FREID part 1

Why did homo sapiens develop a variety of adaptations to the foot such as a great toe in a more adducted position, a medial longitudinal arch, and a thick plantar fascia?

To support the forces and biomechanics associated with higher-intensity quadrupedal gait

To expend greater energy due to an overabundance of calories in a past environment

To enhance tree climbing ability

To support the forces and biomechanics associated with bipedal gait

To support the forces and biomechanics associated with bipedal gait

The more adducted position of the great toe helped with what part of gait

toe off

The medial longitudinal arch helped form a more stable ___ and aided in __ plane stabilization which was crucial in developing an efficient bipedal gait

midfoot

frontal

A stiffened plantar fascia aided in stiffening the __ to form a longer __ which was necessary in absorbing and dissipating the greater loads associated with bipedal gait.

midfoot

lever

Which of the following is NOT true of the structure of our quadrupedal ancestors’ feet?

Our ancestors had a great toe in a more abducted position to better grip during climbing

Our ancestors’ feet could not function to adequately absorb and dissipate load during bipedal gait

Our ancestors had a stiffened midfoot in order to absorb and dissipate ground reaction forces associated with quadrupedal gait

Our ancestors’ feet lacked an arch because they were evolved for quadrupedal gait and tree climbing.

Our ancestors had a stiffened midfoot in order to absorb and dissipate ground reaction forces associated with quadrupedal gait

A stiffened midfoot allows for the formation of a longer lever through which the _ and __ complex can absorb load at higher velocities of bipedal gait

gastrocnemius and soleus complex

Which was NOT a reason why we may have developed more robust plantar fascia?

To assist in toe off and plantarflexion

To bring the tarsals into external torsion

To resist tensile forces at the foot

To passively pronate the foot

To passively pronate the foot

The plantar fascia, in part, functions to prevent the collapse and pronation of the foot.

Which of the following would be a functional exercise for the flexor hallucis longus and brevis?

An arch draw, AKA the short foot exercise. The foot is placed on the ground and you try to push your great toe into the ground as you raise your arch, effectively “shortening the foot.”

A towel curl. A towel is placed under the foot and you curl your toes in order to bring the towel closer to you.

Picking up marbles with your toes

Resisted great toe flexion using a band or manual resistance. Resistance is provided through the use of a band around the toe or some other manual force. The participant, with their toes in the air, curls the great toe against the applied force.

An arch draw, AKA the short foot exercise. The foot is placed on the ground and you try to push your great toe into the ground as you raise your arch, effectively “shortening the foot.”

The flexor hallucis longus and brevis function primarily in a closed chain in order to support the arch against ground reaction forces

What is the primary function of the posterior tibialis in functional human motion such as gait?

To plantarflex the foot in both open and closed chain motion

To dorsiflex the foot in both open and closed chain motion

To invert the foot in an open chain

To bring the foot into slight supination in a closed chain

To bring the foot into slight supination in a closed chain

When the posterior tibialis brings the foot into slight supination, the arch becomes more stable and rigid due to passive structures such as the _ _ and the _ locking mechanism.

plantar fascia

calcaneocuboid locking mechanism

The arch is maintained through the function of three main structures. The posterior tibialis, the flexor hallucis longus and brevis, and the plantar fascia along with other smaller intrinsic stabilizers. What is a likely outcome when the function of the posterior tibialis is compromised?

There is a cascade of effects that results in an unstable midfoot.

The anterior tibialis functions in place of the posterior tibialis in order to bring the foot into slight supination during gait

The flexor hallucis longus and brevis, along with the plantar fascia, function to adequately maintain the arch

There is no impact to arch stability

There is a cascade of effects that results in an unstable midfoot.

Also, the posterior tibialis brings the foot into slight supination which creates a rigid midfoot through which the plantar fascia can further add to its stability through its resistance against tensile forces. As such, the function of the plantar fascia is also decreased when the function of the posterior tibialis is compromised. With this decreased function, the arch is likely to become unstable.

What is the evolutionary mismatch of the foot?

The great toe is located in an adducted position similar to our quadrupedal ancestors. This adducted position is maladapted to our current bipedal gait and puts undue stress on the other arch stabilizers, the posterior tibialis and the plantar fascia.

