Lower limb Flashcards
Preparation
- Ensure your room is clean, tidy and safe. As with other exams this is the key
- Set the appropriate preliminary exposure factors and programme on the software.
- Set up the equipment you need (i.e. wall bucky, free detector or cassettes).
- Get your markers out and ready to use.
- Wash your hands. Follow infection control protocols.
- Ensure there are no hazards
Exposure factors: foot
60kV 2mAs
Exposure factors: ankle
60kV 2.5mAs
Exposure factors: Tib/fib
60Kvs 4mAs
The foot: possible clinical indications
- OA/Pain
- Trauma
- Stress fracture?
- Osteomyelitis
- Foreign body?
- Follow-up imaging
- Congenital abnormalities (with justification of why imaging will help)
- Hallux vagal (pre-operative assessment)
Dorsoplantar foot (DP) technique
- Patient seated on x-ray table
- Hips and knees flexed
- Plantar aspect of foot placed on IR
- Ensure anatomy is with IR boundaries
- Ensure foot is perfectly flat/straight
- Unaffected leg is abducted away from affected leg
- Central ray with 15 degrees cranial angulation (can use 15-degree pad with vertical beam)
- Cuboid-navicular joint
Essential image characteristics of Dorsoplantar foot (DP) technique
- Include all bones of the foot
- Include all skin borders
- Include the malleoli (can be hidden injuries there)
- Foot is not internally or externally rotated
- Tib/fib are straight and not superimposed over foot (do not flex the knee)
- Physical markers
- No artefacts
Oblique foot technique: patient position
- Place foot in unexposed part of image receptor
- From DP position, patient leans affected leg medially so that sole of foot is approx. 30-45 degrees to IR
- Can utilise 45 degrees radiolucent pad under lateral aspect of foot
- Unaffected leg is abducted away from affected leg
- Centred over cuboid-navicular joint
- Vertical beam (take 15 degrees angle off from DP)
Essential image characteristics of Oblique foot technique
- Include all bones of the foot
- Include all skin borders
- Clear view through intertarsal and tarsometartarsal joints
- Good exposure from toes to tarsus
- Include the malleoli (can be hidden injuries there)
- Physical markers
- No artefacts
- No over or under internal rotation (MTs too superimposed or not superimposed)
Lateral foot technique: Patient position
- Patient lies of affected side
- Hips and knees flexed
- Lateral aspect of affected foot in contact with image receptor
- Sole of foot 90 degrees to IR
Lateral foot technique: Centring point
- Central ray vertical to the IR
- Bases of MT joints
Essential image characteristics: Lateral foot technique
- Include all bones of the foot
- Include all skin borders
- Clear view through intertarsal and tarsometartarsal joints
- Good exposure from toes to tarsus
- Include the malleoli (can be hidden injuries there)
- Physical markers
- No artefacts
- No over or under internal rotation (MTs too superimposed or not superimposed)
Additional views: Foot technique
Weight Bearing DP – Guaranteed joint is going to be flat, and gives clear indication as to what forces affect the joint
Weight Bearing Lateral- See any displacement when weight is on it.
Tangential- Might be able to see where the foreign body is.
Hallux: DP, Oblique and Lateral
- DP and Oblique are same technique as DP and Oblique foot respectively. Centre over the Metatarsophalangeal joint.
- Lateral: From the DP position, rotate the foot medially until the medial aspect is in contact with the image receptor.
- Pull the other toes back with a bandage (can improvise with pads or plastic aprons)
If pain in metatarsals then x-ray whole foot.
Calcaneum: possible clinical indications:
Injury (fall from a height landing on feet)
Pain/Swelling
Follow up (fracture clinic)
Query Osteomyelitis
Query Foreign Body
Query bone pathology (cyst)
(No longer X-ray for calcaneal spurs in many Trusts as there is no surgical solution)
Lateral calcaneum: Patient position
Patient lies on affected side
Leg is externally rotated until malleoli are superimposed
Ankle remains in dorsiflexion
Lateral aspect of foot in contact with image receptor
Heel in middle of unexposed side of image receptor
Central ray vertical to the image receptor & 2.5cm distal to medial malleolus
Similar to lateral ankle just centred differently
Axial calcaneum: Patient position
Patient seated on x-ray couch with legs extended
Internally rotate affected ankle until medial and lateral malleoli are equidistant from image receptor
Place heel at bottom of image receptor
Dorsiflex foot so that sole of foot is perpendicular to image receptor
Central ray with 40 ° cranial angulation
At level of base of 5th MT in midline of plantar aspect of heel
Primary aim is the elongate the calcaneum
Ankle
- Anterior-posterior (ap)/ AP Mortise
- Lateral
Ankle: possible clinical indications
OA/Pain
Trauma/? Bony Injury (E.g. Inversion injury)
Follow-up assessment (fracture clinic)
? Foreign Body
Swelling/Hot to touch? Septic Arthritis
Fall from Height
Thoracic pain following fall…what is the correlation?
AP mortise ankle: Patient position
Patient seated on x-ray couch with legs extended
Unaffected leg abducted away from affected leg
Posterior aspect of affected ankle placed on image receptor, with heel at bottom
Medially rotate affected ankle until medial and lateral malleoli are equidistant to the image receptor
Dorsiflex foot so that sole of foot is perpendicular to image receptor
AP mortise ankle: Centring point
Central ray vertical to the image receptor
Midway between both malleoli