By Dr. Marcus Judge

OSCE

In any OSCE examination, it is important to understand the pathology and reasoning behind each sign and symptom you elicit, even if the patient is 'normal'. This article explains how to examine the ankle and foot. It covers the key findings to look for, what each sign means and which conditions it may indicate.

The ankle and foot examination follows the standard musculoskeletal framework of look, feel and move. This is followed by a set of special tests and an assessment of the neurovascular status of the foot (the state of its nerves and blood supply). As with every joint examination, you are comparing one side against the other and trying to localise pathology to bone, joint, tendon, ligament, skin, nerve or blood supply.

Contents

  1. Introduction
  2. General Inspection
  3. Look (Inspection)
  4. Gait Assessment
  5. Feel (Palpation)
  6. Move (Range of Movement)
  7. Special Tests
  8. Neurovascular Assessment
  9. Completing the Examination
  10. Quiz

Introduction

Wash your hands and put on personal protective equipment (PPE, such as gloves and an apron) if appropriate.

Introduce yourself to the patient and ensure to mention your grade e.g. 3rd year medical student/junior doctor/consultant.

Confirm the patient's details, usually by checking three points of identification: full name, date of birth and NHS/hospital number.

Obtain consent for the examination, ensuring to explain what the examination will entail. A useful way to explain it is "I would like to look at your ankles and feet, feel for any tender areas, and then ask you to move them and walk a few steps. Is that alright?".

Adequately expose both lower limbs from the knees down, so that the knees, ankles and feet can be compared side to side. The patient should also have their footwear and socks removed, as the shoes themselves give valuable clues (see General Inspection).

Position the patient sitting on the edge of the couch initially. Remember that a complete examination requires the patient to stand and walk, so ensure they are able and well enough to do so.

Ask the patient if they have any pain anywhere before you begin, and watch their face for discomfort throughout. This is both good practice and avoids you losing marks for causing the patient pain.

General Inspection

Begin with a general inspection of the patient from the end of the bed. Assess whether the patient looks comfortable or is in pain. Note their general wellbeing and body habitus (build or body shape). Extra body weight loads the foot, which matters in tibialis posterior dysfunction (failure of the tendon that supports the inner arch of the foot). Obesity also raises the risk of gout (a crystal arthritis that classically affects the big toe joint). A patient who is systemically unwell with a hot, swollen joint may have septic arthritis or gout, both of which are important not to miss.

Look around the bedside for objects and clues:

  • Mobility aids such as walking sticks, crutches, a frame or a wheelchair, which indicate the degree of functional impairment.
  • Orthotic devices (braces and supports) such as ankle-foot orthoses (AFOs), insoles or a moon boot (a protective walking boot), which suggest an existing diagnosis such as foot drop (inability to lift the front of the foot) or a healing fracture.
  • Footwear: examine the patient's shoes for asymmetrical wear of the sole, which reflects an abnormal gait or weight-bearing pattern, and for any custom adaptations.
  • Prescriptions or medications at the bedside, such as analgesia or disease-modifying anti-rheumatic drugs (DMARDs, drugs that slow inflammatory joint disease), hinting at conditions like rheumatoid arthritis (an autoimmune arthritis that inflames the joints).

Look (Inspection)

Inspection should be performed both with the patient standing (weight-bearing) and sitting/lying (non-weight-bearing), as some abnormalities only become apparent when the foot is loaded. Ask the patient to stand and inspect the feet and ankles from the front, sides and behind, then re-inspect with the patient seated.

From the front, look at the skin and toes for:

  • Scars, suggesting previous surgery or trauma.
  • Swelling, which may be generalised (suggesting effusion, which is excess fluid inside a joint, or oedema) or localised to a single joint (suggesting arthritis, gout or infection).
  • Skin changes such as erythema (redness, from infection or active inflammation) and psoriatic plaques (raised scaly patches of psoriasis, a skin condition) on extensor surfaces, which are associated with psoriatic arthritis. Also look for ulceration and calluses (thickened skin), which form over areas of abnormal pressure and are particularly important in diabetic and neuropathic (nerve-damaged) feet.
  • Toe deformities such as hallux valgus (lateral deviation of the great toe with a prominent medial bunion) and, less commonly, hallux varus (medial deviation), along with claw toes, hammer toes and mallet toes (bent toes that differ in which toe joint is bent; some are flexible and some are fixed). Hallux valgus is common, especially with age and in women, and is linked to poorly fitting footwear, family history and flat feet. Toe deformities can also be seen in rheumatoid arthritis.
  • Nail changes such as pitting and onycholysis (the nail lifting off the nail bed), which occur in psoriasis, or fungal involvement.

