Types

Types

An external fixator is a frame outside the body that fixes the pins a screws inside the body in place.

There are three different external fixators:

  • Unilateral
  • V-Shape
  • Circular
Unilateral External Fixators

Unilateral External Fixators

Unilateral external fixators

A unilateral external fixator goes on the side of the limb. They are set on the outer side of the thigh or the inner side of the leg.

Trademarked names of the devices we currently use are: Orthofix®, Heidelber®, Judet®, Wagner®, and FSA®.

Large screws connect the unilateral fixator to the bone.

 

 

 

V-Shape Fixators

V-Shape Fixators

 

Circular External Fixators

Circular external fixators stabilise bone fragments better than unilateral external fixators.

They use small wires and pins to allow for better stability, but they are much more uncomfortable than unilateral fixators. Because of this, most patients opt for the unilateral choice.

The inventor of the external fixator, Ilizarov, modeled his creation on the bicycle wheel. The fixator, much like the wheel, keeps its strength by having multiple wires connect up to the centre. This makes the wheel both lighter and stronger.

 

 

 

Circular External Fixators

Circular External Fixators

Choice of External Fixator

An external fixator is chosen based on the following criteria:

 

  • How complex the case is. If the patient is undergoing multiple corrections, the circular fixator is the best option.
  • Which bone is being lengthened. Unilateral fixators are best for the femur. Any kind of fixator can be used for the tibia.
  • The surgeon’s personal choice.

 

 

 


possible-corrections

Possible corrections

External fixators can correct any kind of deformation in principle.

However, some deformations are just too complex to fix by lengthening a single bone.

A foot deformity is particularly difficult, since the foot contains so many bones. Each bone must be corrected one by one for the treatment to work. External fixators cannot correct an entire foot deformation at once as that would require holding 11 bones at once.

We get around this by correcting the most important bone first, followed by the less important bones afterwards. Longer bones can be corrected and lengthened at the same time. Corrections can happen gradually, after the operation. In some cases preoperative correction is also possible.

Constraints and Follow-Up

Pins wires and screws are used to hold external fixators in place. These components pass through the soft tissue to connect the “dirty” environment to the sterile environment. This makes infection very likely. To reduce the likelihood of infection, the patient must visit the surgeon on a weekly basis after the operation. These visits can become less frequent over time.

Patients are advised to keep their fixators clean by avoiding contaminants such as dust and bathing regularly. Fixators do not rust, and so can be washed in water with ease.

Adjustments have to be made to the nuts on the lengthening device every day by the patient. Four adjustments per day can create a single mm of correction. Adjustments do not usually cause the patient any pain, though there are often psychological side effects of wearing the frame. However, these disappear over time.

Complications

There are numerous complications that could arise when patients use external fixators. These arise because the fixator needs to be kept in place as long as possible, to help with the lengthening, but it has to be taken off as soon as possible to avoid serious infection.

Here is a list of some of the complications patients can see:

Infections

Infections are the complication that is most common. The areas around the pins, wires and screws are most prone to infection. Antibiotics can treat infections in this area quite well. It has been said by some surgeons that there is no way to avoid infections at all when using an external fixator.

Joint stiffness

The pins do not allow for free and easy soft tissue movement. This often results in a decrease in joint mobility, especially when a fixator is worn for several months. Once the fixator is removed, normal motion should return to the joint over time.

Axis deviations

External fixators generate a large force with their level arms. This makes accurate bone positioning difficult to control. When the fixator is removed, the bone will be soft and therefore prone to remodelling. This can lead to deformation. Sometimes the soft bone curbs, which creates more deformation. The best way to combat this complication is for the patient to wear a cast for a period after the operation.

Fractures

It is very rare that external fixators will cause fractures. They happen in around 1 in 10 cases. Once again, wearing a cast after the removal of the fixator is the best way to avoid this.

Osteopenia/osteoporosis

Osteopenia, meaning low bone mass, or osteoporosis, meaning brittle bones, will happen in nearly every case. Once the fixator is removed, this should resolve itself.

The Ilizarov Institute in Russia has found that calcium levels in the body are 100gm lower during these procedures. To counterbalance this, additional calcium and vitamin D should be taken by all patients.

