Functional Anatomy Of The Foot And Ankle

Question 1

Groups of the bones of the foot

Answer 1

The bones of the foot provide mechanical support for the soft tissues; helping the foot to withstand the weight of the body whilst standing and in motion.

They can be divided into three groups:

Question 2

Regions of the foot

Answer 2

The foot can also be divided into three regions:

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Question 3

Talus Bone

Answer 3

The talus is the most superior of the tarsal bones. It transmits the weight of the body to the foot.

It has three articulations:

Question 4

Calcaneus bone

Answer 4

The calcaneus is the largest tarsal bone and is inferior to the talus.

It constitutes the heel and has two articulations:

Question 5

Navicular

Answer 5

the navicular (Latin navicula = little boat). Positioned medially, it articulates with the talus posteriorly, all three cuneiform bones anteriorly, and the cuboid bone laterally

On the plantar surface of the navicular, there is a tuberosity for the insertion of part of the tibialis posterior tendon.

Question 6

The Cuboid

Answer 6

The cuboid is furthest lateral and is cuboidal in shape.

It articulates proximally with the calcaneus and distally with the fourth and fifth metatarsals.

The inferior (plantar) surface of the cuboid is marked by a groove for the tendon of peroneus (fibularis) longus.

Question 7

The 3 cuneiforms

Answer 7

The three cuneiforms (medial, intermediate (or middle) and lateral) are wedge- shaped bones.

They articulate with the navicular proximally, and the first, second and third metatarsals distally.

The wedge shape of the cuneiform bones helps to form the transverse arch of the foot.

Tibialis anterior, tibialis posterior and peroneus (fibularis) longus all insert onto the medial cuneiform.

Question 8

The metatarsals

Answer 8

The metatarsals are located in the forefoot between the tarsal bones proximally and the phalanges distally.

They are numbered I-V from medial to lateral. Each metatarsal is convex dorsally and consists of a base (proximally), shaft, neck and head (distally).

The joints between the metatarsal bases and the tarsal bones are called tarsometatarsal joints.

The joints between the metatarsals and the adjacent metatarsals are called intermetatarsal joints.

The joints between the metatarsal head and the proximal phalanx are called metatarsophalangeal joints.

Question 9

The phalanges

Answer 9

The phalanges are the bones of the toes. The second to fifth toes all have proximal, middle and distal phalanges.

The great toe has only two; the proximal and distal phalanges. The phalanges are similar in structure to the metatarsals; each phalanx consists of a base, shaft and head.

Question 10

The ankle joint

Answer 10

The ankle joint (or talocrural joint) is a synovial joint between the bones of the leg (tibia and fibula) and the foot (talus).

Functionally, it is a hinge joint, permitting dorsiflexion and plantarflexion of the foot

The tibia and fibula are bound together by strong tibiofibular ligaments at the distal tibiofibular joint.

Together, they form a bracket-shaped socket known as a mortise

The trochlea of the talus fits snugly into the ankle mortise (also known as the malleolar fossa).

trochlea of the talus is wedge shaped; it is broad anteriorly, and narrow posteriorly

In dorsiflexion, the anterior part of the trochlea is held in the mortise, and the joint is more stable.

In plantarflexion, the posterior part of the trochlea is held in the mortise, and the joint is less stable.

The only movements that take place at the ankle joint are dorsiflexion and plantarflexion.

Plantarflexion of the ankle is produced by the muscles in the posterior compartment of the leg (gastrocnemius, soleus, plantaris and tibialis posterior).

Dorsiflexion of the Naples is produce by the muscles in the anterior compartment of the leg (tibialis anterior, extensor hallucis/longus and peroneus tertius. The range of dorsiflexion is usually limited by passive resistance in the muscles of the posterior compartment

Question 11

The lateral ligament

Answer 11

The lateral ligament has 3 parts:
The anterior talofibular ligament between the lateral malleolus and the neck of the talus
The posterior talofibular ligament between the malleolar fossa and the lateral tubercle of the talus
The calcaneofibular ligament between the top of the lateral malleolus and the lateral surface of the calcaneus

Theses ligaments resist inversion of the foot

Question 12

The medial/deltoid ligament

Answer 12

The medial (or deltoid) ligament is stronger and resists excessive eversion of the foot.

Its fibres fan out from the medial malleolus to attach to the talus, calcaneus and navicular.

Inversion and eversion of the foot do not occur at the ankle joint but rather at the subtalar, calcaneocuboid and the talocalcaneonavicular joints of the midfoot.

The functional significance of inversion and eversion is to allow walking on uneven surfaces.

Question 13

The subtalar joint

Answer 13

The subtalar joint is the articulation between the talus and calcaneus.

It is a plane type of synovial joint. The subtalar joint is on an oblique axis and is the major joint within the foot at which eversion and inversion movements take place.

Eversion is produced by the muscles of the lateral compartment of the leg (peroneus longus and peroneus brevis) and by peroneus tertius from the anterior compartment of the leg.

Inversion is produced by the tibialis anterior (anterior compartment) and tibialis posterior (deep posterior compartment) muscles.

The shape of its articulating surface means that the subtalar joint has no role in plantar or dorsiflexion of the foot.

Question 14

Arches of the foot

Answer 14

The foot supports the weight of the body and is important in locomotion (i.e. walking and running).

The main weight bearing bones during standing are the heel and the heads of the metatarsals.

