The foot and ankle

In this chapter the examination starts with the foot and ankle. On a live patient the examination should first be dir­ected to the part of the body with the problem (see the section on ‘The history’ in this chapter).

Look

Watch the patient walking, both with their shoes on and barefooted.

Look at the shoes for signs of abnormal wear.

The wear on the shoe tells you about rubbing nut pressure. The normal wear pattern is for a corner to be worn off the posterolateral side of the heel (the normal point for heel strike). There may then be a circular wear pattern under the ball of the big toe (where toe off occurs as. the foot provides its final drive and then lifts off). These two areas of wear may be linked in a very old shoe by a line of wear along the lateral side of the sole where most of the weight is taken during the stance phase of the stride.

Skin

Look for calluses, corns, bunions and scars, particularly in the following.

   At the base of the big toe for a bunion.

A bunion is a red swelling on the medial side of the metatarso­phalangeal joint consisting of inflamed skin, a subcutaneous bursa and an osteophyte on the joint margin of the medial side of the metatarsal head (Fig. 20.1). In gout the whole metatarsal phalangeal joint will be red and swollen.

   Under the metatarsal heads.

in rheumatoid arthritis the fat pad under the metatarsal heads thins, and the heads become prominent and tender immediately beneath the skin of the sole of the foot. The patient complains of pain in the sole of the foot when walking as if walking barefoot on pebbles. Areas of thickened callous skin form over the metatarsal heads.

   Over the dorsum of interphalangeal joints and over the tips of the toes in patients with claw toes.

Feet do not fit easily into most shoes, even when they are normal. If the toes have started to claw then the pulp of the toe will be driven into the floor of the shoe, while the dorsum of the interphalangeal joints will be driven into the top of the shoe (a sort of contracoup injury) (Fig. 20.2).

    Over the base of the fifth metatarsal if the patient is walking on the outside of the foot.

A bunion can form on the outside of the foot at the base of the fifth metatarsal. This is sometimes called a bunionnette.

The counter of shoes (the part that wraps around the heel) can rub on the calcaneum producing a bunion on the insertion of the achilles tendon into the bone.

   Check also for scars, cuts and redness everywhere on the foot including the sole of the foot.

 Soft tissues (swelling and wasting)

 Swelling in the foot is commonly seen on the dorsum only. In the ankle joint it is commonly seen at the front of the ankle.

Wasting is in seen in neurological conditions, and there may be wasting in the clefts between the metatarsals. Wasting may be associated with clawing of the toes (see Fig. 20.2).

Bone

With the patient standing, the heel should be in very slight valgus. The medial side of the foot (the arch) does not nor­mally quite touch the ground, but is not raised so high that you can put a finger between it and the ground. The heel pad, the lateral side of the foot, all the metatarsal heads and the pulps of all the toes are on the ground when the patient is standing erect and relaxed. The toes should be relatively straight, not clawed (flexed at the interphalangeal joints and extended at the metatarsal phalangeal joint) or hammered (extended at the distal interphalangeal, and metatarsal phalangeal joint, flexed at the proximal interphalangeal joint) (Fig. 20.3).

Feel

Skin

Inflammation. Feel for heat. Sensation. In neuropathies, such as that caused by diabetes, the distal sensation may be lost, and the toes may be numb. In nerve compression in the spine (e.g. prolapsed intervertebral disc) it should only be neces­sary to compare the two sides by testing the sole, the medial side and lateral side, each of which is supplied by a different nerve root.

Soft tissue

Pulses. The easiest foot pulses to feel are the posterior tibial behind the medial malleolus, and the dorsal pedis between the proximal ends of the first and second metatarsals (Fig. 20.4). The toes should also be tested for capillary fillings.

Swelling. Feel the ankle joint for an effusion. It may even be possible to feel cross-fluctuation if there is a tense effusion in the ankle joint.

