Major Bones of Foot and Ankle
1-Tibia
The second largest bone in the body
Weight-bearing part of the lower limb
Three parts:
Proximal part: articulates with the femur
The medial and lateral condyles form the tibial plateau
medial condyle – more weight-bearing
intercondylar eminence – located between the condyles
covered with articular cartilage
attachment site for the menisci, ACL, and PCL
tibial tuberosity – attachment site for patellar ligament
Shaft(diaphysis): triangular in cross-section
Anterior border – shin of the leg, begins with the tibial tuberosity
Posterior surface – soleal line present where soleus muscle originates, nutrient artery is here
Lateral border – attachment to the interosseous membrane
Distal part: articulates with talus
medial malleolus here – with talus forms the upper part of ankle joint
fibular notch – where fibula articulates with tibia forming distal tibiofibular joint
2-Fibula
Lateral and non-weight-bearing one of the two
Head of the fibula: articulates with the lateral condyle of the fibula – proximal tibiofibular joint
The shaft: the interosseous membrane attaches to the medial border
Anterior surface: extensor tendons originate
Posterior surface: flexor tendons originate
Lateral surface: The peroneal tendons originate
Distal Fibula: lateral malleolus present – lateral wall of ankle joint, ankle stability!!
medial surface – articulates with talus
anterior surface – articulates with tibia (distal tibiofibular joint)
3-Talus
Most superior of the tarsal bones
Transmits the body weight from the cruris to the foot
Three articulations:
Superiorly – Ankle joint, between the talus, tibia and fibula
Inferiorly – Subtalar joint, between talus and calcaneus
Anteriorly – talonavicular joint, between talus and navicula
Main function: transmit forces from the tibia to the calcaneus
No muscles originate from or attach to the talus
4-Calcaneus
Largest and strongest of the tarsal bones
Forms the heel of the foot
Lies beneath the talus and posterior to the cuboid
Two articulations:
Superiorly – subtalar joint, between talus and calcaneus
Anteriorly – calcaneocuboid joint, between calcaneus and cuboid
Surfaces:
Superior Surface: Articulates with the talus
Three talar facets present: Posterior facet (largest)
Middle facet (onsustentaculum tali)
Anterior facet
Sulcus calcanei between the superior and middle facets
Sulcus calcanei+sulcus tali = sinus tarsi
Inferior Surface: weight-bearing part
Calcaneal tuberosity present
Attachment site for intrinsic muscles and plantar fascia
Anterior Surface: Articulates with talus
Posterior Surface: Attachment site for the Achilles tendon
Medial Surface: Has sustentaculum tali: supports talus
bears middle talar facet
groove inferiorly for the FHL tendon
Lateral Surface: Peroneal trochlea: separates fibularis longus and brevis tendons
Boat shaped
On the medial side of the foot
Between the talus and the cuneiforms
Maintains medial longitudinal arch
Surfaces:
Posterior Surface: Concave
Talonavicular joint
Anterior Surface: Convex
Divided into three parts articulating three cuneiforms
Medial Surface: Navicular tuberosity present
The tibialis posterior tendon attaches
Lateral Surface: In some there is a facet articulating with the cuboid
Inferior Surface: Attachment for plantar ligaments
Arch support
Superior Surface: No articulation present
6- Cuboid Bone
Cube-shaped
On lateral side of the foot
Between calcaneus and 4-5th metatarsals
Maintains lateral longitudinal arch
Posterior Surface: Articulates with calcaneus – calcaneocuboid joint
Anterior Surface: Two facets articulating with 4-5th metatarsals
Medial Surface: Midtarsal joint
Has facets for: lateral cuneiform and navicular bone
Lateral Surface: No articulation
Inferior Sunface: Has groove for fibularis longus tendon
Attachment for long plantar ligament
Superior Surface: Rough and non-articular
7- The cuneiforms
Three wedge-shaped bones
Between the navicular bone and the metatarsals
Three are present: medial, intermediate, lateral
Support medial and tansfers arches
Medial cuneiform: Largest one
On the medial side of the foot
Articulations: Posterior – with the navicular bone
Anterior – with the base of the first metatarsal
Lateral – eith the intermediate cuneiform
Inferior surface: attachment site for tibialis anterior and fibularis longus
Intermediate cuneiform: Smallest one
Articulations: Posterior: with the navicular bone
Anterior: with the base of the 2nd metatarsal
Medial: with medial cuneiform
Lateral: with lateral cuneiform
Lateral cuneiform: Between intermediate cuneiform and the cuboid
Articulations: Posterior: with the navicular bone
Anterior: with the base of the 3rd metatarsal
Medial: with the intermediate cuneiform
Lateral: with the cuboid bone
8- The metatarsals
Each has a base, a shaft and a head
Bases: Articulate with the tarsal bones
II-IV articulate with each other via intermetatarsal facets
Shaft: Long, slightly curved, and triangular in cross-section
