feet, ankle, tib and fib Flashcards
find a diagram and label the talus bones
what 5 bond landmarks can be found on the foot/ankle
- medial/lateral malleoli
- base of 5th metatarsal
- metatarsophalangeol joint/ metatarsal heads
- tubercle of navicular
- calcaneal tuberosity
what should you see on a DP foot xray
- entire foot and soft tissue
- metatarsals are equally spaces
- superimposition of tarsals and metatarsal bones
- body trabecular detail and soft tissue outline
which direction is the foot turned for an oblique foot xray
Eversion, towards medial side , medial rotation
what should be seen on an oblique dp foot xray
- 3-5 metatarsals free of superimposition
- bases of first and second metatarsals superimposed on medial and intermediate cuneiforms
- navicular, lateral cuneiform and cuboid with less superimposition than in DP projection
what should be seen on a lateral foot xray
- entire foot
- ankle joint
- superimposed plantar surfaces of metatarsal heads
- bony trabecular detail
- sot tissue
difference between dorsi and plantar flexion
- dorsiflexion = 90 degree with feet
- plantar flexion = point foot
why must the foot not droop when taking an ankle xray
- it will cause the calcareous to be superimposed by the fibula
what is an AP ankle view also known as
mortice view
what should be seen on a lateral ankle xray
- distal end of fibula projected over posterior half of distal tibia
- talar dome superimposed with clear joint space
- base of 5th metatarsal included
- bony trabecular detail
- soft tissue
what is the typical secondary ossicle found on the tip of the lateral malleolus, not to be confused with an avulsion fracture
- os subfibulare
where would you centre for a lateral calcaneus view
- 2.5cm distal to medial malleolus
what should you see on a lateral calcaneus view
- no rotation
- talar dome superimposed and tuberosity in profile
- sinus tarsi open
- calcaneocuboid and talonavicular joints open
what is the sinus tarsi
a small hollowed out space between the calcaneus (heel bone) and the talus (ankle bone), which together form the subtalar joint.
what does the sinus tarsi contain and what is its main function
- contains ligament, nerves, blood vessels
- controls stability of ankle and important for balance and proprioception (sense of self-movement and body position)
what is the sustentaculum tali and what is its main function
- horizontal bony shelf that articulates with talus
- essential for standing upright and prevents ankle rolling inwards upon weight bearing
what is bohlers angle
- a line drawn from the superior point of the posterior calcanea tuberosity to the highest midpoint of the posterior articular facet
AND - a line from the highest midpoint of the posterior articular facet to the anterior process
what is the average bohlers angle
20-40 degrees
what should you see on an axial calcaneus
- no rotation
- 1st and 5th metatarsals not projected over calcaneum
- subtler joint clear and open
why must the knee and ankle joints be included on a tib and fib xray
as the proximal end of fib may also be fractured if there is a fracture of distal fib, tibia or widening of mortise joint
why is it assumed that a fracture of distal or proximal end of tib or fib spans across the whole shaft
- due to the bony ring rule
- (if you see a fracture or dislocation in a ring bone or ring bone equivalent, look for another fracture or dislocation.)
hence the entire length of both bones must be demonstrated in scan
what is another name of the toe
hallux
where is the centering point of big toe lateral
first metotarsal-phalangeal joint
what should be seen on a lateral big toe xray
- distal and proximal phalange
- distal 2/3rd of metatarsal
- clear joint spaces
why is a lateral toe projection important in terms of diagnosis
- good for hyeprflexion (stubbing) injuries
- undisplayed avulsion fracture of distal phalanx of big toe can be missed on DP or DP oblique big toe scan
for DP toes, the tube may be raised by what degree of angle
15 degrees
where is the centering point for toe xrays
at the metatarsal-phalangeal joint of affected toe
what must be included on toe xray
affected toe up to the distal phlanx, down to 1/3rd of metatarsal and adjacent toe
what angle must the foot be leaned medially for DP oblique
45 degrees
what are the different centering points for oblique foot
if all toes need to be included then centre at the 3rd metatarsal-phalangeal joint
for single toes, entered over metatarsi-phalangeal joint of individual toe
what might occur if the foot is over rotated medially for oblique DP xray
toes will overlap
what is tarsal coalition
2 bones grow into one another connected by a bridge of bone, cartilage or strong fibrous tissue
what is pseudo-epiphysis
- epiphysis looking end of bone where an epiphysis is not normally located
e.g pseudo-epiphysis found at the distal end of the 1st metatarsal when the growth plate is actually found at the proximal end
how can you tell the difference between a normal variant vs fracture
normal varient =
- smooth edge
- rounded
- found in characteristic locations
- non-symptomatci
fracture
- rough edges
- Lucent, linear or non-linear appearance
- symptomatic
