Orthopaedic Surgery - Foot and Ankle Anatomy and Examination

Basics

For normal function, the foot should be plantigrade, meaning that it rests evenly on the ground, and it should permit painless weight bearing and propulsion.

Foot and ankle function depends on coordinated activity of both extrinsic muscles, which originate in the leg, and intrinsic muscles, which originate within the foot.

Extrinsic Muscles

The major extrinsic muscle-tendon groups can be divided functionally into dorsiflexors, evertors, plantarflexors, and invertors.

Dorsiflexors

The principal anterior extensor tendons include the tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus.

These tendons cross superficially over the anterior ankle and are readily palpable.

Because of their superficial position, they are vulnerable to laceration from sharp objects.

Evertors

The primary evertors are the peroneus longus and peroneus brevis.

Their muscle bellies lie along the lateral leg, and their tendons pass posterior to the lateral malleolus.

Damage to the peroneal tendon sheath or superior peroneal retinaculum may allow the tendons to subluxate or dislocate over the lateral malleolus.

Plantarflexors and Invertors

Several important tendons pass posteromedial to the ankle.

The posterior tibial tendon is the major dynamic inverter and an important supporter of the medial longitudinal arch.

In adults, posterior tibial tendon degeneration, tenosynovitis, or rupture can contribute to adult-acquired flatfoot deformity.

Extrinsic Toe Flexors

The major extrinsic flexors of the toes are the flexor digitorum longus and flexor hallucis longus.

They contribute to toe flexion and assist with propulsion during gait.

Intrinsic Foot Muscles

The intrinsic muscles consist of one dorsal layer and three plantar layers.

Together, they control fine toe movements, support the arches, and contribute to balance and stabilization during stance.

Muscle Imbalance

An imbalance between intrinsic and extrinsic muscle forces may contribute to deformities such as hammer toes, claw toes, and mallet toes.

Bony Anatomy

Most bones and major bony landmarks of the foot and ankle are readily palpable, making systematic examination particularly useful.

The foot is conventionally divided into the hindfoot, midfoot, and forefoot.

Ankle Joint

The ankle, or tibiotalar joint, is formed by the articulation of the distal tibia, fibula, and talus.

It primarily permits plantarflexion and dorsiflexion.

Range of Motion

Normal ankle motion is approximately 40° of plantarflexion and 20° of dorsiflexion, although values vary among individuals.

Ankle Ligaments

Syndesmotic Ligaments

The distal tibiofibular syndesmosis is stabilized by the anterior and posterior tibiofibular ligaments, together with other components of the syndesmotic complex.

Injury to this complex produces a high ankle sprain.

Deltoid Ligament

The superficial and deep portions of the deltoid ligament extend from the medial malleolus to the talus, calcaneus, and navicular region.

They provide important medial ankle stability.

Lateral Ligament Complex

The lateral ankle is supported by the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and posterior talofibular ligament (PTFL).

The ATFL is the ligament most commonly injured during a typical inversion ankle sprain.

Hindfoot

The hindfoot consists principally of the talus and calcaneus.

These bones articulate at the subtalar joint.

Subtalar Motion

The subtalar joint permits inversion and eversion, with an overall motion arc of approximately 40°.

This motion allows the foot to adapt to irregular or uneven surfaces.

Talus

The talus is covered extensively by articular cartilage and has a relatively vulnerable blood supply.

Fracture or major subtalar dislocation can disrupt its vascular supply and lead to avascular necrosis.

Calcaneus

The calcaneus is the major weight-bearing bone of the heel and acts as an important shock absorber.

An axial load after a fall from height is a classic mechanism of calcaneal fracture.

Midfoot

The midfoot is organized into two principal rows.

Proximally, the navicular and cuboid articulate with the hindfoot.

Distally, the three cuneiforms and cuboid articulate with the metatarsals through the tarsometatarsal joints.

Tarsometatarsal Complex

Ligaments connect most adjacent metatarsal bases.

A notable exception exists between the first and second metatarsal bases, where there is no strong direct intermetatarsal ligament.