Highly cushioned and restrictive footwear decreases foot function which may lead to a variety of common injuries to the foot and other structures up the kinetic chain.

There were few changes to our foot structure throughout our evolutionary history, but there were significant changes to function. This change in function puts forces through our feet that we have not adapted to properly absorb and dissipate.

The plantar fascia evolved to aid our ancestors in gripping trees while climbing. That structure is now maladapted to our bipedal function today and cannot absorb and dissipate the forces we put it under.

Highly cushioned and restrictive footwear decreases foot function which may lead to a variety of common injuries to the foot and other structures up the kinetic chain.

When wearing more restrictive footwear, the great toe is in a disadvantageous position to stabilize the foot. Restrictive footwear is even associated with increased rates of hallux __ which can further limit the ability of the great toe to stabilize the arch in a closed chain.

valgus

What is NOT a consequence of prolonged use of cushioned and restrictive footwear without targeted foot training?

Because prolonged use of cushioned and restrictive footwear can lead to foot weakness, as the base of support, foot weakness impacts function and structure up the kinetic chain

The continued use of cushioned and restrictive footwear can lead to greater balance and proprioception.

Modern shoes with elevated heels, stiff soles, cushioning, and arch support may facilitate different gait form than appears to be common among habitual barefoot runners

Shoes can contribute to weak and inflexible feet because the shoe absorbs much of the ground reaction force that the arch has evolved to dissipate.

The continued use of cushioned and restrictive footwear can lead to greater balance and proprioception.

Thickly cushioned and restrictive footwear limits how well your foot can grip the ground to create stability. With decreased arch stability, we find decreased balance as well. Proprioception is also decreased when wearing modern shoes because any proprioception of the foot is associated with the sole of the shoe rather than the ground itself.

The introduction of barefoot or minimalist shoe walking for someone that has worn cushioned and restrictive footwear for a majority of their life would result in which of the following? Assume that the introduction of the barefoot or minimalist shoe walking was done gradually to allow for proper tissue adaptation.

A decrease in arch height due to greater stretching forces on the plantar fascia.

An increase in fall risk due to decreased balance

A decrease in flexor hallucis longus and brevis strength.

An increase in strength and size of the intrinsic foot musculature as well as greater foot stability and function.

An increase in strength and size of the intrinsic foot musculature as well as greater foot stability and function.

minimalist footwear increased the demand on intrinsic arch musculature. With this demand came increased muscle hypertrophy and strength.

The use of highly cushioned shoes encourages what type of foot strike?

Heel strike

Forefoot strike

Medial foot strike

Midfoot strike

Heel strike

Individuals in western cultures tend to be more likely to develop hallux valgus because:

Wide toe boxes common in modern shoes allow for greater adduction of the great toe, which increases the risk of hallux valgus.

Culturally, individuals are more likely to wear cushioned and restrictive footwear more often, which constricts movement of the great toe.

Hallux valgus is heavily influenced by genetics and the gene for hallux valgus risk is more prevalent in western cultures.

The more active western lifestyle leads to overuse of the foot dysfunction of the abductor hallucis.

Culturally, individuals are more likely to wear cushioned and restrictive footwear more often, which constricts movement of the great toe.

Restrictive footwear places the great toe in an adducted position. Over time, this decreases the function of the abductor hallucis and increases risk of joint deformation and hallux valgus.(bunions)

What is a possible consequence of decreased flexor hallucis strength and function?

Increased stress and injury risk to both the posterior tibialis and the plantar fascia because they have to absorb and dissipate greater forces.

Decreased risk of injury to the flexor hallucis group because the flexor hallucis group will not have to contract as strongly to allow for proper arch function.

Increased great toe abduction because the abductor hallucis has to compensate for decreased flexor hallucis group function

Increased arch stiffness because the function of the flexor hallucis group is to allow for decreased arch stiffness.

Increased stress and injury risk to both the posterior tibialis and the plantar fascia because they have to absorb and dissipate greater forces.

What structure(s) are likely weak if pes planus (flat feet) is observed?

The flexor hallucis group and/or the posterior tibialis

The quadriceps and/or the gluteus maximus

The extensor hallucis longus and/or the anterior tibialis.

