Page 177 - ASOP ROT Study Guide

10.2 Infection

Infection may occur after open fractures or after internal fixation: it is notable that the commonest
cause of bone infection in the western world is surgery! Although infection may delay or prevent
union this is not always inevitable. Provided a fracture is held stable then it will unite despite
infection. If there is infection and movement then nonunion is most likely. This phenomenon is ill-
understood but suffice it to say that if a fixed fracture is infected then, provided it is stable, it may
be temporarily treated by drainage of any pus collection and by antibiotics until union has occurred.

If an open fracture that is not stable, or an unstable but fixed fracture, becomes infected then
stabilization by external fixation followed by surgical wound cleansing and later bone grafting will
be required.

10.3 Fat Embolism

The cause of fat embolism remains unclear. It was originally said to be due to the precipitation of
marrow fat in the lungs. The breakdown of fats to fatty acids is said to precipitate an inflammation
of the lungs (pneumonitis). However, the condition seems part of a more generalized abnormal
response to injury. It is not common, but is found typically after the fracture of a long bone in men
under twenty. The symptoms usually commence within two to five days from injury and may
initially simply present as rapid and shallow breathing (tachypnea) and mild confusion. The
injured person may have a rash on the chest and neck but this is by no means universal. Early
diagnosis is highly dependent on the clinician's awareness of this complication and on the carrying
out of appropriate investigations.

In severe cases the respiratory distress increases to the point where ventilation is required, but even
with this support, the condition carries a significant mortality. Unfortunately and most
distressingly, younger men are more prone to the full blown condition and fatalities do occur.
Early diagnosis followed by treatment with high percentage oxygen and chest physiotherapy reduces
the consequences, but late diagnosis is less than helpful. Steroids given early or even
prophylactically are said to reduce the severity but this remains controversial.

10.4 Renal Failure

People with massive soft tissue injury who are trapped for prolonged periods, particularly where
they are shocked or the trapped limbs are relatively starved of blood (ischemic), are prone to
develop kidney failure. Myoglobin, which is the oxygen carrying material in muscle, is found in
abundance in the kidneys of people who die from mis set of circumstances. The reason for this
is unknown.

10.5 Compartment Syndrome

Sometimes referred to as Volkmann's ischemia, this condition can occur in the upper or lower
limbs following a fracture with excessive localized soft tissue swelling. Classically occurring in the
forearm, it may also occur in the calf.

All muscles are surrounded by tough fibrous tissue called fascia. Groups of muscles are surrounded
by a thicker layer of fibrous tissue (the fascial sheath). This sheath supports the muscles and gives
them shape as well as anchoring them to bone and surrounding soft tissues.

The fascial sheaths act as boundaries between groups of muscles, creating isolated compartments
containing muscles, blood vessels and nerves. If a bone is broken then bleeding will occur into the
adjacent compartments and there will also be swelling from the inflammatory reaction. Both these
factors lead to an increase in pressure within the compartment. Rises in pressure may reduce blood
flow locally to the muscles. The reduced local muscle blood supply results in ischaemia. It is not
understood why this only happens occasionally but it appears to be related to severity of injury.
Rarely, compartment syndromes can occur without fracture and they can also be precipitated in
association with exercise - for example shin splints. "Shin splints" is the term used to describe the
often agonizing pain some athletes get in their shins when they run, often early in a training
schedule. Why chronic shin splints occur is not fully understood.