Femur - AP

Radiographic Positioning

Adult

Other related pages of interest Applied Radiography Radiographic Anatomy Radiographic Protocols

Name of projection	Femur - AP This table looks at the proximal femur. See table below for the distal femur.
Area Covered	Majority of femoral shaft, femoral head, femoral neck, acetabulum,
Pathology shown	Fractures, tumours, infection
Radiographic Anatomy	Femur Radiographic Anatomy
IR Size & Orientation	35cm x 43cm Portrait
Film / Screen Combination	Regular (CR and DR as recommended by manufacturer)
Bucky / Grid	Moving or stationary grid
Filter	No
Exposure	70 kVp 16 mAs
FFD / SID	100cm
Central Ray	Directed to mid-femur Perpendicular to the IR
Collimation	Centre: Position the upper edge of IR at the level of anterior superior iliac spine (ASIS) Shutter A: To full 43 cm Shutter B: Within 1.25cm (half an inch) of the skin line If the entire femur cannot be included in a single image, two must be taken with a minimum of 5 cm (2 inches) overlap. The size of the second IR will depend on the coverage required. In this case it may be simply an AP knee.
Markers	Distal/LateralMarker orientation is AP
Shielding	Gonadal shielding may obscure essential anatomy (check your department's policy guidelines)
Respiration	Not applicable
Positioning	Patient supine Check there is no pelvic rotation (do this by checking that the ASIS's on each side are equal distance from the table top) Internally rotate who leg 15 degrees to get the femur in true AP (this places the femoral neck in profile) NOTE: do NOT internally rotate if fracture is suspected
Critique PACEMAN	Positioning AP positioning of the femur is evidenced by The femoral neck is shown in profile The greater trochanter is in profile laterally The lesser trochanter is super-imposed by the femoral neck Area Covered Majority of femoral shaft, obturator foramen, pelvic brim, ischial spine, acetabulum, femoral head, femoral neck Collimation Centre: Position the upper edge of IR at the level of ASIS Shutter A: To full 43 cm (17 inches) Shutter B: Within 1.25cm (half an inch) of the skin line Exposure Bony trabeculation is evident on the femoral shaft Soft tissues are well visualised
Special Notes	Pelvic rotation If the pelvis is rotated one side will be postioned closer to the IR The side closest to the IR will exhibit The ischial spine without super-imposition of the pelvic brim A decreased obturator foramen The side furtherest from the IR will exhibit The ischial spine closer to the acetabulum An increased obturator foramen External foot position Failure to internally rotate the foot results in the femur not being in an AP position, this will result in: foreshortening of the femoral neck more of the lesser trochanter is visualised with increasing external rotation. NOTE: Do NOT attempted to internally rotate the femur if a fracture is suspected

Name of projection	Femur - AP This table looks at the distal femur. See table above for the proximal femur. The AP femur projection must cover the entire femur and include the hip joint and the knee joint. If this can not fit onto one film, two must be taken with a minimum of 5 cm (2 inches) overlap. The size of the second IR will depend on the amount of coverage required. In this case it may be simply an AP hip.
Area Covered	Distal 2/3rds of femur, femoral condyles and epicondyles, knee joint, proximal tibia and fibula
Pathology shown	Fractures, lesions
Radiographic Anatomy	Femur Radiographic Anatomy
IR Size & Orientation	35cm x 43cm Portrait
Film / Screen Combination	Regular (CR and DR if available )
Bucky / Grid	Table bucky
Filter	No
Exposure	70 kVp16 mAs
FFD / SID	115cm
Central Ray	Directed to mid-femur Perpendicular to the IR
Collimation	Centre: Position the lower edge of IR 5cm (2 inches) below the knee joint Shutter A: To full 43 cm (17 inches) Shutter B: Within 1.25cm (half an inch) of the skin line
Markers	Distal/Lateral Marker orientation is AP
Shielding	Gonadal (check your department's policy guidelines)
Respiration	Not applicable
Positioning	Patient supine Knee fully extended Internally rotate knee until it is in true AP, about 5 degrees Femur aligned to table and mid-point of IR NOTE: if fracture is suspected do not rotate leg
Critique PACEMAN	Positioning AP positioning of the femur is evidenced by Femoral epicondyles are in profile Femoral condyles are symmetrical Super-imposition of the fibula head by the tibia is about 0.5 cm (one quarter of an inch) The knee joint space is open but appears narrowed due to the divergent rays Tibial anterior and posterior margins are super-imposed also due to divergent rays Area Covered Distal 2/3rds of femur, femoral condyles and epicondyles, knee joint, proximal tibia and fibula Collimation Centre: Position the lower edge of IR 5cm (2 inches) below the knee joint Shutter A: To full 43 cm (17 inches) Shutter B: Within 1.25cm (half an inch) of the skin line Exposure Bony trabeculation is evident on the femoral shaft Soft tissues are well visualised
Special Notes	Effect of incorrect knee rotation The condyle furtherest from the IR will appear larger. Use this to determine which way to rotate the patient to obtain a true AP position