Biomechanics Of Ankle (2) Flashcards
How many bones and joints are in the ankle?
28 bones and 27 joints
What is the stability aspect of the ankle?
Base of support for weight bearing activities
What does the ankle act as?
Rigid lever for effective push off during gait
What is the mobility aspect of the ankle?
Dampen torsions from proximal joints
Shock absorber
Conform to different terrain
What makes up the forefoot?
Metatarsals
Phalanges
What makes up the midfoot?
Navicular
Cuboid
Cuneiforms
What makes up the hindfoot?
Talus
Calcaneus
What is dorsiflexion of the talocrural joint?
15-20°
What is plantar flexion of the talocrural joint?
45-50°
What plane does the talocrural joint move in?
Sagittal plane
What plane does the subtalar joint move in?
Coronal plane
What are the movements of the subtalar joint?
Inversion and eversion
What plane does the transverse tarsal move in?
Transverse plane
What are movements of the transverse tarsal?
Adduction and abduction
What are the movements of supination in the closed chain?
Calcaneal inversion
Abduction and dorsiflexion of the talus
Elevates ML arch
What are the movements of supination in the open chain?
Calcaneal inversion
Adduction and plantar flexion of talus
What are movements of pronation in the closed chain?
Calcaneal eversion
Adduction and plantar flexion of talus
Lowers ML arch
What is the movement of pronation in the open chain?
Calcaneal eversion
Abduction and dorsiflexion of talus
What are the tibiofibular joints?
Proximal
Interosseus membrane
Distal
What is the Syndesmosis of the fibula?
Distal fibula and fibular notch of tibia
What is the function of the anterior and posterior tibiofibular ligaments?
Restrict motion and stabilize mortise
Where do the proximal and distal tibiofibular joints work together at?
Knee and ankle joints
What is the movement of the tibia in closed chain?
Tibia performs movement around the fibula due to absorbing most of the body weight
What does supination in the ankle produce?
Distal and posterior glide of the fibula
What does pronation in the ankle produce?
Proximal and anterior glide with external rotation of the fibula
What does plantar flexion produce?
Distal glide and medial rotation of the fibula
What does dorsiflexion produce?
Proximal glide and external rotation of the fibula
What type of joint is the talocrural joint?
Modified hinge synovial
What is the most congruent joint in the body?
Tenon/mortise articulation
What are characteristics of the tenon/mortise articulation?
Wider anterior
No muscular attachments
Limited blood supply
What is the mortise?
Rectangular cavity
What is the tenon?
Projection shaped for insertion into mortise
How does the axis shift in talocrural coupling?
With movement from the transverse plane of the lower leg to frontal plane of the foot
What does lower leg rotation initiate?
Movement of the talus which causes simultaneous motion in all 3 joints
What is closed packed position of the talocrural joint?
Dorsiflexion
What is open packed position of the talocrural joint?
10-20° of plantar flexion
What is the capsular pattern of the talocrural joint?
PF more limited than DF
What are the deltoid ligaments?
Tibionavicular
Tibiocalcaneal
Posterior and anterior tibiotalar
What do the deltoid ligaments resist?
Valgus/eversion
What percentage of ankle sprains occur in the deltoid ligaments?
5-10%
What are the lateral ligaments?
Anterior and posterior talofibular
Calcaneofibular
What percentage of ankle sprains occur in the lateral ligaments?
85%
What is the most injured ligament of the lateral ligaments?
Anterior talofibular ligament
What is the strongest ligament of the lateral ligaments?
Posterior talofibular ligament
What type of joint is the subtalar joint?
Synovial joint
What is the triplanar motion of the subtalar joint used to do?
Dampen rotational forces and maintain foot contact
What is the closed pack position of the subtalar joint?
Supination which causes a rigid lever
What is the open packed position of the subtalar joint?
Neutral between pronation and supination leading to more mobility and shock absorption
What is the capsular pattern of the subtalar joint?
Varus more limited than valgus
What does talar adduction during pronation cause?
Internal rotation of lower leg
Pronated subtalar joint in weight bearing imposes internal rotation force on the lower leg that can affect what?
Hip and knee
What may be related to anterior knee pain?
Excessive hip rotation which causes medially facing patella
What does the transverse tarsal joint separate?
Hindfoot from midfoot
What type of joint is the Talonavicular joint?
Ball and socket
What is the function of the spring ligament?
Supports Talonavicular joint and medial longitudinal arch
What is the Talonavicular joint used for?
Mobility
What is the calcaneocuboid joint used for?
Stability
What supports the lateral longitudinal arch?
Long plantar ligament
What does the transverse tarsal joint increase?
ROM of subtalar pronation and supination
What does the transverse tarsal joint compensate for?
Hindfoot positioning
What does the transverse tarsal joint enable the forefoot to do?
Remain flat regardless of hindfoot pronation or supination
What do both the subtalar and transverse tarsal joint do on level surfaces?
Pronate which allows foot to absorb shock of body weight during early stance
What does the transverse tarsal joint do during mid stance?
Supinates to ensure contact between lateral border of foot and ground
Why do the subtalar and transverse tarsal joints supinate in late stance?
To increase stability of stance limb locking in a closed pack position
What is pes planus?
Lack of medial longitudinal arch (flat footed)
What type of joints are tarsometatarsal joints?
Planar synovial joints
What forms the tarsometatarsal joint?
Distal tarsals and bases of metatarsals
How does the tarsometatarsal joint maintain forefoot contact with ground?
Rotating to adjust the forefoot position
What type of joint is the metatarsophalangeal joint?
Condyloid synovial
What are the sesamoid bones?
Two small bones on plantar surface of 1st metatarsal head
What is the function of the sesamoids?
Anatomic pulleys for flexor hallucis brevis
What does the sesamoid protect?
Flexor hallucis longus tendon from trauma
What are the sources of stability of the plantar arches?
Wedged shaped mid tarsal bones
Medial longitudinal arch
Plantar aponeurosis
Intrinsic foot muscles
What does the plantar aponeurosis increase foot stability during?
Metatarsal phalangeal extension during push off (windlass effect)
How is the tie rod during non weight bearing?
Relaxed
How is the tie rod during weight bearing?
Tensioned
Pes cavus
Increased medial longitudinal arch (supinated foot)
What are related injuries to pes planus?
Plantar fasciitis
Knee pain
Patellar tendinitis
Stress fractures (2 and 3 MTs)
What are injuries related to pes cavus?
Plantar fasciitis
Ankle inversion sprains
IT band syndrome
Stress fracture (5th MTs)