Hallux valgus bunion of the great toe SimpleMed

Image - Hallux valgus, showing lateral deviation of the great toe and a prominent medial bony bump (bunion). This deformity is common, especially in women, and is aggravated by narrow footwear

Creative commons source by Lamiot [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

From the sides, assess the medial longitudinal arch:

  • A flattened arch (pes planus, or flat foot) occurs when the arch collapses towards the floor. It may be flexible and asymptomatic, or rigid. New, painful, unilateral flat foot in an adult should raise suspicion of tibialis posterior tendon dysfunction, as this tendon is the key dynamic support of the medial arch.
  • An abnormally high arch (pes cavus) is associated with neuromuscular conditions such as Charcot-Marie-Tooth disease (an inherited nerve disease causing muscle weakness and wasting) and other causes of muscle imbalance in the foot.

From behind, inspect the heel and Achilles tendon for:

  • Hindfoot alignment: the heel should lie in slight valgus (a few degrees pointing outward). Excessive valgus is seen with a collapsing flat foot, while varus (heel pointing inward) is seen with pes cavus.
  • The "too many toes" sign: when standing behind the patient, more toes than usual are visible lateral to the heel. This reflects forefoot abduction and hindfoot valgus and is a sign of tibialis posterior dysfunction.
  • Calf muscle wasting, suggesting disuse, a chronic tendon problem or a lower motor neuron lesion (damage to the nerve running from the spinal cord to the muscle).
  • Swelling or a gap in the line of the Achilles tendon, which may indicate a rupture.

Finally, inspect between the toes and the soles for maceration (soggy, broken-down skin), ulceration, calluses and signs of infection. These areas are easy to forget but clinically vital, especially in diabetic patients.

Neuropathic diabetic foot ulcer over a pressure area SimpleMed

Image - A neuropathic ulcer on the sole, sitting over a high-pressure area. Ulcers like this are painless because of the underlying sensory neuropathy, which is exactly why inspecting the soles and between the toes must never be skipped in a diabetic foot

SimpleMed original image, credit 'SimpleMed original'

Gait Assessment

Ask the patient to walk to the end of the room, turn, and walk back while you observe. A normal gait cycle is divided into a stance phase (the foot is on the ground) and a swing phase (the foot is moving forward). Abnormalities at any point give clues to the underlying problem.

Look specifically at:

  • The stance phase: is it shortened on one side because weight-bearing is painful? This produces an antalgic (painful) gait, in which the patient spends as little time as possible on the affected limb.
  • The swing phase and heel strike: a patient with foot drop has weak ankle dorsiflexion (lifting the foot upwards). Classic causes are a common peroneal nerve palsy (weakness from damage to the nerve at the outer knee) or an L5 radiculopathy (a pinched or irritated L5 nerve root). The patient cannot lift the foot clear of the floor, so they lift the knee high (a high-stepping gait) and the foot may slap down.
  • Push-off: weakness of plantarflexion (pointing the foot downwards), for example after an Achilles tendon rupture, reduces the power of toe-off.
  • Width of gait and stability: a broad-based gait may indicate poor proprioception (the sense of where your limbs are) or a neurological cause.

You can also ask the patient to walk on their heels. This tests ankle dorsiflexion, and therefore the deep peroneal nerve and the L4/L5 nerve roots. Then ask them to walk on their tiptoes. This tests plantarflexion and calf power, and therefore the tibial nerve and the S1 nerve root, as well as the integrity of the Achilles tendon. An inability to tiptoe walk is a useful screening sign for both Achilles pathology and S1 weakness.

Feel (Palpation)

Before palpating, ask again about pain and watch the patient's face. Begin by assessing temperature, running the back of your hand along the leg, ankle and foot and comparing sides. Increased warmth over a joint suggests active inflammation or infection, whereas a cold foot raises concern about arterial insufficiency (a poor arterial blood supply).

