Hemifacial microsomia, also known as hemifacial shortening, first and second gill arch syndrome, is the most common congenital craniofacial malformation after cleft lip and palate, with an incidence of about 1/3500 to 1/5600 of births. hemifacial microsomia can involve multiple anatomical sites and vary in severity, manifesting as shortening of the affected face, weakness of subcutaneous soft tissues, chin deviation, facial nerve, transverse facial cleft and external ear deformity. The skeletal deformities are most common and important, including mandibular dysplasia, which is considered to be the key point leading to other craniomaxillofacial deformities. In severe cases, the maxilla, zygoma, zygomatic arch and craniotemporal bones may be involved.
Treatment of short hemifacial deformities is a systematic project. First, even after early treatment in childhood, deformities of varying degrees may remain in adulthood and require further correction. Secondly, patients who should have been treated early but have not undergone any treatment due to their conditions, the deformity of these patients is often more severe and requires staged surgery for reconstruction, and the third case is patients whose deformity is so mild that they need to wait until adulthood to undergo surgery. In the face of this group of patients, an individualized treatment plan needs to be designed according to the aforementioned principles of treatment for facial asymmetrical deformities. Here we talk with patients and their families about the treatment principles and specific treatment methods in different cases, hoping to provide some guidance.
Treatment of mild facial deformity
In this case, the facial asymmetry is mild, the affected side of the face is narrower than the opposite side, the chin is located in the middle of the face or slightly to the affected side, the occlusal relationship is normal, the jaw plane is basically horizontal, and there is no obvious deflection of the jaw movement when opening and closing the mouth.
In the choice of treatment plan, we mainly use the method of external contouring to reconstruct the contour. Commonly used methods include.
1, healthy side zygomatic bone osteotomy lowering, healthy side mandible outer plate removal.
2, the affected side of the zygomatic bone augmentation, the affected side of the mandibular plate bone graft or Medpor placement filling.
3, chin osteotomy, this kind of deformity as long as the proper treatment, the deformity can be significantly improved, not only can achieve the normal facial shape, and through the contour of the cosmetic method, even can reshape a more beautiful or handsome face.
Treatment of moderate facial deformity
It is manifested as the affected side of the upper and lower jaw bone dysplasia, both sides of the face is obviously asymmetric, accompanied by the occlusal surface tilt and chin obvious oblique, open and close the jaw to the affected side.
If the development of the mandible on the affected side is still acceptable and suitable for orthognathic surgery, Le Fort I osteotomy rotation of the maxilla, sagittal split osteotomy rotation of the mandible and chin osteotomy displacement can be used to correct the occlusal plane and straighten the facial median axis. The second stage then underwent further adjustment of the external contour in accordance with the treatment of mild facial deformity described above. In general, the affected side of the face is still narrow, and the width of the face can be adjusted by means of bone grafting or Medpor placement of the outer plate of the affected mandible. Soft tissue dysplasia on the affected side can also be corrected with autologous fat injections.
Treatment of severe facial deformities
In patients with severe occlusal plane inclination, it is often difficult to perform maxillary Le Fort I osteotomy and mandibular sagittal split osteotomy rotation to correct jaw plane deviation at the same time due to the restriction of the adjacent soft tissue retraction and poor development of the mandibular ascending branch on the affected side, and it is better to perform mandibular ascending branch and body retraction lengthening first to correct the mandibular deformity, and then perform maxillary Le Fort I osteotomy rotation descent in the second stage to correct the The affected side of the open jaw. The specific methods are described below.
The DO technique has been widely used in the field of craniomaxillofacial surgery since 1992, when foreign scholars first applied the Distration Osteogenesis (DO technique) to the mandibular lengthening of short hemifacial deformities. Compared with traditional orthognathic surgical techniques, the greatest advantage of the traction osteogenesis technique is that the bone traction process not only lengthens the dysplastic jaws, but most importantly, it also lengthens the surrounding soft tissues, including muscles, nerves, and blood vessels, which significantly improves the surgical results and is believed to reduce the recurrence rate after surgery.