The gastrocnemius/soleus complex and/or the peroneus longus

The flexor hallucis group and/or the posterior tibialis

Why is a heel strike running gait associated with greater risk of stress fractures?

Heel striking does not allow the gastrocnemius/soleus complex to function eccentrically to aid in force absorption and dissipation. Without the aid of this complex, the rate of impact loading increases drastically, forcing connective tissue such as bone to absorb and dissipate greater loads.

The increased activation of the posterior tibialis associated with heel striking increases arch stiffness. This arch stiffness decreases the amount of force that the arch musculature can dissipate. The excess load is then absorbed and dissipated by bony structures which increases the risk of stress fractures.

The statement above is false. Heel striking during running gait is not associated with increased risk of stress fractures.

Heel striking necessitates that the foot lands under the center of gravity with a flexed knee. This pattern decreases the amount of load the gastrocnemius/soleus complex and the quadriceps can absorb and dissipate. The load is instead absorbed and dissipated by bony structures such as the tibia, which increases the risk of stress fractures.

Heel striking does not allow the gastrocnemius/soleus complex to function eccentrically to aid in force absorption and dissipation. Without the aid of this complex, the rate of impact loading increases drastically, forcing connective tissue such as bone to absorb and dissipate greater loads.

a study found increased impact loading rates to be associated with increased risk of _ . It also found that increased loading rates are associated with _ _, which does not allow significant force dissipation by the gastroc/soleus complex.

stress fracture

heel striking

What is the primary function of the gastrocnemius and soleus complex?

To function concentrically to bring the foot into a supinated position to increase arch stiffness.

To function concentrically to bring the foot into a pronated position to increase arch stiffness.

To function eccentrically to create force through plantarflexion of the foot to increase both vertical and horizontal propulsion.

To function eccentrically to absorb and dissipate the greater loads associated with proper running and sprinting mechanics.

To function eccentrically to absorb and dissipate the greater loads associated with proper running and sprinting mechanics.

When individuals sprint, there is typically a shift to __ striking. The _ _ group and _ _ help to create a stable midfoot in order to form a longer lever through which there is greater mechanical advantage for the gastroc and soleus to absorb, dissipate, and create force.

forefoot

flexor hallucis group and posterior tibialis

An unstable arch can increase the chances of

dynamic knee valgus

In which of the following cases would the short term use of a foot orthotic for arch support be warranted?

An individual has extremely high arches, but has no pain or injuries. An arch support may be used to decrease stress on the plantar fascia while running until the arch is adequately strengthened.

An individual develops a knee injury that is symptomatic in dynamic knee valgus positions. An arch support may be used to increase foot stability in order to increase knee stability in the frontal plane while the individual improves frontal plane knee biomechanics by increasing foot and gluteus medius strength.

An individual has excellent foot strength, but has a weak gluteus medius. Research has shown that the use of an arch support during a single leg squat can increase gluteus medius activation. Therefore, the individual should use an arch support while training.

An individual has pes planus, but has no pain or injury. An arch support may be used to increase arch height until the arch is strengthened.

An individual develops a knee injury that is symptomatic in dynamic knee valgus positions. An arch support may be used to increase foot stability in order to increase knee stability in the frontal plane while the individual improves frontal plane knee biomechanics by increasing foot and gluteus medius strength.

Which of the following would NOT be a possible consequence of weak foot musculature up the kinetic chain?

Decreased gluteus medius strength due to the center of gravity shift associated with pes planus. When there is excessive lateral lean to maintain balance, there is decreased activation of the gluteus medius.

Decreased frontal plane knee stability. The knee does not have frontal plane dynamic knee stabilizers, so it is reliant on foot and hip strength. When the foot is not strong, there is decreased knee stability.

Decreased balance. Stability starts at the foot, so if the foot is not stable, there will be decreased stability all the way up the kinetic chain.

Decreased dynamic knee valgus during activities such as jumping and sprinting. Foot musculature plays a small role in frontal plane knee stability when compared to the increased activation of the quadriceps that becomes necessary when the foot is weak.