Nerve and vascular lesions

If a patient is injured during surgery, lesions can be caused. Though this rarely happens, lengthening is stopped when it does until the patient has fully recovered. This can take up to 9 months.

Stage treatment

Lengthening

There are four phases in the lengthening procedure:

 

  • Distraction
  • Fixation and dynamization
  • Fixator removal and casting
  • Cast removal

 

The length of distraction depends on how much length is requested. Most patients grow at 1mm per day. This means distraction lasts for 2 months if a patient wants to achieve 6cm. Patients can walk whilst wearing their fixators during this phase but it will be extremely uncomfortable, so barely any patients actually do it.

The fixation period involves no adjustments being made to the fixator. The duration of this period depends on the required gain one again. For 6 cm of gain, the fixation period must last for 6 months. Walking is more feasible in this stage as the body adapts to its new length.

In dynamization, bolts on the fixators are released. This activates muscles and loads the bone. The bone actually loads itself at this point through its own healing powers. This stage takes around 1 month. Some devices mean this stage can be skipped over.

Casts need to be kept on for at least one month. Sports cannot be played during this time, as it is not worth the risk of fracture.

To gain 8-10cm, an external fixator must be worn for a total of 10-18 months.

Gradual correction of a single axis malalignement

Gradual correction has 4 phases:

 

  • Fixation for bone healing
  • Dynamization
  • Removal

 

This whole process takes around a month. If correction happens before the operation, there is no need for an external fixator.

Fixation can take 3 months. This is the typical length of time it takes to fix a bone fracture. Dynamization usually happens before the fixator is removed.

Psychological aspect

Preoperative phase

Psychological, familial, and social support : deciding on surgery and its subsequent implications.

Considering all of the implications of going through lengthening is very important. This includes not just physical, but psychological effects.

Patients should consider their work situation before they start the one year lengthening process.

Many of our procedures require psychological consultation from a professional before they can be carried out. Patients must discuss the reasons they want the procedure, and the risks it might have.

If a patient wants to solve domestic, professional or interpersonal problems through limb lengthening, they are informed that this is not what they should be doing. A gain of 4-6cm to a limb will not solve any of their issues, and therapy is a better alternative.

Surgery timing will be arranged around the engagements of the patient.

Surgery is not advised for young children who are pushed into surgery by their parents while they are still growing (before age 16). If the parents wait for their child to turn 16, they will see much better results when they bring their child in for surgery.

Patients aged 35-40 needs special monitoring by a team of professionals.

Patients should meet and greet other people who have already gone through the surgery. This will give them a support network of people who know what they are going through. Seeing photos or real life people wearing external fixators will help mentally prepare the patients for the surgery.

Decisions to have surgery should always take place over time, and be considered carefully. Children must take active parts in decision making since their own personal body image is affected by the surgery. In cases of bilateral lengthening, and other cases, we will provide psychological support for children.

Postoperative period

Children will certainly not like the idea of wearing an external fixator. They are ugly and cumbersome. for some patients the sheer shock of wearing a fixator is actually the worst part of the whole process. One way of dealing with this issue is simply hiding the fixator from the child by covering it with, say, a blanket. This can really help.

Strong family support is needed for children. Who will often be very distressed. Parents should think about the long term factors.

Children should not be isolated after the surgery. They should be encouraged to continue friendships and activities they enjoy.

Parents’ concerns

Parents of children with every kind of deformity may wish to transform their child into an idealised version of themselves. This idealisation has dire consequences for the child. Parents should avoid this and accept the children for who they are. Fixing deformations, or making a short child taller will not make the child “normal”. Elements of dwarfism will always be present in children with dwarfism. Surgery cannot get rid of those. All it can do is change the child’s height, ever so slightly. In many cases, it would be better for the parents to seek psychological help for themselves, instead of forcing their child to have an operation.

Possible complications

There are always possible complications with this surgery. Sure, the statistics may be low, but if you experience a complication, statistics don’t mean anything to you. Patients have to accept this risk before they have surgery.

Children are unable to anticipate these complications. Parents should make sure they are not being overly protective, though.

Parents and surgeons should talk a lot. These discussions will help the process. No one would buy a car without talking to the car salesman first. Why should surgery be any different?