Biomech unit 2: F & A Joint Structure and Function

What bones make up the talocrural joint?

trochlea of talus and distal tibia and fibula

Distribution of force onto the talus

- ~90-95% of body weight comes through tibia through talar head
- 5-10% of body weight comes through fibula through lateral talus

Articular cartilage of the talus

- THICKKK (~3mm)
- needs to be thick because of the large amount of compressive forces acting on it
- will compress ~30-40% when load is put on it

Mechanoreceptors of the talocural joint ligaments

mostly free nerve endings and ruffini receptors

What ligaments are most vs least likely to be injured?

- most: anterior talofibular ligament (ATFL)
- least: deltoid ligaments

What motion do certain ligaments limit?

-Calcaneofibular ligament: resists inversion
-deltoid ligaments: resists extreme eversion

Movements that stretch deltoid ligament (tibiotalar fibers)

-eversion
-dorsiflexion w/ associated posterior talus w/in mortise (posterior fibers)

Movements that stretch deltoid ligament (tibionavicular fibers)

-eversion
-abduction
-plantarflexion w/ associated anterior slide of talus w/in mortoise

Movements that stretch deltoid ligament (tibiocalcaneal fibers)

-eversion

Movements that stretch anterior talofibular ligament

-inversion
-adduction
-plantarflexion w/ associated anterior slide of talus w/in mortise

Movements that stretch calcaneoufibular ligament

-inversion
-dorsiflexion w/ associated posterior slide of talus w/in mortise

Movements that stretch posterior talofibular ligament

-abduction
-inversion
-dorsiflexion w/ associated posterior slide of talus w/in mortise

What is the orientation of the talocrural axis of rotation?

-slightly deviated from a mediolateral axis as it goes through the tips of the malleoli
-the slight deviation allows for:
-dorsiflexion+abduction+eversion=pronation
-plantarflexion+adduction+inversion=supination

Normal ROM of talocrural joint

- neutral at 90 degrees
-15-25 degrees of dorsiflexion
-40-55 degrees of plantarflexion

Roll and slide of talocrural joint dorsi vs plantar flexion

-dorsiflexion: talus rolls anteriorly, slides posteriorly
-plantarflexion: talus rolls posteriorly, slides anteriorly

Bones of the subtalar joint

talus and calcaneus

Articulating surfaces of the subtalar joint

-posterior articular surface is larger and has it's own joint capsule
-anterior & medial surfaces are smaller and share a joint capsule

Ligaments that stabilize the subtalar joint

-calcaneofibular ligament stabilizes posteriorly and limits excessive inversion
-tibiocalcaneal fibers of deltoid limit excessive eversion
-talocrural ligament provides most support

axis of rotation of the subtalar joint

-lateral posterior heel through subtalar joint and comes out the anterior, medial, and superior direction
-~42 degrees off of horizontal plane and ~16 degrees off of sagittal plane

Movements of the subtalar joint

-inversion and eversion
-mostly accessory movements

Bones/joints of the transverse tarsal

talonavicular joint and calcaneocuboid

What movements does the transverse tarsal joint allow for?

-cooperative movement of pronation/supination
-allows us to adjust to various contours of surfaces and maintain balance
-accessory movements to subtalar

What type of joint and types of movements occur at the talonavicular joint?

-resembles ball and socket joint --> covex talus, concave navicular
-navicular spins w/in the joint to allow for twisting, bending, etc

What ligament stabilizes the talonavicular joint?

-spring ligament
-spans from susenaculum talus to navicular

If spring ligament is damaged, what condition will a pt experience?

pes planus

Describe the movement/purpose of the calcaneocuboid joint

-Not a lot of movement at the joint
-Provides stability to the lateral aspect of the foot
-allows for translation of the propulsion/body weight onto the foot

what are the ligaments that hold the calcaneocuboid joint together dorsally?

calcaneocuboid ligament and bifurcated ligament

what are the ligaments that hold the calcaneocuboid joint together on the plantar side?

long and short plantar ligaments

Where is the primary movement of the transverse tarsal?

-at the talonavicular joint, spins
-allows for pronation and supination

What are the 2 axes of rotation of the transverse tarsal?

-longitudinal
-oblique

Orientation and action of longitudinal axis of transverse tarsal

-almost in line with the anterior-posterior axis of movement
-allows for inversion and eversion

orientation and action of longitudinal axis of transverse tarsal

-runs vertically and medially
-facilitates motion of abduction in dorsiflexion and adduction in plantar flexion

what are the bones/joints that are a part of the distal intertarsal joints?

-cuneonevicular joint
-cuboideonavicular
-intercuneiform
-cuneocuboid

purpose/movement of the distal intertarsal joints?

-assist with pronation and supination by translating movement up to the forefoot
-also provides significant stability of the transverse arch

What is another name for the tarsometatarsal joint?

Lisfrac joint

What tarsal and metatarsal bones articulate with each other?

-1st metatarsal & medial cuneiform
-2nd metatarsal & intermediate cuneiform
-3rd metatarsal & lateral cuneiform
-4th and 5th metatarsal & cuboid

What is a significant function of the 1st TMT joint?

-assists medial longitudinal arch
-shares/distributes the load of the body weight out through the forefoot

What amount of movement does each tarsometatarsal joint allow for?

- 2nd and 3rd: least amount of movement, most stability
-1st, 4th, and 5th: greatest mobility

What happens to the 1st ray/TMT joint when you are NWB and plantarflex?

1st TMT slightly everts

What happens to the 1st ray/TMT joint when you are NWB and dorsiflex?

1st TMT slightly inverts

What does the slight inversion/eversion of the TMT joint allow for?

allows for high flexibility/adaptability of the medial aspect of the foot to adapt and conform to uneven surfaces

What are the bones of the metatarsophalangeal joint?

-metatarsal (convex)
-proximal end of phalanx (shallow concave)

What are the ligaments of the metatarsophalangeal joint?

-collateral ligaments (run obliquely)
-plantar plate (grooved, thick ligament on plantar surface)
-transverse metatarsal ligaments

What tendon passes through the groove of the plantar plate of the 1st MTP joint?

tendon of flexor hallucis brevis

What is the purpose of the plantar plate?

helps for greater force distribution and propulsion

What is the purpose of the deep transverse metatarsal ligaments?

help build congruency b/w plantar plates, they are very important for propulsion of the foot --> important for toe off phase of our gait

How many DoF does the metatarsophalangeal joint have/what planes does it move in?

-2 DoF
-extension and flexion --> sagittal plane and ML axis
-abduction and adduction --> horizontal plane and vertical axis
-Passive ROM:
-toe extension: ~65 degrees
-great toe extension: ~85 degrees
- flex: 30-40 degrees

what are the bones of the interphalangeal joint?

proximal and distal phalanges

what are the ligaments of the interphalangeal joint?

-collateral ligaments (run obliquely)
-plantar plate
-joint capsules

What plane and movements does the interphalangeal joint perform?

extension and flexion in the sagittal plane along the ML axis