Decreased dynamic knee valgus during activities such as jumping and sprinting. Foot musculature plays a small role in frontal plane knee stability when compared to the increased activation of the quadriceps that becomes necessary when the foot is weak.

There are a variety of connective tissue, such as the ACL, MCL, LCL, meniscus, etc. that help to passively stabilize the knee, but no muscles to actively stabilize the knee. Instead, the knee is reliant on _ and _ musculature to stabilize the knee in the frontal and transverse planes.

foot and hip

The three main structures that help to stabilize the arch are…

• plantar fascia

• posterior tibialis

• flexor hallucis group

plantar fascia

passively assists in maintaining arch

gives tension in heel to toe walking

gives stable forefoot while running

lengthens as we put toe down

assist in locking mechinaims in sprinting to increase lever arm to inc force

posterior tibialis

open closed

supports arch when under load

open chain: inverts the foot

closed chain: helps in stabilizing and raising arch

brings the foot into slight supination/inversion to create locking of the transverse tarsal joint to a stable midfoot

flexor hallucis group

Actively assist in stabilizing the arch

open chain: flexes great toe

closed chain: assists in stabilizing arch against GRF (lifts arch)

changes in foot to promote bipedal to be able to get food efficently

1. Robust, adducted 1st MTP: Positions great toe in line with other digits

2. Stiffer lateral column helped to convert a grasping foot into a propulsive lever (insde of arch)

3. Thick plantar fascia and “spring” ligament

4. Highly developed gastrocnemius soleus complex

5. Flattened subtalar joint

6. Calcaneus with robust posterior tuberosity

7. Calcaneocuboid joint locking mechanism

8. Elongated midfoot

what dose adducted 1st MTP help with

facilitates push-off (great toe extension)

frontal plane stablity

supports arch

what dose plantar facia help with

Resist tensile forces at the foot

Absorb load with gait

Assist in toe off and plantar flexion

Put metatarsals in external torsion

what is external torsin

duck feet?

what dose more develped gastrocnemius soleus complex help with

Dissipate ground reaction force eccentrically

what dose flatter subtalar joint help with

Decrease mobility and increase stability in foot

increased joint congruency

Calcaneus with robust posterior tuberosity

Calcaneocuboid joint locking mechanism

Elongated midfoot

benfits

robust posterior tuberosity gives attachment for achillies

in supinated foot when joint axis cross and lock to length moment arm of calf and increase MA

arch and soft tissue structures are

ex

natural shock absorber

ex: Fat pad on the calcaneus

Shift to _ and _ _ strike with increased loads as center of gravity

is on top of base of support

mid and forefoot strike with inc speed

__ helps equally distributed peak pressures during load bearing

Wide toe box

internal forces active and passive and joint surface forces examples

Active

○ Muscle/tendon

Passive

○ Ligaments and fascia

Joint surface forces

○ Tension

○ Compression

unipedal in bipedal gait for

what % of walking and running

70% walking

100% running

gait phase sup or prone

Heel strike –

Midstance – →

Terminal stance to pre swing – →

Heel strike – supinated

Midstance – supinated → pronated

Terminal stance to pre swing – pronated → supinated

Foot & Ankle Rigidity/Supination goal and how its done

Main goal = gait efficiency

● During walking:

○ Supination → joint locking → rigid lever for movement efficiency

Foot & Ankle Malleability/Pronation goal and how its done

Main goal = force dissipation

● During walking:

○ Pronation → unlocking of the midfoot → force dissipation

direct effects of modern footwear

1. decreased intrinsic musculature development and arch function

   1. decreased flexor hallus and post tib strength b/c weaker arch b/c dont have to work as hard

   2. poor pressure distribution across gait cycle (narrower so less distribution so more force on heel metatarsals and hallux

2. facilitate different gait form

   1. increased heel strike even during running, which increases loading(high peak plantar pressure and pressure impulse)

   2. increased stride length and decreased cadence

3. increased rate of hallux valgus because of narrow toe box

   1. affects structures up the chain

   2. bunions when big toe moves to midline so you get pain in the joint and decreased arch stability and over foot weakness