The tarsal and metatarsal bones of the foot are traditionally described as being arranged in medial longitudinal, lateral longitudinal and transverse arches

The arches are maintained by the shape of the interlocking bones, the ligaments of the foot, the intrinsic muscles of the foot and the pull of the long tendons of extrinsic muscles (i.e. muscles in the anterior, lateral and posterior compartments of the leg).

The transverse arch is a ‘half-arch’ two of which, when the feet are together, form a complete arch.

The medial longitudinal arch is of most importance clinically. It is formed by the calcaneus, talus, navicular, three cuneiforms and the medial three metatarsals

The plantar aponeurosis and the spring ligament (plantar calcaneonavicular ligament), together with the tibialis anterior and the peroneus (fibularis) longus tendons play major roles in maintaining the integrity of this arch.

The muscles supporting the medial longitudinal arch are the tibialis anterior, tibialis posterior, peroneus (fibularis) longus and flexor hallucis longus.

The lateral longitudinal arch is formed by the calcaneus, cuboid and lateral two metatarsals.

Contraction of the peroneus (fibularis) brevis muscle may help in supporting the lateral longitudinal arch.

In the standing position, the arches sink somewhat under the weight of the body, the individual bones lock together, the ligaments binding them are under maximum tension and the foot becomes an immobile ‘pedestal’.

As soon as walking commences, the tension is released from the arches which unlock and become a mobile lever system with a spring-like action

Question 15

Anterior compartment of the leg

Answer 15

There are four muscles in the anterior compartment of the leg: tibialis anterior, extensor digitorum longus, extensor hallucis longus and peroneus (fibularis) tertius.

Collectively, they act to dorsiflex and invert the foot at the ankle joint. The extensor digitorum longus and extensor hallucis longus also extend the toes.

The muscles in this compartment are innervated by the deep peroneal (fibular) nerve (L4-L5), and the blood supply is via the anterior tibial artery.

Question 16

Tibialis Anterior

Answer 16

The tibialis anterior muscle is the strongest dorsiflexor of the foot.

To test the power of the tibialis anterior, the patient can be asked to stand on their heels with their forefeet raised off the ground.

Tibialis anterior originates from the lateral surface of the tibia. The tendon passes deep to the extensor retinacula at the ankle and inserts onto the medial cuneiform and the base of the first metatarsal.

Actions: Dorsiflexion and inversion of the foot.

Innervation: Deep peroneal (fibular) nerve.

Question 17

Extensor Digitorum longus

Answer 17

The extensor digitorum longus (EDL) muscle lies lateral and deep to the tibialis anterior muscle. The tendons of the EDL can be palpated on the dorsum of the foot.

EDL originates from the lateral condyle of the tibia, the medial surface of the fibula and the interosseous membrane.

The fibres converge into a single tendon which passes deep to the extensor retinacula of the ankle then divides into four tendons on the dorsum of the foot.

The tendons insert onto the middle and distal phalanges of the second to fifth toes.

Actions: Extension of the lateral four toes and assists in dorsiflexion of the foot.

Innervation: Deep fibular nerve.

Question 18

Extensor Hallucis longus

Answer 18

The extensor hallucis longus muscle is located deep to extensor digitorum longus and tibialis anterior. It originates from the medial surface of the fibular shaft.

The tendon crosses anterior to the ankle joint, beneath the extensor retinacula, and attaches to the base of the distal phalanx of the great toe

Action: Extension of the great toe and assists in dorsiflexion of the foot.

Innervation: Deep fibular nerve.

Question 19

Peroneus (fibularis) tertius

Answer 19

The peroneus (fibularis) tertius muscle is not present in all individuals.

Peroneus (fibularis) tertius originates from the medial surface of the fibula, inferior to the origin of EDL.

The tendon descends with the EDL, beneath the extensor retinacula, until they reach the dorsal surface of the foot.

The tendon then diverges from EDL and inserts onto the base of the fifth metatarsal.

Actions: Eversion and assists in dorsiflexion of the foot.

Innervation: Deep fibular nerve.

Question 20

Lateral compartment of the leg

Answer 20

There are two muscles in the lateral compartment of the leg: the peroneus (fibularis) longus and peroneus (fibularis) brevis.

Both muscles evert the foot and both are innervated by the superficial peroneal (fibular) nerve.

Note: From the anatomical position, only a few degrees of eversion are possible. In reality, the role of these muscles is to stabilise the medial margin of the foot during running and prevent excessive inversion.

Question 21

Peroneus (Fibularis) Longus

Answer 21

Peroneus (fibularis) longus is the larger and more superficial muscle within the lateral compartment.

It originates from the upper lateral surface of the fibula and the lateral tibial condyle.

The fibres converge into a tendon, which descends into the foot, posterior to the lateral malleolus

The tendon crosses under the midfoot and inserts onto the plantar surface of the medial cuneiform and base of the first metatarsal

Actions: Peroneus longus everts and assists in plantarflexion of the foot. It also supports the medial and transverse arches of the foot.

Innervation: Superficial fibular (peroneal) nerve, L4-S1.

Question 22

Peroneus (fibularis) Brevis

Answer 22

The peroneus (fibularis) brevis muscle is deeper and shorter than the peroneus (fibularis) longus.

It originates from the inferolateral surface of the fibular shaft

The tendon of peroneus brevis descends with the tendon of peroneus longus into the foot.

The peroneus brevis tendon passes posterior to the lateral malleolus, where it lies deep to the tendon of peroneus longus.