Lisfranc Ligament

The strong Lisfranc ligament extends from the medial cuneiform to the base of the second metatarsal.

It is a key stabilizer of the tarsometatarsal complex.

Forefoot

The forefoot consists of five metatarsals and 14 phalanges.

These structures contribute to balance, load distribution, and propulsion.

Gait Cycle

The gait cycle can be divided into stance and swing phases.

Stance Phase

The stance phase consists broadly of heel strike, foot-flat or midstance, and toe-off.

Heel Strike

At heel strike, the tibialis anterior and long toe extensors are active.

The foot undergoes pronation, which increases midfoot flexibility and allows better absorption of impact and accommodation to the ground.

Foot Flat

As weight progresses over the foot, the posterior tibialis and peroneal muscles contribute to dynamic control.

External rotation of the leg and subsequent foot supination help make the midfoot more rigid and stable for weight bearing.

Toe-Off

During push-off, the gastrocnemius-soleus complex becomes highly active.

This produces plantarflexion and propels the body forward.

Windlass Mechanism

Dorsiflexion of the toes, particularly the great toe, tightens the plantar fascia.

This windlass mechanism elevates the medial longitudinal arch and increases midfoot rigidity.

The foot is thereby converted from a flexible shock absorber into a stable lever for push-off.

Swing Phase

During swing, the tibialis anterior and long toe extensors remain active to dorsiflex the ankle and prevent the toes from dragging.

Clinical History

A thorough history should establish the nature of the patient’s symptoms and relevant systemic factors.

Acute Injury

For trauma, the mechanism should be documented carefully because it can suggest the injured bone, ligament, tendon, or joint.

Pain

Pain should be characterized according to severity, location, quality, radiation, duration, aggravating factors, and relieving factors.

Mechanical Symptoms

Locking, catching, clicking, giving way, or instability may suggest an intra-articular or ligamentous abnormality.

Neurologic Symptoms

The patient should be asked about numbness, dysesthesia, tingling, burning, or weakness.

Relevant Medical History

Important conditions include diabetes mellitus, neurologic disease, peripheral vascular disease, and inflammatory arthritis.

Surgical History

Previous surgery involving the foot, ankle, leg, or associated joints should be documented.

Functional History

Shoe wear, occupation, sports participation, and recreational activities can provide important information about repetitive loading and functional demands.

Physical Examination

The involved extremity should always be compared with the contralateral side.

The examination should be performed both standing and seated when possible.

Standing Examination

Alignment

While the patient stands, foot and ankle alignment should be observed.

Viewed from behind, the hindfoot can be categorized as varus, neutral, or valgus.

Too-Many-Toes Sign

When more lateral toes are visible from behind on the affected side than on the opposite side, the finding is called the too-many-toes sign.

This suggests forefoot abduction associated with collapse of the medial arch, as seen in flatfoot deformity.

Gait

The patient’s gait should be observed for abnormalities such as steppage gait, circumduction, scissoring, or an antalgic pattern.

Heel Rise

Double- and single-leg heel-rise testing evaluates dynamic foot function.

It helps assess posterior tibial tendon strength, arch reconstitution, hindfoot inversion, and balance.

Seated Examination

Vascular Examination

The dorsalis pedis pulse is palpated on the dorsum of the foot, typically just lateral to the extensor hallucis longus tendon.

The posterior tibial pulse is palpated posterior to the medial malleolus.

Venous Status

The foot and ankle should also be examined for pitting edema, venous stasis changes, skin discoloration, and other evidence of vascular insufficiency.

Sensory Examination

Sensation should be assessed according to peripheral nerve distribution.

Superficial Peroneal Nerve

The superficial peroneal nerve supplies most of the dorsum of the foot.

Deep Peroneal Nerve

The deep peroneal nerve is tested in the first dorsal web space.

Saphenous Nerve

The saphenous nerve supplies the medial border of the foot.

Sural Nerve

The sural nerve supplies the lateral border of the foot.

