Cosmetic limb lengthening is a relatively straightforward procedure with a relatively low complication rate comparing to some other orthopaedic procedures including limb lengthening for leg length discrepancy following trauma.

In general, we can divide the complications into three different categories:

        a. Implant related

        b. Surgery related

        c. Patient related

Implant related complications highly depend on the type of implants/devices used to increase the length of the bone. It is widely accepted that motorised nails (Fitbone and Precice) are related to lower complication rates comparing to mechanical nails (ISKD, Alizzia). This is mainly due to the control we can exert over the nail - when to start and when to stop lengthening. Motorised nails need external power (electric or magnet) to increase the nail length and when the power is removed the nail will remain static. In some mechanical nails a certain rotation is required to trigger the mechanism for the nail to grow. In certain cases, the trigger can be very small, and the nail will continue growing out of control. Without intervention the leg length can be increased beyond the body’s capabilities causing irreversible damage to the muscles, tendons and nerves resulting in a significant impact on the leg’s function.

Probably one of the most dramatic complications is the breakage of the nail (Picture 1).

Rare, but it does happen. It is usually not a detrimental complication for the limb lengthening process but if not managed correctly it can quickly get out of control resulting in shortening of the leg and/or deformity with potential non-union of the leg. In any case additional surgery is required but it depends what kind of surgery and how it is delivered. As always certain skills are required for a smooth procedure.

A quite often but not so detrimental complication related to limb lengthening is a screw backing out. Because of the force exerted on a screw/peg, the screw/peg will start moving and if the direction of the screw is in line with the forces of the nail, the screw is more likely to come out. If the screw/peg comes out of the nail completely the whole construct will collapse resulting in leg shortening. In the case that we only have one screw/peg we have to reinsert it and if there is a tendency for the screw to come out again, we would need to prevent the backing out with a plate, which can be secured on the top of the screw. Early and appropriate intervention is the key.

Surgery related complications are relatively low. For example, if the corticotomy is not completed (when the bone is not broken) the nail will not be able to pull the bone ends apart, hence there will be no increase in the length of the bone. Usually, the only solution is to re-break the bone if the patient still wants to continue with lengthening. Without it the bone will heal the break so quickly, that we will not be able to pull it apart.

During the surgery the nerves and vessels, muscles and tendons can be damaged. In case of major vessel injury additional surgery is required to repair the damaged vessel. If the nerves are damaged the problems will only be spotted after the surgery and would also require additional surgery to minimise the damage. The same applies to the muscles and tendons. Ideally all of these structures should be protected during the procedure with a metal instrument.

As the femur (thigh bone) is not straight, when some of the nails are straight it is crucial that this fact is included in the preop planning as if we try to get a straight nail into a curved canal, the nail will either have to deform or come out of the bone. Even before that, the reamers which are used for the canal preparation for the insertion of the nail can come close to perforating or actually perforate the bone, leaving a weakened bone which can easily fail after nail insertion and the beginning of the lengthening process. The main factor to prevent this is to choose the correct length nail and the correct nail entry point to compensate for the deformity.

Any surgical intervention carries a risk of infection. As cosmetic limb lengthening is done in healthy people the risk is again quite low. What is extremely important if there is an infection after the surgery, is that it is dealt with in a timely manner and even more importantly in a correct way. There is no universal plan for what to do with an infection, but the surgeon’s experience with dealing with infection is crucial.

It would be quite unusual for a patient not to be compliant with instructions post-surgery but in the event that, for example, the lengthening is not commenced in the prescribed period the bone gap will heal and will not allow the nail to move the ends apart and a new surgery will be required. Earlier than allowed weight-bearing can certainly negatively impact the nail which is not designed to be weight-bearing causing pain, stiffness and potential construct failure. One can argue that loads on a nail during physiotherapy are the same or more or less the same as during walking. However, not many people can perform 1000 repetitions of straight leg raises in a day, whilst 1000 steps are a far easier and more achievable target. On the other hand, if people do not exercise during the lengthening period the joint around the bone which is getting lengthened will get stiffer with a possibility that the changes can become permanent if not reacted upon. A higher speed of lengthening than normal will usually result in no new bone formation which will then require reverting of the lengthening, compressing the gap and starting again. Whilst some surgeons like to advertise “fast lengthening”, the success of this is only related to the response of the patient to it and cannot be predicted. We know that 1/3 of patients will heal a defect of a thigh bone regardless of our action but we have no way of knowing who that person is going to be prior or during the surgery.

As in any other field of work, it is crucial to get the right people for the right job.

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