It inserts onto a tubercle on the base of the fifth metatarsal.

Actions: Peroneus brevis everts the foot. It may also play a role in supporting the lateral longitudinal arch.

Innervation: Superficial fibular (peroneal) nerve, L4-S1.

Question 23

Posterior compartments of the leg

Answer 23

The posterior compartment of the leg contains seven muscles organised into two smaller compartments: the superficial posterior compartment and the deep posterior compartment.

The two compartments are separated by fascia.

Collectively, the muscles of the posterior compartment plantarflex and invert the foot. They are innervated by the tibial nerve, a terminal branch of the sciatic nerve.

Question 24

Superficial posterior compartment of the leg

Answer 24

The muscles of the superficial posterior compartment form the characteristic ‘calf’ shape of the posterior leg.

They all insert into the calcaneus via the calcaneal (Achilles) tendon.

To minimise friction during movement, there are two bursae associated with the calcaneal tendon:
-Subcutaneous calcaneal bursa, between the skin and the calcaneal tendon.

Question 25

Gastrocnemius

Answer 25

The gastrocnemius is the most superficial of all the muscles in the posterior leg

The lateral head of gastrocnemius originates from the lateral femoral condyle, and the medial head from the medial femoral condyle.
The fibres converge and form a single tendon which combines with the tendons of soleus and plantaris to form the calcaneal tendon; this inserts onto the calcaneal tuberosity.

Actions: Gastrocnemius plantarflexes the foot at the ankle joint. As it crosses the knee joint, it also assists in knee flexion.

Innervation: Tibial nerve.

Question 26

Plantaris

Answer 26

Plantaris is a small muscle with a long thin tendon that can easily be mistaken for a nerve in cadaveric dissections. It is absent in 10% of people.

Plantaris originates from the lateral supracondylar line of the femur.

The muscle descends medially, condensing into a tendon that runs down the leg, between the gastrocnemius and soleus.

The tendon blends with the gastrocnemius and soleus in the calcaneal tendon.

Actions: Plantaris is a very weak plantarflexor of the foot at the ankle joint and a very weak flexor of the knee. It is not functionally important for either of these movements and hence can be harvested by plastic surgeons for reconstructive surgery elsewhere, without leaving any motor deficit.

Innervation: Tibial nerve.

Question 27

Soleus

Answer 27

Soleus is located deep to the gastrocnemius and plantaris muscles.

It is large and flat and is named soleus due to its resemblance to a sole, which is a type of flat fish.

Soleus originates from the soleal line of the tibia and the proximal fibula. Inferiorly, it inserts with gastrocnemius and plantaris, via the calcaneal tendon, onto the calcaneal tuberosity

Actions: Soleus plantarflexes the foot at the ankle joint.

Innervation: Tibial Nerve.

Question 28

Deep posterior compartment of the leg

Answer 28

There are four muscles in the deep posterior compartment of the leg

Popliteus acts only on the knee joint.

The remaining three muscles (tibialis posterior, flexor hallucis longus and flexor digitorum longus) act on the ankle and foot.

Question 29

Popliteus

Answer 29

Popliteus is located superiorly in the deep posterior compartment of the leg.

It lies posterior to the knee joint, forming part of the floor of the popliteal fossa (here).

Popliteus originates from the tibia proximal to the soleal line. From there, it passes superolaterally to insert onto the lateral condyle of the femur and the posterior horn of the lateral meniscus

Actions: Popliteus laterally rotates the femur on the tibia, ‘unlocking’ the knee joint so that flexion can occur.

Innervation: Tibial nerve

Question 30

Tibialis Posterior

Answer 30

Tibialis posterior is the deepest of the four muscles of the deep posterior compartment of the leg.

It lies between the flexor digitorum longus and the flexor hallucis longus.

Tibialis posterior originates from the interosseous membrane between the tibia and fibula and from the posterior surfaces of the two bones.

The tendon enters the sole of the foot by passing posterior to the medial malleolus and inserts onto the plantar surface of the navicular and medial cuneiform bones.

Actions: Tibialis posterior inverts and plantarflexes the foot and maintains the medial arch of the foot.

Innervation: Tibial nerve.

Question 31

Flexor Digitorum longus

Answer 31

Flexor digitorum longus (FDL) is a smaller muscle than flexor hallucis longus.

It is located medially in the deep posterior compartment of the leg.

FDL originates from the medial surface of the tibia and enters the sole of the foot by passing posterior to the medial malleolus

In the sole of the foot, it crosses superficial to the flexor hallucis longus tendon then divides into four tendons that insert onto the base of the distal phalanx of each of the lateral four digits

Action: Flexor digitorum longus flexes the lateral four toes and assists in plantarflexion of the ankle and inversion of the midfoot.

Innervation: Tibial nerve.

Question 32

Flexor Hallucis Longus

Answer 32

The flexor hallucis longus (FHL) muscle is found on the lateral side of the deep posterior compartment of the leg. [Note: this feels somewhat counter-intuitive, as it originates on the opposite side of the leg to the great toe, which it acts upon.]

FHL originates from the posterior surface of the fibula, passes posterior to the medial malleolus and inserts onto the plantar surface of the base of the distal phalanx of the great toe.

Action: Flexor hallucis longus flexes the great toe and assists in plantarflexion of the ankle and inversion of the midfoot.

Innervation: Tibial nerve.

Question 33

Tibial nerve

Answer 33

The tibial nerve is the larger terminal branch of the sciatic nerve and has the root values L4-S3.

