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An external fixator is a device used to stabilise and/or correct the position of a bone. It is attached to the bone using wires or half pins. These pass through the skin, muscles and bone; on some frames the wires pass all the way through the limb.

The main reasons to use an external fixator are: stabilization of a fracture, correction of a bent bone and bone lengthening. The fixators can be adjusted so that complex corrections can be made to the position of the bone.

There are two main types of external fixator used: Monolateral and Circular. The type of frame used depends upon your individual circumstances.

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Half-pins connect the bone to a strong bar which is placed along one side of a limb. There are several different types. At the RNOH we use one that can be adjusted using an Allen key. (Fig. 1) This allows for changes of the length or position of the bone.

There are two main kinds: The Ilizarov fixator and the Hexapod.

Each fixator is assembled to your individual needs. The number of rings, wires and half-pins will vary from person to person. Your surgeon will be able to give you an idea of what your frame will look like.

The Ilizarov fixator

This is a frame consisting of rings, which are connected by straight rods. (Fig. 2) The rings are attached to the bone using tensioned wires, these wires pass all the way through the limb. The rods can be finely adjusted to change the length or position of the bone.

The Hexapod

Like the Ilizarov fixator, rings are connected to the bone using wires and/or half pins. However, rather than there being straight rods between the rings, there are six telescopic struts. (Fig. 3). Engineers will recognise this as the Gough-Stuart platform, which is often used in machinery and robotics. There are several different types, one such fixator, the Taylor Spatial Frame uses computer software to generate instructions to move each strut in order to improve the position of the bone.

If your external fixator is being used to correct the position or length of your bone, you will normally start to adjust your fixator 6 - 7 days after your operation. Individual instructions will be given and you will be supported until you feel confident and competent to carry out the adjustments to the frame.

The main reasons to use an external fixator are: stabilization of a fracture, correction of a bent bone and bone lengthening. The fixators can be adjusted so that complex corrections can be made to the position of the bone.

Pin site infection

The most common complication of having an external fixator is pin site infection.

Symptoms of a pin site infection may include:

  • Increased pain in the area
  • Spreading redness of the skin
  • Nerve damage
  • Increased discharge or pus (not always present)
  • Increased swelling
  • Difficulty weight bearing
  • You have a temperature or feel unwell

Pin site infections are treated with oral antibiotics in the first instance. If you suspect you have an infection you should visit your GP at the earliest opportunity for assessment and if necessary, the prescription of antibiotics. It is important that you complete a course of antibiotics once started. If your infection does not respond to antibiotics prescribed by the GP you should contact a member of the Limb Reconstruction Team.

Meticulous pin site care will minimize the risk of pin site infection. You will be shown how to care for your pin sites as well as have some practice whilst you are in hospital. If necessary, we may arrange for some nursing support in the community once you are discharged from hospital.

Joint Stiffness and soft tissue tightness

This can be a problem and may affect your ability to mobilise. It is of prime importance that you perform the exercises that the Physiotherapists provide, or wear any necessary splints as instructed. In severe cases, surgery may be required to release tightness in the soft tissues to allow a full range of movement.

Joint Instability

Following long lengthening procedures there is a small risk of dislocation of the surrounding joint. This particularly applies to the hip and the knee when lengthening a femur and to the knee when lengthening a tibia. This is monitored during the lengthening process and whilst it may be prevented with aggressive physiotherapy, its occurrence may lead to abandoning further lengthening.

Nerve and blood vessel injury

Rarely nerves and blood vessels can become damaged. This can be either at the time of surgery or during the subsequent lengthening or repositioning of the bone. You should inform nursing and/ or medical staff if you experience pain, numbness or pins and needles. Should this occur during the lengthening process this may mean that we slow down the rate of adjustment or even stop lengthening. Usually this wears off, but in some cases it may become permanent. It is important that you inform a member of the Limb Reconstruction Team should these symptoms occur.

Acute Compartment Syndrome

Acute Compartment Syndrome is a painful condition that occurs when swelling or bleeding causes increased pressure within the muscle compartments. It will usually be diagnosed and treated when you are already in hospital, however, it can occur several days after surgery.

The main symptoms are:

  • Severe pain which is constant. The pain may worsen upon movement when the muscles are stretched.
  • Tingling or burning sensation in the area.
  • The skin in the affected area may become pale, cold, tense and hard
  • Reduced strength and movement in the affected area

Acute compartment syndrome is a medical emergency. If you experience any of these signs or symptoms, you should inform a member of your consultant’s team or attend your local accident and emergency department immediately.

Further information about Acute Compartment Syndrome can be found in the booklet:

Deep Vein Thrombosis (DVT)

There is a risk of developing a DVT. This is a blood clot which is treated by medication that thins the blood. Your risk factors for this occurring will be assessed by medical staff and if necessary you will be placed on anticoagulation therapy.

Pressure Ulcers

A pressure ulcer is damage to the skin and underlying tissue. They can be caused by pressure, shear or friction.

Pressure ulcers tend to form where bone causes the greatest force on the skin. This is caused when the body is in contact with the mattress, chair or another part of the body. Areas such as the bottom, heel, hip, elbow, ankle, shoulder, back and the back of the head are vulnerable.

They can also be caused if your limb swells excessively within the external fixator causing the skin to be in contact with the clips holding dressings in place or the rings or bars of the fixator.

You should always elevate your limb should it become swollen and ensure the clips holding the dressings in place are not tight or digging into your skin. If your skin is touching the rings or bars of the fixator please inform the Limb Reconstruction Team.

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