Distraction Osteogenesis (callus distraction, callotasis, osteodistraction) is a surgical procedure in which the bones of the jaws are gradually lengthened by daily use of an internal distractor device. This procedure would allow for the soft tissue to grow gradually with the bone as a unit. Patients with birth malformations and growth deformities of the head and neck region causing abnormal growth of the jaws and face are good candidates for Distraction Osteogenesis. This procedure is preformed to correct a functional abnormality and aesthetic deformities as well.
Distraction Osteogenesis (D.O.) is indicated in cases where there is a large distances of bone lengthening required (more than 8-10 millimeters), there is limitations with the surrounding muscle and skin due to scar tissues or malformation in infants and children. This great distance of movement in an instance would create instability and relapse of the bone if performed in one setting.
Children with small growth of the lower jaw (Mandibular Retrognathia) as in Pierre Robin Sequence (cleft palate, small lower jaw and retruded position of the tongue), and small growth of the upper jaw (Maxillary Hypoplasia) as in patients with cleft lip & palate, are one the most common causes implicated in obstructive sleep apnea in children with congenital birth deformity. These malformations that effect the jaw will place the tongue in a returded position. As a consequence of these facial malformations, patients would have difficulties with proper air exchange, inability to feed which will lead to Obstructive Sleep Apnea (OSA), Gastroesophogeal Reflux Disease (GERD) along with growth and brain developmental abnormalities.
In adults long standing Dentofacial deformities such as Tempromandibular Joint (TMJ) Dysfunction or abnormal growth of the jaws which require them to undergo corrective jaw surgery for large type of movements will make them a good candidate for D.O. as well.
The procedure is performed in a hospital setting under general anesthesia. Depending if one or two jaw surgery is performed, the length of surgery could be anywhere between two to four hours. Usually there is one to three nights of hospital stay for observation. In cases where there is a severe sleep apnea associated with other medical conditions patients are require to stay longer.
The Distraction Osteogenesis technique involves creating a surgical cut in the bones close to area being lengthened. Then a device is applied to the jaw which separates the bony edges gradually and creates an area in which the new bone and soft tissues are generated. Once a seven day healing has passed after the surgery (1 to 7 days depending on the site and age of the patient), then the distraction device is activated by turning a key four times a day (by the patient, parent or doctor) until the desired bone lengthening is achieved. The distraction device is left in place without activation for period of 8 to 10 weeks (normally 6 to 8 weeks depending on the site and the length of distraction) in order to stabilize and harden the new bone segments before removal. This would also lengthen the soft tissue or scar that would other wise cause a relapse of the surgical movement in a standard corrective jaw surgery. The device used in our practice are internal and do not create a cosmetic or social issues for our patients.
Advantage of D.O. over one time large surgical movements is that D.O. appears to have a decreased potential for relapse, less damage to the underlying nerves especially with large movements, no need for bone grafting, widening of the lower jaw which is difficult with routine surgical expansion and three dimensional vector changes during the therapy.
No absolute contraindications to treatment exist. However, there are some relative contraindications such as; there must be adequate bone bulk in the area of surgery, less ideal results in older patients due to decreased number of cells.
Complications include inflammation at the area where the device is placed, temporary joint discomfort and numbness of the chin and lips which all are usually temporary. Patients could experience a mild to moderate amount of pain when the device is activated daily, which could be controlled adequately by over the counter pain medications.
In our practice we prefer to perform internal D.O. in patients with congenital birth defects or acquired Dentofacial deformities that require longer than usual movements. Please refer to the posted Power Point presentation for further information on the science and technology of this technique presented at the International Society for Craniofacial Surgery.