One of the main problems after mandibular traction lengthening in adults is the post-traction occlusal relationship problem with severe mandibular deviation, and leveling the jaw plane and reconstructing a good occlusal relationship is the key to the surgery and directly affects the surgical result.
Based on the above mentioned problems, we propose a method to correct the severe jaw deflection deformity in adults by first-stage mandibular traction and second-stage orthognathic surgery.
Surgical indications.
Severe occlusal plane inclination and simultaneous treatment methods for the above-mentioned moderate deformity (Le Fort type I osteotomy of the maxilla and sagittal splitting of the ascending mandible) are more difficult. The main reason is that the soft tissues and muscles on the affected side are shortened longitudinally, and the mandibular rotation and descent is subject to soft tissue pulling and tension, so even if the osteotomy is completed, it is difficult for the maxilla and mandible to be positioned in the expected median position. Therefore, it is appropriate to install a mandibular lengthening device in the first stage to lengthen the mandible on the affected side, so that the skewed mandible can be gradually rotated back to the median position of the face, and then the maxillary osteotomy can be done in the second stage to level the occlusal plane. The important thing is that through mandibular lengthening, the skewed mouth angle can also be significantly improved, which cannot be achieved by other methods.
Surgical steps and procedure.
Pre-operative cranial X-rays were taken to understand the development of the affected mandible and mandibular joint and to measure the bilateral mandibular differences. Three-dimensional CT reconstruction was used, and the data were imported into special software for surgical simulation and design to determine the position of the osteotomy line, the direction of traction, and the length of the proposed traction.
1. Phase I surgery: extraoral approach with built-in retractor placement
The main advantages of the extra-oral approach are: (1) the design of the osteotomy line, the determination of the traction direction and the placement of the extender are more convenient. (2) Since it is not connected to the oral cavity, infection or chronic inflammation in the operative area is avoided and new bone formation is ensured. ③It allows longer retention of the lengthening device without affecting daily life and work, in order to increase the stability of the new bone.
Bone lengthening was started 7 days after surgery, and the lengthening rate was 1mm/day. After lengthening was completed, the lengthener was retained for about 6 months to ensure the maturation and stability of the new bone.
With the first-stage mandibular traction, the mandibular ascending branch and the surrounding shortened soft tissues were lengthened simultaneously, the mandibular jaw plane was adjusted from tilted to horizontal, and the angle of the affected side of the mouth dropped. At the same time, due to the descent of the mandible, a posterior open jaw was created on the affected side, providing space for the osteotomy of the maxilla to descend in the second stage.
2. Phase II surgery.
It was performed about 6 months after the phase I surgery. Preoperative X-ray and 3D CT were reviewed to observe the new bone formation. A dental model was taken and an occlusal guide was made. The classic maxillary Le Fort I osteotomy was used to rotate and lower the maxilla, close the posterior open jaw, place the occlusal guide, and perform temporary intermaxillary ligation and strong internal fixation of the maxilla using a small titanium plate.
In order to ensure bone healing after maxillary osteotomy, autologous iliac bone or mandibular bone outer plate can be transplanted into the post-osteotomy gap and fixed properly, whose main function is to bridge the broken end of the bone to ensure bone healing, maintain the stability of the maxillary osteotomy after descending, and increase the bone volume of the affected side of the maxilla to increase the fullness of the affected side.
The extension was also removed through the original extra-oral incision and the incision scar was repaired. If the chin remains skewed or poorly positioned, chin shaping will be performed at the same time to adjust it.
3.Three stage surgery. The remaining asymmetrical deformity will be adjusted after six months to further improve the facial contour and symmetry.
Pre- and post-operative frontal photos of severe hemifacial shortening deformity
Pre- and post-operative oblique position photos
Pre- and post-operative comparison of occlusal plane and crooked angle of mouth