Dorsal surface is smooth; plantar surface is rough for ligament and muscle attachments
Heads: Round and convex
Articulate with phalanxes – MTP joint
1st metatarsal: the shortest but the strongest
Bears significant weight during gait
2nd metatarsal: the longest one
Contributes to midfoot stability
5th metatarsal: Attachment to fibularis brevis
9-The Phalanges
Each foot has 14 phalanges
The toe has 2 phalanges, the rest has 3
Each has a base, shaft and a head
Bases: Proximal phalanges aarticulate with the head of the metatarsals
Middle and distal phalanges articulate with adjacent phalanges
Shaft: Short and flattened dorsoplantar
Slightly concave on the plantar surface
Heads: Shaped like a pulley for hinge-type joints
Distal phalanges: Supports the nail bed and pulp of the toe
MTP joint: between proximal phalanges and the metatarsals
Interphalangeal joints: between phalanges
Accessory Bones of the Foot and Ankle
1-Os Trigonum
Accessory bone located at the posterior aspect of the talus
Incidence: 5-15% and mostly bilateral
Develops from a secondary ossification center of the talus
Due to failure of fusion of the lateral tubercle of the posterior talar process
May form pseudojoint with the talus
Close to subtalar and posterior tibiotalar joints
FHL runs close to the os trigonum
Clinical Significance:
Posterior ankle impingement syndrome: During plantar flexion, compressed tibia and calcaneus causing pain
Common in people exposed to repetitive plantar flexion such as dancers, football players etc
Symptoms: pain, swelling, and tenderness mostly during plantar flexion
Differential Diagnosis: mostly mixed up with the fracture of posterior talar process
Diagnosis: may ve put with lateral ankle x-rays and ankle ct
Management: mostly asymptomatic, if symptomatic use the RICE protocol,
Located on the medial side of the foot
Often bilateral, 4-21% of population
Arises from a secondary ossification center of the navicular bone
Due to failure of fusion during development
Medial to navicular bone, adjacent to the navicular tuberosity
In close relation to tibialis posterior tendon, thetendon may intert onto it
Clinical Significance
Accessory navicular syndrome: Pain and tenderness over the medial midfoot
Aggravated by footwear or activity
May alter the function of tibialis posterior tendon causing tibialis posterior tendon deficiency and acquired pes planovalgus
Diagnosis: AP and oblique foot radiographs
Treatment: If symptomatic weight loss and physical therapy are the first steps
Surgery if persistent symptoms after conservative treatment and if tibiotalar arthrosis present
3- Os Peroneum
Accessory bone located on fibularis longus tendon attachment site
Often bilateral and 5-26% of the population
Found on the lateral side of the foot, near the cuboid bone
Typically lies at the level of the calcaneocuboid joint
Develops from a secondary ossification center within the tendon
Clinical Significance:
Usually asymptomatic, incidental finding
Painful os Peroneum Syndrome: Lateral midfoot pain associated with fracture, diastasis, or displacement of the os peroneum
Pain on os peroneum may indicate a rupture of fibularis longus tendon
Differential Diagnosis: avulsion of cuboid
Diagnosis: best seen on lateral and oblique foot radiographs
Treatment: mostly RICE protocol, if persistent pain present or tendinopathy present surgery needed
Sesamoid Bones of the Foot and Ankle
1-Hallucal Sesamoids
Two sesamoids located beneath the head of the first metatarsal
Medial sesamoid – tibial sesamoid
Lateral sesamoid – fibular sesamoid
They lie on the plantar surface of the first metatarsal head, in close relation to flexor hallucis brevis tendon
Function: Increase the lever arm of flexor hallucis brevis
Absorb and redistribute weight-bearing forces
Protect the flexor hallucis longus tendon
Clinical Significance:
Sesamoiditis: Inflammation causing plantar pain beneath the first MTP joint
Fractures: May be acute or chronic, not to be confused with bipartite sesamoid
AVN: Most commonly medial sesamoid is affected, plantar pain with weight-bearing and tow-off phase of gait. Local tenderness and swelling present
Displacement of sesamoids contributes to hallux valgus deformity
Diagnosis: Best seen on axial views and lateral foot radiographs
Treatment: Usually treated conservatively – RICE protocol and NSAIDs
2- Sesamoid Bones of the Lesser Metatarsals
On plantar surfaces of metatarsals II-V and adjacent to flexor tendons
Usually single and smaller than hallucal sesamoids
Mostly remain cartilaginous and non-ossified
Reduce friction and pressure at the metatarsophalangeal joints
Assist in load distribution during forefoot weight-bearing
Clinical Significance:
Usually symptomatic
May lead to metatarsalgia – plantar forefoot pain
Fracture and AVN are rare when compared to hallucal sesamoids
Mostly not visible on radiographs due to lack of ossification
Treatment: mostly conservatice – RICE protocol and NSAIDs