injuries
around the ankle
Minor injuries around the ankle must be one of the commonest
presenting conditions in a casualty department. Most of these are minor sprains
which only require RICE (Rest, Ice, Compression, Elevation). Nonsteroidal
anti-inflammatory drugs may help the pain, reduce swelling and speed
rehabilitation. A simple sprained ankle is usually the result of a patient going
over on their ankle (an inversion and internal rotation of the foot on the
tibia). On examination tenderness is confined, to the lateral side of the ankle
and is localised over the ligament. The bone itself is not tender. More serious
injuries to the ankle have a pattern characterised by the way in which the
injury occurred. The injuries caused by inversion and external rotation of the
foot on the tibia occur in a sequence. First, the posterior part of the distal
fibula fractures off (Fig. 23.41). If the injury is more serious then the foot
continues to rotate and the medial collateral ligament fails or the tip of the
medial malleolus is pulled off. At this stage the ankle becomes unstable.
Finally, if the force continues further, the posterior capsule fails by ripping
off the posterior
If
the deforming force on the foot is pure inversion then it is usual for the
lateral structures to fail first. There is either a rupture of the lateral
ligament or avulsion of the tip of the fibula. If, however, only the ligament is
ruptured the X-ray may look normal as there will be no fracture visible and the
ankle at rest will lie in its normal anatomical position. If the ankle is
stressed while the X-ray is taken, by holding the foot inverted using
lead-protective gloves, the full extent of the injury will be immediately
apparent on the X-ray (see Fig. 23.43). If the injury is more serious, and
especially if there is a medial compression element to the fracture, then a
vertical shear fracture may develop separating off the medial
Value
of the history
The history may be helpful in defining what type of ankle injury is
likely. Remember that the fracture may have occurred because the ankle was
held stationary while the body continued to move. The patient’s description of
the injury may need translating into the actual movements of the foot on the
tibia and fibula.
Examination
The neurovascular status of the foot should always be tested first. In
an ankle dislocation, the circulation to the foot may be compromised, as is the
viability of the skin over the extruded talus. Reduction of the fracture is an
emergency, if skin necrosis is to be avoided (see Fig.
23.46).
Palpation
should start at the proximal fibular head. The Maisonneuve-type fracture is an
external rotation of the foot on the ankle. The fibula rotates with the talus,
avulsing the anterior diastasis but fracturing just below the knee at the fibula
neck. The fracture is not normally noticed on an X-ray centred on the ankle, and
therefore only clinical examination will reveal the tenderness which warns you
to look for this fracture. Careful palpation down the full length of the fibula
and on to the lateral collateral ligament will reveal whether there is likely to
be a fracture of the fibula or a tear of the ligament. Similar palpation of
the medial malleolus and deltoid ligament will give information about the medial
side of the ankle. It is always worth including the fifth metatarsal head in
this examination, as an inversion of the ankle can result in an avulsion
fracture of peroneus tertius from the metatarsal head.
Investigation
Two X-ray views of the ankle will be needed. Most fractures are much
better seen in one view than another. The posterior
Unusual
fractures of the ankle
A direct compression force, such as caused by landing on the feet from a
height, can drive the talus up into the tibia, destroying the tibial plafond.
The principle of management is
Twisting
injuries to the ankle in unusual positions such as full plantar flexion may
produce a chip fracture of the talus (see Fig. 23.47). These fractures can be
difficult to see as they can be very posterior and lie hidden behind the rest of
the talus in a normal X-ray. A shoot-through view of the ankle joint in full
plantar flexion should reveal the injury.
Footballers
who use the front of the foot for kicking a ball can develop a prominent
osteophyte on the front of the tibia, which can then fracture. The appearance of
the ankle joint even before a fracture has occurred can be quite unusual because
of the prominent osteophyte.
Management
If the injury to the ankle joint is stable with the foot plantigrade
then the fracture can be treated in a simple plaster. This should be split for
the first 24 hours to allow for swelling, but can then be closed. A very careful
check should be made that the talus is stable within the mortice. If you are
dealing with an unstable fracture pattern, then the plaster will need changing
regularly to maintain a close fit as the swelling goes down. Regular checks
using X-rays will also be necessary to make sure that displacement has not
occurred.
