Limb Deformity Correction and Lengthening

Limb Lengthening

Limb Lengthening is a process by which a bone is surgically cut using a special technique whereby there is minimal damage to its blood supply and then progressively lengthened in a controlled fashion using a device called Fixator.

The Fixator is usually a Ring Fixator, also called Ilizarov Fixator, after the Russian Surgeon who invented the technique or a Rail like Fixator, commonly called Ortho Fix after the company who marketed it.

The Ilizarov Fixator consists of multiple rings and threaded rods connecting them and nuts and bolts for fastening. The rings usually go around the limb except in areas like the shoulder / hip where it goes only half way around. The Fixator is attached to the bone by means of pins about 6mm thick or by multiple thin wires. These are tensioned so that they act like tight springs and hold the bone in place while the lengthening is in progress and till the bone heals the gap.

What Conditions require Limb - Lengthening ?

• Birth defects leading to short limbs like Thigh Bone Deficiency (Proximal Focal Femoral Deficiency) or Leg Bone deficiency (Fibular / Tibial Hemimelia)
• Genetic Abnormalities like Achondroplasia , Hypochondroplasia etc.. which cause Dwarfism
• Familial Short Stature ( Called Stature Lengthening)
• Secondary to Bone Infection which lead to eating away of bone by the infection / formation of gaps with abnormal movement.
• To bridge a gap where there has been a bone loss due to injury, accident or tumour (a procedure called Bone Transport)

How much length can be gained by this procedure?

There has been lot of advertisement and some surgeons have achieved up to 100 % length of the bone lengthened. This is usually associated with some difficulty during the course of lengthening and healing of bone. Generally we can say that up to 40 % of length of the normal bone can be achieved, though anything more than 30% of a bone length is achieved at the cost of some degree of discomfort and complications.

How long has the fixator to be kept?

The fixator is required till the lengthened area matures and heals. This usually depends on the amount of lengthening to be achieved. Given that the bone is lengthened at a rate of 1 mm per day starting 7 days after surgery, this means that for a lengthening of 20 mm it will take 20 days. The area usually takes twice as long to mature (40 days). So that would mean a fixator would remain in place for 67 days. This proportionally increases with the amount lengthened and any additional difficulties encountered during lengthening.

What Difficulties are usually encountered?

There are many difficulties that are commonly seen. Most of them are minor and require some preventive and early intervention. Others are not so and may require some minor surgical procedures.

Pin Infection:

The most common irritation patients face is the infection along the wires where they enter the skin.

• This can be superficial and easily treated with wound dressing and pin cleaning. Sometimes these can spread to the bone, loosen the wire. Then the wire may require to be removed and re-inserted at a different place to keep the strong hold on the bone. This procedure can however, in most cases be performed under local anaesthesia.
• Nevertheless, this is something that can be avoided by careful adherence to pin-care as advised by the surgeon.

In sufficient bone formation during lengthening:

Usually this is a problem when long lengthening is done, or patient distracts the Fixator too fast for the bone to get bridged. This may cause slowing down of the lengthening for the bone growth to catch up. In some cases the bone may fail to catch and this may require a procedure under a short anaesthesia to apply some bone stimulants to that area.

Secondary Deformity or breakage at the Lengthening area:

This occurs after the lengthened area bends due to poor strength when compared to surrounding bone. This may require additional procedures like metal rod insertion into the bone to help it bear the body load. If there is a breakage at the lengthened area, it may also require bone grafting along with the metal rod insertion.