Radiographic Procedures: Essential Projections of the Leg, Knee, Intercondylar Fossa, Patella, and Femur

Artifact Removal: Remove all artifacts from the anatomy of interest to ensure clarity in imaging.
- Shoes
- Socks or hose (elastic can create artifacts)
- Heavy fabrics such as denim can obscure views.
- Undergarments may also need to be removed.
Gown Provision: Provide the patient with a gown to eliminate artifacts stemming from regular clothing.

Ambulatory Patients:
- Can be seated or supine on the x-ray table.
- The affected limb should rest on the image receptor (IR) placed on the tabletop.
- The Bucky tray is used for larger parts.
Non-Ambulatory Patients:
- Position adjustment to ensure maximum patient comfort.
- Transfer from a stretcher to the table is not required.
- Use a grid image receptor for larger body parts.

Follow the textbook guidelines for IR size and collimation.
- Use the smallest IR that will clearly demonstrate all areas of interest.
- Long bones may require two images to demonstrate the entire bone and adjacent joints.
- Avoid using a larger field size than necessary to prevent scatter radiation.

Standardized SID as part of procedural protocol is set to 40 inches for the majority of projections.

Right or left side markers must be included in the images for point of reference.
Additional identification markers should be included where required—in the blocker or elsewhere on the final image.
Avoid using digital annotation solely for marking sides on images.

Special provisions should be made for pediatric patients and patients of reproductive age.
Other measures include:
- Close collimation to focus the x-ray beam.
- Use of optimum technique factors to minimize radiation exposure.

AP (Anteroposterior)
Lateral (Mediolateral)
- For both projections, either placement of the cassette in a “kiddie” corner or two films may be necessary to capture the entire leg.

Must be 1 inch (2.5 cm) on the sides and 1½ inches (4 cm) beyond both the ankle and knee joints.

Patient Position: Supine.
Part Position:
- Ensure pelvis is without rotation.
- Femoral condyles should be parallel with the IR.
- Ankle must be flexed to place the foot in a vertical position.
CR (Central Ray): Perpendicular to the center of the leg.
SID: 40 inches.

Evidence of proper collimation.
Ankle and knee joints should be visible on one or more images.
The entire leg must appear without rotation; proximal and distal articulations of the tibia and fibula moderately overlapped.
Fibular midshaft should be free of tibial superimposition, ensuring clarity in soft tissue and bony trabecular detail.

Patient Position:
- Rotate towards the affected side so the patella is perpendicular to the IR.
Part Position:
- The lateral surface of the leg should be resting on the IR.
- The patella must be perpendicular to the IR.
- Femoral condyles should be superimposed and perpendicular to the IR, with the knee flexed if necessary for a true lateral view.
CR: Perpendicular to the midpoint of the leg.
SID: 40 inches.

Evidence of proper collimation.
The knee and ankle joints should be visible on one or more images.
The entire leg must be positioned in true lateral alignment; the distal fibula should lie over the posterior half of the tibia with slight tibial overlap at the proximal fibular head.
Moderate separation of the shafts of the tibia and fibula is ideal, except for their articular ends.
Soft tissue features and bony trabecular detail should be clearly visible.

Patient Position: Supine.
Part Position:
- Knee should be fully extended, if possible.
- Femoral epicondyles must be parallel to the IR.
CR Variable: Based on the measurement from the anterior superior iliac spine (ASIS) to the tabletop (see angle adjustments below).
- <19 cm = 3 to 5 degrees caudad.
- 19 to 24 cm = perpendicular.
- >24 cm = 3 to 5 degrees cephalad.
- CR enters ½ inch (1.3 cm) below the apex of the patella.
Collimated Field: Adjust to 10 x 12 inches (24 x 30 cm).

Evidence of proper collimation.
The knee must be fully extended if patient's condition allows.
The entire knee should appear without rotation with symmetric femoral condyles and the tibial intercondylar eminence centered.
Tibial head should exhibit slight superimposition of the fibular head when the tibia is normal.
The patella must be completely superimposed on the femur.
An open femorotibial joint space should be present with interspaces of equal width on both sides, given normal conditions.
Visibility of soft tissue and bony trabecular detail is essential.

Patient Position: Turned toward the affected side with the affected knee flexed and brought forward while the unaffected limb is extended behind.
Part Position:
- Flex the knee 20 to 30 degrees to show maximum volume of the joint cavity.
- If a patella fracture is suspected, limit flexion to 10 degrees to prevent fragment separation.
- The femoral epicondyles must be perpendicular to the IR with superimposing condyles.
CR: 5 to 7 degrees cephalad, entering the knee joint 1 inch (2.5 cm) distal to the medial femoral epicondyle.
Collimated Field: 10 x 12 inches (24 x 30 cm).

Evidence of proper collimation.
The knee should be flexed 20 to 30 degrees in a true lateral position, signified by superimposed femoral condyles.
Observe anterior surface distances from the patella to medial condyle for overrotation or underrotation adjustments.
Ensure the fibular head and tibia are slightly superimposed for an accurate view; too much or too little rotation alters this appearance.
Soft tissue and bony trabecular detail should be distinguishable.

Patient Position: Upright, facing the radiation source.
Part Position:
- Center knees to IR with toes straight and balance evenly distributed across both feet.
- Ensure knees are extended.
CR: Horizontal and perpendicular to the center of the IR, entering ½ inch (1.3 cm) below the patellar apex.
Collimated Field: Adjust to 14 x 17 inches (35 x 43 cm).

Evidence of proper collimation, ensuring both knees are visible without rotation.
Joint spaces of knees should be centered appropriately in the exposure.