not superimposing affected hip. No grid lines. - Optimal density, visualize femoral head and acetabulum without over exposure of neck and shaft of femur

Answer 14

(lateral oblique when patient has limited ROM of unaffected side) - IR 10x12 landscape or 14x17 for prosthesis, 40 SID, 80-90 kVp - Pt supine affected side near edge of table with both legs fully extended. Neutral position of legs. Place IR on table bucky, or in grid holder positioned below table/stretcher. Tilt IR about 15º from vertical so IR is perpendicular to CR. **Suspend respiration** - CR angled mediolaterally with 15-20º posterior angle from horizontal. Collimate to 4 sides of anatomy - Anatomy: Lateral oblique views of acetabulum, femoral head and neck, trochanters. - Position: Femoral head and neck visualized in profile with minimal superimposition of greater trochanter. Lesser trochanter projected posterior to femoral neck. Femoral head, neck, and trochanters in center of IR - Optimal density-no motion. Due to angle, lesser trochanter seen more

Answer 15

- IR 14 x17 landscape, 40 SID, 75-85 kVp - Pt supine with legs extended, support for knees. Align MSP to CR and midline of table/IR. Ensure no rotation of pelvis (equidistance of ASIS). Angle CR 20-35º for males and 30-45º for females **cephalad**. Suspend respiration - Direct CR to midline (MSP) 1-2” distal to superior border of pubic symphysis or greater trochanters. Collimate to 4 sides of interest - Anatomy: Demonstrates superior and inferior rami of pubis, body and ramus of ischium with minimal foreshortening or superimposition. - Position: No rotation demonstrated by obturator foramina and bilateral ischia equal in size and shape. Correct CR angle evidenced by ant/inf pelvic bones with minimal foreshortening. Midpoint of pubic symphysis center of collimated field. - Optimal exposure demonstrates body and sup rami of pubis well demonstrated without over exposure of ishium. No motion

Answer 16

Assessment for posterior displacement or inward or outward rotation of anterior pelvis - IR 14x17 landscape, 40 SID, 75-85 kVp - Pt supine legs extended knee support. Align MSP to CR and table/IR. No rotation (ASIS equal) - CR angle 40º **caudad**- near perpendicular plane of inlet. CR enters midpoint between ASIS level - Anatomy: Axial projection to demonstrate pelvic ring-inlet in entirety - Position: No rotation-ischial spines fully demonstrated and equal in size and shape. Proper centering and angulation, evidenced by demonstration of the superimposed anterior and posterior portions of the pelvic ring. Center of inlet to center of collimated field. - Optimal exposure demonstrates superimposed anterior and posterior portions of pelvic ring, ala are overexposed. Sharp bony trabeculae of pubic and ischial bones. No motion

Answer 17

- IR 10x 12 portrait for unilateral, 14x17 landscape for bilateral, 40 SID, 75-85 kVp. - Bilateral for comparison. Pt semi-supine. Position for side up or side down- posterior oblique position. Place pt. 45º posterior oblique, ensure both pelvis and thorax are at 45º. Support with wedge. Align femoral head and acetabulum of interest to midline of TT/IR. Center IR perpendicular to CR at level of femoral head - CR affected side down: perpendicular and centered 2” distal and 2” medial to downside ASIS - CR affected side up: perpendicular and centered 2” directly distal to upside ASIS - Collimate to 4 sides of interest. - Anatomy: Downside of acetabulum, anterior rim of acetabulum and posterior (ilioischial column) and iliac wing demonstrated. - Position: Upside of acetabulum, posterior rim of acetabulum and anterior iliopubic column and obturator foramen demonstrated. Proper obliquity- open and uniform hip joint space at the rim of acetabulum and femora head. Obturator foramen should be open for upside oblique and closed for downside oblique. Acetabulum centered to IR and collimation field. - Optimal exposure of acetabulum and femoral heads, bony trabecular detail. Sharp markings, no motion