It innervates the skin of the posterolateral side of the leg, lateral side of the foot and the sole of the foot; and provides motor innervation to the deep and superficial posterior compartments of the leg.

The tibial nerve arises from the sciatic nerve at the apex of the popliteal fossa.

It crosses the popliteal fossa, giving off branches to the muscles of the superficial posterior compartment of the leg. It also gives off a branch that, together with a branch from the common peroneal nerve, contributes to the formation of the sural nerve

the sural nerve innervates the posterolateral aspect of the leg and lateral border of the foot.

The tibial nerve then passes deep to the soleus muscle to enter the deep posterior compartment of the leg. Here, it lies between the flexor digitorum longus and flexor hallucis longus muscles

The tibial nerve innervates the muscles of the deep posterior compartment of the leg. At the ankle, it passes beneath the flexor retinaculum behind the medial malleolus, and gives off a medial calcaneal branch to the heel.

It then divides into medial and lateral plantar nerves to supply the sole of the foot.

In summary, the tibial nerve supplies the following muscles:
Posterior thigh:

Question 34

Common perineal nerve

Answer 34

The common peroneal (fibular) nerve is the smaller terminal branch of the sciatic nerve. It has the root values L4 – S2 (not S3)

It provides motor innervation to the short head of biceps femoris in the thigh and supplies the muscles of the anterior and lateral compartments of the leg.

It also provides cutaneous innervation to the skin of the anterolateral leg, and the dorsum of the foot.

The common peroneal nerve arises from the bifurcation of the sciatic nerve at the apex of the popliteal fossa.

It travels along the superolateral border of the popliteal fossa on the medial border of biceps femoris. It then winds around the neck of the fibula to pierce the peroneus longus muscle and divides into the superficial and deep peroneal nerves.

Before it divides, it gives off a cutaneous branch which supplies the skin of the upper lateral leg.

The muscles supplied by the common peroneal nerve are:

Question 35

Super Peroneal (fibular) nerve

Answer 35

The superficial peroneal nerve (L4-S1) arises from the bifurcation of the common peroneal nerve into the superficial and deep peroneal nerves.

It innervates the lateral compartment of the leg. The superficial peroneal nerve commences at the neck of the fibula and descends between ‘peroneus longus & brevis’ and the lateral aspect of extensor digitorum longus

It supplies peroneus longus and brevis and then continues as a purely cutaneous nerve supplying the anterolateral leg.

When it reaches the distal third of the leg, it pierces the deep fascia to run subcutaneously and supplies the dorsum of the foot, excluding the first webspace (which is supplied by the deep peroneal nerve), the medial border of the foot (supplied by the saphenous nerve) and the lateral border of the foot (supplied by the sural nerve)

In summary, the muscles supplied by the superficial peroneal nerve are:

Question 36

Deep peroneal nerve

Answer 36

The deep peroneal nerve (L4,5) arises from the bifurcation of the common peroneal nerve into the superficial and deep peroneal nerves.

It innervates the anterior compartment of the leg. It commences at the neck of the fibula and passes between the peroneus longus muscle and the neck of the fibula.

It enters the anterior compartment of the leg by piercing the intermuscular septum.

It then pierces extensor digitorum longus and lies adjacent to the anterior tibial artery in the anterior compartment of the leg, following the course of the artery.

Together, the two structures pass between the tibialis anterior and the extensor digitorum longus in the proximal portion of the leg, then between the tibialis anterior and the extensor hallucis longus in the distal leg.

The muscles supplied by the deep peroneal nerve are:

Question 37

Surat nerve

Answer 37

The sural nerve is formed from the union of the medial and lateral sural cutaneous branches of the common peroneal and tibial nerve in the posterior leg and passes behind the lateral malleolus to enter the foot.

It supplies the skin over the lateral border of the foot

As it has a relatively small cutaneous distribution and no motor branches, it can be harvested for use in reconstructive surgery, leaving just a tiny area of anaesthesia (loss of sensation).

Question 38

The popliteal artery

Answer 38

The popliteal artery is the continuation of the superficial femoral artery as it passes through the adductor hiatus.

In the popliteal fossa, it gives off genicular branches that supply the knee joint (Latin ‘genu’

Question 39

The anterior tibial artery

Answer 39

The anterior tibial artery passes anteriorly between the tibia and fibula, through a gap in the interosseous membrane, to enter the anterior compartment of the leg.

Together with the deep peroneal nerve, it passes between the tibialis anterior and the extensor digitorum longus in the proximal leg, then between the tibialis anterior and the extensor hallucis longus in the distal leg.

It passes under the extensor retinaculum into the dorsum of the foot, where it becomes the dorsalis pedis artery.

Question 40

The posterior tibial artery

Answer 40

The posterior tibial artery arises from the bifurcation of the tibioperoneal trunk at the inferior border of the popliteus muscle.

It descends in the deep posterior compartment of the leg lying successively on the tibialis posterior muscle, flexor digitorum longus, the tibia and the posterior ankle joint.

It is covered superficially by the deep transverse fascia of the leg, which separates it from the soleus muscle in the superficial posterior compartment.

The posterior tibial artery is accompanied by the tibial nerve and its two venae comitantes (small veins that accompany an artery); these are sometimes referred to collectively as the ‘tibial vein’. It passes behind the medial malleolus to enter the sole of the foot via the tarsal tunnel together with the tibial nerve.

