3 - Lower Extremity Positioning Flashcards
Three planes
- Sagittal
- Frontal
- Transverse
Sagittal
Divides the body into right and left halves
Frontal
Divides the body into anterior (front) and posterior (back) portions
Coronal
Transverse
Divides the body into superior (upper) and inferior (lower) portions
Positions of the body
- Erect or Vertical (Standing or sitting)
- Supine (Lying on back)
- Prone (Lying on stomach)
- Lateral Recumbent (Lying on side)
Proximal
Nearest to the trunk or point of origin
Distal
Farthest from the trunk or point of origin
Terms for x-ray
THIS WILL BE ON THE BOARDS
- View
- Projection
View
That portion closest to the film cassette
Projection
That portion which the X-ray beam enters
Example of view and projection
Anterior-Posterior (AP) projection can also be considered a Posterior-Anterior (PA) view
Osseous anatomy of the lower limb
- Lower Leg
- Tarsal (Rearfoot)
- Metatarsals (Forefoot)
- Sesamoids
- Phalanges
- Accessory Bones
Lower leg bones
- Tibia (forms medial malleolus)
- Fibulat (forms lateral maleolus)
Tarsal bones (rearfoot)
- Calcaneus
- Talus
- Navicular
- Cuboid
- Cuneiforms (Medial, Intermediate, Lateral)
What was a AP radiograph of the foot previously called?
DP = Dorsal Plantar
No longer used
Metatarsals (forefoot)
First through fifth metatarsals
Sesamoids
- Bones within a tendon
- Sesamoids under the first metatarsal are constant
Phalanges
- Proximal
- Middle
- Distal
Ankle joints
- Tibia
- Fibula
- Talus
Talocalcaneal joint (subtalar joint)
- Talus
- Calcaneus
Talonavicular joint
- Talus
- Navicular
Calcaneocuboid joint
- Calcaneus
- Cuboid
Medtarsal or choparts joints
Talonavicular Joint and Calcaneocuboid Joint
Tarsometatarsal or lisfrancs joint
Joint between tarsal bones and five metatarsals
Metatarsal phalangeal joint
Joint between metatarsal and phalanges
Interphalangeal joints
Joints between phalanges
Now we are moving on to the standard radiographic images of the foot and ankle
Just so you know…
Seems like this is the “heart” of the lecture (what you need to know for exam)
Looking at the pictures and radiographs on the slides will likely be useful for this
Anterior-posterior (AP) radiograph
- Structures Demonstrated: Phalanges, Sesamoids, Metatarsals and Tarsal Bones
- Central ray: Angle 15° Cephlad, Base of Third Metatarsal
Patient positioning for AP radiograph
Standing with foot on exposable side of film in angle and base of gait on Orthoposer
This is therefore an AP projection
Medial-oblique (MO) view
- NOTE: An MO view is the same as a lateral oblique projection
- Structures Demonstrated – Phalanges, Metatarsals, Tarsal Bones and Sesamoids
- Central Ray – Angle tube 45° aim at Lateral Cuneiform
Patient positioning for a MO view
Patient Position – Standing in angle and base of gait on Orthoposer
Lateral-oblique (LO) view
- NOTE: this is the same as a medial-oblique projection
- Structures Demonstrated – Phalanges, Metatarsals, Tarsal Bones and Sesamoids
- Central Ray – Angle tube 45° aim at Medial Cuneiform
Patient positioning for a LO view
Patient Position – Standing in angle and base of gait on Orthoposer
Lateral projection of the foot
- NOTE: this is the same as a medial view of the foot (because it is against the cassette)
- Structures Demonstrated – First Metatarsal, Hallux, Medial Cuneiform, Navicular, Talus and Calcaneus
- Central Ray - 90° or perpendicular to the Lateral Cuneiform
Patient positioning for a lateral projection of the foot
Standing in angle and base of gait on Orthoposer
Raised lateral hallux projection
- Structures Demonstrated – Proximal and Distal Phalanges of the Hallux
- Central Ray - 90° or perpendicular to the center of the Hallux
Patient position for raised lateral hallux projection
Standing in angle and base of gait on Orthoposer with foam under Hallux to decrease overlap of other toes
Sesamoid or plantar axial radiograph
- Structures Demonstrated - Inferior aspect of the Metatarsals and Sesamoids
- Central Ray - 90° or perpendicular to the film and aim at inferior heel
Patient positioning for sesamoid or plantar axial radiograph
Standing with foot on block
Calcaneal axial radiograph
- Structures Demonstrated – Subtalar or Talocalcaneal Joint and the Calcaneus
- Central Ray - 45° aimed at the posterior Subtalar or Talocalcaneal Joint
Patient position for calcaneal axial radiograph
Patient standing on the film in angle and base of gait
Anterior-posterior of the ANKLE
- Structures Demonstrated – Tibia, Fibula, Talus and Ankle Joint
- Central Ray – Anterior Ankle Joint
Patient position for AP of the ankle
Patient standing on Orthoposer with back of leg against the film
Ankle mortise
- Structures Demonstrated – Tibia, Fibula, Talus and Ankle Joint: Decreases overlap between Tibia and Fibula
- Central Ray – Anterior Ankle Joint
Patient position for ankle mortise
Same as Anterior-Posterior (AP) with foot rotated toward midline 15°
What is the difference between an AP ankle and an ankle mortise?
The angle of rotation of the foot is the only difference between AP ankle and ankle mortise - know that the AP ankle is the more natural foot position and when we do an ankle mortise, we have to internally rotate the foot 15 degrees
There is MORE overlap with an ankle AP, there is LESS overlap when internally rotating for the ankle mortise (see slide 61)
Lateral projection of the ankle
- Structures Demonstrated – Tibia, Fibula, Talus, Calcaneus and Ankle Joint
- Central Ray - 90° or perpendicular to the film with ray entering Lateral Malleolus
Patient position for lateral projection of the ankle
Standing with Medial Malleolus against film
Ottawa rules
Established in 1992
Uses an instrument for assessment of foot and ankle
- Ability to walk 4 steps
- Pain in posterior edge or tip of malleoli
- Pain at navicular or base of fifth metatarsal
Designed to rule out fractures
Describe a study done to assess accuracy of the Ottawa rules
- Level 2 – Systematic review of prospective level 2 studies
- 27 studies with 15,581 patients
- Evidence demonstrated that Ottawa rules are accurate in excluding fractures of the ankle and mid-foot. Greater than 98% sensitivity.
- Should reduce unnecessary radiographs by 30-40%
Not really used in the US because the 2% will get you into trouble because you will miss them and it will be malpractice
Test questions
- Pretty basic
- Know the difference between the different types of radiographs
- Know the difference between projection and view definition
- What type of radiograph would you order to see certain bones
- Know AP ankle and ankle mortise, what the difference is, and why you would select one over the other
- The position of the patient is more of a “skill” so it is not going to be focused on as much
