Distraction Osteogenesis for Jaw Lengthening: What Patients Need to Know

The Three Phases of Distraction

Distraction osteogenesis proceeds through three distinct phases, each serving a critical role in the bone-forming process.

• Latency phase (5 to 7 days after surgery): The bone cut has been made and the distraction device is in place, but no movement occurs yet. This rest period allows an initial blood clot and early healing tissue to form at the osteotomy site.
• Active distraction phase (typically 2 to 4 weeks): The device is activated daily, usually by turning a screw or rod that separates the bone segments by approximately 0.5 to 1.0 millimeters per day. This slow, steady separation stimulates the body to produce new bone in the widening gap. The total duration depends on how much lengthening is needed.
• Consolidation phase (typically 8 to 12 weeks): Once the desired length is achieved, the distractor remains in place without further activation. During this phase, the new bone matures, mineralizes, and strengthens. The device is removed in a second, shorter surgical procedure once imaging confirms that the new bone is solid.

Congenital Conditions

• Hemifacial microsomia: A condition where one side of the jaw and face is underdeveloped. Distraction osteogenesis can lengthen the short side to improve symmetry.
• Pierre Robin sequence: A condition characterized by a very small lower jaw (micrognathia), a tongue that falls backward (glossoptosis), and airway obstruction. Mandibular distraction in infancy can move the jaw forward enough to open the airway and avoid tracheostomy.
• Treacher Collins syndrome: A genetic condition causing underdevelopment of the facial bones, including the lower jaw and cheekbones.
• Nager syndrome and other craniofacial syndromes: Various conditions that result in significant jaw and facial skeletal deficiency.

Acquired Conditions

• Jaw deficiency from trauma: Severe fractures or injuries that result in bone loss or growth disturbance, particularly in children whose jaws are still developing
• Post-tumor resection: After removal of a jaw tumor, distraction can regenerate bone in the defect without requiring a bone graft from another body site
• Obstructive sleep apnea: In select cases, mandibular distraction or maxillomandibular advancement through distraction can enlarge the airway in patients with severe sleep apnea who have not responded to other treatments
• TMJ ankylosis: Fusion of the jaw joint that restricts opening and jaw growth. After the fused joint is released, distraction can restore jaw length.

The Initial Surgery

The surgeon begins by making an incision to access the jawbone. For mandibular distraction, this is often done through an incision inside the mouth, though external devices may require a small skin incision. The distraction device is attached to the bone on either side of the planned cut using small screws or pins.

Once the device is securely positioned, the surgeon makes a precise cut through the bone (osteotomy) between the two attachment points. The cut goes completely through the bone but the device holds the segments in their original position. The incision is then closed with stitches.

The surgery typically takes 1 to 3 hours, depending on the complexity and whether one or both sides of the jaw are being treated. Most patients stay in the hospital for 1 to 3 days after the procedure.

Types of Distraction Devices

Two main categories of distraction devices are used, each with specific advantages.

• Internal (buried) devices: Placed entirely under the skin and activated through a small arm or screw that exits through the skin or mucosa. These are cosmetically favorable because they are hidden. They can only move bone in one direction (the direction the device is designed to move).
• External devices: Attached to the bone with pins that extend through the skin and connect to an external frame. These are more versatile because they can be adjusted in multiple directions during the distraction process. They are more visible but offer greater control over the direction and amount of bone movement.
• Curvilinear devices: A newer type of internal device that moves bone along a curved path rather than a straight line. These are useful for mandibular distraction because the natural shape of the jawbone is curved.

Daily Activation Process

After the latency period (5 to 7 days of no movement), the distraction phase begins. The device is turned once or twice daily, either by the patient (in older children and adults) or by a parent or caregiver (in younger children). Each turn advances the bone segments apart by a specific amount, typically 0.5 to 1.0 millimeters per day.

The activation process is usually quick, taking less than a minute. Some patients report a brief feeling of pressure or mild discomfort during the turn, but it is generally well tolerated. Your surgeon will provide detailed instructions and demonstrate the activation technique before you leave the hospital.

Recovering From the Initial Surgery

After the initial surgery, expect swelling and discomfort for 1 to 2 weeks. Pain medication is prescribed and is typically needed for the first 5 to 7 days. A soft or liquid diet is required initially, with gradual progression to softer solid foods as comfort allows.

• Swelling peaks around day 2 to 4 and gradually improves over 2 to 3 weeks
• Antibiotics are prescribed to prevent infection around the device pins or screws
• Keep the device activation arm and any skin exit sites clean as directed by your surgeon
• Attend all scheduled follow-up appointments during the distraction phase so the surgeon can monitor progress and adjust the treatment plan if needed

Consolidation Phase and Device Removal

Once the target length is achieved, the device stays in place during the consolidation phase (typically 8 to 12 weeks) while the new bone matures. During this time, the new bone transitions from soft, immature tissue to hard, mineralized bone. Your surgeon will use X-rays or CT scans to assess bone density before scheduling device removal.

Device removal is a shorter, less involved surgery than the initial placement. For internal devices, it typically requires a brief outpatient procedure under general anesthesia. Recovery from device removal is generally faster, with most patients resuming normal activities within a few days.

Long-Term Follow-Up

After device removal, ongoing follow-up is important to monitor the stability of the result. In growing children, the treated area may need additional intervention in the future as the jaw continues to develop. Orthodontic treatment is often needed before or after distraction to align the teeth and optimize the bite.

For patients who underwent distraction for airway obstruction, sleep studies and periodic assessments of breathing function help ensure the airway remains adequate as the child grows.

Insurance Coverage

When distraction osteogenesis is performed for a medically necessary reason, such as airway obstruction, a congenital defect, or post-trauma reconstruction, most medical insurance plans cover the procedure. Pre-authorization is typically required, and your surgeon's office can help coordinate the approval process.

For cases involving congenital craniofacial conditions, many states have mandates requiring insurance coverage for treatment. Check your state's regulations and your specific plan details. If you are underinsured, inquire about financial assistance programs at the hospital or surgical center.

Situations Where Distraction May Be Recommended

• An infant with Pierre Robin sequence or severe micrognathia whose airway is compromised and who faces a possible tracheostomy
• A child with hemifacial microsomia whose jaw asymmetry is worsening and affecting dental development or function
• A patient who needs more jaw advancement than conventional orthognathic surgery can safely achieve in a single procedure (typically more than 10 to 12 millimeters)
• A patient with jaw bone loss from tumor removal or trauma where a bone graft is not feasible or has failed
• An adult with severe obstructive sleep apnea related to jaw position who has not improved with CPAP or other treatments

Choosing the Right Surgeon

Distraction osteogenesis requires specialized training and experience. When evaluating surgeons, ask specifically about their training in this technique, how many distraction procedures they have performed, and their outcomes. The procedure is best performed by an oral and maxillofacial surgeon or craniofacial surgeon with specific experience in distraction osteogenesis.