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Craniofacial distraction osteogenesis is a technique to elongate the bones of the mandible, midface, and cranial vault. It is successful in treating a variety of conditions, including mandibular hypoplasia, midface hypoplasia, and craniosynostosis. This activity reviews the evaluation and treatment of craniofacial malformations and highlights the role of the interprofessional team in evaluating and treating this condition. Objectives: Summarize the physiology of normal craniofacial development and osteogenesis. Identify the various craniofacial abnormalities that serve as indications for craniofacial distraction osteogenesis. Describe the techniques and complications involved in craniofacial distraction osteogenesis. Outline how the importance of collaboration and coordination among the interprofessional team can enhance patient care when performing craniofacial distraction osteogenesis. Access free multiple choice questions on this topic.

Distraction osteogenesis describes the new growth of bone created by gradually separating two bony surfaces after an osteotomy. Initially described in the mandible in Germany in the 1930s, the technique takes advantage of the sequence of events during normal osteogenesis after any bony injury; the initial injury site initially develops a fibrous callus, which subsequently ossifies.[1] If the fracture is not immobilized, this ossification will not complete and a fibrous union results. While this is undesirable after an accidental fracture (the basis for casting or other rigid fixation after fractures), the intentional movement of an osteotomy along a controlled vector gradually stretches this fibrous callus, which is subsequently immobilized allowing ossification. The net result is a lengthening of the bone at the site of the osteotomy. This technique has become widely used for malformations of the cranial skeleton and is used to elongate the mandible, midface, and calvarium. The advantages of the approach are its creation of strong bone in a controlled manner, resistance to relapse, and adaptive changes of the soft tissue envelope. Craniofacial distraction osteogenesis has proven extremely successful in treating a variety of both non-syndromic and syndromic patients with craniofacial abnormalities, providing both a cosmetic and functional result that is superior when compared to other techniques.[2][3]

Complications From Distraction Osteogenesis Relapse: Some degree of relapse is likely to occur with any distraction osteogenesis, especially that of the mandible. However, overcorrection of 10 to 30% depending on the anatomic site will often account for the expected degree of relapse and yield a good clinical result. Device Failure: This is defined as occurring when the device itself breaks and is relatively uncommon. There are different rates published in the literature, and they are slightly different according to the location of distraction. The highest rates of device failure ar in mandibular distraction, but even then, they are near 1%. Device Extrusion: This is a rare complication where the device extrudes through the skin, migrating through the bone rather than moving the bone itself. This is a manifestation of orthodontic, rather than the desired orthopedic forces. The root cause is the impingement of the bony segments or other reasons that the bones cannot move freely in the desired vector. It is essential to test the mobility of the segments in relation to the osteotomy under direct, intraoperative, visualization to ensure they are free to move in the desired vector. Injury to Tooth Buds: This is principally encountered in mandibular distraction osteogenesis, though it can occur in the maxilla as well. This can be avoided with careful preoperative planning based on preoperative planning, careful placement of osteotomies as far (dentally) distally as possible, and avoidance can potentially be enhanced via 3D imaging and virtual surgical planning, allowing for optimization of the osteotomy site. Nerve Injury: The inferior alveolar nerve, branches of the facial nerve, as well as the supraorbital and infraorbital nerves, are at risk of injury depending on the approach used and the bone to be distracted. Care with the plane of dissection, as well as the location of the osteotomy, will help to avoid nerve injury. The technique described above will minimize the risk of inferior alveolar nerve injury during mandibular distraction. Permanent or severe injuries to the facial nerve are very rare, accounting for <1% of complications of all craniofacial distraction procedures.

