Download Session 3

Session 4
• Look at the ankle (talocrural joint) and the subtalar joint (hind foot)
• Anatomy of the joints
• Muscles and how the joints move (biomechanics)
• Structure of tendons and Achilles tendinitis
• Some common conditions including sprained ankle, involvement of
the common peroneal nerve, the importance of retraining balance
Ankle and hindfoot
• Note medial malleolus, lateral malleolus, inferior
tibiofibular joint, talocrural joint and subtalar joint form
the 3 joint complex
Looking down on the talus bone
• Note the circumference of the medial aspect of the
trochlear surface
• The trochlear surface is convex
• The circumference of the lateral aspect is longer which
will influence the movement which occurs at the ankle
• Moving forwards the talus has a neck and convex head
which articulates with the navicular (not shown) on the
medial side of the foot
The calcaneus
• A – looking down on the calcaneus, 3
areas for articulation with the talus.
Note the angulation of the talus on
the calcaneus
• B – Looking at the underneath surface
– note the groove for the tendon of
flexor halluces longus which bends the
toe
• C – side view of the calcaneus
showing the areas for articulation
with the talus
• Note the domed surface of the talus which
articulates with the tibia
• The navicular on the medial side of the foot
and the cuboid on the lateral side of the foot
are also shown
Anterior view of the talocrural joint and lateral
view of the subtalar joint
• View to show the relationship of the
hindfoot to the midfoot and forefoot
Lateral ligaments of the ankle
• The inferior tibiofibular joint has anterior and posterior
ligaments plus an interosseous ligament inside the joint
• The lateral ligament of the ankle has 3 portions
• Anterior – from the fibula to the talus – this is the
ligament most frequently injured in a sprained ankle
• The middle band – from the fibula to the calcaneus
• The posterior band from the fibula to the talus
• Note the large gap in between the anterior and middle
bands of the lateral ligament
Medial ligament of the ankle
• The medial ligament is fan shaped and
more substantial
• The capsule of the ankle is thin and weak
particularly anteriorly and posteriorly
• The stability of the joint is dependent on
the ligaments
Interosseous ligament of the subtalar joint
• Interosseous talocalcaneal ligament lies in the tarsal
canal
• It is a very strong ligament and is composed of
collagen with little elastin
Muscles of the anterior shin
• Lateral to the tibia – tibialis anterior, extensor digitorum longus,
extensor hallucis longus, peroneus longus
• Tibialis anterior pulls the ankle up into dorsiflexion
• Extensor digitorum and extensor hallucis dorsiflex the ankle
and extend the toes
• These muscles are surrounded by fascia – inelastic tissue which
can cause problems if there is bleeding into the area or rapid
development of the muscle. Anterior compartment syndrome
– see later
• Note also the retinacula over the front of the ankle. This is
bands of fascia which prevent the tendons from bowstringing
outwards when the muscle contracts
Muscles of the lateral aspect of the calf
• Peroneus longus and brevis are the main muscles to note
• Their tendons run under the lateral malleolus
• Peroneus longus passes under the sole of the foot to insert
into the base of the first metatarsal and into the medial
cuneiform (cf next week)
• The tendon of peroneus brevis runs along the outside of the
foot to insert into the base of the 5th metatarsal
• The action of these muscles which evert the foot are very
important in preventing an inversion sprain of the ankle
Muscles of the posterior calf
• Gastrocnemius is the most superficial muscle
• It has a medial and lateral head arising from the medial
and lateral femoral condyles
• The muscle bellies insert into an aponeurosis
• Underneath gastrocnemius is soleus
• This originates from the posterior fibula and tibia
• The muscle fibres unite to form a tendon which blends
with the aponeurosis of gastrocnemius to become the
tendo achilles (calcaneal tendon) which inserts onto the
calcaneus
Deep posterior muscles of the calf
• Middle – tibialis posterior – arises from the interosseous
membrane between the tibia and fibula, it also arises
from the fibula
• In the lower calf it forms a tendon which runs around
the medial malleolus and under the instep of the foot to
insert into several bones of the foot (cf next week)
• The muscle can plantarflex and invert the foot
• Flexor digitorum longus arises from the tibia. The
tendon passes alongside tibialis posterior going around
the medial malleolus into the foot
• The muscle flexes the toes and plantarflexes the ankle
• Flexor hallucis longus – arises from the fibula and the
interosseous membrane
• The tendon grooves the posterior tibia and talus before
passing under the instep
Synovial sheaths of the tendons
• The tendons are held down by bands of
fascia – the retinaculae
• They are protected by synovial sheaths
shown in blue
Movements at the Talocrural joint
• In dorsiflexion there is some slide and
roll of the talus within the mortice of
the tibia and fibula
• The anterior and middle fibres of the
ligament slacken whilst the posterior
portion becomes tight
• In plantar flexion the anterior capsule of
