Anatomy and Positioning of the Knee Joint and Lower Limb
Continuation of Chapter 6: Tibia, Fibula, and Knee Anatomy
Tibia and Fibula (Anterior View)
**Key Anatomical Features:
Anterior crest**: A prominent ridge on the anterior side of the tibia.
Articular facets (tibial plateau): Flattened surfaces at the proximal end for articulation with femur condyles.
Body of fibula: Long, thin portion of the fibula.
Fibular notch (of tibia): Notch on the lateral side of the tibia for articulation with the fibula.
Intercondylar eminence: Projects between the medial and lateral condyles of the tibia, containing medial and distal intercondylar tubercles.
Lateral condyle: The external articulation point for the femur.
Lateral malleolus: The distal end of the fibula forming the outer ankle.
Medial condyle: The internal articulation point for the femur.
Tibial tuberosity: Projection on the anterior surface of the tibia where patellar ligament attaches.
Tibia and Fibula (Lateral View)
**Key Anatomical Features:
Articular facets (tibial plateau)**: Positioned at an angle of 10°-20° to the horizontal.
Apex of styloid process: Protruding point of the fibula.
Body (shaft) of fibula: Diaphysis of fibula.
Body (shaft) of tibia: Diaphysis of tibia.
Fibular head: Proximal end of fibula that articulates with the tibia.
Lateral malleolus: Found at the distal end of the fibula.
Medial malleolus: Found at the distal end of the tibia.
Fibular neck: The narrowing of the fibula below the head.
Tibial tuberosity: A landmark visible from the lateral view.
Femur (Anterior View)
**Key Anatomical Features:
Longest and strongest bone** in the human body.
Patella: Positioned ½ inch (1.25 cm) above the joint.
Femur (Posterior View)
**Key Anatomical Features:
Note a 5°-7° angle** at the distal medial and lateral condyles, aiding function and stability.
Knee Joint (Oblique View)
**Components and Configuration:
Femorotibial and patellofemoral joints** are the main articulating surfaces within the knee.
Four major ligaments:
Posterior cruciate ligament (PCL): Stabilizes the knee from the back.
Anterior cruciate ligament (ACL): Prevents forward movement of the tibia.
Fibular collateral ligament (LCL): Provides lateral stability.
Tibial collateral ligament (MCL): Provides medial stability.
Knee Joint (Anterior View)
**Key Anatomical Relationships:
Anterior cruciate ligament (ACL)** visible in the anterior view, stabilizing the joint.
Lateral condyle and lateral meniscus contributing to lateral support.
Fibular collateral ligament (LCL) and patellar surface of femur demonstrated.
Posterior cruciate ligament (PCL) and medial condyle visible.
Medial meniscus, assisting in load distribution, is discerned.
Transverse ligament: Linking the two menisci.
Tibial (medial) collateral ligament (MCL) alongside the fibula and tibia.
Menisci (Superior and Sagittal Views)
**Anatomical Details:
Lateral meniscus** visible along with the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL).
Articular capsule encasing the bones.
Medial meniscus observable, accounting for medial support.
Quadriceps femoris tendon attachment aiding in knee movement.
Bursa structures (suprapatellar and infrapatellar) supporting joint function.
Bones and Joints Summary
Joints of Lower Limb:
Patellofemoral joint: Connection between the patella and femur.
Proximal tibiofibular joint: Articulation between fibula and tibia at the proximal end.
Distal tibiofibular joint: At the distal end of the leg.
Knee joint: Major joint for flexion and extension.
Ankle joint: For foot movement and support.
Intertarsal joints: Articulations within the foot.
Tarsometatarsal, metatarsophalangeal, and interphalangeal joints for fine motor control and support.
Classification and Mobility for Joints of Lower Limb
All joints, except the distal tibiofibular, are classified as:
Synovial: Cadent joints that facilitate smooth movements.
Fibrous: Joints with limited flexibility.
Mobility Types:
Diarthrodial: Freely movable joints.
Amphiarthrodial: Slightly movable.
Assessment of Movement Types in Joints
Quiz: Identifying movement types for various joint classes:
Interphalangeal (IP), Metatarsophalangeal (MTP), Intertarsal, Ankle, Femorotibial, Patellofemoral, Proximal tibiofibular joints are examined.
Technical and Positioning Considerations for Imaging
Gonadal shielding and four-sided collimation for imaging protection and clarity.