The arrangement of the structures behind the medial malleolus is (Medial to lateral):

Question 41

The peroneal (fibular) artery

Answer 41

The peroneal (fibular) artery arises from the bifurcation of the tibioperoneal trunk at the inferior border of the popliteus muscle.

It descends on the medial side of the fibula in a fibrous canal between tibialis posterior and flexor hallucis longus, within the deep posterior compartment of the leg.

It gives rise to perforating branches, which penetrate the intermuscular septum to supply muscles in the lateral compartment of the leg.

Question 42

The dorsalis pedis artery

Answer 42

The dorsalis pedis artery is the direct continuation of the anterior tibial artery in the dorsum of the foot.

It gives off a deep branch which passes between the first and second metatarsals to the sole of the foot, where it anastomoses with the lateral plantar artery to complete the plantar arch.

Question 43

The pulses of the lower limb

Answer 43

There are four sites at which pulses can palpated in the lower limb. These are the femoral, popliteal, posterior tibial and dorsalis pedis pulses.

The femoral pulse can be palpated as it enters the femoral triangle, midway between the anterior superior iliac spine of the pelvis, and the pubic symphysis (the mid-inguinal point; remember the mnemonic MIPA: mid- inguinal point = artery) .

The popliteal artery is the hardest pulse to palpate. It lies deep in the popliteal fossa, and requires deep palpation to feel it. To make this easier, you should ask the patient to slightly flex their leg; this relaxes the deep fascia in the roof of the popliteal fossa so that your fingertips can press the popliteal artery against the bony floor of the popliteal fossa (which makes the pulse easier to feel).

The dorsalis pedis pulse is located by palpating the dorsum of the foot, immediately lateral to extensor hallucis longus tendon.

The posterior tibial pulse can be palpated in the tarsal tunnel, just below and behind the medial malleolus.

Question 44

Veins of the leg

Answer 44

The deep venous drainage system of the lower limb is located beneath the deep fascia of the lower limb. As a general rule, the deep veins accompany and share the name of the major arteries in the lower limb.

Often, the artery and vein are located within the same vascular sheath so that their arterial pulsations aid venous return.

Venous return is also aided by the contraction of the muscles within the leg during walking; this is why venous pooling tends to occur in the feet and legs when standing still for long periods, leading to reduced venous return, and sometimes to syncope (fainting).

Question 45

Dorsal venous arch

Answer 45

The main venous structure in the foot is the dorsal venous arch, which drains into the great (long) and small (short) saphenous veins at its medial and lateral ends respectively

Question 46

Vance comitantes of the anterior tibial artery

Answer 46

The venae comitantes (accompanying veins) of the dorsalis pedis artery on the dorsum of the foot continue in the leg as the venae comitantes of the anterior tibial artery in the anterior compartment of the leg.

They are sometimes referred to as the ‘an

Question 47

Medial and lateral plantar veins

Answer 47

The medial and lateral plantar veins arise from the plantar venous arch in the sole of the foot.

These veins form the venae comitantes of the posterior tibial artery (also known collectively as the ‘posterior tibial vein

Question 48

Peroneal vein

Answer 48

The venae comitantes of the peroneal (fibular) artery are similarly sometimes referred to as the peroneal (fibular) vein.

On the posterior surface of the knee, peroneal (fibular) vein drains into the posterior tibial vein, which in turn unites with the anterior tibial vein to form the popliteal vein.

The popliteal vein enters the thigh via the adductor hiatus. Here it changes its name to the femoral vein

Question 49

Popliteal fossa

Answer 49

The popliteal fossa, like the femoral triangle, it is a specific anatomical region of the lower limb.

The popliteal fossa is a diamond-shaped depression on the posterior aspect of the knee

It has four borders, formed by the muscles of the thigh and the superficial posterior compartment of the leg:

Question 50

compartment syndrome

Answer 50

Compartments of the limbs are bound by bone and deep fascia. These compartments contain the muscles with their nerve and blood supply, together with nerves and vessels to more distal parts of the limb.

Trauma (blunt or penetrating) to a fascial compartment may lead to haemorrhage and/or oedema and cause a rise in intra- compartmental pressure. This is known as compartment syndrome.

The clinical signs are severe pain in the limb, which is excessive for the degree of injury, increasing and not relieved by analgesia.

The pain is classically exacerbated by passive stretch of the muscles. If compartment syndrome is suspected, surgical decompression (fasciotomy) should be performed of all affected compartments.

Question 51

Consequences of compartment syndrome

Answer 51

Short-term consequences:
The increase in intracompartmental pressure leads to decreased perfusion of muscle.

Ischaemic muscle releases mediators which further increase capillary permeability and exacerbate the rise in intracompartmental pressure. In severe untreated cases, rhabdomyolysis (muscle necrosis) and acute kidney injury can result.

Neurovascular signs develop late in the process and are often undeveloped at the time of diagnosis. If the compartment pressure exceeds the systolic arterial pressure, there will be loss of peripheral pulses and increased capillary refill time.

Nerve fibres are susceptible to ischaemia; the thin cutaneous nerve fibres are affected more quickly than the motor fibres, so distal paraesthesia precedes loss of motor function.

Long-term consequences:
As above, rhabdomyolysis can result in acute kidney injury which may become chronic.

The necrotic muscle may also undergo fibrosis leading to Volkmann’s ischaemic contracture, a permanent painful and disabling contracture of the affected muscle groups

Question 52

Ankle fractures

Answer 52

Fractures and fracture-dislocations of the ankle are common.

