Ankle and Foot

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Anatomy 

The ankle is the part of the lower limb encompassing the distal portion of the leg and proximal portions of the foot. The ankle encompasses the ankle joint, an articulation between the tibia and fibula of the leg and the talus of the foot. See the page for ankle joint for more information.

The foot is the part of the lower limb distal to the ankle joint. It is covered on its dorsal surface by loosely adherent skin and on its plantar/inferior surface by thick hairless skin that is tough and strongly adherent to the underlying plantar aponeurosis. The foot contains 26 small bones that are designed for weight bearing and force distribution. The bony alignment creates three arches the provide efficient weight distribution while avoiding compression of plantar neuro-vascular structures. The three arches, medial and lateral longitudinal and the transverse arch together create an architectural vault, which is one of the strongest load-bearing structures known to mankind.

Bones

The bones of the foot are named as follows:

• The tarsals - Talus, calcaneus, navicular, cuboid, cuneiforms (medial, intermediate and lateral)

• The metatarsals - numbered from medial or first (big toe), to lateral or fifth (little toe)

• The phalanges - toes 2-5 each have 3 phalanges. The first or big toe (hallux) has only two

Muscles

Foot muscles

The dorsum of the foot has only one muscle (maybe 2 depending on classification). This is the extensor digitorum brevis (some authors name the most medial part of this muscle extensor hallucis brevis). Tendons are the main collagenous structures in the dorsum. The tendons connect anterior/dorsiflexor compartment muscles of the leg to the foot bones.

The plantar aspect of the foot contains the tough fibrous plantar aponeurosis covering muscles and tendons arranged in 4 layers, numbered from 1 superficial to 4 deep:

1. Layer 1 consists of the abductor didgiti minimi, flexor digitorum brevis, abductor hallucis
2. Layer 2 consists of the quadratus plantae, the lumbricals, and the long tendons of flexor digitorum longus and flexor hallucis longus
3. Layer 3 consists of the flexor hallucis brevis, adductor hallucis and flexor digiti minimi brevis
4. Layer 4 consists of the interosseous muscles and the long tendons of peroneus/fibularis longus and tibialis posterior

Ligaments

Ankle ligament injury is the most frequent cause of acute ankle pain. Hence, it is important to understand the anatomy of ankle ligaments for correct diagnosis and treatment.

The ligaments around the ankle can be divided, depending on their anatomic position, into three groups: the lateral ligaments, the deltoid ligament on the medial side, and the ligaments of the tibiofibular syndesmosis that join the distal epiphyses of the tibia and fibula.

The lateral collateral ligament complex (LCL) consists of:

1. Anterior talofibular ligament: it is the most frequently injured ligament of the ankle. This ligament plays an important role in limiting anterior displacement of the talus and plantar flexion of the ankle.
2. Posterior talofibular ligament: The posterior talofibular ligament originates from the malleolar fossa, located on the medial surface of the lateral malleolus, coursing almost horizontally to insert in the posterolateral talus. It is the strongest ligament of the lateral ankle. plays only a supplementary role in ankle stability when the lateral ligament complex is intact.
3. Calcaneofibular ligament: The calcaneofibular ligament originates from the anterior part of the lateral malleolus. Its primary role is to restrain inversion in a neutral or dorsiflexed position, restrains subtalar inversion, thereby limiting talar tilt within the ankle mortise.
   

The medial collateral ligament (MCL), also known as deltoid ligament, is composed of two layers; superficial and deep. The MCL is a multifascicular ligament, originating from the medial malleolus to insert in the talus, calcaneus, and navicular bone. It primary restrains to valgus tilting of the talus. Both the superficial and deep layers individually resist eversion of the hindfoot. It also stabilizes ankle against plantar flexion, external rotation, and pronation.

The ligaments of the tibiofibular syndesmosis consist of anterior or anteroinferior tibiofibular ligament, the posterior or posteroinferior tibiofibular ligament, and the interosseous tibiofibular ligament. The syndesmotic ligament complex ensures the stability between the distal tibia and the fibula and resists the axial, rotational, and translational forces that attempt to separate the tibia and fibula.

Neurovasculature

Nerves of the dorsum of the foot

The plantar nerves

Cutaneous innervation of the dorsum is by the superficial and deep peroneal/fibular nerves. Cutaneous innervation of the plantar aspect is by the medial and lateral plantar and tibial nerves. Dorsal motor innervation is by the deep peroneal nerve to extensor digitorum brevis and extensor hallucis brevis. Plantar motor innervation is via the medial and lateral plantar nerves (terminal branches of the tibial nerve). Arteries crossing into the foot accompany nerves of corresponding names. Therefore the anterior tibial or dorsalis pedis artery, and the posterior tibial artery, are the terminal branches of the medial and lateral plantar arteries.

Clinical Examination

Ankle & Foot Examination

Special Tests

• Anterior drawer of the ankle

• Ligament Tests

• Squeeze Test

• Kaltenborn Foot & Ankle
• Windlass test

Outcome Measures

1. Foot and Ankle Disability Index
2. Foot Function Index (FFI)

Conditions

• Achilles tendonitis
• Achilles rupture
• Ankle & foot fractures
• Ankle & foot arthropathies
• Ankle sprain
• Ankle Impingement
• Anterior ankle impingement syndrome
• Ankle ssteochondral lesions
• Calcaneal fractures
• Calcaneal spurs
• Compartment syndrome of the foot
• Compartment syndrome of the lower leg
• Calf strain
• Hallux valgus
• Hallux rigiditus
• Lisfranc injuries
• Metatarsalgia
• Peroneal rendonitis
• Plantarfasciitis
• Posterior tibial tendon dysfunction
• Retrocalcaneal bursitis
• Shin splints
• Sinus tarsi syndrome
• Tarsal tunnel syndrome
• Tibiofibular diastasis

Procedures

• Total ankle arthroplasty

References