the joint tenses as does the anterior
band of the ligament
Combined movement of the talocrural joint
• Several important features to note – the talus is
wider anteriorly than posteriorly
• When the foot is in full dorsiflexion the inferior
tibiofibular joint widens slightly, the fibula rotates
laterally and glides superiorly
• Therefore movement at the ankle causes
movement in the inferior and superior tibiofibular
joints. This is important in to consider in sprains
of the ankle (cf later)
• Because the circumference of the lateral surface
of the trochlear of the talus is longer on the
lateral side plantarflexion occurs with inversion,
dorsiflexion with eversion
Movement of the tibia when lunging
• If you stand with the right foot forwards and
perform a lunge movement the tibia moves
over the surface of the talus as shown
• This produces medial tibial rotation
• If rotation movements of the tibia and fibula
are lost after trauma full range of movement
at the ankle cannot be achieved
Combined movements of the subtalar joint
• The axis of the subtalar joint is offset in
relation to the TC joint by 16 degrees along a
line which would fall inside the big toe
• It is also aligned 42 degrees upward from the
horizontal axis
• Movements at the subtalar joint, as seen
below, are eversion and inversion
• There are combined movements associated
with these movements details below
• It is easiest to imagine the subtalar joint as a
rowing boat under the ankle which can tip the
boat in each direction
Visualising the subtalar joint as a rowing boat
• It is easiest to imagine the subtalar joint as a rowing boat
under the ankle which can be tipped in from side to side
Subtalar joint as a mitred hinge
• Classically the subtalar joint is considered as a mitred hinge
(Inman and Mann 1973)
• Note for next week that inversion of the subtalar joint (heel)
leads to supination of the foot
• Eversion of the subtalar joint leads to pronation of the foot
• Note also that the tibia rotates internally with pronation and
rotates externally with supination
Combined movements in action
Any Questions?
Course of the sciatic nerve in the posterior
thigh
• Note the close relationship to piriformis
muscle in the buttock
• Tightness in this muscle can irritate the
nerve
• It also runs in close proximity to the
hamstring muscles
• Pain in this area could be related to
problems with the muscle or nerve
• The nerve divides in the middle of the thigh
into the tibial branch running down into the
calf and the common peroneal nerve
Course of the common peroneal nerve
• The nerve divides into superficial and deep branches
• Note the that the deep branch winds round the neck
of the fibula
• It is vulnerable to damage from fractures of the upper
end of the fibula and trauma to the ankle, due in
particular to the movement of the fibula with ankle
dorsiflexion
• Note the proximity of the cutaneous branches to the
lateral aspect of the ankle
• In severe inversion sprains of the ankle the nerve can
be subject to traction causing pain and altered
sensation
• Abnormal nerve function may also affect joint
proprioception
Function of tendon
• Link between muscle and bone, muscle compliant bone stiff, graduated
change in tissue characteristics between these two situations. Minimises
areas of concentrated stress
• Muscle belly bulky, tendon allows application of force at a distance.
Tendon works like a lever arm reducing the forces required to produce
movement
• Contrasting roles – tendons of fingers – low stresses and strains but high
precision. Achilles – withstands multiples of the body weight. Also acts
like a spring to store energy when stretched and release it at push off
• Requires degree of stiffness to provide efficient force transfer but also
elastic to enable stretching and storage of energy
• Tendons have slightly different structures depending on specific function
Structure
• Cellular component-tenocytes 10% of dry
weight
• Sensitive to mechanical loading
• Extracellular matrix – 60-90% type I
collagen
• Also contains 0.5-3% elastin, 2-5%
proteoglycans, small amounts of other
collagens
• Collagen interspersed with proteoglycans
rich matrix
• Collagen molecules crosslink to build
collagen fibrils, aggregated into fibres,
fascicles, and then tendon
• The hierarchical organisation of the
tendon gives tensile properties
Transition of tendon to bone
• Bone/tendon junction area of transition
between the more flexible tendon and stiffer
bone
• Changes from type I to type II and III
fibrocartilage
• As closer to the bone mineralised
fibrocartilage
• Then gradual transition to bone
• Called enthesis
• Often bursae between tendon and bone to
protect the tendon
Structural differences in tendo achilles
Structure of tendo achilles
• In energy storing tendons, like the achilles,
stretching causes sliding of the fascicles
• With age ability of fascicles to slide may
decrease increasing the risk of injury
• The tendon also has a tendon sheath or
paratenon – protects and enhances
movement
• Some tendons have an epitenon producing
synovial fluid helping to reduce friction
Behaviour of the tendon under tension
• As force is applied to stretch the tendon
the crimp of the fibres is pulled out
• The gradient of the elastic region is