The mechanism of injury for an ankle fracture is usually an inversion or eversion injury. When we see a patient with an ankle fracture, we also need to consider their co-morbidities (e.g. diabetes, neuropathy, peripheral vascular disease, smoking) as these are likely to affect fracture healing.

Diabetics for example, have a fracture-healing time that is approximately double that of non-diabetics.

We also need to assess the integrity of the overlying soft tissues.
Fracture blisters are relatively common after ankle fractures and surgery often needs to delayed until after the blisters have healed.

Sometimes the skin over the fracture blister becomes necrotic, so healing can take a considerate amount of time.

Open ankle-fractures (where the skin barrier is breached and there is a direct communication between the fracture and the external environment) are also common and require urgent surgery with extensive irrigation and debridement to reduce the risk of osteomyelitis (infection of the bone).

Question 53

Fractures of the ankle when looking at the ankle as a ring in the coronal plane

Answer 53

In the normal ankle, the talus is seated firmly in a mortise comprising the distal tibia and the medial and lateral malleoli. The ankle joint and associated ligaments can be visualised as a ring in the coronal plane:

Question 54

Sprained and 5th metatarsal fracture

Answer 54

An ankle sprain refers to a partial or complete tear of one or more ligaments of the ankle joint.

90% of these heal with just rest and time; those that do not heal can cause late ankle instability and sometimes require surgery.

The following factors can contribute to an increased risk of ankle sprains:

Question 55

Achilles’ tendon rupture

Answer 55

Rupture of the Achilles tendon most commonly occurs in men aged 30-50 years during recreational sports (“weekend warriors”) that require bursts of jumping, pivoting, and running (e.g. tennis, badminton, football).

Mechanisms of injury include:

Question 56

Hallux vagus

Answer 56

Hallux (big toe) valgus (distal part deviated laterally) involves:

Question 57

Hallux rigidus

Answer 57

Hallux rigidus is osteoarthritis (OA) of the 1st metatarsophalangeal joint (MTPJ), resulting in stiffness of this joint (hence ‘rigidus’).

This joint is normally under tremendous stress during walking as, with each step, a force equivalent to twice the body weight passes through this very small joint.

This is probably why it is so prone to developing OA. Other secondary causes can include gout and previous septic arthritis.

The commonest symptom is pain in the MTPJ on walking and on attempted dorsiflexion of the toe. In severe cases, the pain may be present at rest.

Patients tend to compensate for the pain by walking on the outside of their foot (i.e. inverting the foot and walking on the lateral border).
The range of dorsiflexion of the toe becomes severely restricted due to the arthritis (see middle image), although plantar flexion is usually retained.

A dorsal bunion (osteophyte) may develop on top of the joint and rub on the patient’s shoes (see bottom image).

Question 58

Treatments for Hallux ridigus

Answer 58

Initially, treatment of hallux rigidus involves activity modification, analgesia, orthotics or aids and sometimes intra-articular steroid injections.

A rigid sole orthotic is a very stiff shoe insert that prevents motion at the 1st MTPJ. This will help prevent the pain caused by dorsiflexion of the toe whilst walking.

If conservative management fails to control the symptoms sufficiently, surgery may be considered. The current ‘gold standard’ treatment is arthrodesis (fusion) of the 1st MTPJ. In this operation, the joint is excised so that it is effectively replaced by a ‘fracture’.

The ‘fracture’ is then stabilised with screws and normal fracture healing subsequently fuses the joint.
Arthroplasty (replacement) of the 1st MTPJ may be considered and there are now some specialised prostheses available for this joint.

Question 59

OA of the ankle joint

Answer 59

A major difference between OA of the ankle and that of the hip of knee is that nearly all cases of OA of the ankle are secondary arthritis.

70-80% of cases occur in a joint that has previously suffered trauma (e.g. fracture, severe sprain). This is referred to as post-traumatic arthritis.

The initial injury may heal with full return of ankle function. However, in some cases, the subsequent development of OA leads to further symptoms within a couple of years of the injury, and in others the onset of symptoms can be delayed for decades.

A further 12% of cases of ankle OA are secondary to inflammation in the ankle joint (e.g. rheumatoid arthritis, reactive arthritis).

Other risk factors include joint stress (e.g. ballet dancers, footballers) and obesity.

The remainder of cases (approx. 7%) have no identifiable precipitating cause and are therefore referred to as primary ankle arthritis.

Patients with primary OA of the ankle tend to be older, experience less pain, and have a better range of motion than those with secondary OA.

The gold standard treatment for OA of the ankle is arthrodesis (fusion). The results from ankle fusion are very good. Patients can walk very well after an ankle fusion as they still have mobility of the mid-foot and fore-foot. There is often no discernible limp.

Alternatively, an ankle arthroplasty (joint replacement) may be considered. However, this is a more major operation that carries risks such as prosthetic loosening and prosthetic infection. As the results are so good after ankle fusion, for most patients, fusion is the preferred option instead.

Question 60

Toe deformities affecting the lesser toes (2nd

Answer 60

Claw toes often affect all four of the small toes at the same time.

The toes are hyperextended at the Metatarsal-phalanges joint and flexed at the Peripheral phalanges joint (and sometimes also at the Distal phalanges joint so that the toe curls under the foot). Corns may develop over the dorsum of the toe or under the head of the metatarsal.