Alignment criteria: Ensuring part is parallel to Image Receptor (IR) and CR perpendicular.
Proper anatomical side marker inclusion.
Technical Considerations**
Suggested kV range: 50-70 kV.
Short exposure time to minimize motion blur.
Small focal spot for improved detail.
Adequate mAs for proper exposure on images.
Use of grids for anatomy exceeding 10 cm.
Radiographic Examination of Tibia and Fibula
Radiographic routine includes both AP (anterior-posterior) and lateral views.
AP Leg:
True AP position established.
CR directed to midpoint of leg for optimal imaging.
Evaluation Criteria (AP Leg):
Full visibility of tibia and fibula.
Inclusion of knee and ankle joints.
Partial superimposition at proximal and distal ends.
Optimal exposure parameters confirmed.
Additional Leg Imaging Protocols
Mediolateral Leg: CR positioned to midpoint of leg.
Evaluation Criteria (Lateral Leg):
Full visibility of tibia and fibula with proper alignment.
Knee and ankle joints are depicted accurately.
Proximal head of fibula should be superimposed by the tibia, ensuring no rotation.
CR Angle for AP Knee:
Parallel to tibial plateaus, positioned ½ inch (1.25 cm) distal to the apex of the patella.
Evaluation Criteria for AP Knee
Open femorotibial joint space.
Centering of knee joint within the field of collimation.
Proper visualization of the femoral articular facets.
Optimal exposure factors clearly defined.
On Positioning Variations in Knee Imaging
AP Medial Oblique:
45° medial rotation required.
CR directed ½ inch (1.25 cm) distal to apex of patella.
Evaluation Criteria for Oblique Knee Views:
Medial oblique: Proximal tibiofibular joint opens adequately.
Lateral oblique: Superimposition of fibula over mid-tibia.
Optimal exposure maintained.
Mediolateral Knee Imaging and Planning
Mediolateral Knee:
Angle CR 5°-7° cephalad, directed 1 inch (2.5 cm) distal to medial epicondyle.
Evaluation Criteria (Lateral Knee):
Superimposition of femoral condyles.
Patella visualized in correct profile, indicating no rotation.
Patellofemoral joint space should be open for accurate diagnostic imaging.
Special Imaging Techniques for the Knee
AP Weight-Bearing Knee:
CR perpendicular to the image receptor.
Evaluation Criteria for AP Weight-Bearing Knee:
Knee joints centered correctly within the field.
Avoidance of knee rotation.
Should confirm that joint spaces are adequately visualized.
Advanced Projections for Bilateral Knee Imaging (Rosenberg Method)
Rosenberg Method:
Radiographic projections including routine AP, oblique, and lateral views.
Special techniques involve weight-bearing positioning.
Intercondylar Fossa Imaging and Methods
Routine PA Axial Projections:
Camp-Coventry method involves internal flexion of the knee at 40°-50°.
CR perpendicular to the lower leg, centered to the popliteal crease.
Evaluation Criteria (PA Axial Projection):
Clear profile of the intercondylar fossa.
No noticeable rotation in images.
Enhanced visualization of articular facets and intercondylar eminence.
Holmblad Method Procedures and Standards
Performing the Holmblad Method:
The patient leans forward at 20°-30° during imaging.
CR maintained perpendicular to the IR, centrally aimed at the popliteal crease.
Proposed Techniques for Patella Imaging
Routine Procedures:
PA, Lateral, and multiple Tangential methods (Merchant, Inferosuperior, Hughston, Settegast).
PA Patella Imaging:
Centering CR perpendicular to the mid-patella area at the popliteal crease.
Evaluation Criteria for PA Patella:
Proper centering within collimation fields.
No rotation evident in images.
Further Considerations for the Patellofemoral Joint
Merchant Bilateral Method:
Knees flexed at 40°.
CR angled 30° from horizontal to capture appropriate projections.
Alternative Tangential Projections for Enhanced Visualization
Inferosuperior Projection:
Requires 40°-45° flexion of the knees, CR angled 10°-15° from the lower legs.
Hughston Method:
Requires knee flexion of 40°, with CR intended at 15°-20° to lower leg.
Radiographic Errors and Quality Control Assessment
Critiquing Radiographs:
Examples include identifying errors noted in both lateral and medial oblique knee films for quality improvement.
Quiz and Knowledge Assessment
Determining required CR angles for different projections:
Exploring variations by measuring distances from ASIS to tabletop and beyond.