Systematically palpate the bony and soft tissue structures, feeling for tenderness, swelling and irregularity:

  • The malleoli (the bony bumps on the inner and outer sides of the ankle) and the ankle joint line.
  • The Achilles tendon: tenderness and thickening suggest Achilles tendinopathy (painful degeneration of the tendon), while a palpable gap suggests rupture.
  • The medial structures, including the course of the tibialis posterior tendon behind the medial malleolus.
  • The lateral ligament complex (anterior talofibular ligament in particular), which is the most commonly injured ligament in an inversion ankle sprain (the foot turns inwards).
  • The midfoot and tarsal bones, the base of the fifth metatarsal (a common site for an avulsion fracture, where a tendon or ligament pulls off a fragment of bone) and the metatarsals.
  • The metatarsophalangeal (MTP) joints (the joints at the base of the toes): squeeze across the MTP joints. Pain here (a positive "squeeze test") can be an early sign of rheumatoid arthritis, but a negative test does not rule arthritis out, because the test misses many cases. The first MTP joint is the classic site of gout (podagra, which means gout in the big toe joint).

Where there is swelling around the ankle, you can attempt to detect an effusion. Tenderness over a specific structure points to a specific cause. Localising it allows you to tell, for example, a ligament sprain from a bony fracture or a tendon problem.

Move (Range of Movement)

Assess movement actively first (ask the patient to perform the movement themselves) and then passively (you move the joint while the patient relaxes). Comparing active and passive ranges helps localise the problem. If active movement is reduced but passive movement is full, the issue is likely muscular, tendinous or neurological (a problem generating or transmitting the force). If both are equally reduced, the problem is more likely within the joint itself (such as arthritis or a mechanical block). Always compare the two sides.

Assess the following movements, stabilising the limb above the joint being tested:

  • Ankle (talocrural joint): dorsiflexion and plantarflexion. Ask the patient to point the foot up towards them (dorsiflexion, roughly 20°) and down away from them (plantarflexion, roughly 40-50°). This is the main hinge for walking.
  • Subtalar joint (just below the ankle joint): inversion and eversion. Stabilise the lower leg and cup the heel, then turn the sole inward (inversion) and outward (eversion). This movement allows the foot to adapt to uneven ground; it is often restricted and painful in subtalar arthritis.
  • Midtarsal joint (the joints between the hindfoot and midfoot): rotation of the forefoot. Fix the heel with one hand and gently rotate the forefoot with the other to assess midfoot movement.
  • The toes: flexion, extension, and abduction/adduction, particularly at the great toe (first MTP joint). Ask the patient to curl, straighten, and fan the toes; loss of toe abduction (spreading the toes apart) can accompany the small-muscle wasting of a peripheral neuropathy (damage to the nerves of the limbs). Painful or restricted movement of the first MTP joint, especially on dorsiflexion, is termed hallux rigidus (osteoarthritis of the joint).

During passive movement, feel and listen for crepitus (a grating or crackling sensation from roughened joint surfaces, which can occur in osteoarthritis). Note whether movement is limited by pain or by a true mechanical block.

Special Tests

A small number of focused special tests help confirm specific diagnoses suggested by the rest of the examination.

Simmonds' (Thompson's) calf squeeze test assesses the integrity of the Achilles tendon. Ask the patient to kneel on a chair or lie prone with the feet hanging over the edge of the couch, then squeeze the calf. In a normal limb, squeezing the calf muscles (gastrocnemius and soleus) shortens them, and because the force is transmitted through an intact Achilles tendon, the foot plantarflexes. If the Achilles tendon is ruptured, the force cannot reach the foot and there is no plantarflexion. This is a positive test. A patient with a ruptured Achilles tendon may still be able to push the foot down weakly, because other muscles (the toe flexors, flexor hallucis longus and flexor digitorum longus, and tibialis posterior) can take over some plantarflexion. Weak active plantarflexion therefore does not rule out a rupture. In one study of 174 patients with a clinical diagnosis of a complete tear, the calf squeeze test was positive more often than feeling for a gap in the tendon.

Assessing tibialis posterior function is useful when a flat foot is found. Ask the patient to stand on tiptoes: normally the heel swings into varus (inward) as the tibialis posterior locks the midfoot for an efficient push-off. In tibialis posterior dysfunction, the patient may be unable to perform a single-leg heel raise on the affected side, and the heel fails to invert. Resisted inversion of the plantarflexed foot directly tests the strength of the tendon.

Where an ankle sprain is suspected, the stability of the lateral ligaments can be assessed with two tests. The anterior drawer test tests the anterior talofibular ligament: stabilise the lower leg and draw the heel forwards. The talar tilt test tests the calcaneofibular ligament: invert the hindfoot. Excessive movement compared with the other side suggests ligamentous laxity (a loose, over-stretched ligament) or rupture. These tests should be performed gently and are often deferred in the acute, painful setting.