Claw toes result from a muscle imbalance which causes the ligaments and tendons to become unnaturally tight. This is usually due to neurological damage and may be secondary to conditions such as cerebral palsy, stroke, diabetes or alcohol dependence.

Trauma, inflammation and rheumatoid arthritis can also cause claw toe.

Question 61

Toe deformities affecting the lesser toes (2nd

Answer 61

Hammer toe is a deformity in which the toe is flexed at the PIPJ, whereas a mallet toe is flexed at the DIPJ. These deformities can affect any toe but are most common in the second toe.

Causes include ill-fitting pointed shoes, and pressure on the second toe from an adjacent hallux valgus. If a tight shoe causes a toe to stay in a flexed position for too long, the muscles contract and shorten.

This makes it harder to extend the toe. Over time, the muscles cannot extend the toe, even when the shoes are not being worn.

Question 62

Toe deformities affecting the lesser toes (2nd

Answer 62

Curly toes are congenital and usually involve the 3rd to 5th digits. They are usually bilateral and are more common in those with a family history of curly toes

Curly toes are thought to develop because the tendons of the flexor digitorum longus (FDL) or flexor digitorum brevis (an intrinsic muscle of the foot) are too tight.

Most children are asymptomatic. Treatment is usually conservative with passive extension of the toes and stretching of the flexor tendons. Surgery is rarely needed and is only considered after the age of 6 years in children whose curly toes cause them pain on activity.

Question 63

Achilles tendinopathy

Answer 63

Achilles tendinopathy is a degenerative not an inflammatory process

Although the Achilles tendon can withstand great stress from running and jumping, it is also prone to tendinopathy or degenerative change.

The tendinopathy can develop:

Question 64

Flat foot

Answer 64

The term ‘flat foot’ implies that the medial arch of the foot has collapsed so that the medial border of the foot almost touches the ground. Valgus refers to the valgus angulation of the hindfoot

Most young children appear flat footed as their arches have not yet developed and there is also a large amount of subcutaneous adipose tissue in the sole of the foot (the medial fat pad).

Flat feet are a common cause of parental anxiety but are ‘normal’ in young children. The medial longitudinal arch of the foot begins to form in children around the age of 5 years.

It is only if the deformity persists into adolescence, or recurs during or after adolescence, that it is considered abnormal.

Orthotics are ineffective in promoting the normal development of the arch and should not be prescribed.

However, it is very important to distinguish between flexible and rigid flat feet.

The vast majority of patients will have flexible flat feet. They have no medial arch whilst standing normally, but when standing on tip-toes, a normal medial arch appears and the hindfoot returns from valgus deviation into a normal alignment.

Rigid flat feet, however, are always abnormal; they usually develop as a result of tarsal coalition (failure of the tarsal bones to separate during embryonic development).

When patients with rigid flat feet stand on tiptoe, no arch appears and the hindfoot remains in valgus - often symptomatic and therfore requires treatment

Question 65

Adult acquired flatfoot

Answer 65

In adults, an acquired flexible flat foot results from dysfunction of the tibialis posterior tendon, which usually supports the medial longitudinal arch of the foot whilst walking.

The condition most commonly occurs in middle-aged females; they give a history of a change in shape of their foot and often describe pain behind the medial malleolus.

Known risk factors for acquired flat foot include obesity, hypertension and diabetes. Flat feet can also occur temporarily during pregnancy, due to increased laxity of the ligaments.

The lack of support of the medial arch by tibialis posterior leads to stretching of the spring ligament (plantar calcaneonavicular ligament) and the plantar aponeurosis.

Stretching of the ligaments results in the talar head being displaced inferomedially, flattening the medial longitudinal arch and producing lateral deviation of the hindfoot.

Symptoms improve in 80% of these patients following the use of orthotics (insoles) to support their medial arch and physiotherapy to improve muscle strength. Some patients, however, require either surgical reconstruction or, if secondary OA has developed, arthrodesis of the joints of their hindfoot.

Question 66

Diabetes mellitus and foot issues

Answer 66

Foot disease is a common and serious complication of diabetes and includes infection, ulceration or destruction of the tissues of the foot.

Foot disease affects approximately 15% of people with diabetes mellitus and is responsible for 25% of all hospitalisations in diabetic patients.

50% of all major amputations are carried out in diabetic patients and 66% of these will have their other leg amputated within five years.

If you combine this with there being a 50-70% mortality for all patients within 5 years of a major amputation, amputation has a worse prognosis than a lot of cancers.

Question 67

Charcot arthropathy

Answer 67

Poorly-controlled diabetes can lead to Charcot arthropathy, which involves progressive destruction of the bones, joints and soft tissues.

Charcot arthropathy most commonly involves the ankle and foot, but can affect other joints such as the knee. A combination of neuropathy, abnormal loading of the foot, repeated microtrauma (with non-healing microfractures), and metabolic abnormalities leads to inflammation causing osteolysis (bone resorption), fractures, dislocation and deformity.

As a result of their neuropathy, the patient has reduced ability to detect touch, temperature, and pain.

They may therefore continue to walk on a Charcot foot, making the injury worse. Neuropathy also leads to muscle spasticity (e.g. tight Achilles tendon), which exacerbates the deformity. In severe cases, a rocker-bottom foot may develop

Treatment comprises optimisation of glycaemic control and reduction of the load placed on the affected joints.

However, this can be challenging as there is reduced bone stock and the bones are soft (due to inflammation).

