Femur Radiographic Technique Flashcards
What are the standard projections for a femur radiograph in adults?
AP femur (supine) and lateral femur (supine)
*AP proximal (hip down with grid) AP distal (knee up, no grid)
*Lateral proximal (hip down with grid), lateral distal (knee up, no grid)
Full AP and lateral femur for children with no grid, IR placed diagonally.
What are the sample adult exposure factors for a proximal femur radiograph?
Use 70 kVp and 20-25 mAs with a grid
SID/FFD set at 100 cm, tube angle at 0°, broad focal spot size
Ensure image orientation is portrait with hip at the superior aspect.
Describe the positioning and technique for an AP proximal femur radiograph.
Patient lies supine with legs extended, IR in table bucky with grid
Top of IR aligned with ASIS level, unaffected leg abducted
Affected leg is internally rotated to centralize the patella
Use a vertical central ray perpendicular to the IR centered on the femur shaft
Collimation includes hip joint, 2/3 proximal femur, and skin borders.
What are the positioning steps for a lateral proximal femur radiograph?
From the AP position, patient rolls onto affected side with femur against the table
The IR is positioned in the table bucky with a grid, top aligned with ASIS level
Unaffected limb is supported on foam pads behind the patient
Central ray is perpendicular to the IR, centered on the proximal femur shaft
Collimation includes hip joint, 2/3 proximal femur, and skin borders.
How should a patient be positioned for an AP distal femur radiograph?
Patient lies supine with legs extended, IR directly under affected femur
Ensure the knee joint is included, unaffected leg abducted
Rotate the affected leg internally to centralize the patella
Vertical central ray is centered on the distal femur shaft
Collimation includes knee joint, 2/3 distal femur, and skin borders.
What is the correct technique for a lateral distal femur radiograph?
Patient rolls onto the affected side with femur against the table, knee flexed
IR positioned under the affected femur in either portrait or diagonal orientation
Center the affected limb on the IR, ensuring 5 cm below the knee joint is included
Vertical central ray perpendicular to IR, centered on the distal femur shaft
Collimation includes 5 cm distal to knee joint, 2/3 distal femur, and skin borders.
What are the key image evaluation points for an AP proximal femur?
Ensure the ROI includes hip joint, ASIS, and proximal 2/3 femur with skin borders
True AP positioning evidenced by femoral neck profile, lateral greater trochanter, and lesser trochanter overlap
Bone and soft tissues should be well visualized with bony trabeculation evident.
Describe the proper evaluation for a lateral proximal femur image.
ROI should include hip joint, ASIS, and proximal 2/3 femur with skin borders
Greater trochanter superimposes the femoral neck, and femur is centered in the field
No superimposition of the opposite thigh, and bone and soft tissues are clear.
What positioning error occurs if the femur is not internally rotated for a proximal femur x-ray?
The femoral neck will appear foreshortened, and the lesser trochanter will be more visible with increased external rotation.
What are the primary clinical signs of a neck of femur (NOF) fracture?
The affected limb often presents shortened and externally rotated due to the iliopsoas muscle pull, especially in elderly patients after a minor fall.
What are the key image evaluation points for an AP distal femur radiograph?
Region of Interest (ROI): Ensure the ROI includes the distal 2/3 of the femur, knee joint, proximal tibia and fibula, and skin borders.
Positioning Indicators: Proper AP positioning is shown by the femoral epicondyles in profile, with approximately one-third of the fibula head superimposed by the tibia.
Knee Joint Space: The knee joint should appear open, though it may appear narrowed due to divergent rays.
Exposure and Contrast: Bone trabeculation should be evident along the femoral shaft, with both bone and soft tissues well visualized.
