L5 - Biomechanics of the foot and ankle Flashcards
Name the bones of the lower leg.
What do they form?
What structures are the “ankle bumps”?
- Tibia
- Fibula
Form ankle mortise
–> the ankle mortise is the joint formed by the tibia, fibula, and talus bones
Medial/lateral malleolus
See NDC p.3 for illustration
Name the parts of the foot + each’s bones.
- Hindfoot: talus, calcaneus
- Midfoot: navicular, cuboid, cuneiform x3
- Forefoot: metatarsals, phalanges
See NDC p.4 for illustration
Name the joints of the ankle/foot + what bones form them.
- Ankle (talocrural)
–> Tibia/fibula with talus - Subtalar
–> Talus with calcaneus - Distal tibofibular (syndesmosis)
–> Tibia with fibula
See NDC p.5 for illustration
Name the planes of foot motion + the motion?
- Sagittal plane: dorsiflexion/plantarflexion
- Frontal plane: eversion/inversion
- Transverse plane: abduction/adduction
See NDC p.7 for illustration
Motion of the foot
What is another name for dorsiflexion/plantarflexion of the foot? (sagittal plane)
Sometimes called flexion/extension
See NDC p.7 for illustration
Motion of the foot
What is another name for inversion/eversion of the foot? (frontal plane)
Inversion/eversion sometimes called
- supination/pronation
- adduction/abduction
See NDC p.7 for illustration
Motion of the foot
What is another name for abduction/adduction of the foot? (transverse plane)
Adduction/abduction sometimes called
- internal/external rotation
- varus/valgus
–> vaLgus = knees together SO feet out
See NDC p.7 for illustration
Why does the foot have triplanar motion?
It moves in 3 planes at once because its axis of movement does NOT line up with cardinal planes.
What is supination? (3)
Describe the foot. (2)
Describe the sole + part of foot that we walk on.
Plantarflexion, inversion, adduction
–> Rigid foot, stable
- The sole of the foot is pointing in
- Walk on outside of foot (lateral)
See NDC p.8 for illustration
What is pronation? (3)
Describe the foot. (2)
Describe the sole + part of foot that we walk on.
Dorsiflexion, eversion, abduction
–> Flexible foot, better for shock absorption
- The sole of the foot is pointing out
- Walk on inside of foot (medial) (flat foot)
See NDC p.8 for illustration
Describe the effect of tibia rotations on foot movement.
Tibia internal rotation: foot pronation (eversion,
abduction) –> flat feet
Tibia external rotation: foot supination (inversion,
adduction) –> high arch
What is the importance of foot-shank movements?
It helps transfer movement and forces from ground to foot to leg.
Describe the ankle joint (talocrural)
- classification
- degree of movement + movement
Mitered hinge joint
1 degree of freedom: plantarflexion and dorsiflexion
Some say 6 degrees of freedom… yes but muscles don’t control these
See NDC p.10 for illustration
Describe the axis of the ankle joint (talocrural).
What happens movement occurs at the foot when the ankle dorsiflexes?
Axis runs from medial side to lateral, inferior and posterior
–> Might move during movement
Dorsiflexion = eversion
See NDC p.11 for illustration
Does the ankle joint (talocrural joint) follow the concave-convex rule?
Yes!
Describe the concave-convex rule for dorsiflexion of the ankle joint (talocrural).
Concave: tibia and fibular
Convex: talus
Contact area moves anterior and tibia translates ANTERIOR w.r.t to talus
–> or talus translates POSTERIOR w.r.t. to tibia
- start plantarflex, going to dorsiflex = talus rotation posterior relative to tibia
- squatting = tibia rotation anterior relative to talus
Describe the concave-convex rule for plantarflexion of the ankle joint (talocrural).
Concave: tibia and fibular
Convex: talus
Contact area moves posterior and tibia translates POSTERIOR w.r.t. to talus
–> or talus translates ANTERIOR w.r.t. to tibia
- start dorsiflex, going to plantarflex = talus rotation anterior relative to tibia
What is the point of knowing the ways joints move (kinematics) ? (concave-convex rule)
- Guide treatments
- Joint replacement: we need to recreate the joint
What is a treatment to improve dorsiflexion after sprain, immobilization?
Is it effective?
Increasing posterior glide (translation) of talus w.r.t. tibia—-with movement
–> Improvement in dorsiflexion: yes, +6cm ROM
See NDC p.13 for graph
How do we measure functional dorsiflexion ROM?
