Recording-2025-02-04T17:03:05.050Z

Lateral Medial Projection

• Projection Type: Lateral-medial projection can be performed in the lateral position using a 14x17 IR, either in portrait or diagonal orientation.

• Bone Length: Regardless of the IR orientation, the length of the bone will remain consistent.

• Patient Fit: If the patient is too large to fit diagonally on a 14x17 IR, two images can be taken sequentially (referred to as one of two, two of two).

  • Overlap Requirement: Ensure at least a 2-inch overlap between images for a complete view.

  • Initial Image: For knee pain, start imaging including the knee joint, placing the marker at the base of the IR.

  • Subsequent Image: Use a smaller IR (e.g., 10x12) for the next image focusing on the distal area, ensuring overlap with the first image's collimated field.

Image Acquisition Techniques

• Patient Positioning: Patient should roll onto their affected side with the unaffected leg placed either in front or behind to maintain a true lateral view. Preference is to place it in front of the affected leg to prevent under-rotation.

• CR Entry Point: Central Ray (CR) should be perpendicular, entering at the mid-tibia-fibula area. For one of two, two of two, the CR should align with the center of the IR.

• Dorsiflexion: Dorsiflex the foot if the patient is able to avoid over-rotation of the distal part of the leg.

• Marker Placement: For AP views, markers should be placed laterally. Always remember body part markers should be positioned laterally away from the midline.

Image Evaluation Criteria

• Collimated Field: Ensure the field extends at least 2 inches beyond both the knee and ankle joints.

• Fibular Head Alignment: Half of the fibular head should be superimposed over the tibia proximally. The fibula’s distal end should superimpose the posterior half of the tibia.

• Interosseous Space: An open interosseous space between the tibia and fibula is vital for proper imaging.

• Proximal and Distal Views: The tibial tuberosity should be visible in profile, with an open patellofemoral joint space and distal femur showing superimposition of anterior and posterior condyles. This is due to the natural medial condyle sloping 5-7 degrees from the lateral aspect.

• Bony Detail: Inclusion of trabecular detail and soft tissue visualization is essential without clipping.

• Cross-Table Imaging: In trauma situations, a lateral medial projection may be performed using a cross-table method. Utilize a sponge or towel to elevate the leg if needed, with appropriate caudal angulation to aid in joint visibility.

Knee Projections

• Tibial Plateau Angulation: Being aware that the tibial plateau slopes posteriorly by 10 to 20 degrees is crucial for proper CR angles during imaging.

• CR Measurement: When measuring from ASIS to the tabletop, adjust CR angles based on patient size (larger patients may require a cephalic adjustment). 3-5 degrees cephalic for larger patients, and caudal for smaller patients.

• Weight Bearing Views: Often necessary in arthritis perspective, take AP kneeling projections for evaluating weight-bearing knees.

• Angle for Oblique Views: Similar angle as the AP projection must be utilized in oblique views, along with maintaining hip mobility and patient comfort in positioning.

• Evaluation of Obliques: Ensure the patella is captured over the appropriate epicondyles with a proper lengthening or foreshortening based on rotation direction.

• Examining Hardware: Imaged knee must precisely encompass any prosthesis or surgical hardware, operating with sufficient collimation to display all critical details.

• Compression of Anatomy Artifacts: Awareness to remove or correctly position patient clothing that may obscure critical anatomy during examination. Summer attire often expedites this process.

Special Considerations

• Pediatric Imaging: Understanding growth plates and determining developmental age via radiological indicators are crucial in pediatric evaluations.

• Shielding Practices: Patient shielding continues during lower extremity x-rays, dropping off with pelvic and hip imaging.

• Patella Palpation: Avoid using the term