Acquired
foot problems
Injury
The foot is one of the commonest sites of injury in the body. Because of
its relatively rigid structure a great deal of force is necessary to injure the
hindfoot. The forefoot including the toes is relatively exposed and therefore
susceptible to injury. Also, the high forces going through the foot mean that it
is a common site for stress fractures. The principles of fracture management are
discussed elsewhere. The foot does present particular difficulties in diagnosis
because of the complexity of local bony and joint anatomy. This means that the
importance of careful history taking, examination and investigation cannot be
emphasised enough. The commonest missed injury is a tarsometatarsal dislocation.
In
all foot injuries the full extent of the injury needs to be appreciated, with
soft-tissue injuries often being associated with bony injuries. Post injury
rehabilitation is important to treat these elements of the injury.
Infection
Infections in the foot can be considered to be minor and common, or
major and fortunately rarer. With a significant proportion of the world’s
population remaining barefoot, minor skin trauma is a frequent cause of local
infection. In the shod population poor shoe fitting has the same effect. The
increased incidence of diabetes means that this is now a potent cause of major
infections. With the combination of vascular insufficiency, neuropathy and poor
cellular function, infection due to diabetes can be extremely difficult to
treat. This has considerable implications for the patient. It is also part of
why diabetes and its complications represent the greatest single cost drain on
many health services in the world.
A
careful history and examination must be aimed at elucidating predisposing
factors, assessing the extent of the infection, including evidence of more
generalised spread. Even with relatively minor bacterial infections lymphatic
spread is not uncommon. This leads to lymphangitis and involvement of regional
lymph nodes. Investigations must be aimed at establishing the extent of the
infection, the nature of the organism involved and any increased risk factors
such as poor peripheral blood supply or diabetes. Wound swabs, culture of
discharged material and skin scrapings or nail clippings can be helpful in
identifying the organism. A full blood count, plasma viscosity, blood sugar and
blood cultures can be helpful in determining the exact diagnosis and monitoring
the benefit of treatment. Plain X-rays remain the baseline investigation of
deeper infection, but newer investigation modalities such as magnetic resonance
imaging (MRI) can give extremely helpful information on the deeper spread of
infection and particularly address the issue of soft-tissue spread.
Basic
principles of management involve rest, elevation, antibiotics and, where
necessary, surgical débridement. Regular dressings are needed. Desloughing
agents and dressings which keep the recovering granulation tissue moist are
important.
Minor
infections
These include a variety of extremely common conditions including fungal
infections, varrucas, infected blisters, infected bursitis and ingrowing
toenails. Associated with ingrowing toenails are paronychia, which need formal
surgical drainage. Infections created by chronic or repetitive trauma need the
underlying cause treating in order to prevent their recurrence. A good example
of this is the ingrowing toenail. This will usually need surgical treatment to
get it to settle once infection has been established for any length of time. If
the infection is severe simple nail removal maybe sufficient to settle the
infection but recurrence is relatively common. Wedge resection of the border of
the nail and the associated nail bed is the treatment of choice in most cases;
this can be aided by phenolisation. It is important to neutralise the phenol on
the nail after application. In some cases complete resection of the nail and
nail bed (Zadik’s procedure) may be necessary.
Fungal
infections are relatively common and can be important as they can cause
generalised discomfort that can
Major
infections
Diabetes accounts for a substantial number of the major foot infections
seen. These may be superficial, often associated with ulceration. Deeper
infection may involve soft tissues only with abscess formation or can involve
bones (osteitis or osteomyelitis). This type of infection can also involve local
joints (pyogenic arthritis). The presence of poor vascularity and
neuropathy further complicates both diagnosis and management. Neuropathy can
lead to Charcot changes in the foot, disrupting joint stability and foot
architecture (Fig. 31.6). This leads to increased pressure under the sole of the
foot due to the loss of the normal capacity of the foot to absorb load. In
addition the bony disruption produces a high incidence of prominence under the
sole. This then leads to ulceration. There is a progression from this
superficial form of infection through deep infection and abscess formation to
osteomyelitis. If not brought under rapid control this will go on to gangrene.
Treatment
If ulceration is present without the presence of deeper infection the
clear aim is to heal the skin. After desloughing the ulcer and removing
hyperkeratotic skin the ulcer can be dressed locally. The application of a
skin-tight plaster of Paris changed on a weekly basis will allow the vast
majority of ulcers to heal. It also allows the patient to be mobile. Deep
infection without abscess formation can be treated by strict rest, elevation,
soft-tissue support and antibiotics. Any form of abscess needs to be drained
urgently and the deeper tissues thoroughly débrided. Ulcers which are deeply
penetrating in certain sites are more of a problem than elsewhere. The heel is a
particular problem in that ulcers lead to a permanent loss of the heel pad. Once
an ulcer is healed the use of appropriate insoles and shoes can prevent further
ulceration this is much more difficult to achieve when the ulcer has been in the
heel.
When
fixed deformity occurs as a consequence of neuropathy or Charcot changes due
consideration should be given to corrective surgery. The stage of development of
the Charcot changes has to be considered. The changes progress through three
stages. Stage 1 involves generalised inflammation and fragmentation of bone.
In stage 2 the inflammation starts to settle and the bone starts to show signs
of
Ultimately
if tissues are clearly not viable then an appropriate amputation should be
planned. This should be undertaken at a level where there is a realistic
chance of the wound healing.
Other
serious infections
Probably the commonest serious ‘primary’ infection is seen in the
madura foot. The causative organism of this is Nocardia madurae; this is
a filamentous organism similar to actinomyces. World-wide its incidence is
still high, affecting particularly populations in the Asian subcontinent and
in Africa who go barefoot. It is also has an increased incidence in other areas
of the world including southern USA, the South American states and the West
Indies. The organism almost certainly gains access to the foot through minor
penetrating injuries or splits in the skin. Subsequently the foot forms multiple
painless nodules, which ultimately form vesicular eruptions. These ulcerate and
form sinuses. These then become secondarily infected. Treatment involves rest,
elevation, and antibiotics for the secondary infection and protracted treatment
with dapsone or similar agents. Ultimately if the infection persists and leads
to disability then amputation can be considered.
Other
types of major infection include tuberculosis, bacterial osteomyelitis and/or
arthritis, and finally infections such as guinea worm.