Wasting and gaps. Feel the tendoachilles passing up from the heel into the calf muscle. If it is ruptured it may be possible to feel a gap in the tendon.

However, an acute rupture is usually so bruised and tender that the gap is not as easy to feel as it should be. The site of tenderness will give you a clue as to whether the rupture is mid-substance or is at the musculo­tendinous junction (much higher in the calf). It is important to distinguish between these two as the management and prognosis are very different.

Tenderness. The extensor tendons of the toes in the dot-sum of the foot and up the front of the tibia will be very tender and may even produce crepitus if there is tenosyn­ovitis. If they are tender, ask the patient to move the tendons and you may feel crepitus under your fingers.

Bone

Tenderness. In injuries around the ankle, start feeling at the proximal fibula head, just below the knee. The Maisonneuve fracture is a sprain of the ankle with a spiral fracture of the fibula proximally. Palpate for tenderness down the length of the fibula to its tip (the lateral malleolus), and then over the lateral collateral ligament as it passes from there to the calcaneum. Then palpate down the medial side of the leg, down the tibia, to the tip of the medial malleolus and on to the medial deltoid ligament. Feel the talus and navicular, on the dorsomedial side of the forefoot. Feel the fifth metatarsal head on the lateral side of the midfoot (a common site for a fracture after an inversion injury).

After a fall from a height check for tenderness in the calcaneum, as this may be fractured. If the forefoot has been trap­ped (frequently behind the pedals of a car in a head-on crash) then check for tenderness in the bones of the forefoot. These may be both fractured and dislocated if the forefoot is twisted.

Move

Active

Ask the patient to walk towards you then away from you. Look for limps.

The Windlass test. Make the patient stand on their toes while you look from in front and from behind. Some patients’ feet look very flat when at rest. This can simply be a physiological flat foot. As soon as these patients stand on their toes, the arch forms (Fig. 20.5). In pathological flat foot the arch does not form.

Other movements. You should also ask them to move their toes, and move the ankle through a full range of movement (flexion, extension, inversion and eversion).

Passive

The Apley test. If you hold the heel in one hand and the fore­foot in the other, the ankle, subtalar and metatarsal mobility can be tested one after the other without moving your hands. Rocking the ankle by moving your hands in opposite directions, like a see-saw, tests ankle mobility. Tilting the foot out­wards and inwards using both hands together tests subtalar movement. Twisting the forefoot while holding the hindfoot still tests midtarsal mobility (Fig. 20.6).

Hallux rigidus and claw toes. The metatarsal phalangeal joint of the big toe is stiff in hallux rigidus.

In claw toes the metatarsophalangeal joint is commonly dislocated with the phalanx riding dorsally over the metatarsal head (Fig. 20.2). Check for passive correction of the metatarsal phalangeal joint and proximal phalangeal joints.

Stability

Stability of the ankle and foot joints is not easy to test, especially after acute trauma.

If the ankle is dislocated the talus will be visible pressing hard against the skin anterior and lateral to the foot. It should be reduced at once both to save the skin (which may otherwise become necrotic) and to make the patient more comfortable.

Resisted

Test for power of extensor hallucis longus (Fig. 20.7). Remember, this muscle is specifically served only by the L5 nerve root, and is a key test for damage to this nerve in a prolapsed intervertebral disc.

In polio and other neurological disorders, each muscle will need to be tested in turn. One way to do this is to put the tips of your fingers over the muscle body, or its tendon, while holding the limb still with the other hand. The patient is asked to try to move the limb against the resistance that you have created. Your fingertips will detect whether there is any activity in the muscle, as the movement itself might be produced by alternative muscles, the so called ‘trick manoeuvres’. The power of each muscle can be graded using the Medical Research Council (MRC) power scale (Table 20.6).

Simmonds’ test. The patient lies face down, feet over the end of the bed. Squeeze the calf and the foot should passively dorsiflex (Fig. 20.8). If it does not, the tendoachilles is likely to be ruptured.