leg, ankle, foot prac Flashcards
external tibial torsion
20 – 40˚ normal values
tibia
most common bone prone to stress fracture: 90% of tibial stress fractures affect the posteromedial tibia near the junction of the middle and distal 1/3 of the bone, where the cortex of the shaft is narrow.
tibia is the larger of the 2 bones in the leg, both distally & proximally indicating its importance in force transfer / weight-bearing.
foot (pes)
The skeleton of the foot consists of 7 tarsal bones, 5 metatarsal bones, 14 phalanges and a variable number of sesamoid bones.
hindfoot
talus and calcaneus
midfoot
rest of tarsals
forefoot
metatarsals and phalanges
Which metatarsal is shortest?
1st
Which metatarsal is longest?
2nd
Which metatarsal has the thickest diaphysis?
What does this suggest?
1st - shock absorption/weight transfer
Compare the relative length of the metatarsals & phalanges of the foot with the metacarpals & phalanges of the hand.
The metacarpal bone of the thumb - great mobility, is directed at an acute angle from that of the index finger, and is capable of a considerable range of movements at its articulation with the carpus.
* The metatarsal bone of the great toe assists in supporting the weight of the body, is constructed with great solidity, lies parallel with the other metatarsals, and has a very limited degree of mobility.
Phalanges: those of the foot are smaller and their movements are more limited than those of the hand.
Compare the mobility and function of the 1st ray & hallux with the that of the thumb.
hallux = very stable, force transfer thumb = mobile
medial longitudinal arch
higher = calcaneus, talus, navicular, medial cuneiform and 1st MT - reference point is tubercle of navicular
lateral longitudinal arch
calcaneus, cuboid, 5th MT
transverse arch
head of talus, cuneiform, cuboid, base of MTs
Give 3 functions of the arches of the foot:
shock absorption
energy return in locomotion
protection
DISTAL TIBIOFIBULAR JOINT:
a fibrous syndesmosis and its stability is crucial to the integrity of the talocrural joint.
Inferior tibiofibular joint injury
“high ankle sprain”
combination of DF & external rotation of the foot relative to the leg. During DF the anterior portion of the talar dome is located between the distal tibia & fibula, additional ER of the foot rotates the talus in the mortise forcing a separation of the distal tibia & fibula. This can tear the anterior tibiofibular ligament and as the talus pushes on the fibula it can produce a spiral fracture of the distal fibula. More severe injuries affect the talar dome and/or the medial malleolus.
ANKLE JOINT (TALOCRURAL JOINT)
The talocrural joint is synovial hinge joint supported.
what supports the tibiofibular joint
- anterior tibiofibular ligament
- posterior tibiofibular ligament
- interosseous membrane
ankle joints ligament
medial deltoid ligament: - anterior tibiotalar - posterior tibiotalar - tibiocalcaneal - tibionavicular • lateral ligaments - anterior talofibular ligament - calcaneofibular ligament - posterior talofibular ligament
Which ligament is most commonly injured in an ankle sprain? Explain why.
ATFL - generally spain laterall ligaments
- withstrands least force to failure, when in PF, loose pack position which stresses ligament
SUBTALAR JOINT:
joint between the 3 articulating facets of the talus and the 3 of the calcaneus (complex motion). The subtalar joint translates rotation of the foot into motion of the tibia and vice versa. The axis of the STJ is inclined ~ 450 anterior to posterior and directed slightly medial to the long axis of the foot.
SUBTALAR JOINT: ligaments
- calcaneofibular & tibiocalcaneal ligaments A/A
- interosseous ligament within the sinus tarsi
- cervical ligament
TRANSVERSE TARSAL JOINT
talonavicular + calcaneocuboid move together
Movements = supination & pronation.
pronation at transverse tarsal
can ‘functionally’ increase foot DF range of motion, however, excessive mobility of the midfoot requires stabilisation by the passive supporting structures and increased activity in the extrinsic and intrinsic foot muscles which may lead to overload and injury.
Note the bifurcate ligament
dorsal calcaneocuboid + dorsal calcaneonavicular
Ligamentous support for the talonavicular / talocalcaneonavicular joint is provided by the:
- dorsal calcaneonavicular ligament (superior portion of bifurcate ligament)
- plantar calcaneonavicular (spring) ligament (=primary support)
Ligamentous support for the calcaneocuboid joint is provided by the:
- dorsal calcaneocuboid ligament (inferior portion of bifurcate ligament)
- plantar calcaneocuboidal ligament (short plantar ligament)
- long plantar ligament
- The last 2 provide substantial support for the lateral longitudinal arch of the foot.
