Chapter 104 - Foot Trauma

Question 1

primary blood supply to the BODY of the talus

Answer 1

artery of the tarsal CANAL (a branch off of the posterior tibial artery)

Question 2

role of the deltoid artery

Answer 2

contributes some vascularity to the medial talar body
lies in the deep portion of the deltoid ligament

Question 3

primary blood supply to the HEAD and NECK of the talus

Answer 3

artery of the tarsal SINUS (branch off both the anterior tibial artery and the peroneal a)

Question 4

hawkins classification of talar neck fractures

Answer 4

i: non-displaced - risk of AVN 0-13%, risk of arthritis 0-30%
II: displaced neck fracture with subluxatio of the subtalar joint - risk of AVN 20-50%, post traumatic arthritis 40-90%
III: displaced neck with dislocation from subtalar AND tibiotalar joints - risk of AVN 80-100%, post traumatic arthritis - 70-100%
IV: neck plus Subtalar, tibiotalar, and talonavicular dislocation

Question 5

what type of screws are often used in talus fractures to allow for post op MRI?

Answer 5

titanium (non-ferrous -> less metal artifact)

Question 6

hawkins sign suggesting intact vascularity is seen at what time point? compared to osteonecrosis which is seen at what time point?

Answer 6

hawkins sign (subchondral osteopenia) - 6-8 weeks
osteonecrosis 3-4 months

Question 7

what is the most common malunion in talar neck fractures?

Answer 7

varus malunion - limits foot eversion

Question 8

fractures of the talar body require what type of surgical approach?

Answer 8

usually require dual approach when the articular surfaces are displaced >2mm
talar body fractures will often require medial or lateral malleolar osteotomies

Question 9

mechanism of injury: lateral process of the talus

Answer 9

dorsiflexion, external rotation

Question 10

most common complication of lateral process of the talus fracture

Answer 10

subtalar arthritis

Question 11

superomedial fracture fragment of the calcaneus is also called what?

Answer 11

the constant fragment - in that it usually retains it anatomic position - ie remaining constant in position
fracture fragment has the sustentaculum on it

Question 12

improved outcomes in surgical management of calcaneal fractures if what factors are present?

Answer 12

patient age <40
female sex
simple fracture ptterns

Question 13

negative surgical outcomes for cal fractures in what factors?

Answer 13

male
older
smoking
diabetes
workers comp
heavy duty job
high degree of fracture comminution

Question 14

what are the benefits of sinus tarsi approach?

Answer 14

lower risk of wound complications
able to operate earlier

Question 15

loss of talar declination angle leads to what functional deficit?

Answer 15

loss of dorsiflexion

Question 16

medial navicular avulsion results from what?

Answer 16

stress from posterior tibialis muscle

Question 17

plantar navicular avulsion results from what?

Answer 17

stress from calcaneonavicular (spring) ligament

Question 18

when to operate on navicular fractures?

Answer 18

if >25% of articular surface is involved

Question 19

lis franc ligament runs from what two structures

Answer 19

base of the second metatarsal to the medial cuneiform bone

Question 20

mechanism of injury of lis franc dislocations

Answer 20

1. direct dorsal force
2. axial loading with twisting on a plantarflexed foot
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Question 21

normal anatomic relationships of the TMT joints

Answer 21

1. medial aspect of the 2nd metatarsal should be aligned with the medial aspect of the middle cuneiform
2. medial aspect of the fourth metatarsal should be aligned with the medial cuboid bone
3. diastasis >2mm between the first and second metatarsal bones is pathologic

Question 22

treatment of lis franc injuries

Answer 22

if bony - perform ORIF
if purely ligamentous - fuse primarily - decreased risk of secondary surgery

Question 23

shortening of first metatarsal fractures leads to what?

Answer 23

transfer metatarsalgia

Question 24

most common place for stress fracture in the foot

Answer 24

neck of the second metatarsal

Question 25

treatment of type I, pseudojones, fractures

Answer 25

weightbearing as tolerated and stiff soled shoe

if symptomatic non-union, excise the fragment and reattach peroneus brevis

Question 26

treatment of true Jones fracture

Answer 26

non-weightbearing in short leg cast in recreational athlete - refracture rate 33%
orif or IM screw in athletes followed by short period of NWB, running resume at 6 weeks

Question 27

what foot deformity predisposes to type III jones fractures

Answer 27

cavovarus deformities (increase the mobility of the 1st tmt joint -> increases stress to lateral column) (charcot marie tooth, etc)

Question 28

sesamoid fracture mechanism of injury

Answer 28

direct impact with compression and hyperdorsiflexion of the gret toe -> transverse fracture
tx = padding, wbat in hard soled shoe

Question 29

complication of sesamoidectomy

Answer 29

fibular sesamoidectomy - hallux varus
tibial sesamoidectomy - hallux valgus

Question 30

most common direction of subtalar dislocation

Answer 30

medial - eg talus is lateral to the rest of the foot

Question 31

irreducible subtalar dislocation caused by what?

Answer 31

button holing of the talus thru the EDB or TN capsule or peroneal tendon interposition

Question 32

irreducible lateral subtalar dislocation cause by what?

Answer 32

tibialis posterior tendon interposition or talonavicular capsule

Question 33

what injury is most predictive of need for foot amputation?

Answer 33

multiple metatarsal fractures