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Questions and Answers
What patient position must be achieved to ensure a true AP position of the knee?
What patient position must be achieved to ensure a true AP position of the knee?
The leg must be slightly rotated inward (internally rotated).
List two key evaluation criteria for an AP knee radiograph.
List two key evaluation criteria for an AP knee radiograph.
The femoral and tibial condyles should appear symmetrical, and the patella should be superimposed on the midline of the femur.
What is the significance of performing an AP weight-bearing knee view?
What is the significance of performing an AP weight-bearing knee view?
It can reveal narrowing of joint spaces that may appear normal in non-weight-bearing views.
Where should the CR enter for an AP intercondylar knee projection?
Where should the CR enter for an AP intercondylar knee projection?
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What are the optimal kVp and mAs settings for an intercondylar knee X-ray?
What are the optimal kVp and mAs settings for an intercondylar knee X-ray?
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What is the recommended knee flexion angle when obtaining a PA axial radiograph of the intercondylar fossa?
What is the recommended knee flexion angle when obtaining a PA axial radiograph of the intercondylar fossa?
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What anatomical landmarks should be included in the evaluation criteria for an intercondylar knee radiograph?
What anatomical landmarks should be included in the evaluation criteria for an intercondylar knee radiograph?
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In the interpretation of a PA weight-bearing knee radiograph from the Rosenberg view, which joint space is particularly assessed?
In the interpretation of a PA weight-bearing knee radiograph from the Rosenberg view, which joint space is particularly assessed?
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What positioning is necessary for the patient when taking a PA Rosenberg view radiograph of the knees?
What positioning is necessary for the patient when taking a PA Rosenberg view radiograph of the knees?
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What is the appropriate CR angle when capturing a Rosenberg view of the knees?
What is the appropriate CR angle when capturing a Rosenberg view of the knees?
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What are the primary bones that make up the knee joint?
What are the primary bones that make up the knee joint?
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Name the ligaments that strengthen the medial and lateral aspects of the knee joint.
Name the ligaments that strengthen the medial and lateral aspects of the knee joint.
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At what age does the patella begin to appear on an x-ray?
At what age does the patella begin to appear on an x-ray?
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What is the significance of the Anterior Cruciate Ligament (ACL) in knee function?
What is the significance of the Anterior Cruciate Ligament (ACL) in knee function?
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What are some indications for performing a knee x-ray?
What are some indications for performing a knee x-ray?
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What should be done to prepare a patient for a knee x-ray?
What should be done to prepare a patient for a knee x-ray?
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What is the recommended kVp range for an AP knee x-ray?
What is the recommended kVp range for an AP knee x-ray?
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In an AP knee x-ray, where should the x-ray beam be centered?
In an AP knee x-ray, where should the x-ray beam be centered?
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What is the central ray angulation recommended for a lateral knee X-ray?
What is the central ray angulation recommended for a lateral knee X-ray?
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Describe the patient positioning for a lateral knee X-ray.
Describe the patient positioning for a lateral knee X-ray.
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What are the primary anatomical inclusions in a lateral knee X-ray?
What are the primary anatomical inclusions in a lateral knee X-ray?
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What is the purpose of the horizontal beam lateral knee view?
What is the purpose of the horizontal beam lateral knee view?
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What is the optimal density and contrast for in a lateral knee X-ray?
What is the optimal density and contrast for in a lateral knee X-ray?
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How should the central ray be angled for an axial patella/silhouette view?
How should the central ray be angled for an axial patella/silhouette view?
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In the skyline view of the knee, which parts of the anatomy need to be included?
In the skyline view of the knee, which parts of the anatomy need to be included?
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What is the typical kVp range used for lateral knee X-rays?
What is the typical kVp range used for lateral knee X-rays?
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What kind of fractures can the horizontal beam lateral knee view detect?
What kind of fractures can the horizontal beam lateral knee view detect?
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What is a common protocol for assessing osteoarthritis of the knee?
What is a common protocol for assessing osteoarthritis of the knee?
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What are the main characteristics of osteoarthritis as it presents in patients over 50?
What are the main characteristics of osteoarthritis as it presents in patients over 50?
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How can varus deformity be described, and what is one method used for its assessment?
How can varus deformity be described, and what is one method used for its assessment?
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What are 'loose bodies' in a joint, and what is a common cause of their occurrence?
What are 'loose bodies' in a joint, and what is a common cause of their occurrence?
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What does total knee replacement (TKR) involve and mention one possible complication?
What does total knee replacement (TKR) involve and mention one possible complication?
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Describe Osgood Schlatter Disease and its common age group.
Describe Osgood Schlatter Disease and its common age group.
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Define the term 'bipartite patella' and how it differs from a fracture.
Define the term 'bipartite patella' and how it differs from a fracture.
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What is the typical cause of a patella fracture?
What is the typical cause of a patella fracture?
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Explain patellofemoral dislocation and its common consequences.
