Tibia, Ankle and Foot
Injuries
Mechanism of injury
High-energy
injuries commonly result from axial loading, direct blows or crush injuries,
e.g. falls or jumps, motor vehicle accidents. Tibial shaft injuries are severe,
and risk neurovascular injury and compartment syndrome.
Low-energy
injuries tend to occur from twisting at the ankle joint, particularly ankle
inversion. The medial tibiotalar ligament is strong, unlike the weaker
fibulotalar and fibulocalcaneal ligaments on the lateral side. Hence most ankle
sprains are on the lateral side, caused by inversion of the foot.
Examination
Look A dislocated ankle will
look deformed. Bruising and swell-ing around ankle and foot is not specific for
fracture, although bruising over the calcaneus is likely to indicate a
fracture.
Feel Widespread mild soft
tissue tenderness is common in ankle injuries and needs to be differentiated
from specific areas of bony tenderness. Examination must never be rough, but if
poor-quality information is collected from the clinical examination,
poorquality decisions will be made. Check neurovascular status.
Move The function of the foot
and ankle is critically dependent on the subtalar joint. Support the calcaneus
in your non-dominant hand and use your dominant hand to:
•
Flex and extend at the ankle.
•
Invert and evert at the subtalar joint.
•
Twist the forefoot while holding the calcaneum tight.
Imaging
•
A dislocated ankle should be reduced before taking X-rays.
•
Use the Ottawa rules (opposite).
•
Ordering both foot and ankle radiographs together implies inadequate
examination.
•
CT is useful in injuries to the mid and hindfoot.
•
Radiographs of toes other than the big toe are unlikely to change
management, and should not generally be performed.
Management
Patients
with an open fracture must have intravenous antibiotics urgently; the injury
should be photographed and then covered in a saline-soaked dressing pending
urgent theatre. Taking a picture of the wound is useful for the surgeon as it
will be covered by dressing and plaster.
Analgesia
includes splintage and reduction of fractures. Elevation will reduce pain and
tissue oedema, which facilitates surgery, and reduces the risk of compartment
syndrome. Neurovascular status must be recorded, particularly before and after
fracture/dislocation reduction.
Disposal: who can go home?
Admit
patients with the following.
•
Open fractures.
•
Dislocated ankles.
•
Failed closed reduction/unstable fracture.
•
Fractured talus or calcaneus.
•
Tarsometatarsal dislocation: Lisfranc injury.
Patients with
stable fracture pattern injuries, who are unlikely to need surgery and who have
no evidence of complications, can usually go home. The initial cast should be
either a backslab or a split cast; this is because swelling will occur over the
first 24 hours after injury. Casts should ensure that the foot is at 90° to the
leg to maintain soft tissue length, except for Achilles tendon plasters, which
are plantarflexed.
Patients
should receive written instructions covering monitoring for signs of
neurovascular compromise/compartment syndrome, (Chapter 15) cast care, advice
to elevate the limb and follow-up arrangements. If crutches are necessary,
patients should be shown how to use them.
Common diagnoses
Ankle sprain
If a
fracture is ruled out using a decision rule or radiograph, the likely diagnosis
is a ‘sprained ankle’ – partial rupture of the lateral ligament complex, e.g.
fibulo-talar and fibular-calcaneal.
In addition
to short-term rest, ice and elevation, patients may benefit from physiotherapy.
Compression bandages do not help, but for more severe sprains, immobilisation
in a backslab for one week, together with crutches, is advisable.
The mortice
joint of the ankle is responsible for its structural integrity. If the mortice
is intact on one side, the fracture will be stable, and may be managed in
plaster. If both sides are unstable, internal fixation will be necessary.
The calf
muscle may tear in a sudden contraction, common in tennis. Treatment is rest, analgesia
and physiotherapy.
Occurs when
jumping (basketball, racquet sports) – or due to quinolone antibiotics.
Squeezing the calf muscles normally causes foot plantarflexion – this does not
occur with a complete rupture, which can be confirmed by ultrasound. Complete
rupture is repaired, but partial rupture is managed in plaster.
The second
and third metatarsals are most affected by stress fractures. The tendon of
peroneus brevis attaches at the base of the fifth metatarsal. Inversion
injuries may cause avulsion of this tendon with a flake of bone.
These are
easily missed in the ‘sprained foot’. Look specifically at the navicular,
talus, cuboid and the inferior border of the malleoli for a flake of bone that
has been avulsed by a ligament.
Diagnoses not to miss
Talar fracture
Falls on an
inverted foot, or forced foot dorsiflexion (‘aviator’s fracture’) may cause a
talar fracture. The talus has a central role in both ankle flexion/extension and
inversion/eversion. Fractures of the talus often have poor outcomes due to a
circuitous blood supply, with high rates of avascular necrosis.
These
injuries are rare, complex and often missed. The history may be of a crush type
injury. Typical signs and symptoms include pain, swelling over midfoot (TMT
joints) and the inability to bear weight. X-ray findings are subtle and may
appear normal. Consider this diagnosis if pain is very high despite no apparent
deformity.
Calcaneal
fractures are generally caused by a fall from a height. Fractures are usually
comminuted and are associated with fractures of the lumbar spine and wrists,
which should be examined carefully.
