11 - Radiographic Interpretation

Question 1

Normal radiograph

Answer 1

• Systematic approach
• First look at the soft tissue going around the foot
• If you can’t see soft tissue (only see bone), there is a good chance the settings in the tube head wasn’t good
• If the soft tissue looks similar to the bone, there was probably underpenetration
• You should be able to see soft tissues, cortices, joint spaces
• Determination of foot type
• Foot is a 3-D object
• So, take 3 views of the foot

Question 2

3 common views of the foot

Answer 2

• AP
• Lateral
• Medial oblique

Question 3

Foot types

Answer 3

• Normal foot type
• Supinated foot type
• Pronated foot type

Question 4

Things you should NOT see on a normal foot

Answer 4

• Increased soft tissue attenuation & densities (swelling)
• Breaks in the Cortex (fracture, bone infection)
• Widening or decreasing of the joint space, and alignment (infection, arthritis)
• Mechanical Deformities (HAV, Hammertoes, Tailor’s Bunion)
• Accessory Bones
• Gas in the Soft Tissues
• White vessels (this means they have calcification of the vessels which is pathological)
• Black spots on bottom surface of foot can be ulceration or a breakdown of tissue

Question 5

Determining the foot type

Answer 5

• X-ray taken in the weightbearing position
• Standard views include: AP (top), lateral (side), oblique (45 degree angle)

The radiograph should be labeled as weightbearing or non-weightbearing

If the radiograph is taken in the non-weightbearing position you CANNOT determine the foot type * Need a “loaded” foot to determine foot type*

Question 6

Talus bone

Answer 6

• The position of the Talus is the key to the interpretation of the normal vs. abnormal foot type
• Talus is a PASSIVE BONE
• This means there are no tendons attached to the talus ***
• The talus will ONLY move in relation to the calcaneus ***

Question 7

Talar position with lateral view

Answer 7

The body of the talus is normally parallel with the weight supporting plane

Question 8

Talar position with AP film

Answer 8

• The head of the talus is closely bound to the calcaneus and is superimposed over the anterior portion of the calcaneus
• The outline of the sustentaculum tali may be visualized

Question 9

Cavus foot type

Answer 9

• High arch
• Increased Calcaneal Inclination Angle
• Posterior Break in the Cyma Line
• Bullet Hole Sign (slide 17)

Question 10

Pronated foot type

Answer 10

• Decreased angle of the Calcaneus
• Lowered Arch
• Anterior Break Cyma Line

Question 11

Calcaneal position lateral view

Answer 11

• Angle of Inclination
• Density of the sustentaculum tali
• Lateral tuberosity

Question 12

Cyma line

Answer 12

Representation of the midtarsal articulation

• Talonavicular Joint
• Calcaneocuboid Joint

Question 13

Lateral view of Cyma line

Answer 13

• Should form a smooth S
• When discussing a deformity it is always in relation to the Talonavicular joint
• Because the Calcaneocuboid joint is SO stable that it does not move

Question 14

AP view of Cyma line

Answer 14

• Smooth S curve
• Not as accurate as the lateral view
• Less implications

Question 15

Lis Franc’s ligament

Answer 15

Plantar ligament from the Medial Cuneiform to the 2nd Metatarsal Base (strong)

This forms the Lis Franc’s joint or tarsometatarsal joint

Question 16

Lis Franc’s disruption or injury

Answer 16

The bones of the midfoot have very tight articulations - you should NOT see a separation greater than 2 mm between these bones - If you do see a large separation, there is a good chance there has been an injury of the ligaments

Could also see a deviation of the first or other metatarsal

Question 17

Centers of ossification

Answer 17

• Growth plates in locations depending on the particular bone
• Some bones ossify earlier than others

Question 18

Navicular ossification

Answer 18

• Primary center of ossification will appear between 11 months and 3 years and 8 months
• The average is 3 years
• A secondary center of ossification may occur on the tuberosity of the navicular bone

** 3 YEARS **

Question 19

Lateral cuneiform ossification

Answer 19

• Lateral cuneiform ossification will occur within the first year

** 1 YEAR **

Question 20

Intermediate cuneiform ossification

Answer 20

• Intermediate cuneiform ossification will occur between 1 year and 2 years and 11 months

** 2 YEARS **

Question 21

Medial cuneiform ossification

Answer 21

• Medial cuneiform ossification will occur between 11 months and 2 years and 11 months

** 2.5 YEARS **

Question 22

Print the chart on slide 32

Answer 22

Said we will focus on this but only went over bones above (navicular, cuneiforms)

Went through x-rays on 33 and 34 to determine the age of the individual based on the ossification centers that were present on x-ray

Question 23

Accessory ossicles

Answer 23

• Small bones usually from a secondary ossification center that fail to unite with the remaining portion of the bone
• Often times confused with fractures
• Certain locations on an X-ray that occur more frequently than others
• Always check with Bilateral Films
• Most often asymptomatic

Question 24

Common accessory ossicle

Answer 24

• Accessory navicular (Os tibiale externum)
• Os peroneum
• Os trigonum

Question 25

Os trigonum

Answer 25

- Failed fusion of the Posterior Process of the Talus - Confused often with a fracture “Shepherd’s Fracture” where you fracture off this process - Typically the fracture will have a little sharp point or a 90 degree angle whereas a process would be rounded - Ossicles are typically bilateral, so this can help you differentiate as well

Question 26

Bipartite sesamoid

Answer 26

- Often confused with a fracture of a sesamoid bone - You can get a sharp edge, which would mean a fracture of this has occurred - If you have a cartilagenous surface between the bones, you may be confused as to what you are looking at - May need to use a bone scan to figure it out

Question 27

Gas formation in the soft tissue

Answer 27

- Gas forming bacterial infection - Looks like bubbles - Look at other views to confirm - Clinically, you may see some hemmorrhagic blistering associated with this (blood blister) - If you rub you fingers over top of this tissue, it may sound like crinkling

Question 28

Hallux abducto valgus deformity

Answer 28

- Many angles involved - Angle between first metatarsal and second metatarsal will be increase (increased IMA) - Because of the high IMA, it will cause the position of the hallux to change - The hallux will go into an abducted position (pointing away from the midline of the body) - You will see the valgus deformity - Look for an irregular edge and bump on the medial side of the first metatarsal head

Question 29

Fractures

Answer 29

- Breaks in the cortex of the bone | - Can be described in a variety of ways

Question 30

Extra-articular fracture

Answer 30

Extra articular, non comminuted, nondisplaced fracture of the 5th metatarsal shaft Slide 44

Question 31

Intra-articular fracture

Answer 31

Intraarticular (within the joint) Non comminuted Slide 45

Question 32

Hammertoe deformity

Answer 32

- Joint contractures are noted - The superimposition of the other digits - Might be able to see arthritic changes associated with the hammertoe deformity - This will correlate with the reason that the deformity is rigid, semi-rigid or flexible - Due to long-term adaptation, we see long term adaptation within the joint - Patient may need soft tissue procedure, implant, fusion, etc. based on arthritic changes

Question 33

Calcaneal fracture

Answer 33

- Non-weightbearing - Slide 47 is a "text book" example of a calcaneal fracture - There are other ways to determine if there is a subtle fracture that we cannot see radiographically

Question 34

Calcified vessel

Answer 34

- Tunica media - Does not narrow the lumen - Example: Calcified dorsalis pedis

Question 35

NOTE: went back to this at very end of lecture

Answer 35

- Can't always see the lateral cuneiform - You can see superimposition of the cuneiforms - Take your time and try to trace the individual bones - Especially if there has been trauma - Make sure you actually do see a fracture and it isn't just a joint space