CONDITIONS TREATED

The particular mechanism of an injury causing bone fracture or joint disclocation can lead to a range of damage to nerves such that they no longer transmit impulses normally. A greater incidence of high-grade nerve injuries occurs with open fractures, with nerves either being lacerated or interposed between fracture fragments. Dysfunction of peripheral nerves results from damage to the neuron, to the Schwann cells (that insulate the nerve axons), or to the outer myelin sheath. For example, the force of injury in shoulder dislocation will affect the type of nerve injury sustained. Where fractures are associated with dislocations, as is often seen in shoulder dislocations, it is vitally important to anatomically reduce and fix any bone fractures seen. This enables good function to be restored when nerve recovery occurs.

Compression injuries can be induced by fractures, hematomas, and compartment syndrome, which causes high pressure in the surrounding tissue that compresses the arterial blood supply of the nerve, with possible cell damage and cell death. Although the peripheral nervous system is relatively robust, delays in assessment and treatment of compartment syndrome can lead to nerve injury in the forearm. In a fracture, concussion or compression of the nerve causes neurapraxia and fractures of the humerus can cause radial nerve paralysis.

In cases of traumatic hip dislocation, such as a bad fall or road traffic accident, the sciatic nerve can be compressed by the head of the femur, or lacerated by bone fragments. Imperfect healing can also lead to nerve damage, for example in elbow trauma, scarring can jeopardize the normal gliding of the ulnar nerve in the elbow because of adherence to scar tissue, fracture callus, or heterotopic bone.

Nerve injury may be apparent immediately after injury but may also develop later. For example, even without fracture or dislocation of the knee, nerve function to the foot may be affected by a stretch or contusion injury.