Distraction osteogenesis

Distraction osteogenesis
Specialty	{{#statements:P1995}}
ICD-9-CM	78.3, 84.53
MeSH	D019857

Distraction osteogenesis, also called callus distraction, callotasis, and osteodistraction, is a surgical process used to reconstruct skeletal deformities and lengthen the long bones of the body. A corticotomy is used to fracture the bone into two segments, and the two bone ends of the bone are gradually moved apart during the distraction phase, allowing new bone to form in the gap. When the desired or possible length is reached, a consolidation phase follows in which the bone is allowed to keep healing. Distraction osteogenesis has the benefit of simultaneously increasing bone length and the volume of surrounding soft tissues.

Although distraction technology has been used mainly in the field of orthopedics, early results in rats and humans indicated that the process can be applied to correct deformities of the jaw. These techniques are now extensively used by maxillofacial surgeons for the correction of micrognathia, midface, and fronto-orbital hypoplasia in patients with craniofacial deformities.

History

In 1905, Alessandro Codivilla introduced surgical practices for lengthening of the lower limbs. Early techniques had a high number of complications, particularly during healing, and often resulted in a failure to achieve the goal of the surgery.

In 1934, the New York Hospital For Joint Disease worked on an early method developed by Ilizarov. The major item that the US team of surgeons developed was the metal frame the leg was placed in to hold it perfectly in place until the cut made in the bone was healed over.

The breakthrough came with a technique introduced by Russian orthopedic surgeon Gavriil Ilizarov. Ilizarov developed a procedure based on the biology of the bone and on the ability of the surrounding soft-tissues to regenerate under tension; the technique involved an external fixator, the Ilizarov apparatus, structured as a modular ring. Although the types of complications remained the same (infection, the most common complication occurring particularly along the pin tracks, pain, nerve and soft tissue irritation) the Ilizarov technique reduced the frequency and severity of the complications. The Ilizarov technique made the surgery safer, and allowed the goal of lengthening the limb to be achieved.

Difficulties arising during distraction osteogenesis

Difficulties that may arise during distraction osteogenesis are commonly classified in medical scientific literature according to the standard introduced by professor Dror Paley in a 1990 article. Paley distinguished among problems (defined as "a difficulty that arises during the distraction or fixation period that is fully resolved by the end of the treatment period by non operative means"), obstacles, and complications.

Techniques

See also: Limb lengthening methods

Using exclusively an external fixator

The most common is the Ilizarov surgery with the Ilizarov external fixator. Other methods include Wagner, and Judet, and equipment such as the Taylor Spatial Frame and TrueLok Hex. Helong Bai (8th Hospital in Chongqing, China) developed the technique "Micro-wound" with a different apparatus.

Ilizarov surgery

Main article: Ilizarov apparatus

Gavriil Ilizarov (left) with one of his patients

Ilizarov surgery, developed by Gavriil Ilizarov, a Russian orthopedic surgeon, in 1951, is the oldest and most common method of distraction osteogenesis. It often brings complications, while some new methods have a much lower rate of complications.

The process involves the following:

• Shattered and devascularised bones are removed from the patient, leaving a gap;
• The healthy part of the upper bone is broken into two segments with an external saw;
• The leg is then fitted with the Ilizarov frame that pierces through the skin, muscles, and bone;
• Screws attached to the middle bone are turned 1 millimetre (mm) per day, so that new bone tissues that are formed in the growth zone are gradually pulled apart to increase the gap. (One millimetre has been found to be the optimal bone distraction rate. Lengthening too fast overstretches the soft tissues, resulting not only in pain, but also in the inability of the bone to fill up the gap; too slow, and the bone hardens before the full lengthening process is complete.)
• After the gap is closed, the patient continues to wear the frame until the new bone solidifies; the waiting period before the frame can be removed is usually one month per centimetre of lengthened bone.

Information graphic on distraction osteogenesis; shows the approximately 160-day process of limb lengthening using Ilizarov method, from the stage of evaluation, hospitalisation, lengthening, consolidation to the remobilisation.

Ilizarov surgery is extremely painful, uncomfortable, infection-prone, and often causes unsightly scars . Frames used to be made of stainless steel rings weighing up to 7 kilogram (kg), but newer models are made of carbon fiber reinforced plastic, which though lighter, are equally cumbersome.

Derivative devices provide physicians better control over the bone axis and angle during elongation, such as the Taylor Spatial Frame (TSF) which is computer assisted. The downside of these developments are their relative complexity and resulting longer learning curve.

For decades, the Ilizarov procedure was the best chance for shattered bones to be restored, and crooked ones straightened. Breakthroughs in distraction osteogenesis in the 1990s, however, have resulted in less painful (albeit more expensive) alternatives, such as unilateral rails.