Explain patellofemoral dislocation and its common consequences.
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What are the radiographic features indicative of osteoarthritis?
What are the radiographic features indicative of osteoarthritis?
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What is the distinguishing feature of valgus deformity?
What is the distinguishing feature of valgus deformity?
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Study Notes
Knee Anatomy
- Medial and lateral femoral condyles (medial is larger than lateral)
- Tibial plateaus
- Intercondylar eminences or spines
- Medial and lateral tibial condyles
- Femur
- Patella
- Tibia
- Fibula
Joints
- Patellofemoral joint
- Proximal tibiofibular joint
- Medial and lateral femorotibial joints
Ligaments
- Lateral and Medial Collateral Ligaments (LCL and MCL)
- Strengthen the medial and lateral aspects of the joint
- Anterior Cruciate Ligament (ACL)
- Located in the center of the knee
- Controls rotation and forward movement of the tibia
- Posterior Cruciate Ligament (PCL)
- Located in the center of the knee
- Controls backward movement of the tibia
Knee Ossification
- Patella starts to be seen on an x-ray between 2-6 years old
- Growth plates usually fuse around puberty
Knee Radiography Indications
- Trauma
- Acute Sporting Injury
- Pain
- Lumps
- Loss of Function
- Foreign Body
- Swelling
- Reduced Range of Movement (ROM)
- Infections
- Mobile Patella
- Previous Surgery
- Cuts
- Bruising
- Clicking
- Deformity
Knee Radiography Preparation
- Correct Patient Identification
- Pregnancy Check
- Explanation of Procedure
- Remove necessary clothing, gown with opening to the back
- Patient to lay on the x-ray table
- Lead apron
AP Knee
- Xray: AP Knee
- kVp: 60-70 kVp
- mAs: 7-10 mAs
- FFD: 100-110 cm
- CR: 24x30 plate
- DR: Imaging Receptor
- Cassette: Long axis of image receptor parallel with long axis of affected leg
- Centre: Centre approx. apex of patella
- Collimation: Four sides to the outer margins of the knee. Include to skin edge. Pt supine with both legs extended
- Patient Position: Femoral condyles equidistant to imaging receptor. Leg is slightly rotated inward (internally rotate) to place knee in a true AP position.
AP Knee Evaluation Criteria
- Regional anatomy included—distal femur and proximal tibia and fibula, including soft tissue
- Femorotibial joint space open
- Femoral and tibial condyles should appear symmetrical
- Patella superimposed on midline of femur
- Medial half of fibula head superimposed on tibia
- Density and contrast optimal to visualise bone & soft tissue
AP Weight-Bearing Knee
- Often done bilaterally. Position as per AP Knee view.
- Patient needs to stand straight, knees fully extended and body weight equally distributed on the feet.
- Centre between both knees.
- Weight-Bearing may reveal narrowing of joint spaces that often appears normal on non-weight-bearing view.
- Used for osteoarthritis, orthopaedics, pre/post op, varus/valgus deformity.
AP Intercondylar Knee
- Xray: Intercondylar Knee
- kVp: 60-70 kVp
- mAs: 7-10 mAs
- FFD: 100-110 cm
- CR: 24x30 plate
- DR: Imaging Receptor
- Cassette: Long axis of cassette perpendicular with long axis of affected leg. CR will be perpendicular to the long axis of the tibia, parallel to tibial plateau
- Centre: CR will enter knee 1 cm distal to apex of patella
- Collimation: Sufficient to include the bounds of the knee joint so soft tissue edge. Landscape rectangular shape. Pt supine- Flex affected knee by 40-60 degrees depending on patient presentation. Ensure no rotation of the leg internally /externally.
- Patient Position: Get the imaging plate as close to the posterior side of the knee as possible- place sponges/other support needed.
Intercondylar Knee Evaluation Criteria
- Regional anatomy included—distal femur and proximal tibia and fibula, including soft tissue
- Intercondylar fossa open (not superimposed by apex of patella)
- Femorotibial joint space open
- Intercondylar eminence separated and in the center of the intercondylar fossa
- No rotation—Femoral and tibial condyles appear symmetrical
- Density and contrast optimal to visualize bone & soft tissue
PA Weight-Bearing Knee Rosenberg View
- Rosenberg view is usually done bilaterally.
- Pt is erect facing upright Bucky.
- Knees bent 45 deg, resting knees against upright Bucky.
- CR—Angle the x-ray tube 10 deg caudad—center at the level of the knee joint.
- The maximum stresses in the knee joint occur between 30° - 60° of flexion.
- The Rosenberg view is more sensitive for joint space narrowing (cartilage loss) than the weightbearing AP views and is useful for the assessment of knees with early degenerative change.
Lateral Knee
- Xray: Lateral Knee
- kVp: 60-70 kVp
- mAs: 7-10 mAs
- FFD: 100-110 cm
- CR: 24x30 plate
- DR: Imaging Receptor
- Cassette: Long axis of image receptor parallel with long axis of affected leg.