Knee to wall test:
Max distance of heel, when knee can touch wall without heel lifting.
Describe the subtalar joint.
- classification
- bones forming it
- function
Hinge joint (uniaxial)
Talus and calcaneus: anterior, middle and posterior facets on each
Function: translate motion between foot and tibia
–> Walk on uneven ground, pivot, etc.
See NDC p.14 for illustration
What are the movements of the subtalar joint?
- Inversion/eversion
- Abduction/adduction
Describe the axis of the subtalar joint.
From medial superior: runs lateral, posterior inferior
Describe the shape of the posterior and anterior parts of the subtalar joint.
What does this cause?
Posterior: talus is concave, calcaneus convex
Anterior: talus is convex, calcaneus is concave
–> much variability
Can NOT be described as a simple machine (e.g. ball and socket or hinge)
What does the axis of movement in the subtalar joint cause?
For every degree of motion produced in the frontal a plane, a degree of motion will be produced in the transverse plane.
So X inverson/eversion = X abduction/adduction
Name the ROM for the ankle/subtalar movements.
- Dorsiflexion
- Plantarflexion
- Inversion
- Eversion
Dorsiflexion 10° to 20°
Plantarflexion 35° to 55°
Inversion 20° to 30°
Eversion 4° to 28°
How do the midfoot and forefoot contribute to motion of the foot?
They contribute to the entire motion of the foot in all three planes.
Describe the change in dorsilfexion/plantarflexion of the ankle during gait. (4)
–> sagittal ankle angle
At heelstrike (10%): a bit of plantarflexion
–> lowering foot to ground
Single leg stance (20-50%): dorsiflexion
–> tibia moves anterior relative to foot = functional dorsiflexion
Pushoff (65%): a lot of plantarflexion
–> push foot of the ground
Leg in air (80-100%): dorsiflexion
–> clear the ground + prepare for heelstrike
See NDC p.22 for illustration
Describe the change in inversion/eversion of the ankle during gait. (4)
–> frontal ankle angle
At heelstrike (0%): rapid eversion
–> we need a flexible foot to absorb the shock = pronation (includes eversion)
At pushoff (65%) inversion
–> we need a rigid foot to push off the ground = supination (includes inversion)
See NDC p.23 for illiustraiton
What parts of the foot experience the most pressure?
What can this cause?
- Heel
- Metatarsals
Lots of pressure can cause stress fractures
- heel not so much because it has a fat pad
- metatarsals at risk
See NDC p.24 for illustration
Name the collateral ligaments of the ankle.
What movement do each restrict?
How can we assess these ligaments?
- Lateral collateral ligament
–> resist inversion/varus stress - Medial collateral ligament (deltoid)
–> resist eversion/valgus stress
To assess them, cause the movement they restrict
See NDC p.26 for illustration
Name the lateral collateral ligaments.
What movement do they resist?
- Posterior talofibular
- Anterior talofibular
- Calcaneofibular
–> resist inversion/varus stress
See NDC p.26 for illustration + IDENTIFICATION
Name the medial collateral ligaments.
What movement do they resist?
- Posterior tibiotalar
- Anterior tibiotalar
- Tibionavicular
- Spring ligament
- Tibiospring
–> resist eversion/valgus stress
See NDC p.26 for illustration + IDENTIFICATION
Name the arches of the foot.
- Medial longitudinal arch
- Lateral longitudinal arch
- Transverse arch
See NDC p.27 for illustration
What is the function of the foot arches? (3)
- Protect nerves, vessels, and muscles on plantar surface
- Absorb shock
- Release stored energy
What bones form the medial longitudinal arch?
From posterior to anterior:
1. Calcaneus
2. Talus
3. Navicular
4. Medial cuneiform
5. 1st metatarsal
See NDC p.27 for illustration
What bones form the lateral longitudinal arch? (3)
Posterior to anterior:
1. Calcaneus
2. Cuboid
3. 5th metatarsal
See NDC p.27 for illustration
What supports the arches?
- Boney shape
- Ligaments
- Muscles
- Plantar fascia
What bones form the transverse arch? (3)
Lateral to medial:
1. Cuboid
2. Cuneiforms
- Also metatarsal
See NDC p.27 for illustration
Name the arch types.
- Pes cavus
- Pes planus
What is pes cavus?