4. decreased proprioception

do shoes cause in hallux valugs in men or women

both but more women

Indirect Effects of modern footwere

1. When one component of arch stability fails, other components compensate

   1. plantar fascia, posterior tibialis, and the flexor hallucis

2. Improper loading mechanics and overloading connective tissue structures (e.g. bones, fascia)

   1. running with heel strike leads to calcaneus dealing with GRF so forces is pushed up the chain knee more forward, not under COG

      1. leads to stress fracture, plantar fasciitis

   2. running with forefoot strike leads to arch structures dealing with GRF with a longer lever for eccentric calf to lower heel slow, greater knee flexion, and knee under COG

3. Consequences of decreased foot function up the chain

   1. can’t activate glute max

      1. Maintaining the arch increased Gluteus medius activation during

         the single leg squat (orthotics could help with this in acute phase)

   2. Increased dynamic knee valgus because big toe can't stabilize arch so foot pronates and increases q angle

   3. increases fall risk b/c of weak flexor hallux

heel vs forefoot stike

similar GRF but increased vertical loading rate with heel strike

can cause stress fracture and plantar fascitits

how should Orthotics be used

Orthotics may need to be used early on when treating those with foot

dysfunction to prevent orthopedic issues up the kinetic chain

Orthotics should be avoided once natural foot biomechanics are

restored

foot structres that are

• Passive

● Active extrinsic muscles

● Active intrinsic muscles

Passive:

○ Plantar fascia and the spring ligament

○ Fat pad on the calcaneus

● Active extrinsic muscles

○ Posterior tibialis

○ Flexor hallucis longus

● Active intrinsic muscles

○ Flexor hallucis brevis

○ Abductor hallucis

abductor hallucis

● Functions in an open chain to abduct the phalanx on the 1st metatarsal (ellipsoid) joint

Enables the “big toe” to be positioned to support the

arch and assist in maintaining frontal plane stability up the kinetic chain.

● The segments prior to the great toe are connected via plane joints. When the muscle contracts these joints compress and lock, stabilizing the moment arm, and allowing for abduction of the great toe.

things to look for in foot exam

medial and lateral malilio achilles bisection

medial arch

navicular tuerosity(if lower to ground then excess pronation)

big toe alignment

forefoot vs midfoot vs rearfoot

are feet turned in or out or supinated or pronated

SL stance

Gait

ankel dorsiflextion

10-25 degress normal (need 10 for normal gait)

when dorsiflextion with knee bent then Achilles and gastroc not in the equation

when dorsiflextion with knee straght then Achilles and gastroc are in the equation

great toe dorsifextion

need 45 for normal gait

what might someone do if they have hallux valgus

Supination to stabilize

lateral external rotation of leg

what might somone do if they have limited ankle dorsiflextion

arch collapse

foot turns outward as they transition to toe-off

what might someone do with limited big toe extension

duck walk to get toe off and to increase contact and stability

medial arch muscles weaken

what might someone do who has flat feet

can’t maintain subtaylor neutral

more dynamic knee valgus

arch collapse into pronation

increase Q angle

What was the driving force behind the evolutionary changes to the knee, hip, and pelvis structures?

The changes at the knee, hip, and pelvis allowed for faster locomotion to evade predators.

The changes at the knee, hip, and pelvis increased function and force production in the sagittal plane.

The changes at the knee, hip, and pelvis were necessary to become bipedal in order to be more energy efficient over longer distances to obtain food.

The changes at the knee, hip, and pelvis occurred to improve our ancestors’ ability to climb.

The changes at the knee, hip, and pelvis were necessary to become bipedal in order to be more energy efficient over longer distances to obtain food.

Bipedal gait is 4x more energy efficient than quadrupedal gait.

Which of the following adaptations did NOT favor increased stability at the patella (required by the introduction of greater frontal plane forces placed on the knee by bipedalism)?

The development of a more triangularly shaped patella.

The formation of deeper intercondylar grooves.

The transition of the gluteus medius from a hip extensor to a hip abductor.

The development of an obliquity angle at the femur.

The development of an obliquity angle at the femur.

obliquity angle positives and negatives

obliquity angle is to bring the foot, the base of support, under the center of gravity in order to increase frontal plane stability and reduce aberrant motion patterns such as excessive lateral movement during gait. However, the obliquity angle also increases the q-angle and dynamic knee valgus which can decrease stability at the knee and patella.