- Centre: Medial aspect of knee joint.
- Collimation: Four sides to the outer margins of the knee. Pt to roll onto affected side, to superimpose the femoral epicondyles. Flex knee 20-30 deg.
- Patient Position: Place a sponge under the ankle so the long axis of the tibia/fibula is parallel to the image receptor. Other leg can be either behind or in front of the affected leg. Angle central ray 4-7 deg cephalad, depending on patient presentation.
Lateral Knee Evaluation Criteria
- Regional anatomy included —distal femur and proximal tibia and fibula, including soft tissue
- Femoropatellar joint space open
- Femoral condyles should appear superimposed
- Patella in profile
- Fibular head only slightly superimposed over tibia
- Density and contrast optimal to visualize bone & soft tissue
Horizontal Beam Lateral Knee
- Used for acute knee injuries.
- Detects lipohaemarthrosis = intra-articular fracture with escape of fat and blood from the bone marrow into the joint.
- Demonstrates a fluid level in the suprapatellar pouch.
- Approx. 5 degrees caudal angulation.
Patella Movement
- Angle of tube depends on the flexion of the knee.
Axial Patella / Skyline View
- Xray: Skyline Knee
- kVp: 60-70 kVp
- mAs: 7-10 mAs
- FFD: 100-110 cm
- CR: 24x30 plate
- DR: Imaging Receptor
- Cassette: Long axis of image receptor perpendicular with long axis of affected leg.
- Centre: Centre to apex of patella
- Collimation: Four sides to the outer margins of the patella and joint space. Pt supine with the affected leg extended. Bend affected knee 45 deg (depending on patient presentation).
- Patient Position: Image receptor resting on mid-thigh and tilted so perpendicular to the central ray. Pt can hold the image receptor in position for a supine position. Angle central ray so it’s parallel to the patella and traveling through the joint space.
Skyline Knee Evaluation Criteria
- Regional anatomy included —distal femur and patella, including soft tissue
- Base and apex of patella superimposed
- Femoropatellar joint space open
- Patella in profile
- Femoral condyles appear symmetrical
- Density and contrast optimal to visualize bone & soft tissue
Knee Pathology
Fracture
- Peri-prosthesis fracture
Dislocation
- Patellofemoral dislocation = patella becomes dislocated from the groove in the femur
- Patellofemoral Subluxation = due to ruptured ligament and the knee will temporarily dislocate and then relocate
- Femorotibial (rare) = femur and tibia dislocate
Osteoarthritis
- Common protocol includes weight-bearing views
- Caused by repetitive & mechanical stresses over many decades. Often in people over 50.
- Presentation includes pain, stiffness and locking joints.
- Obvious visual deformity may include uneven gait and varus or valgus deformity.
Osteoarthritis Radiographic Appearance
- Decreased joint space
- Joint margin osteophytes (bone spur)
- Subchondral (bone below cartilage in a joint) bone sclerosis (pathological hardening)
Loose Bodies
- Presentation includes pain, catching & joint locking
- Caused by trauma or degenerative disease.
- Usually well demonstrated on intercondylar projection.
Varus Deformity
- “Bow legged”
- Angular deformity of lower legs outwards
- Medial joint destruction
- Assessed with long leg radiographs.
Valgus Deformity
- “Knock knee”
- Angular deformity of the lower legs inwards
- Lateral joint destruction
- Assessed with long leg radiographs.
Total Knee Replacement (TKR)
- Replace articular surfaces of femur, tibia and patella
- Complications—instability, bone fracture, infection, loosening of prosthesis
- Key imaging principle: Always include all of hardware—including cement.
Fabella
- Accessory ossicle in the gastrocnemius muscle
- Occurs in 10-30% of the population.
Dislocation
- Patellofemoral dislocation = patella becomes dislocated from the groove in the femur.
- Patellofemoral Subluxation = due to ruptured ligament and the knee will temporarily dislocate and then relocate.
- Femorotibial (rare) = femur and tibia dislocate
Patella Fracture
- Caused by direct force to the patella or sudden forceful contraction of the quadriceps tendon.
- Point tenderness, swelling, large joint effusion.
- Transverse (most common), communited, pathological fracture.
Bipartite & Tripartite Patella
- Commonly mistaken for a fracture.
- Bipartite = 2 part patella.
- Tripartite = 3 part patella.
- Congenital condition where there is a fusion failure of the accessory ossification center.
Osgood Schlatter Disease
- Occurs in active children aged 9–16 coinciding with periods of growth.
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Description
Test your knowledge on knee anatomy, joints, ligaments, and ossification. This quiz covers key structures such as the femur, tibia, and patella, as well as important ligaments like the ACL and PCL. Additionally, learn about indications for knee radiography and their relevance in clinical settings.
