Mohi El-Shazly, Consultant Orthopaedic Surgeon, Droitwich Knee Clinic
This is a relatively new and fast developing subspecialty of Orthopaedic and Trauma Surgery that encompasses a variety of procedures with the ultimate aim of helping improve the quality of life for patients with various complex and difficult lower limb problems, using often minimally invasive biological techniques of external fixation, quite often resulting in limb salvage. More commonly it provides the BIOLOGICAL solution to problems that would otherwise end up with joint replacement surgery at an early and relatively young age.
Below are a few examples of limb reconstruction procedures:
Some fractures refuse to heal for various reasons. In some cases, all that is needed is providing the correct biological environment for the fracture to heal. Modern techniques of external fixation provide such an environment with sufficient stability of the fracture at the same time allowing some micromotion which is now known to stimulate the fracture into healing. In more difficult cases, slow distraction techniques help stimulate the fracture to heal by what is called callus distraction. This is particularly useful for even more difficult cases with bone loss, where the defect can be made up by new bone formation at a different site. This is called bone transport. The beauty about modern external fixators is that we have full control over the position of the bone ends from the outside without resorting to repeated surgery. We can therefore stabilise, stimulate or lengthen the leg by stretching the callus.
Figure 1. Before Non-united fracture of upper tibia
Figure 2. During
Sheffield Ring Fixator& Physiostim applied
Figure 3. After
End of Treatment
Deformities may be congenital or acquired usually as a result of fractures in the past which have healed in a bad position. This may have a variety of implications, commonly causing damage to joints over the years and resulting in early arthritis due to the malalignment.
So what can be done?
Well, an external fixator is applied to the leg and using a minimally invasive approach, usually through a tiny incision, an osteotomy (surgical division of the bone) is performed very carefully preserving the soft tissue attachments and blood supply to the area. The deformity can then be gradually corrected at home by the patient by turning a screw or nut on the external fixator until x-ray measurements show that the deformity is fully corrected. Again in the process, the gap created fills with the patients own new bone formation, unlike other open techniques where bone grafting is frequently necessary.
What if I go too far with the corrections?
No problem, you can just as easily go back until the correction is as accurate as possible.
So what then?
The hinges on the fixator are locked and the fracture allowed to heal usually by being stimulated by the micromotion produced by weight-bearing, which is encouraged at a very early phase with these techniques.
Do you mean the patient can walk with the fixator on?
Of course, during the correction the patient is taught to walk with crutches taking minimal weight. Once the correction is complete, the patient is allowed to take increasing amounts of weight until full weight bearing long before full healing of the osteotomy. In fact this weight-bearing allied with the unique characteristics of the fixator stimulate healing of the fracture. Mobility in terms of joint motion and early weight-bearing is encouraged.
Is it very painful?
Some pain is inevitable in the immediate postoperative period. This is however easily controlled with simple pain-killers for a short period. Subsequently very little in the way of analgesia is required. When the fixator is near a joint, it can cause some restriction of movement, but this is largely overcome by encouragement of active exercises very early on.
Do I need another operation to have the fixator removed?
Not necessarily, this can often be done in the out-patients' clinic. No anaesthetic is required and the screws and wires are removed with little or no discomfort.
Sounds wonderful, any possible complications?
Yes. The most common problem is pin track infection. Of course it depends on the complexity of the case and how long the fixator remains in place. The vast majority of these are superficial which are treated either with simple pin-site care or with oral antibiotics for a few days. By and large this is regarded by most limb reconstruction surgeons and patients as an inevitable nuisance rather than a serious complication. It hardly ever leaves any residual problems.
So what is the alternative?
"Conventional" techniques of corrective osteotomy involve big open wounds, insertion of plates and screws or intramedullary nails and bone graft from the patient’s hip or a bone bank to fill gaps and encourage healing.
Some people are born with short limbs. Others develop shortening due to various abnormalities of their growth plates or after a serious fracture that has healed in a shortened position. Leg length discrepancy can cause problems with walking and eventually low back pain and spinal deformity.
So what can be done?
Modern techniques allow gradual stretching of the leg using either an external fixator or intramedullary nail (a special lengthening nail). Following the operation, the patient performs the lengthening himself at a very slow rate of 1 mm per day, until the desired length is achieved. Then the lengthened area is allowed to heal until it is fully consolidated.
So what fills the gap created by the lengthening?
The osteotomy is performed carefully preserving the soft-tissue attachment and blood supply to the area. This is then left for a week or ten days. During this period, fluffy new bone starts forming, this is called callus. At this stage, the lengthening starts and gradually stretches the callus. The stretching actually stimulates more bone formation. This is called callus distraction. Therefore the body forms its own bone without the need for bone grafting.
Wow! Sounds great, who invented this technique?
A Russian surgeon called Gavriel Ilizarov developed this technique using tensioned fine wire techniques and a circular external fixator. For many years in the fifties and sixties he worked in a little known centre in Kurgan, Siberia, where he developed and perfected his techniques. Later a number of Italian surgeons visited Kurgan and introduced these techniques to the west. A number of modern monolateral and circular fixators have been developed by Orthofix (Verona) and other companies. These are now widely used at the Droitwich Knee Clinic including the Sheffield Ring Fixator.
You mean there is more than one kind of external fixator?
In broad terms there are two kinds. Monolateral fixators for simpler corrections and circular fixators for more complex deformities.
This is one of the most difficult problems to tackle and can lead to chronic long-term disability, often ending in amputation, particularly if associated with a nonunited fracture. It is one situation when major open surgery is often required to eradicate the infection, take out any dead bone which would cause persistence of the infection. Once the infection is eradicated, one of the techniques described above can be used to fill the gap created by the excised bone e.g. bone transport.