Lecture 12: Ankle and Foot Arthrology (Test 3)

Question 1

characteristics of the proximal tibiofibular joint

Answer 1

synovial
lateral/inferior to knee
head of fibula + lateral region on lateral condyle of tibia
flat/oval covered in articular cartilage
1-3mm translation

Question 2

what strengthens the proximal tibiofibular joint

Answer 2

capsule
tendon of biceps femoris
popliteus

Question 3

describe the distal tibiofibular joint

Answer 3

syndesmosis = bound by interosseous membrane

fibular notch on tibia + distal medial surface of fibula

slight movement associated with dorsiflexion

must be stable for proper talocrural joint function

strongest bond = interosseous ligament/membrane

anterior and posterior tibifibular ligaments stabilize

Question 4

describe the structure/funcyion of the talocrural joint

Answer 4

trochlea and sides of the talus with the “mortise” formed by distal tibia/fibula

shape is what provides a major source of stability

Question 5

describe how compressive forces pass through the talus/tibia/fibula

Answer 5

90-95% of compressive forces pass through talus and tibia

5-10% pass through the talus and fibula

Question 6

what protects the intra articular subchondral bone of the ankle

Answer 6

lined with 3mm of articular cartilage

Question 7

articular capsule is reinforced by what

Answer 7

collateral ligaments

Question 8

why do ligaments enhance muscular stability

Answer 8

because they contain mechanoreceptor

Question 9

what limits inversion/eversion as well as AP translation of the talus

Answer 9

the mortise shape of the joint

Question 10

describe the deltoid ligament

Answer 10

triangular shape (apex is at distal medial malleolus)

limits extremes of eversion (multi joints/multi directional stability)

injury is uncommon due to strength and the associated bony block of the lateral malleolus

if injured, mechanism = landing or extreme twist of ABD (ER) and eversion

Question 11

describe the superficial and deep sets of the deltoid ligament

Answer 11

superficial = 4 bands of fibers

deep set = short vertical fibers (attach close to the joint line - AP fibers)

Question 12

80% of sprained ankles involve what ligament

Answer 12

lateral collateral ligaments

inversion ankle sprains; involve calcaneus in slight inversion at heel contact and medial malleolus cannot block

Question 13

what are the lateral collateral ligaments

Answer 13

anterior and posterior talofibular and calcaneofibular

Question 14

describe the anterior talofibular (ATF) ligament

Answer 14

anterior lateral malleolus to the neck of the talus

most frequently injured

mechanism = inversion/adduction (IR) especially with PF (anterior slide of talus()

Question 15

describe the calcaneofibular (CF) ligament

Answer 15

inferior and posterior from apex of lateral malleolus to calcaneus

resists inversion at the talocrural joint especially with full DF (posterior slide of talus)

Question 16

describe the posterior talofibular (PTF) ligament

Answer 16

from posterior lateral malleolus to lateral tubercle of talus

stabilizes talus in mortise

limits ABD/ER of talus (posterior slide of the talus)

Question 17

osteokinematics of talocrural joint

Answer 17

one degree of freedom primarily

Question 18

describe the axis of the talocrural joint

Answer 18

axis through body of talus and tips of both malleoli; lateral malleolus is inferior and posterior to the medial so it is not purely in the mediolateral axis

also inclined 10 deg superior and 6 deg anterior

Question 19

what movements occur with plantar flexion and dorsiflexion of the ankle? why?

Answer 19

dorsiflexion = also slight abduction and eversion

plantar flexion = slight adduction and inversion

technically slight supination and pronation but its small so generally ignored

this additive movement is due to the pitch of the axis (not purely ML axis)

Question 20

what is the neutral position of the talocrural joint

Answer 20

neutral = 0 degrees; this is when the foot is at 90 degree angle to leg

Question 21

DF and PF present at talocrural joint

Answer 21

DF = 15-25 degrees

PF = 40-55 degrees

Question 22

what is the contribution of accessory motion of the foot to the osteokinematics of the talocrural joint

Answer 22

accessory motions may contribute up to 20-30%

Question 23

describe the arthrokinematics of open chain dorsiflexion

Answer 23

talus rolls forward and slides posterior

mortise is wedged and closed packed position is reached (tibia and fibula slide apart slightly)`

Question 24

describe arthrokinematics of closed chain dorsiflexion

Answer 24

tibia moves anterior

Question 25

what ligaments are taut with dorsiflexion

Answer 25

calcaneofibular and posterior talofibular ligaments

posterior tibiotalar portion of the deltoid

Question 26

extreme dorsiflexion can cause injury to where

Answer 26

distal tibiofibular syndesmosis injury

high ankle sprain

Question 27

what direction would you mobilize the talus to gain dorsiflexion

Answer 27

posterior

Question 28

arthrokinematics of open chain plantar flexion

Answer 28

talus rolls posteriorly and slides anteriorly

Question 29

arthrokinematics of closed chain plantar flexion

Answer 29

tibia moves posteriorly

Question 30

what ligaments are taut with plantar flexion

Answer 30

anterior talofibular and the tibionavicular ligaments

Question 31

extreme plantar flexion can cause impingement of what

Answer 31

distal tibia and posterior talus or calcaneus

especially with os trigonum (rare accessory bone)

Question 32

describe the stability of the ankle during plantar flexion

Answer 32

the wider anterior aspect of the talus moves oit of the mortise and puts the ankle into a loose packed position

the bony stability of the ankle in decreased

Question 33

describe the movement at the talocrural joint during heel contact, foot flat, and right after heel off

Answer 33

heel contact = rapid plantar flexion

foot is flat during foot flat

DF continues until just after heel off; helps with force for push off’ closed packed position; ligaments are taut and mortise is secure)

Question 34

what is the subtalar joint

Answer 34

joint between talus and calcaneus

calcaneus moves relative to fixed talus (in mortise) for NWB

WB = leg and talus move over calcaneus (which is relatively fixed due to WBing)

structure of the joint allows foot to assume positions that are independent of the leg (i.e. walking across a steep hill or quickly changing direction)

Question 35

what are the articulations of the subtalar joint

Answer 35

posterior, middle, and anterior facets on talus and calcaneus

posterior articulation = 70% total area; concave talus rests on convex posterior facet of calcaneus; tight interlocking shape, BW, and muscles hold tight

anterior and middle articulations are smaller/nearly flat joint surfaces

Question 36

ligaments that check the subtalar joint

Answer 36

seperate capsules for posterior and middle/anterior

calcaneofibular limits inversion

tibiocalcaneal fibers of deltoid limits eversion

interosseous and cervical limit all motions (but especially inversion)

Question 37

describe the axis of the subtalar joint

Answer 37

axis is through lateral/posterior heel through the subtalar joint in anterior/medial/superior direction

42 degrees from horizontal plant

16 degrees from sagittal plane

Question 38

arthrokinematics if the subtalar joint involve what

Answer 38

sliding motion at 3 facets

curvilinear arc

Question 39

osteokinematics of the subtalar joint

Answer 39

there are 3 components due to the axis

1-eversion/inversion
2-abduction/adduction
3-DF/PF

overall motion is pronation and supination

Question 40

describe NWB pronation and supination at the subtalar joint

Answer 40

pronation = calcaneus moves into eversion, abduction, DF

supination = inversion, adduction, PF