Using exclusively an intramedullary nail

The techniques that use an intramedullary nail without an external fixator are: Albizzia, Bliskunov-Dragan, Guichet, Fitbone and ISKD.

The Guichet Method

Invented in 1987 by Jean-Marc Guichet, the Albizzia nail was created during his residency at the University Center (CHU) of Dijon, France. The Albizzia nail is inserted into the bone canal after it is calibrated with a reamer. The nail is then fixed to the ends of the bone fragments with screws. The nail consists of two sliding tubes that rotate in relation to the other, allowing for the nail to extend through a series of “clicks.” After insertion, the patient “clicks” the nail by turning the knee and leg (femoral nail) or foot (tibial nail) alternating inward and outward rotations to gradually lengthen. 15 clicks per day results in 1mm of gain. Expansions of up to 10 cm have been reported. The Albizzia nail is used in almost 30 countries and over 3,000 nails have been implanted.

In 2009, Guichet patented the Guichet Nail. The Guichet Nail is an improved version of the Albizzia nail because it uses stronger steel that allows for full weight bearing activity almost immediately after surgery. Furthermore, the Guichet Nail is customizable for size to ensure maximum comfort and efficiency for patients with smaller bones. Although there is initial pain after the surgery and during the clicks, the Guichet Nail is believed to be less painful than other methods as it is less invasive. Furthermore, as the patient controls the method of “clicking,” the patient is able to reduce pain by determining the most suitable method for themselves.

Intramedullary skeletal kinetic distractor

In 2001, the "Intramedullary skeletal kinetic distractor" (ISKD) was introduced, allowing lengthening to take place internally, thereby drastically reducing the risk of infections and scarring. The ISKD device was designed by J. Dean Cole of Orlando, Florida.

With ISKD, a telescopic rod that can be gradually extended by knee or ankle rotations is implanted into the bone. Lengthening is monitored by a hand-held external magnetic sensor that tracks the rotation of an internal magnet on a daily basis.

ISKD requires a physical leg movement to "click" the device into lengthening. In this method, there is no risk of accidentally over-stretching the bone due to the lengthener being preset to the desired fully extended length. However, there is a risk of growing the bone too quickly. Bone growth is monitored by measuring changes in the magnetic field of an embedded magnet in the system. The poles of the magnet change as the device grows. However, if the motion of the leg makes the device grow too quickly, and the magnet switches poles twice between measurements, then that growth is not recorded. This leads to overly rapid growth which can cause a number of issues such as nerve damage or causing breaks in the bone.

While there is some pain associated with the immediate post-op lengthening, the initial lengthening procedure is not to begin until one week after surgery. Furthermore, there is no noticeable "click" to the patient as there is less than nine degrees of rotation of the two bone segments in relation to one another.

Regularly used at a handful of medical centers mostly in the United States, only several dozens of ISKD devices are implanted each year. An improved version is currently being developed by its manufacturer (Orthofix).

Future technology

Due to shortcomings of current external and internal devices and the evident market potential of cosmetic limb elongation, a growing number of companies are researching potential intramedullary technologies. These include:

• Concepts based on electromagnetic actuation
• Concepts based on smart material integration
• Concepts based on manual actuation
• Concepts based on electronic actuation

Biotechnological advances, such as in stem cell research, may become the next generation standard of care for limb elongation once it matures.

Post-surgical care

Following the initial surgery, patients must undergo a demanding physiotherapy regime comprising stretching exercises and at times, they may be required to be hooked up to a "continuous passive motion" device. The purpose is to avoid stiffness and to stimulate the muscles, nerves and blood vessels to grow alongside the bone. Patients are often prescribed painkillers and are unable to work while undergoing rehabilitation.

Aspects in limb lengthening

Maxillofacial distraction osteogenesis

Correcting the majority of congenital craniofacial defects, as well as some facial injuries resulting from trauma, requires making bones longer. Distraction osteogenesis is an effective way to grow new bone, but it is much more difficult to accomplish in the face than in other areas of the body. Bones must often be moved in three dimensions, as opposed to just one, as in a limb, and scarring must be kept to a minimum. Researchers are attempting to improve the distraction devices used in the face. Until recently, the mechanisms were external and only operated along straight lines. Now, maxillofacial surgeons can use curvilinear devices capable of moving bone in three dimensions.

These new devices still need to be improved. They depend on patient caretakers reliably turning a screw. The next goal is to create devices that will move bone continuously, not in daily increments of 1 mm. These continuously moving devices would cause less pain, wouldn’t require daily patient compliance, and might promote faster bone growth. At the moment, researchers are testing a continuously moving device in animal models, and they have found that the device’s components are durable, that its user interface works, and that it is tolerated by the body. When the position sensor in the device is perfected, the device will be ready to use in people.