Nerve Injury: The inferior alveolar nerve, branches of the facial nerve, as well as the supraorbital and infraorbital nerves, are at risk of injury depending on the approach used and the bone to be distracted. Care with the plane of dissection, as well as the location of the osteotomy, will help to avoid nerve injury. The technique described above will minimize the risk of inferior alveolar nerve injury during mandibular distraction. Permanent or severe injuries to the facial nerve are very rare, accounting for <1% of complications of all craniofacial distraction procedures. Malocclusion: Manipulation of the dentition-bearing bones inherently carries the risk of malocclusion. Even with the use of dental splints, the rate of symptomatic malocclusion is very high in patients undergoing maxillary advancement. Similarly, the future need for orthodontics is very high in patients who have undergone neonatal mandibular distraction. If the patient is to undergo either of these procedures, regardless of age, they should be counseled; they will very likely require orthodontia in the future. Additionally, occlusal complications such as open-bite deformity and temporomandibular joint symptoms may result from suboptimal distraction vectors. Serial radiographs during the active distraction phase help to identify this problem early, when combined with preoperative cephalometric planning. If the occlusal cant is disrupted, this can potentially be corrected if multi-vector, external distractor devices are used. Cerebrospinal Fluid (CSF) Leak: This is rare, though it can occur with either anterior or posterior cranial vault expansion. Often the leaks are small and can be managed conservatively, either by observation or with the placement of a lumbar drain. The risk of CSF leak is highest in anterior craniofacial (LeFort 2, 3, and monobloc) distraction, though it is reportedly lower than the 10% from standard, open, monobloc advancements. This carries the risk of meningitis also, which is as high as 10% in standard open techniques, and slightly lower when employing distraction techniques.[15] The risk of death is low (less than 10%), though it is significantly lower in monobloc advancement when utilizing distraction as opposed to traditional open techniques.[15]

Cerebrospinal Fluid (CSF) Leak: This is rare, though it can occur with either anterior or posterior cranial vault expansion. Often the leaks are small and can be managed conservatively, either by observation or with the placement of a lumbar drain. The risk of CSF leak is highest in anterior craniofacial (LeFort 2, 3, and monobloc) distraction, though it is reportedly lower than the 10% from standard, open, monobloc advancements. This carries the risk of meningitis also, which is as high as 10% in standard open techniques, and slightly lower when employing distraction techniques.[15] The risk of death is low (less than 10%), though it is significantly lower in monobloc advancement when utilizing distraction as opposed to traditional open techniques.[15] Scarring: The use of an irregular (sine-wave) or irregularly irregular (random) incision can minimize scar prominence. Incisions should be closed in layers, and electrocautery should be minimized at the scalp surface to avoid the death of hair follicles. Similarly, Rainey clips should be avoided to avoid pressure necrosis of the follicles at the incision edges. There may be some degree of tension present after the cranial vault is reconstructed, which can precipitate hypertrophic scarring. All techniques available should be employed to allow for tension-free closure of the scalp. If scar hypertrophy does occur, this can be treated later with serial excision of the scar. Additionally, particularly with the use of external devices in mandibular distraction, tension-related scars can be problematic between the proximal and distal percutaneous pins. The skin is often the least-forgiving tissue in such cases, and tension-related scars can develop towards the end of mandibular distraction that can be unsightly. Infection: This is minimized by the use of systemic antibiotics peri-operatively, and topical antibiotics to the incisions postoperatively. In high-risk operations such as LeFort 2, 3, or monobloc advancements, prophylactic postoperative antibiosis is indicated as the untreated meningitis rate approaches 10%. Ceftriaxone is commonly employed, as are other antibiotics that cover skin and hair flora but have good CSF penetration profiles.[2][16][17]

Patients with craniofacial malformations require workup and treatment by an interdisciplinary team that can include craniofacial surgeons, otolaryngologists, neurosurgeons, ophthalmologists, plastic and reconstructive surgeons, speech and language pathologists, clinical dietitians, dentists, orthodontists, geneticists, and social workers. When considering craniofacial distraction osteogenesis, preoperative workup by the interprofessional team is essential to delivering desired outcomes. Nutritional status should be optimized, and expectations of the patient and family must be managed. Preoperative assessment of the patient's occlusion, cranial shape, and position of the orbits should be performed. Preoperative photographs and imaging studies (including cephalometry, nasometry, high-resolution CT scans, and MRI scans, to name a few). The imaging required will vary depending on the individual patient. High-resolution 3-D computed tomography is especially helpful prior to surgery.[2] Postoperatively, patients will be admitted to the hospital for several days and may require a period of intensive care immediately postoperatively, particularly those who have undergone LeFort 3 or monobloc advancement, as they require neurologic monitoring and may have lumbar drains. Many mandibular distraction patients may remain intubated during the distraction phase, and a specific airway plan should be in place in case the endotracheal tube becomes dislodged. Nurses taking care of the patients should be made aware of the daily distraction schedule, and what potential complications may arise. They should pre-medicate the patient for pain relief before each distraction activation (often 1 to 2 times per day) and be aware of any local wound care needs for percutaneous devices. Appropriate physical, occupational, and speech therapy should be provided in the postoperative period. Creating a standardized postoperative pathway that involves the entire interprofessional team has been proven to improve patient outcomes.[20] [Level 3]