Tibial Nerve

The plantar surface of the foot is supplied primarily through branches of the tibial nerve.

Protective Sensation

The ability to perceive a 5.07 Semmes-Weinstein monofilament on the plantar surface correlates with protective sensation.

Loss of this sensation is particularly important in patients with diabetic or other peripheral neuropathy.

Neurologic Examination

Deep tendon reflexes should be assessed when appropriate.

The examination may also include evaluation for Babinski response and clonus when upper motor neuron disease is suspected.

Motor Examination

Strength testing should be combined with palpation of the corresponding tendons.

Ankle Dorsiflexion

Dorsiflexion primarily tests the tibialis anterior.

Ankle Plantarflexion

Plantarflexion is generated mainly by the gastrocnemius-soleus complex.

Eversion

Eversion evaluates the peroneal muscles.

Inversion

Inversion, especially with the foot slightly plantarflexed, assesses the posterior tibial tendon.

Great Toe Motion

Flexion of the distal phalanx of the great toe assesses the flexor hallucis longus, while extension tests the extensor hallucis longus.

Range of Motion

Both active and passive motion should be evaluated.

Ankle Motion

Ankle plantarflexion and dorsiflexion should be measured, preferably with any correctable hindfoot deformity brought into a neutral position.

Subtalar Motion

Hindfoot inversion and eversion assess the mobility of the subtalar joint.

Chopart Joint

Abduction and adduction through the transverse tarsal, or Chopart, joint can be assessed while stabilizing the hindfoot.

Lisfranc Joint

The tarsometatarsal complex should be palpated and stressed gently with plantarflexion and dorsiflexion of the metatarsals.

Pain or instability may indicate a Lisfranc injury.

Metatarsophalangeal and Toe Joints

Motion of the MTP and interphalangeal joints should be assessed for stiffness, instability, pain, and deformity.

Palpation

Systematic palpation helps localize pathology.

Malleoli

The medial and lateral malleoli should be palpated for tenderness suggestive of fracture or ligament injury.

Ankle Joint

The ankle joint should be assessed for joint-line tenderness or effusion, which may suggest synovitis or an osteochondral lesion.

Posterior Tibial Tendon

The posterior tibial tendon should be palpated from behind the medial malleolus to its insertion on the navicular.

Tenderness may indicate posterior tibial tendinitis or tendon dysfunction.

Navicular Tuberosity

The navicular tuberosity is located approximately 2 cm distal and plantar to the medial malleolus.

Tenderness in this region may reflect an accessory navicular, navicular stress fracture, posterior tibial tendon insertional pathology, or talonavicular disorder.

Achilles Tendon

The Achilles tendon and retrocalcaneal bursa should be palpated along the posterior ankle and hindfoot.

The examiner should look for defects, nodules, thickening, swelling, or tenderness suggestive of tendinopathy or rupture.

Peroneal Tendons

The peroneal tendons should be palpated posterior to the lateral malleolus.

The peroneus brevis can be followed to the base of the fifth metatarsal, while the peroneus longus passes beneath the foot through a groove near the cuboid.

Tenderness may reflect tendinitis or associated fifth-metatarsal pathology.

Peroneal Subluxation

The ankle can be circumducted while the tendons are observed and palpated for abnormal subluxation over the lateral malleolus.

Sinus Tarsi

The sinus tarsi lies approximately 1 cm distal to the lateral malleolus.

Tenderness may suggest subtalar joint inflammation or instability.

Syndesmosis

Tenderness between the distal tibia and fibula just proximal to the ankle joint raises concern for a syndesmotic, or high ankle, sprain.

Plantar Fascia

The plantar fascia should be palpated from its origin at the plantar calcaneus.

Tenderness near the medial plantar heel that becomes more pronounced with toe dorsiflexion is characteristic of plantar fasciitis.

Lisfranc Region

Tenderness at the base of the second metatarsal is concerning for a Lisfranc injury.

Plantar ecchymosis in this region is particularly significant.

Sesamoids

The plantar aspect of the great-toe MTP joint should be examined for tenderness related to sesamoiditis or sesamoid fracture.