In distraction osteogenesis procedures involving the face, it is critical that bone movements be carefully planned before a device is implanted. No existing device is capable of changing its trajectory mid-course, and small skeletal changes lead to large changes in the structure of the face. Recently researchers have developed state-of-the-art software capable of simulating the entire process of distraction osteogenesis. The 3-D planning tool uses data from CT scans to create a segmented model of the patient’s skull, and it then calculates the vector of movement required to achieve desirable bone positioning. Outcome CT scans can be overlaid on the original model to assess the effectiveness of the procedure. In the future, researchers hope that the distraction devices used in maxillofacial procedures will continue to improve, along with the corresponding software.

General solid bone regeneration

Distraction osteogenesis
The periosteum appears just below the skin.
bone marrow
Identifiers
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

The most important aspects for the success of bone distraction are an intact medullary blood supply, preservation of soft-tissue envelope, primarily the periosteum (which helps preserve the blood supply) and secondarly bone marrow and the stability of the fixator.

Distraction rate

The distraction rate must be gradual, as a rapid rate of distraction will result in a fibrous union in which the bone pieces are joined by fibrous, rather than osseous tissue.

Too slow of a distraction rate would result in early bone consolidation. A common distraction rate for lower limbs is 1 millimeter per day.

Complications

In a 2004 study, lengthening with an exclusively intramedullary nail, Albizzia, had a "significant lower rate" of benign complications with respect to exclusively external methods (Judet, Orthofix, Ilizarov and Wagner fixators); however it had increased serious complications due to multiple general anesthesia.

Possible uses of distraction osteogenesis

Although distraction osteogenesis is most often used in the treatment of post-traumatic injuries, it is increasingly used to correct limb discrepancies caused by congenital conditions and old injuries. A list of the possible uses of distraction osteogenesis are as follows:

• Congenital deformities (birth defects):
  • Congenital short femur.
  • Fibular hemimelia (absence of the fibula, which is one of the two bones between the knee and the ankle).
  • Hemihypertrophy (a rare genetic condition in which growth is greater on one side of the body. This can be complete (everything from the bone to the skin on one entire half of the body) or partial (just one leg or arm).
  • Ollier's disease.
• Developmental deformities
  • Neurofibromatosis (a rare condition which causes overgrowth in one leg); and
  • Bow legs, resulting from rickets or secondary arthritis.
• Post-traumatic injuries
  • Growth plates fractures;
  • Malunion or non-union (when bones do not completely join, or join in a faulty position after a fracture);
  • Shortening and deformity; and
  • Bone defects.
• Infections and diseases
  • Osteomyelitis (a bone infection, usually caused by bacteria);
  • Septic arthritis (infections or bacterial arthritis); and
  • Poliomyelitis (a viral disease which may result in the atrophy of muscles, causing permanent deformity).
• After tumors
• Short stature
  • Achondroplasia (a form of dwarfism where arms and legs are very short, but torso is more normal in size); and
  • Constitutional short stature.

Cosmetic lengthening of limbs

See also: Anthropometric cosmetology

Generally, doctors tend to discourage cosmetic lengthening for people who want to add a couple of inches to their frames because such people are:

• breaking perfectly functional limbs;
• confining themselves unnecessarily to crutches or a wheelchair for over a year;
• voluntarily subjecting themselves to pain and discomfort;
• exposing themselves to unnecessary risk of infections, of damaged nerves and blood vessels, and fat embolism that can result in death; and
• incurring unnecessary expenses as the procedure is relatively expensive.

People insistent on doing the procedure, however, are required by some doctors to undergo a thorough body image assessment by a psychologist to help determine how far the person's quality of life has been affected by his perceived lack of height, and if doing the surgery will make a marked difference.

In popular culture

The protagonist of the movie Gattaca undergoes a limb lengthening procedure, along with other extreme methods, in order to impersonate another person and thus avoid genetic discrimination.

In Ian Fleming's James Bond novel Dr. No, Dr. No alludes to using leg-lengthing to increase his height to roughly 7 feet tall as part of a larger scheme to mask his identity.

See also

• Bone grafting
• Bone healing
• Fibrocartilage callus
• National Organization of Short Statured Adults (NOSSA)
• Nonunion
• Orthopedic surgery
• Tissue expansion
• Valgus deformity

Conference references

• Leonard B. Kaban, “Bone Lengthening by Distraction Osteogenesis,” CIMIT Forum, October 2, 2007

External links

• Distraction Osteogenesis information from Seattle Children's Hospital Craniofacial Center