Ankle Biomechanics Flashcards
Name some functions of the ankle.
Shock Absorption
A rigid lever for push-off
Adapts to uneven terrain
What type of joint is the distal Tibiofibular Joint?
Syndesmosis joint
How is the distal Tibiofibular joint connected?
Articular capsule
Anterior & Posterior tibiofibular ligaments
What is the Talocrural joint?
Articulation between the distal tibia & fibula with the trochlea of the talus
What type of joint is the Talocrural Joint?
Uniaxial hinge joint
How many degrees of freedom does the talocrural joint have?
1 (Plantar and Dorsal Flexion)
Where is the axis of rotation for the talocrural joint?
10 degrees offset in the frontal plane
6 degrees offset in the horizontal plane
What are the 3 fibers for the deltoid ligament?
Tibionavicular fibers
Tibiocalcaneal fibers
Tibiotalar fibers
What does the Tibionavicular fibers restrict?
(restricts talocrural eversion, PF, & anterior slide of talus)
(restricts talonavicular eversion & abduction
What do the Tibiocalcaneal Fibers restrict?
Talocrural and subtalar eversion
What do the Tibiotalar fibers restrict?
Talocrural eversion, DF, and posterior slide of the talus
Name some of the lateral ligaments of the talocrural joint
Anterior talofibular ligament (ATFL)
Calcaneofibular Ligament
Posterior talofibular ligament
What does the ATFL restrict?
Talocrural PF, anterior slide of talus, inversion, and adduction.
What does the Calcaneofibular ligament restrict?
Talocrural DF, posterior slide of talus, and inversion Subtalar inversion (mostly stretched during DF)
What does the posterior talofibular ligament restrict?
Talocrural DF, posterior slide of talus, inversion, and abduction
Which ligament is the weakest in the lateral region, and is mostly related to inversion ankle sprains?
ATFL
What type of joint is the subtalar joint?
Diarthrodial synovial joint
What is the articulations with the Subtalar joint?
Calcaneus and talus
What is the main action of the Subtalar joint?
Supination (inversion), and pronation (eversion)
What is pronation?
Dorsiflexion, Abduction, Eversion
What is supination?
Plantarflexion, Adduction, Inversion
What does supination allow?
A rigid push-off during gait, (medial sole showing)
What does pronation allow?
Shock absorption with ground reaction forces (lateral sole showing)
What path does the subtalar joint take and where is the axis of rotation?
Curvilinear path
Approximately 42 degrees from the horizontal plane
Approximately 23 degrees from the sagittal plane
Name the ligaments associated with the subtalar joint
Cervical talocalcaneal ligament
Interosseous talocalcaneal ligament
What does the cervical talocalcaneal ligament restrict?
Inversion
binds the calcaneus to the talus
What does the interosseous talocalcaneal ligament restrict?
Limits Eversion
binds the calcaneus to the talus
What is the articulations with the Transverse Tarsal joint?
Calcaneocubiod & talonavicular joints
What type of joint is the Transverse Tarsal joint?
Synovial saddle joint
What are the axis of motion in the transverse tarsal joint?
Longitudinal (inversion/eversion) 15 degrees upward from transverse plane, 9 degrees from longitudinal reference
Oblique (flexion/extension) 52 degrees upward from transverse plane, 50-57 degrees from the frontal plane
What does the spring ligament do?
Supports the medial longitudinal arch
Prevents excessive medial and plantar movement of the talus
What does the medial longitudinal arch consist of?
Calcaneous, Talus, Navicular, Cuniforms, and Medial metatarsals
What’s the keystone of the medial longitudinal arch?
Talonavicular joint?
What supports the medial longitudinal arch?
Plantar Fascia,
Spring ligament
Short & long plantar ligaments
tibialis posterior muscle
What is Pes planus?
dropped arch (overstretched plantar fascia) Commonly connected to overpronation & excess rearfoot varus
During stance phase, what happens to the arch?
decreased arch, increased rear foot pronation w/ increased weight bearing
During the swing phase, what happens to the arch?
Increased arch, decreased rear foot pronation (so supination), w/ decreased weight bearing
What happens with over pronation of the foot?
Hip-increased IR, flexion, adduction
Knee-Increased valgus stress
Rearfoot- increased pronation
Mid/Forefoot- supination (inversion)
What happens when you correct over pronation?
Better storing of elastic energy (better push off)
Able to grip surface better
Decreased stress transmission to other joints
What type of joint is the tarsometatarsal joint?
Plane synovial joint (gliding movements)
Which TMT is most mobile and least mobile?
2nd and 3rd TMT highly immobile
1st TMT most mobile (helps transfer force at push-off)
What type of joint is the MTP joint?
Condyloid synovial joint (biaxial joints)
2 degrees of freedom
What is turf toe?
Hyperextension of first MTP joint
What type of joint is the IP joints?
Synovial hinge joint (Concave on Convex)
1 degree of freedom
What is the Plantar Fascia
Fibrous band that goes from medial plantar tuberosity to MTP plantar plates
What tightens the plantar fascia?
toe extension
What’s the windlass effect?
When Plantar fascia is tight, it inverts calcaneous and elevates arch, helps supinate subtalar joint
Where’s the tarsal tunnel, and what can happen here?
Posterior & inferior to medial malleolus, can cause tibial nerve entrapment
What all runs through the tarsal tunnel
Tibialis posterior Flexor Digitorum Longus Posterior Tibial Artery & Vein Tibial Nerve Flexor Hallucis Longus
What doe the intrinsic muscles of the foot do?
Control arch during midstance of gait
Help lift the arch during the later phases of gait
Stabilize the forefoot during terminal stance
What happens during inversion ankle sprain?
Tear of ligaments of ankle (ATFL most common, followed by CFL)
Happens with PF & inversion
How are ankle sprains graded?
1: Ligament damage, with no instability
2: Ligaments having partial tear, ATFL partial tear, CFL stretches
3: Rupture of of ATFL & CFL ligaments, with partial tear of posterior talofibular & Tibiofibular ligaments
What is a foot drop?
Inability to DF foot
Damage to fibular nerve, (stroke/brain injury, spine problems, muscle disorders)
Treated with bracing, orthotics, physical therapy
What is hallux valgus?
1st metatarsal is adducted phalanges abducted hypermobile 1st metatarsal increased pronation of the foot bunions can form