Which of the following evolutionary changes did NOT contribute to our ability to transition to bipedal gait?

A decrease in femoral obliquity angle to position our feet wider in order to increase our base of support.

Increased femoral condyles size to improve the weight bearing surface of the knee joint.

Enhanced ability to muscularly stabilize the lower extremities in the frontal plane (e.g. the gluteus medius transitioned from a hip extensor to hip abductor)

All of these changes contribute to bipedal gait function

A decrease in femoral obliquity angle to position our feet wider in order to increase our base of support.

There was an increase in femoral obliquity angle to position the feet underneath the center of mass to allow for a more stable single limb gait.

Which of the following muscle(s) does not primarily function in the sagittal plane?

Hamstrings

Quadriceps

Gluteus medius

Gluteus Maximus

Gluteus medius helps in frontal plane

Which of the following is NOT a role of the patella?

Increase the mechanical advantage of the quadricep muscles by moving the attachment site further away from the joint axis

Keep the quadricep moment arm constant throughout the knee flexion range of motion.

Facilitates the knees tracking beyond the toes in the sagittal plane.

Reduced stress to the femoral acetabular joint.

Reduced stress to the femoral acetabular joint.

Which of the following structures does not serve to stabilize the knee joint?

The ilioinguinal ligament.

The anterior collateral ligament (ACL) and the posterior collateral ligament (PCL).

The gluteus medius.

The medial collateral ligament (MCL) and lateral collateral ligament (LCL).

The ilioinguinal ligament.

It functions to protect vital tissue structures of the anterior hip. 

What evolutionary change contributes to the challenge to stabilize effectively on a single limb?

We evolved with the propensity to store calories as fat.

We evolved to have strong supporting/stabilizing musculature in the hips. 

We evolved to have smaller bone structure.

We evolved to have narrower hips to better support childbirth.

We evolved with the propensity to store calories as fat.

What evolutionary changes result in an increased Q-angle at the knee joint?

A wider pelvis and a increased femoral obliquity angle.

A narrower pelvis and an increased femoral obliquity angle. 

A narrower pelvis and a decreased femoral obliquity angle. 

A wider pelvis and a decreased femoral obliquity angle

A wider pelvis and a increased femoral obliquity angle.

Which of the following is false regarding ACL tears?

ACL tears are 2-7x more common in females than males and one reason is due to needed a wider pelvis structure

Training muscles of the trunk and hips, such as the spinal stabilizers and glutes, can help prevent ACL tears.

Stronger feet can play a role in ACL tear prevention. 

ACL tears are 2-7x more common in males than females due to the activities that males are more likely to engage in on a day to day basis. 

ACL tears are 2-7x more common in males than females due to the activities that males are more likely to engage in on a day to day basis.

ACL tears are 2-7x more common in females than males due to wider birthing hips and greater valgus stresses at the knee joint.  

Based on the articles we reviewed, why might we recommend allowing the knees to translate slightly beyond the toes during the squatting motion?

Letting the knees translate beyond the toes decreases stresses on the knee joint.

Letting the knee translate beyond the toes decreases stress placed on the spine/ low back

Letting the knees translate beyond the toes decreases risk to ACL and other ligamentous damage.

Letting the knees translate beyond the toes increases glute engagement during the squat movement.

Letting the knee translate beyond the toes decreases stress placed on the spine/ low back

How might we suggest assessing dynamic knee valgus and the quality of lower body motion /injury risk during an evaluation, and why?

Supine lying to increase accuracy of the measurement.

Bilateral standing to increase accuracy and applicability.

Single leg from the shoulders down to assess overall quality and compensatory motion–serving as more valuable clinical knowledge.

Single leg from the hips down to assess overall quality and compensatory motion–serving as more valuable clinical knowledge.

Single leg from the shoulders down to assess overall quality and compensatory motion–serving as more valuable clinical knowledge.

A dramatic trunk lean can result in a relative Q-angle. This is important when considering holistic movement. 

Which of the following is not an injury/dysfunction associated with greater knee valgus stress?