The patients often do not experience pain, so are not reminded to stop weight-bearing on the foot. They are also often obese which increases the load placed through their softened bones; and they usually have poor glycaemic control and therefore have secondary immunosuppression.

Question 68

Walking and gait

Answer 68

Normal gait requires an energy-efficient interaction between the musculoskeletal and neurological systems of the body.
Gait consists of two phases:

Question 69

5 main attributes needed for normal gait

Answer 69

Stability in stance – we have to be able to transfer weight from one foot to the other and therefore need to be able to stand on one leg. This ability
requires adequate neuromuscular and proprioceptive (joint position sense) function.

Question 70

Process of phases in gait movement

Answer 70

In normal gait, it is the heel that makes the initial contact (strikes the ground first). In some pathological gaits (e.g. diplegic gait), it may be the toes.

For most of the gait cycle, when the right leg is in swing phase, the left leg will be in stance phase and vice versa.

However, there are two periods of time within the normal gait cycle where both feet are in contact with the ground. These are known as periods of double support

As the speed of your gait increases and you walk faster, leading into jogging, running and eventually sprinting, the period of double support decreases.

Running commences as soon as there is a time in the gait cycle in which neither foot is in contact with the ground. This is called double float

The faster you run, the longer the period of double float within each gait cycle. In sprinting, the length of the stance and swing phases effectively reverses so that stance constitutes only 40% of the gait cycle, and swing 60%.

Question 71

Stance and swing gate can be further subdivided into…..

Answer 71

The stance phase is subdivided into:

Question 72

Gait analysis

Answer 72

Gait analysis is the study of a person’s gait. There are two elements to gait analysis:

Kinematics describes the motions themselves i.e. the joint angles, displacements, velocities and accelerations that take place during gait

Question 73

Kinetics

Answer 73

Muscles produce force to:

Question 74

Pathological gaits

Answer 74

Gait abnormalities can be a result of nerve lesions, joint instability, immobility of joints and pain.

Observation and diagnosis of gait abnormalities not only involves observation of the phases of walking and lower limb joint movement, but also involves observations of stride length, arm swing and lateral movements of the shoulders and head.

Question 75

Antalgic gait

Answer 75

In an antalgic gait, patients walk in a manner that reduces pain e.g. in OA of the hip.

They tend to walk with a limp, shortening the stance phase of the painful limb i.e. they spend more time walking on the less painful limb and minimise the time spent weight-bearing on the affected limb.

This automatically means that they have to shorten the swing phase in the unaffected limb. The gait is therefore uneven.

Patients with an antalgic gait often use a walking stick to reduce the load through the painful limb. The walking stick should be used in the hand opposite the painful limb.

This patient can then lean towards the walking stick, shift their centre of gravity away from the painful limb and therefore reduce the load through it during the stance phase

Question 76

Trendelenberg gait

Answer 76

normally in the stance phase, the hip abductors (gluteus medius and minimus) contract to prevent the pelvis dropping on the unsupported side.

When this mechanism fails, the patient will demonstrate a positive Trendelenburg Sign whilst standing on one leg and a Trendelenburg gait whilst walking.

Superior gluteal nerve lesions are not the only cause of a positive Trendelenberg sign and gait. It can result from any of the following:

Question 77

Hemiplegic gait

Answer 77

A hemiplegic gait is due to paralysis of one side of the body.

It most commonly results from a stroke, but it can also occur as a consequence of cerebral palsy or trauma to the central nervous system e.g. head injury, spinal cord injury.

The patients have spasticity (continuous contraction) of the affected side of the body.

The spasticity is most severe in the flexor muscles of the upper limb and the extensor muscles of the lower limb as these are the dominant muscle groups.

Hemiplegic patients therefore typically have a flexed upper limb and an extended lower limb.

The patient cannot flex their hip, knee or ankle, so in order to take a step they need to lean towards the unaffected side of the body then circumduct the paralysed leg.

The patient cannot bear much weight on the paralysed leg so the stance phase on this limb is very short.

Their gait therefore comprises a short step with the unaffected leg followed by circumduction of the affected leg

Question 78

Diaplegic gait

Answer 78

In diplegia, the spasticity affects both lower limbs. This condition most commonly develops in cerebral palsy.

The patient walks with a very narrow-based gait (feet close together), dragging both legs and scraping their toes on the ground.

Spasticity in the hip adductors can cause the legs to cross the midline – this is referred to as scissoring

Spasticity in the hamstrings means that the knees are slightly flexed and spasticity in the gastrocnemius and soleus results in plantar-flexion of the ankles.

In a diplegic gait it is commonly the forefoot that makes the initial contact with the ground

Question 79

High steppage gait

Answer 79

High-steppage gait is seen in patients with weakness of ankle dorsiflexion, resulting in ‘foot drop’.

Causes include:

Question 80

Parkinsonian gait

Answer 80

Briefly, nerve cells in a part of the brain called the subtantia nigra degenerate, leading to reduction in a chemical called dopamine.

Dopamine plays a vital role in regulating body movement.

Patients with Parkinson’s Disease find it difficult to initiate movement.

To counteract this they flex their neck and trunk forwards to move their centre of gravity in front of their lower limbs.

They also take very short steps, known as a shuffling gait and may also exhibit a festinant’ gait, which is the tendency to take accelerating steps.

Patients with Parkinson’s Disease also typically have loss of arm swing whilst walking. They may not notice this themselves but it is extremely useful diagnostically.

Question 81

Ataxic gait

Answer 81

The three causes of ataxia are: