1. The ankle and foot
The ankle and foot
Foot and ankle combine flexibility ( propulsion) with stability(support)
structure because consist of a complex of joints, bony structure,
ligamentous attachments, and muscle contraction. The flexible/rigid
characteristics of the ankle/foot complex provide multiple functions,
1. Ankle joint forces up to 4.5 times body weight to occur while walking.
2. It provides a base of support.
3. It acts as a lever during push-off period of stance.
4. It provides adequate flexibility for absorption of the shock of the body
weight and for accommodation to uneven terrain.
Structure of the ankle and foot (see figure 1).
Bony Parts: It contains a total of 26 bones
Tibia and fibula
Talus and calcaneus
Navicular, cuboid, and three cuneiforms
Five metatarsals and 14 phalanges, which make up the 5 toes (3
phalanges for each toe except the large toe, which has 2 phalanges)
2. Figure 1: Structure of the ankle and foot
Arches of the Foot (see figure 2).
They are formed by the structure and arrangement of the bones (tarsus
and metatarsus) and maintained by ligaments and tendons the arches are
not rigid; they “give” when weight is placed on the foot, and they spring
back as the weight is lifted.
There are 2 types of arches:
Longitudinal arch: divided into medial and lateral parts
•The medial part originates at the calcaneus, rises at the talus, and
descends to the first three metatarsal bones and receives weight of
the body. The medial arch is supported by the spring ligament.
• Lateral part consists of the calcaneus, cuboid, and fourth and fifth
metatarsal bones and acting essentially as a space through which
tendons canpass. It is supported by the long and short
Transverse Arch – side to side concavity from anterior tarsal bones
(calcaneus, navicular, and cuboid) to all fivemetatarsal bones.
3. Figure 2: Arches of the Foot
The factors maintaining the arches of the foot (see figur3).
Figur3: The factors maintaining the arches of the foot.
Functions of the arches:
1. Support the weight of the body in standing.
2. Act as a lever to propel the body in walking and running.
3. During weight bearing, mechanical energy is stored released to assist
with push-off of the foot from the surface.
Transmission of body weight:
The structures of the foot are anatomically linked such that the load is
evenly distributed over the foot during weight bearing.
Approximately 50% of body weight is distributed through the subtalar
joint to the calcaneus, with the remaining 50% transmitted across the
4. metatarsal heads. The head of the first metatarsal sustains twice the load
borne by each of the other metatarsal heads. Tibia is the only true weight-
bearing bone in the body.
Muscle Function in the Ankle and Foot (see figuer4):
Both the extrinsic muscles (11) and the intrinsic (22) muscles of the foot
play a vital role in the mechanics of the foot. (See appendix 1).
Figure 4: Muscles
Muscle control of the ankle during gait
1. The muscles of the anterior compartment (dorsiflexors)
actprimarily during swing and early stance phase. This action
enables the foot to clear the ground during swing phase and then
allows it to be placed gently on the ground after heel strike.
2. The posterior, or calf, group acts from midstance to toe-off.
3. In normal standing, the gravitational line falls anteriorly to the
axis of the ankle joint, creating a dorsiflexion moment. The soleus
muscle contracts to counter the gravitational moment through its
pull on the tibia.
4. The intrinsic muscles of the foot activity in the last half of the
The joints of the foot are divided into three sections—hindfoot
(rearfoot), midfoot, and forefoot (see figure 5-6).
5. Figure 5: ankle and foot joints Figure 6: Joints
1. Talocrural (Ankle) Joint.
2. Subtalar (Talocakanean).
Midfoot (Midtarsal Joints, Transverse Tarsal Joint, Chopart’s
1. Talocalcaneonavicula r joint.
2. Cuneocuboid Joint.
3. Cuneonavicular Joints
4. Cuboideonavicular joint
5. Calcaneocuboid Joint.
1. Tarsormetatarsal Joints.
2. Metathrsophafangeat Joints.
3. Interphalangeal joints.
Important joints of the foot:
Ankle Joint (Talocrural): The talocrural joint is a uniaxia (,modified
hinge, synovial joint) located between the talus, themedial malleolus of
6. the tibia, and the lateral malleolus of thefibula and the movements
possible at this joint are dorsiflexionand plantar flexion.
Subtalar (Talocakanean) Joint: A gliding multiaxialsynovial joint
which consists of the talus on top and calcaneuson the bottom. The
subtalar joint allows movements about an oblique axis, allowing the foot
to side to side motion (inversion and eversion).
Transverse tarsal joint: It is formed of 2 joints that lie sideby-side.
These are the talo-navicular joint (between the headof talus and
navicular), and calcaneo-cuboid joint (between the caleaneus. and
cuboid). It is little to no motion and assists in eversion and inversion.
Locking and unlocking of the ankle joint: During
dorsiflexion, the wide anterior part of the trochlear surface of the talus is
lodged into the narrow posterior part of the superior articular surface
(socket). In this position, the ankle joint is locked as the foot cannot be
moved from side to side. During plantar flexion, the narrow posterior part
of the trochlear surface is lodged in the wide anterior part of the socket.
In this position, the ankle joint is unlocked as the foot can be
movedslightly from side to side.
Accordingly, the ankle joint is locked during dorsiflexion and unlocked
during plantar flexion.
Figure 7: Ankle Ligaments Figure 8:
Ankle Ligaments (see figure 7-8) :
7. Lateral Ankle Ligaments:
Talofibular ligaments: from the lateral malleolus of the fibula to
connects the talus and support the lateral side of the joint .
• Anterior Talofibular Ligament: It is prevents anterior
subluxation of talus when ankle is in plantar flexion.
• Posterior Talofibular Ligament: it is prevents posterior and
rotatory subluxation of the talus.
Calcaneofibular: connecting lateral malleolus to calcaneus.
It acts primarily to stabilize sub-talar joint & limit inversion. it is lax in
normal, standing position due to relative valgus orientation of calcaneus
Medial Ankle Ligaments
Deltoid ligaments: supports the medial side, triangular shaped, apex at
tip of medial malleolus,, base at talus, navicular, calcaneus which has two
- Superficial deltoid which resist talar abduction and primarily
resists eversion of hindfoot. Tibionavicular portion prevents inward
displacement of head of talus, while tibiocalcaneal portion prevents
- Deep deltoid ligament is prevents lateral displacement of talus &
prevents external rotation of the talus and latter effect is
pronounced in plantar flexion, when deep deltoid tends to pull talus
into internal rotation.
Ligaments of the Foot:
Spring ligament: attaches from calcaneus to navicular. It is supports
longitudinal arch and the head of talus especially in standing.
Plantar aponeurosis: runs from calcaneus to proximal phalanges, ties
posterior an anterior sections together and windlass action in ankle, where
full dorsflexion is limited by plantar aponeurosis.
8. Movements of the Foot and Ankle
1. Primary plane motions defined
a. Sagittal plane motion is dorsflexion and plantarfiexion.
b. Frontal plane motion is inversion and eversion .
c. Transverse plane motion is abduction and adduction.
2. Triplanar motions occurring about oblique axes defined
a. Pronation is a combination of dorsiflexion, eversion, and
b. Supination is a combination of plantarfiexion, inversion, and
Plantar flexion(55°), Dorsiflexion(15°), Inversion(35°),
Eversion(20°), Pronation (20°)and Supination(35°).
The ankle and foot during gait:
The biomechanics of the foot are best explained by describing
what happens to the foot during the stance phase of the gait
The impact of the heel as it contacts the floor, with subsequent rapid
loading of the foot, results in a floor reaction that exceeds the body
weight by 20 per cent. The sudden impact is partially absorbed by
lowering the body through plantar flexion of the ankle. It is during this
phase that the foot begins to act like a shock absorber. The ankle
dorsiflexors function during the initial foot contact to counter the
plantarflexion torque and to control the lowering of the foot to the
9. During midstance the entire foot is in contact with the ground (ankle is
neutral again) and the weight of the body is directly over the foot. The
vertical floor reaction is less than the body weight because of the falling
CM. The longitudinal arch of the foot is elevated and the foot everts, with
concomitant motion in the subtalar joint due to the eversion , pronation
and external rotation of the lower limb.
As the body weight shifts forward the foot begins to return to a neutral
position in preparation for heel lift.
The ankle plantarflexors , supinates and the metatarsal phalangeal joints
go into extension begin functioning near the end of mid-stance and during
terminal stance and preswing (heel-off to toe-off) to control the rate of
forward movement of the tibia and also to plantarfiex the ankle for push-
During this period the heel rises rapidly with increased ground reaction,
up to 40 per cent above body weight.
Swing Phase of Gait:
Much of kinetic energy for swinging limb is provided by inertia, which is
augmented by the plantarflexors (85%) and hip flexors (15%). During
swing, the ankle dorsiflexes by the concentric contraction of anterior
tibialis muscle and all other muscles are silent. Sub-talar joint assumes
near neutral position, and toes dorsiflex slightly as foot prepares for next
Common injuries of the ankle and foot
Foot injuries may develop from various causes, such as congenital
malformations of bones, muscular paralysis or spasticity, stresses and
strains in weight-bearing.
Alignment Anomalies of the Foot and Abnormal foot contact (see
10. 1. Pes varus (Club foot).
2. Pes valgus (Pes planus or flat foot).
3. Pes equines.
4. Pes cavus.
5. Pes Calcaneus.
Figure 9: Alignment Anomalies of the Foot.
Injuries Related to High and Low Arch Structures:
Arches that are higher or lower than the normal range have been found to
influence lower extremity kinematics and kinetics, with implications for
injury. High- arched exhibit increased vertical loading rate, with related
higher incidences of ankle sprains, plantar fascitis, and 5° metatarsal
stress fractures. Low-arched exhibit increased range of motion and
11. velocity in rearfoot eversion, as well as an increased eversion to tibial
internal rotation ratio.
Injuries of the Ligaments
Ankle sprains (see figure 10).
Figure 10: Ankle sprains.
Injuries of the lateral ligament
Ankle sprains usually occur on the lateral side because the joint capsule
and ligaments are stronger on the medial side of the ankle. Mechanism
injury of ankle sprain is inversion of the supinated , plantarflexed foot . It
usually occurs when the foot rolls over on the outside of the ankle. When
the ligament is completely torn or detached from the fibula, the talus is
free to tilt in the mortice of the tibia and fibula.
If the lateral ligament fails to heal, chronic instability of the ankle results.
Fractures with Deloid Injury ligament (Maisonneuve fracture):
The medial ligament is immensely strong and if stressed in ankle joint
injuries generally avulses the medial malleolus rather than itself tearing.
Nevertheless tears do occur, and are seen particularly in conjunction with
lateral malleolar fractures. A mechanism is combination of external
rotation at ankle, abduction of hindfoot,& eversion of forefoot while the
upper body externally rotates over the fixed foot.
12. Paralysis or Spasticity:
Paralysis of tibialis posterior alone causes a planovalgus deformity.
Spasticity of Tibialis Posterior cause dynamic varus deformities of foot.
Paralysis (polio) results in development of equinovalgus deformity this is
seen initially during swing phase of gait. Failure to raise the foot
sufficiently during the early swing phase causes Toe drag.
The patient cannot rise on tiptoes, and the gait is severely affected
because inability to increase walking speeds beyond the normal pacing.
However, despite uneven step lengths, she had uniform forward
progression. She had excessive dorsiflexion of the ankle and diminished
plantar flexion on the involved side .
The act of climbing stairs is awkward and slow, and activities such as
running and jumping are all but impossible.
Other soft tissues injuries:
Repeated incidents of forced plantar flexion of the foot which result in
tearing of the anterior capsule of the ankle joint. These may lead to
mechanical restriction of dorsiflexion.
Peroneal tendon disruption (peroneus brevis tear):
Mechanism of this injury is forced dorsiflexion with slight inversion and
concomitant eccentric contraction of the peroneal muscles may produce a
subluxation or dislocation of the peroneal tendons.
Anterior (Talotibial) Impingement Syndrome:
The mechanism of injury is repetitive forced dorsiflexion as demiplie
position in ballet can lead to impingement of anterior lip of tibia on talar
13. Posterior (Talotililal,) Impillgement Syndrome:
The mechanism of injury is repetitive, forced plantarflexion such as may
occur with practicing karate kicks or dancing en pointe.
Shortening of the Achilles tendon
Mechanisms for tendinitis have been proposed by repeated tension or
repeated loading .Shortening results in plantar flexion of the foot and
clumsiness of gait as the heel fails to reach the ground (Insufficient push
Mechanism of Injury are overuse or repetitive stretching of the plantar
fascia associated with training errors or associated with incomplete
rehabilitation (strengthening) following a previous ankle injure because
weak peroneal muscles may inadequately support the arch. Thus placing
additional stress on the plantar fascia. All of which reduce the foot’s
Both the end of the fibula (1) and the tibia (2) are broken .If
both malleoli are broken, this is called a bimallolar fracture or Pott's
The shafts of the second through the fifth metatarsals are the most
common sites of injury. These injuries are perhaps most commonly seen
in athletes involved in endurance running activities.
Pediatric Ankle Fractures
The age distribution of was typical: malleolar fractures predominated
among the younger children, epiphyseal fractures among the older.
Most common epiphyseal injury to ankle is distal tibia caused by
supination and external rotation. Complications of this fracture is :
1. Growth Plate Arrest.
14. 2. Angular Deformities - varus or valgus deformity.
3. Leg Length Discrepancy.
Muscles of ankle and foot
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