- describe foot
- shock absorption
Where is peak pressure? (4)
High medial longitudinal arch.
- rigid foot
- less able to attenuate shock
Higher peak pressure on 1st, 4th, 5th metatarsals and
lateral heel
See NDC p.29-31 for foot shape, pressure image
Do arch types lead to injury? (3)
- No clear injury pattern based on foot type (Oatis 2016; Messier 2018)
- Pes planus associated with arch pain (Menz 2013)
- Pes cavus (high arch): associated with 2nd metatarsal stress fractures (Military recruits, Dixon 2019)
In runners, what was the impact of high arches on injury? (2)
(Williams 2001; Neal 2014)
- Stress fracture 5th metatarsal
- Increased boney injuries
–> peak pressure on metatarsal 1,4,5 + lateral heel
See NDC p.31 for illustration
What is the impact of arch type on vertical GRF (ground reaction)?
A high arch = larger impact force (rigid foot)
A low arch = smaller impact force (flexible foot)
See NDC p.33 for illustration
Describe the plantar fascia.
- attachments
- strength
Attaches from calcaneus tuberosity –> metatarsal,
phalanges, ligaments
Great tensile strength
See NDC p.34 for illustration
What are the functions of the plantar fascia?
- Arch support
- Windlass effect
What is the windlass effect (plantar fascia)
- Supinated (rigid) foot during push-off
- 1st toe (big) extends, stretch plantar fascia
- Plantar fascia supports arch = passive stability
See NDC p.35 for illustration
What is plantar fasciitis?
What are the symptoms?
Inflammation where plantar fascia attaches to calcaneus
Symptoms
1. Pain in the medial heel
2. Worse in morning, first few steps
What are the risk factors for plantar fasciitis?
In athletes VS non-athletes.
Non-athletes: body mass index, ? arch height?
–> unsure
Athletes: Lower medial longitudinal arch = increased
stress on plantar fascia
–> lower arch = less support from bones and more strain on soft tissue (plantar fascia)
What are the 2 types of shoes for running?
- Motion control shoe
- Cushion shoe
Describe the motion control shoe. (3)
- for who
- material
- medial posting?
- For low arch feet (pronated) –> flexible foot
- Stiffer material in sole (last)
- Medial posting: denser material to prevent
pronation
–> lifting the low medial arch
Describe the cushion shoe. (3)
- for who
- material
- medial posting?
- For high arch (supinated) –> rigid foot
- More flexible sole (last)
- No medial posting
Describe the result of the study motion control shoe VS standard shoe (recreational runners).
Recreational runners (n=372)
Motion control shoes prevented injury but more in
runners with pronated feet (flat feet)
Where does the foot strike in rearfoot VS forefoot running?
Which is recommended?
Rearfoot strike = heel
Midfoot/forefoot = toe pad + toes
Forefoot is recommended
- rearfoot = larger loading rate (GRF) at beginning
- forefoot = gradual increase in GRF
See NDC p.40-41 for graph
Describe the impact force when running barefoot VS rearfoot shod.
What happens if we but the rearfooter in barefoot running?
Barefoot = lower impact force
Rearfoot shod = higher impact
However putting a rearfoot striker barefoot actually increase their impact force.
–> doesn’t change the way they land
See NDC p.42 for graph
What is the goal of wearing minimalist shoes?
Is the hypothesis true?
Get benefits of barefoot + protection of shoes.
Allow foot to absorb loads, not the shoes
Hypothesis: Encourage midfoot landing which reduces ground reaction force compared to traditional shoes
Controversy if they decrease injury
–> Increase in injury and/or pain with minimalist
footwear for new users
Describe the changes research found about minimalists shoes.
- ankle/knee/hip angles
- vertical loading rate
- impact force
- No differences in ankle, hip and knee angles/moments (Bonacci et al., 2013)
- Increase in vertical loading rate in novice users (Willy et al., 2014)
- Barefoot running increased impact force in both group
See NDC p.44-45 for graphs
What is the composition of carbon plate running shoes?
What is the function of the carbon plate?
Change the stack height (with rocker), foam and add
carbon plate
Carbon plate and foam compress, then release energy
adding forward momentum.
–> Foam AND Carbon plate make the difference
What are the results of running in carbon plate shoes?
- Improvements in running economy (oxygen
consumption) by 2.8 to 4.2%
–> you don’t use as much oxygen = it is more efficient - Increased step length
- Faster running times