individual to tendon and its
composition
Potential issues with the tendo achilles
• Midportion achilles tendinopathy wide-spread disorder
prevalence of 2.01 per 1,000 patients
• Aetiology - multiple factors including overuse, poor
vascularity, a lack of flexibility, genetic makeup, gender,
endocrine, a high body mass index or metabolic factors
• Located about 2–6 cm proximal to Achilles tendon
insertion
• The painful region coincides with the tendon area
possessing the poorest blood supply
• “tendon pathology continuum model” describes a
discrepancy between load in relation to intrinsic factors
like genetics, adiposity, cholesterol, and diabetes finally
leading to degeneration and insufficient regenerative
capability of an individual achilles tendon
Signs and symptoms
•
•
•
•
Obvious swelling of the affected area
Pain on palpation
Pain on toe standing
Maybe palpable crepitus on plantarflexion
Treatment of achilles tendinitis
•
Conservative modalities include load
modification, eccentric exercises, orthoses,
massage, electrotherapy, cryotherapy,
nonsteroidal anti-inflammatory drugs,
extracorporeal shockwave therapy
• Steroid injection is not recommended as it is
thought that this can weaken the tendon
predisposing it to rupture
• However, about 25 % of the patients continue to
have persistent symptoms
Surgical removal of the affected paratendon
• Minimally invasive techniques have been
found to be most successful in removing
vascularised painful tissue
• This is followed by rehabilitation to restore
range of movement, muscle strength and
tensile properties of the tendon
Partial and complete tears of the tendo
achilles
• Can occur suddenly due to increased stress on
the tendon
• May be an audible snap or pop
• On examination there may be a dip or gap in
the tendon
• Inability to toe stand in complete tear
• Classic test for complete rupture of the
tendon
• Note in a partial tear the foot may still
plantarflex when the calf is squeezed
• If complete tear go to ED
• If left for more than 3 weeks cannot be
repaired
• Depending on age and activity of the
individual the injury may be treated
conservatively
• Surgical repair is more likely to be successful in
preventing recurrent tears
• After surgery rehabilitation is required to
return to full function
Lateral ligament injuries
• The anterior band of the lateral ligament is most
frequently damaged in an inversion sprain
• Typical mechanism is foot down a rabbit hole, foot
on the edge of a kerb
• Swelling, pain and bruising over the lateral aspect of
the foot
• In more severe injuries the calcaneofibular ligament
can also be involved
• The tip of the lateral malleolus can be pulled off
• The inferior tibiofibular joint can be disrupted
• The tip of the base of the 5th metatarsal can be
pulled off by contraction of peroneus brevis
• The lateral malleolus can be fractured
• The cuboid can be subluxed due to the pull of
peroneus longus
• Theproximal tibiofibular joint can be subluxed
• The proximal fibula can also be fractured
Management of mild to moderate sprains
• RICE – Rest, Ice, Compression, Elevation
• Strapping – stirrup pulling the foot into dorsiflexion eversion
to reduce the stress on the ligament
• Figure of eight strapping from the mid foot up to the calf
• Mobilising with a stick if required
• Gentle exercises after a few days to increase range of
movement
• Progression of exercises as pain and swelling allows
• Retraining of balance
Severe ankle sprain
• Extensive bruising affecting the lateral and medial aspects of
the foot
• Bruising over the anterior ankle may suggest damage to the
ankle joint
• Significant swelling
• Inability to bear weight
• A feeling of instability of the ankle
• Suspect complete rupture of one or more ligaments
• Possible fractures
• Seek medical assistance – ED
• Depending on the injury may require immobilisation, surgical
intervention
• Rehabilitation – to increase range of movement, muscle
strength, balance
• If involvement of the common peroneal nerve specific
techniques to restore mobility of the nerve
Sprain of the medial ligament
• This is a less common injury due to the strength of the medial
ligament
• However this can lead to a fracture of the medial malleolus
• Severe pain, inability to bear weight, a feeling of instability,
marked swelling and bruising
• Seek medical help for optimal management
Osteoarthritis of the ankle
Ankle joint replacement
• OA can follow severe ankle sprains or previous
fractures
• If conservative management insufficient
surgery may be considered
• Ankle arthrodesis still considered for younger
patients
• More recently joint replacement provided in
some areas
• Of the 30,000 cases of
ankle osteoarthritis seen by hospital
specialists every year in the UK, only about
1,200 of them will undergo ankle replacement
surgery
• With ankle joint replacement there is a failure
rate of up to 19% after 10 years
Any questions?
Next week
• The foot – bony architecture, muscles, how it can be both pliable to
walk on rough ground but also act as a solid lever at push off
• The importance of the arches of the foot
• The foot in normal gait and posture and its influence in abnormal
alignment of the lower limb
• Common conditions – hallux valgus (bunions), heel pain, hammer
toes