It
is important to keep the foot dorsiflexed in plaster, otherwise a fixed flexion
deformity of the ankle may develop within a few weeks. If the fracture pattern
is stable then weight-bearing can be allowed, but the plaster will need to be
reinforced with a foot piece or an external shoe to protect against wear. If the
fracture is unstable then weight-bearing
If
the injury is of such severity that the ankle joint is unstable and cannot be
held in a stable configuration with plaster alone, then open reduction and
internal fixation must be considered. Avulsion of the medial malleolus can be
reduced and held with a lagged screw, while a vertical shear fracture may
require lag screws and a buttress plate. The oblique fracture of the fibula is
both more difficult to reduce and more difficult to fix and will require a third
tubular plate applied anteriorly or posteriorly with lag screws across. Plates
applied directly to the lateral side of the fibula are too bulky and prevent
closure of the wound.
Timing
of surgery
Unstable ankle injuries produce enormous swelling. If surgery is
attempted when swelling is excessive then it will be impossible to close the
wounds at the end of surgery, and a simple closed fracture will be converted
into a complex open fracture. Surgery should therefore be undertaken within a
few hours of the injury before the swelling has become too great. Otherwise the
ankle should be elevated and a pneumatic splint used, if available, until the
swelling has gone down enough for surgery to be possible. A simple test is to
see whether the skin over the ankle is slack enough to create a small pucker
with pressure between the fingertip and the thumb. If it is not, then it is too
tight for surgery and the wound will not close (Fig.
23.48).
Postoperative
care
The normal aim of internal fixation is to create a stable skeleton so
that full mobilisation can be undertaken. This is unlikely to be achieved in
ankle fractures. The purpose of internal fixation is to create a congruent ankle
joint so that
Ruptured
tendoachilles
This injury occurs most commonly in the middle aged. It occurs without
warning and is often associated with strenuous exercise such as playing a game
of squash. The patient describes hearing a sharp crack behind the heel, and may
look around to see if she or he has been struck. There is immediate pain and
weakness in the ankle. However, the patient may still be able to plantar flex
the foot quite forcibly using the flexor digitorum and flexor hallucis longus.
The diagnosis is therefore not as easy to make as might first appear. In a true
rupture of the tendon there is swelling and tenderness over the tendoachilles
about 3 cm above the heel. If it is possible to palpate deeply, a clear step can
be felt in the tendoachilles, especially when compared with the other side.
Sometimes the swelling is so great and the patient is in so much pain that it is
not possible to feel this step. An alternative injury is a tear at the
musculotendinous junction of gastrocnemius much higher up in the calf. Here the
tenderness is much less well localised, some 10 cm above the heel and overall
the calf is much more swollen. This injury has a completely different treatment
and prognosis, and it is therefore important to distinguish between the two. If
the patient is laid prone on the examination couch with their feet hanging over
the edge, squeezing of the calf produces severe pain in a rupture of the
musculotendinous junction, but in a true rupture of the tendoachilles there is
little pain but the foot fails to plantar flex on pressure (see Chapter 20 on
examination of joints).
Treatment
Treatment of the tear of the musculotendinous junction is immobilisation
with the foot in full plantar flexion and nonsteroidal anti-inflammatory
drugs. As the pain and swelling go down, gentle mobilisation can be started.
Healing is quick as there is a good blood supply.
Treatment
of the ruptured tendoachilles is a completely different matter. There is a very
poor blood supply, and if the ends are not brought into close apposition the
tendon will either fail to heal or heal elongated. Either way, there will be
a severe weakness of plantar flexion of the ankle. Non-operative
treatment consists of putting the leg in plaster with the foot fully plantar
flexed and the knee flexed to 900 initially to bring the tendon ends together.
After 2 weeks the plaster is reduced to a below the knee plaster and the patient
is allowed to mobilise on crutches. Over the next weeks, serial plasters are
applied gradually bringing the foot up to a normal plantar grade position over a
period of 6 weeks. The patient is then allowed to mobilise gently, but full
activity is not allowed for a minimum of 3 months. There is a significant rate
of re-rupture. Healing the second time is even slower and the likelihood of a
fixed plantar flexion deformity even greater. Surgical treatment can be
performed either percutaneously or under direct vision. The tendon ends are
sutured together using strong nylon sutures. The stitches are very difficult to
insert as the tendon is macerated and stitches tend to cut out unless they are
placed very carefully. If the sutures are pulled too tight the tendon tends to
bunch up and then it is impossible to close the wound. There is a significant
incidence of wound breakdown and some people would question whether wound
healing is any faster or the rate of re-rupture any lower in surgical repair
compared with nonoperative treatment.