If the patient describes forefoot pain or a sensation of "walking on a pebble", test for a Morton's neuroma (a benign thickening of a nerve between the toes, most often in the third webspace, between the third and fourth toes). Squeeze the forefoot across the metatarsal heads with one hand while pressing the affected webspace between finger and thumb of the other. A palpable, sometimes audible, click accompanied by the patient's typical pain is Mulder's sign, and points to a neuroma. The pain often radiates into the adjacent toes.

Neurovascular Assessment

No ankle and foot examination is complete without checking that the foot has an adequate blood supply and intact nerves. Both can be compromised by trauma, vascular disease and diabetes.

For the vascular assessment:

  • Note the colour and temperature of the foot. A pale, cold, hairless foot suggests peripheral arterial disease (narrowed arteries in the limbs).
  • Check the capillary refill time by pressing on the pulp of a toe for five seconds; colour should return in less than two seconds. A prolonged refill time suggests impaired peripheral perfusion.
  • Palpate the dorsalis pedis pulse (on the dorsum of the foot, lateral to the extensor hallucis longus tendon) and the posterior tibial pulse (behind the medial malleolus). Absent pedal pulses suggest peripheral arterial disease. NICE advises measuring the ankle brachial pressure index (ABPI, which compares blood pressure at the ankle with that in the arm) as well as examining the foot pulses.

Palpating the dorsalis pedis pulse on the dorsum of the foot SimpleMed

Image - Palpating the dorsalis pedis pulse on the dorsum of the foot, just lateral to the extensor hallucis longus tendon. The posterior tibial pulse is felt behind and just below the medial malleolus

SimpleMed original image, credit 'SimpleMed original'

For the neurological assessment:

  • Test light touch sensation across the dermatomes (the areas of skin supplied by a single nerve root) and the territories of the peripheral nerves supplying the foot. Loss of sensation in a "stocking" distribution (over the foot and lower leg, like a sock) is typical of a peripheral neuropathy, classically caused by diabetes.
  • Where a neuropathic foot is suspected, screen protective sensation (the ability to feel pressure that could injure the skin) with a 10 g monofilament (a thin nylon fibre pressed on the skin to test feeling). Touch it lightly against several points on the sole (such as the pulp of the great toe and the first, third and fifth metatarsal heads) while the patient closes their eyes and reports each touch. Failure to feel it suggests neuropathy and puts the foot at risk of painless ulceration. In diabetes, NICE grades the risk of a foot problem from the whole foot examination, not the monofilament alone, and refers people at moderate or high risk to the foot protection service (a specialist foot care team).
  • Power has already been screened during gait (heel and tiptoe walking), assessing dorsiflexion (deep peroneal nerve, L4/L5) and plantarflexion (tibial nerve, S1).
  • If indicated, test the ankle jerk (Achilles) reflex, which assesses the S1 nerve root. A diminished or absent reflex supports an S1 radiculopathy or a peripheral neuropathy.

The neurovascular status is especially important after trauma, where it must be documented before and after any manipulation or splinting.

Completing the Examination

Thank the patient and ensure they are comfortable and able to redress. Wash your hands.

Summarise your findings concisely, for example: "On examination of the ankle and foot, there was a painful, swollen first metatarsophalangeal joint with overlying erythema, no neurovascular deficit, consistent with acute gout."

To complete the examination, state that you would:

  • Perform a full neurovascular examination of both lower limbs.
  • Examine the joints above and below (the knee and the hip), as pathology and referred pain can involve adjacent joints.
  • Assess the patient's footwear and walking aids, and consider a gait and functional assessment.
  • Arrange relevant investigations. These include plain X-rays of the foot and ankle, guided by the Ottawa ankle rules (a rule that decides who with an ankle injury needs an X-ray) where trauma is suspected. Where examination is inconclusive, consider further imaging such as ultrasound or MRI for a suspected tendon or soft tissue injury.
  • Consider blood tests where indicated. For gout, measure serum urate (the uric acid level in the blood). If it is below 360 micromol/L but gout is strongly suspected, repeat it 2 to 4 weeks after the flare has settled, because levels can be lower during a flare. For an inflammatory arthropathy (inflammatory joint disease), consider inflammatory markers and rheumatoid serology (blood antibody tests for rheumatoid arthritis).

Quiz

Preview the Ankle and Foot OSCE Examination quiz

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