Dr. Axel Becker is a specialist in leg lengthening, a specialist in plastic, aesthetic and reconstructive surgery, a specialist in orthopedics and trauma surgery and carries out cosmetic leg lengthening in his special clinic in Freiburg. For this purpose – only here – a minimally invasive leg lengthening method BETZBONE®, developed by him and unique in the world, is used.

Read about which leg lengthening implants there were and are and get to know the differences between the various systems. And also what basic principles underlie callus distraction/leg extension.

Who actually came up with the idea that legs could be lengthened? Who invented the principle of leg extension?

The inventor of the basic principle of leg extension is Dr. Gavriil Abramovich Ilizarov 1921 – 1992. The surgeon and doctor working in the Russian Federation also invented the apparatus for lengthening limb bones. A device that today bears the name of the inventor. The “Ilizarov apparatus” is a type of external fixation device that was used in orthopedic surgery to lengthen or reshape damaged bones – arms and legs. For example, in the case of broken bones, bone deformations, accidents, etc.

What does the basic principle of leg extension, callus distraction, mean?

The surgeon and doctor discovered that a severed bone forms new pre-bones – called callus – between the severed bone ends. This is how the Ilizarov basic principle of callus distraction emerged.

Callus distraction explained clearly by Dr. med. A. Becker

“If you pull apart a severed bone or the two ends of the bone in a controlled manner, then it is not the case that there is always solid bone here, and it breaks many times every time you pull it apart. Rather, it is the case that the so-called callus is between the ends of the bone sits, which has a structure similar to what I call chewing gum. This (chewing gum-like) structure can be pulled apart at a certain defined speed.

What do you mean by a defined speed? With regard to the callus, this means: If you pull this structure apart too slowly, the structure may ossify again. If you pull the callus apart too quickly, there is a risk that the structure will tear. This can develop into a so-called pseudoarthrosis. A nonunion is a structure in which a bone cannot heal.

So if we use the Ilizarov principle as the basis for modern leg lengthening, this means the following: If legs are to be lengthened, we inevitably have to cut through bones – there is no other way. And we have to pull the two ends of the fracture apart at a defined speed.

WORTH KNOWING: From today’s perspective, the problem when it comes to leg lengthening is not the defined speed at which the ends of the bones are pulled apart. The problem is stabilizing this process. The two ends of the bone must be pulled apart evenly, must not shift, and the three-dimensional direction must be maintained under all circumstances. Otherwise there will be a misalignment, crooked legs, X-legs or O-legs. Of course, this must be prevented at all costs.

What options, techniques and systems are there for this?

Just continue reading in the next section.”

What systems and techniques are needed to lengthen the leg or to pull the callus apart in a defined manner?

Have you read the previous section? Great, then it is clear that the structure between the severed bones must be pulled apart in a controlled manner in order to lengthen the leg. This process requires systems that make it possible to control the speed of distraction (controlled pulling apart) and systems for leg extension that at the same time ensure a high level of stability while the callus is being pulled apart.

What callus distraction systems are there? What stabilization systems are there? What are the advantages and disadvantages?

Let’s talk about external fixators first: What is an external fixator? An external fixator is a device outside the body, such as outside the thigh. The fixator/ring fixator is a special construction with numerous wires, screws and threads that stabilize the bone. Characteristics of the external fixator: Numerous wires and splints pass through the surface of the skin, through soft tissue and through the bone to stabilize it.

This property is also the disadvantage of the external fixator or all external fixators because: All external systems always have a connection to the skin surface and to the bone. Therefore, the risk of germs and bacteria entering the body is always there. At the same time, external fixators are large, rigid devices that severely restrict movement.

What alternative to external fixators and external stabilization systems is there?

The alternative to external stabilization devices are internal stabilization systems, i.e. internal fixators for callus distraction. Internal systems are stabilizations that are not visible from the outside in the form of a nail system that prevents the bone ends from shifting. This nail system is inserted into the bone and stabilizes the bone.

Good to know: If the internal nail systems are only intended for stabilization, we speak of solid nails. If these nail systems have integrated the extension mechanism, we speak of so-called distraction intramedullary nails. In these so-called distraction nail systems, we differentiate between subgroups based on the mechanism of extension. We differentiate between purely mechanical nails, electric nails and magnetic systems.

What are purely mechanical leg lengthening nails?

Purely mechanical stabilization/extension nails are equipped with a “ratchet system”. Distraction/lengthening is achieved by pushing the nail apart. Talk about a thread in the extension system that is connected to a micro-ratchet system. In short, the lengthening of the bone occurs through limited rotation in a circular section. The name of the nail that first had this basic principle is the ALBIZZIA nail. After the production of the ALBIZZIA nail ceased, several other extension and stabilization systems for callus distraction were developed that follow this basic mechanical principle, namely the BETZONE and the GUICHET nail.

The ISKD nail is worth mentioning among the purely mechanical nails. However, this extension nail was withdrawn from the market because the control over the feed mechanism was poor.

Electric extension nails – this is how they work

Electric extension nails have a motor built inside the nail. This motor drives a threaded spindle that is controlled externally by an induction patch field. The patch field is implanted under the skin. An example of an electric nail in this group is the Fitbone.

Magnetic extension nails – this is how they work

Magnetic nails have a purely magnetic propulsion mechanism in the nail. This mechanism is operated and controlled via a remote module. An example of a magnetic nail is the Precice.

Monolateral fixators with solid intramedullary nails

LON is when a nail without an extension mechanism (solid intramedullary nail) is used in combination with an external fixator. LON is an English abbreviation for “Lengthenig over Nail”. In short: The solid nail is not a nail with an integrated distraction mechanism and is always used in combination with an external fixator. Otherwise no extension can take place

By the way: There are special videos on the function of internal fixators in our information library on the website.