Biomechanical Considerations for Distraction of the Monobloc, Le Fort III, and Le Fort I Segments:

Monobloc Differential Distraction Osteogenesis

ABSTRACT

Midface advancement at the monobloc level can be the seminal life event for patients with craniofacial dysostosis. Monobloc reconstruction, when planned appropriately, can simultaneously and definitively address multiple functional and aesthetic deficiencies in these patients. The application of distraction has reduced the morbidity experienced with traditional monobloc surgery. The purpose of this study is to report on the outcomes, stability, and growth in younger patients after monobloc advancement in syndromic craniosynostosis patients. The authors report a consecutive series of thirty patients with craniofacial dysostosis treated through monobloc differential distraction osteogenesis. Detailed history, photographic, and long-term radiographic data are reviewed, including a subset of patients who were skeletally immature at the time of their treatment. Differential distraction allows control of midface pitch, roll, and yaw, optimizing functional and aesthetic outcomes. There were no infectious complications requiring reoperation. The average surgical age for all patients was 12.5 years. For the 7 patients age <7 years, average age was 6 years. For all patients, the mean horizontal movement was 12 mm at nasion and 10 mm at A-point. At mean follow-up (4.8 years entire group and 6.2 years age <7 years group) a positive horizontal advancement of 1.1 mm at nasion and 0.8 mm at A-point was observed. More pronounced positive horizontal changes were seen in the age <7 years group. Monobloc differential distraction osteogenesis affords safe and precise repositioning of the midface. The advancement is skeletally stable and young patients show moderate continued growth.

An Unoperated Crouzon Family Treated with Monobloc Distraction: Challenges and Lessons

Crouzon syndrome (CS) is a rare form of craniosynostosis characterized by bicoronal craniosynostosis and facial features including severe midface hypoplasia, exophthalmos, and hypertelorism. Most patients are diagnosed and treated in early childhood; however, there are a few reports of Crouzon patients treated as adults with monobloc facial advancement. To our knowledge, this is the first report of a family affected by CS treated sequentially with monobloc facial advancement using combined internal and external distraction osteogenesis (rigid external distraction).

Craniosynostosis: Monobloc Distraction with Internal Device and Its Variant for Infants with Severe Syndromic Craniosynostosis

The introduction of distraction osteogenesis to frontofacial monobloc advancement has increased the safety of the procedure. One hundred forty-seven patients with syndromic craniosynostosis underwent frontofacial monobloc advancement using 4 internal distractors. Twenty-five were aged 18 months or less. Ten patients presented with a tracheostomy, 5 (50%) were decannulated after surgery, and 3 others (30%) required an additional intervention before decannulation. Six patients required the addition of a transfacial pin and external traction. Very early frontofacial monobloc with 4 internal distractors is a safe and effective treatment to protect the ophthalmic, neurologic, and respiratory functions in infants with severe syndromic craniosynostosis.

Cleft Lip and Palate: LeFort I Distraction with Halo and Hybrid Internal Maxillary Distractors

Distraction osteogenesis is a viable treatment option for patients with a cleft associated with severe maxillary retrusion. A rigid external distraction device and a hybrid internal maxillary distractor have been used to advance the maxilla allowing for predictable and stable results. These techniques can be applied by itself or as an adjunct to traditional orthognathic procedures. The technical aspects are presented. These procedures tend to be simpler and demonstrate great stability compared to traditional surgical methods. The reasons for stability are discussed.

Successful Treatment of Postoperative Mouth Opening Limitation Following Le Fort III Distraction with Bilateral Coronoidectomies

INTRODUCTION

Distraction osteogenesis is a powerful tool in craniomaxillofacial surgery, allowing for large advancements of osteotomized segments in the setting of a restrictive soft tissue envelope. Despite its benefits, distraction can have negative functional consequences. We present a case of a patient with Crouzon syndrome who developed reduced mouth opening capability after a Le Fort III midfacial advancement with rigid external distraction.

TECHNIQUE

Radiographic evaluation revealed that the coronoid process was restricting the normal excursion of the mandible by contacting the posterior zygoma. The patient was subsequently treated with a bilateral coronoidectomy via an intraoral approach, which improved his interincisal opening. Maximum interincisal distance was improved from 18 mm to 33 mm following bilateral cornoid resection.

CONCLUSION

We report coronoid impingement as a potential complication after Le Fort III distraction. Such a finding suggests the need for a detailed vector analysis in cases undergoing midface advancement with distraction. Post-distraction coronoidectomy is a useful surgical procedure to treat mouth opening limitation due to coronoid impingement against the zygoma after midfacial advancement.

Use of distraction osteogenesis in arrhinia

Nasal malformations such as hemiarrhinia and arrhinia have a very low incidence, although many treatment protocols have been described. In this article, we describe 2 surgical techniques to treat arrhinia depending on the age at the beginning of treatment. In our practice, we use Le Fort III osteotomy with distraction osteogenesis as a pillar of the reconstruction because it allows to improve anteroposterior and vertical projections of the midface, giving a proper platform for nasal reconstruction, decreasing the number of interventions. We report a patient with a hemiarrhinia who has completed appropriate reconstruction results and a patient with total arrhinia in whom the distraction was achieved to create a nasal bone support and improve midface projection.

Three-dimensional position changes of the midface following Le Fort III advancement in syndromic craniosynostosis

Little is known about the positional change of the Le Fort III segment following advancement. To study this, pre- and postoperative computed tomography scans of 18 craniosynosthosis patients were analyzed. The Le Fort III segment movement was measured by creating a reference coordinate system and by superpositioning the postoperative over the preoperative scan. On both the pre- and postoperative scans, four anatomical landmarks were marked: the most anterior point of the left and right foramen infraorbitale, the nasion, and the anterior nasal spine. A significant anterior movement of the four reference points was observed. No significant transversal differences were found. A significant difference between the anterior movement of the nasion and anterior nasal spine was found. In vertical dimension, there was a significant cranial movement of nasion in the study group. In addition, from all patients standardized lateral X-rays were viewed to determine the location and direction of force application that were linked to the outcomes of the three-dimensional movement of the nasion and anterior nasal spine (ANS) and the surgical technique. Conclusively, a significant advancement of the midface can be achieved with Le Fort III distraction osteogenesis in this specific patient group. Counterclockwise movement seemed to be the most dominant movement despite different modes of anchorage.