Patellofemoral joint pain or patellar subluxations

Meniscus injury

Osteoarthritis of the knee

All of the answers are associated with greater knee valgus stress.

All of the answers are associated with greater knee valgus stress.

why did our knees hips and pelvis change

so we could be bipedal and get food more efficiently

why did our pelvis change and how did it change

homo sapiens have bigger brains and we need wider birth cannals

changes that occured in the knee hip and pelvis from past

larger femoral obliquity angles

longer femoral neck

deeper inercondylar grooves

larger condyles

triangular larger pattela

glute medius became more of a frontal plane muscle

result of glute mead becoming a frontal plane muscle

and changed origin to ilium so less aberrant frontal plane movement in bipedalism (glute med now can help increase hip abduction and prevent contralateral hip drop)

benifit of longer femoal neck compared to past

Longer neck of the femur to improve gluteal lever (increases moment arm) and assist with frontal plane stabilization

past Femoral Obliquity angle

what happens now that the angle changed

past 0 degrees

Now increased femoral adduction to place foot closer to midline so foot in under COG in unipeadalism

benifits of deeper intercondylar grooves

less dislocation at knee

The increase of femoral obliquity angle was helpful for COG under BOS but it causes knee valgus, which can lead to lateral knee dislocation so deeper grooves help prevent

benifit of and larger more anteriorly projecting condyles

larger: increase joint SA of distal femur and tibia so less stress because distributed on larger SA

more anterior: helps increase lever arm length and MA for knee extension

benifits of more triangularly shaped patella

fites better in intercondylar groove so less knee dislocation

function of hamstring in open and closed chain

open: flex knee and extend the hip

closed:

• extend knee

• contract concentrically to extend the hip to improve force production

function of quad in open and closed chain

open: extend the knee

closed: eccentrically flex the knee to absorb shock

• Inserts on the patella, which helps knee cap stability

role of patella

increase MA of quads by moving attachment site distally (so moment arm between quads and knee axis is longer than moment arm between hamstrings and knee axis so quads are used more)

keeps quads moment arm constant length in ROM for flexion so knees can track beyond toes

what is ideal for tibia and trunk angle

for them to be the same so quad and hamstings are used evenly

tunk angle too big and tibia angle too small (staight posture) then quad heavy

trunk angle too small and tiba angle too big(leaned far over) then hamstring heavy

direction of ACL

posterior to anterior

lateral to medial

(hand in pocket)

ACL role

resists anterior translation of tibia on femur

limits dynamic knee valgus in SL

are there intinsic muscle in knee

no it relies on hip and foot for stablity and to prevent valgus

glute mead function in open and closed

open: abducts and internally rotates hip

closed: functions against GRF to elevate and stabilize contralateral pelvis

• helps with knee stabilization and prevents valgus

****very important for frontal plane stability

best way to train glute med

closed chain SL while trying to limit frontal plane movements

Ilioinguinal Ligament function

Protects vital tissue

Attachment point for abdominal oblique muscles

cause of the “butt wink” another factor in a narrow base of support squat with the hip hinge.

○Put your spine at risk

2 reasons for the evolutionary mistmatch

high BMI Evolved to store calories for millions of years. Now we suffer from excess

sedentary lifestyle from cultural evolution

results of 2 evolutionary mistmatch reasons

issues and disuse of biomechanically disadvantaged structures, so stablizing structres have to work harder

The Mismatch: The Obstetrical Dilemma

Humans have very long dependent period out of the womb because if left in too long then their heads would be so big that women’s pelvises would be so wide that their gait would not be efficient

what is the Q angle

angle between the quads and the patellar tendon

The Mismatch: Q-angle

women’s larger Q leads to

As hip width increases, so does energy expenditure with gait

Longer moment arm leads to challange intrinsic stability muscles to support knee

so more ACl and meniscal tears in women

Q angle of men and women

men 13 degress

women 18 degress

The Mismatch: Knee Vulnerability

The knee relies on joint congruence and passive intrinsic structures (ligaments and joint capsule) for stability.

Active stability at the knee relies on foot/hip musculature

The Mismatch: Nonfunctional Training

common to train to work out not in SL stance and load the spine and train stablity on unstable surfaces and train with cushioned shoes