Lesser Metatarsal Heads

Tenderness beneath the lesser MTP joints may indicate metatarsalgia.

Intermetatarsal Spaces

Tenderness in the metatarsal interspaces, sometimes accompanied by radiating paresthesias into the toes, may suggest an interdigital neuroma.

Special Tests

Anterior Drawer Test

The anterior drawer test assesses lateral ankle instability, particularly the ATFL.

The examiner stabilizes the distal tibia and translates the heel and talus anteriorly relative to the tibia.

The ATFL is stressed most effectively with the ankle in slight plantarflexion, whereas testing nearer neutral places relatively greater contribution on the broader lateral ligament complex.

Excessive anterior translation or a soft endpoint compared with the opposite ankle suggests instability.

Thompson Test

The Thompson test evaluates integrity of the Achilles tendon.

With the patient prone and the foot hanging freely, the examiner squeezes the calf.

An intact Achilles tendon produces plantarflexion of the foot.

Failure of plantarflexion strongly suggests Achilles tendon rupture.

Lesser-Toe Deformities

Mallet, hammer, and claw toe deformities should be assessed systematically.

Calluses

The location of callus formation helps identify areas of abnormal pressure.

Flexibility

The examiner should determine whether the deformity is flexible and manually correctable or rigid and fixed.

MTP Stability

A modified drawer test can assess MTP joint instability by attempting to translate and reduce the proximal phalanx relative to the metatarsal head.

Hallux Valgus Examination

Calluses and Medial Eminence

Callus formation and tenderness over the medial eminence should be documented.

MTP Motion

Range of motion of the first MTP joint should be assessed with the valgus deformity gently corrected.

This helps identify associated arthritis or stiffness.

First Tarsometatarsal Hypermobility

The lateral forefoot is stabilized while the first metatarsal is translated dorsally and plantarly.

Excessive mobility suggests first tarsometatarsal joint hypermobility.

Lesser-Toe Deformities

Associated lesser-toe deformities should be identified because they may contribute to pain and influence treatment planning.

Laboratory Tests

Laboratory testing is generally guided by the suspected diagnosis.

Suspected Infection

When infection is a concern, laboratory studies may include white blood cell count, erythrocyte sedimentation rate, and C-reactive protein.

Joint Aspiration

Synovial fluid from a suspicious joint should be sent for cell count with differential, Gram stain, culture, and crystal analysis.

Imaging

Plain Radiographs

Radiographs are the first-line imaging study for most structural foot and ankle disorders.

Acute Trauma

When acute fracture or dislocation is suspected and the patient cannot safely stand, non-weight-bearing radiographs are appropriate.

Weight-Bearing Radiographs

When the patient can stand safely, weight-bearing views are generally preferred for evaluation of alignment and deformity.

Standing radiographs demonstrate bony relationships under physiologic load and may reveal pathology that is not apparent on non-weight-bearing images.

Stress Radiographs

Stress views can indirectly assess the integrity of ligamentous structures by demonstrating abnormal joint translation or widening under applied force.

CT

CT provides excellent bony detail and is particularly useful for complex fracture patterns and disorders of the midfoot and hindfoot.

It is valuable for evaluating articular congruity and planning reconstruction.

MRI

MRI is especially useful for soft-tissue and occult osseous disorders.

It can demonstrate tendon and ligament injuries, soft-tissue masses, subtle fractures, marrow abnormalities, and infection.

Bone Scintigraphy

Technetium-99m bone scintigraphy can help localize pathology when pain is vague or multifocal.

It may detect stress fractures, tumors, and other metabolically active skeletal abnormalities, although MRI is often more specific for many modern indications.

General Examination Principles

A complete foot and ankle assessment combines history, standing alignment, gait analysis, vascular and neurologic examination, muscle testing, range of motion, palpation, provocative maneuvers, and appropriately selected imaging.

Because disorders of one region frequently alter mechanics elsewhere, the entire lower extremity should be considered rather than evaluating only the painful site.