57. Orthognathic Surgery and Surgical Distraction for Deformities
in Clefts of the Lip and Palate
- Chintamani Kale and Heemanshu Dave, the two orthodontists who contributed to the preceding chapter have continued to help in this chapter. Ashok Dabir, a senior maxillofacial surgeon in Mumbai figures in this chapter as a very important guide. Nitin Mokal, craniofacial plastic surgeon, who has been a contributor to these short notes in the past has also helped a great deal. The chapter has evolved after several joint meetings between them and the compiler of these short notes. The idea of these meetings was to distill what is germane to deformities of the jaw as related to patients with clefts from the vast literature on Orthognathic Surgery. It became apparent as the discussions progressed that the orthodontist acts like a physician to the maxillofacial surgeon.
- The word ‘ortho’ of Greek origin generally means straight, right, correct or proportionate as opposed to twisted or crooked. The word ‘gnathis’, also of Greek origin derives from the original ‘gnathos’ to mean the jaw. The restoration of the jaws to their rightful position and form by surgical methods is orthognathic surgery. The subject of the previous chapter, Orthodontics for patients with clefts dealt with restoration of dental alignment of the two jaws. In many instances the two specialities, orthodontic as well as orthognathic, overlap each other and therefore Orthognathic surgery is also called ‘dentofacial’ surgery. The nature of the alignment of the teeth and their location (please see Angle’s classification in the previous chapter) also depends on amongst other things the projection of the two jaws. As a general principle when orthodontic treatment is not enough to alter appearance and dental alignment, orthognathic surgery can help. In many instances orthodontic treatment is begun knowing in advance that some form of orthognathic surgery might be required later. In orthognathic surgery the jaws are moved after strategic cuts in ‘one go’. The jaws can also be moved slowly after these cuts by what is known as slow distraction.
- Orthodontic movement of teeth has possibilities and limitations both. In fact Profit and Ackerman, from the United States of America drew what is known as an “envelope” to generally narrate how much of the dental discrepancy can be treated by orthodontia, under what circumstances moulding and non-surgical distraction become necessary and when both are not feasible how maxillofacial surgery including surgical distraction becomes a necessity. The vertical and horizontal axis in the envelop represent ideal positions of the teeth (please see figures below). For example, backward movement of 7 mm and forward movement of 2 mm of the upper incisors is possible by orthodontic treatment alone. Similarly, its downward and upward movement possible by orthodontic treatment is 4 mm and 2 mm respectively. For the lower mandibular incisor, the backward movement is restricted to 3 mm and the forward movement to 5 mm. Similarly, the inferior movement possible is 4 mm and the upward movement a mere 2 mm (please see figures below).
- During the phase of development till about 18 years of age, when the jaws are more pliable pending final ossification, some forward movement of teeth and the jaw can be achieved by traction on the upper jaw without any surgical cut. Since the chapter deals with deformities involving clefts in the maxillary bone, and because in this condition the upper jaw is unable to grow normally both because of inherent deficiency and surgical treatment resulting in raw areas and scars, a contraption to pull the jaw forwards in a patient is shown below. The compliance for this treatment is often unsatisfactory and relapse is known because as soon as the forward displacement is achieved and the treatment is stopped, the maxilla may relapse somewhat to an unfavourable posterior position. In the mandible which is unaffected in its normal forward growth attempts can be made to restrict this growth to achieve a match with the maxilla which may never assume its normal forward growth. Also the mandible in order to achieve normal lip closure tends to rotate upwards resulting in an upward tilt of the symphyseal region. A maxillary appliance can be incorporated with a mandibular extension to reverse these two abnormalities as shown in the figures below.
All illustrations of orthodontic treatment courtesy Chintamani Kale, Orthodontist, Mumbai.
- When the discrepancy exceeds what has been narrated so far, surgical intervention is needed. It might be in the nature of surgical distraction following an osteotomy or a corticotomy or osteotomy followed by immediate surgical advancement. For this purpose, to gauge the mismatch between the maxillary and mandibular skeleton, fixed points are marked by way on a tracing of lateral cephalogram. These multiple points and the angles that they make will determine the nature of surgery. When seen altogether these figures appear like a Byzantine puzzle for a beginner or an average post-graduate student. They have been therefore for convenience of the reader marked four or five points at a time and then all together. Additional figures show the angles and their interpretations so that surgery can be planned.
The drawings of cephalometric analysis and their interpretation courtesy Heemanshu Dave, orthodontist, Mumbai.
- A survey of literature as well as major works on Orthognathic surgery reveal that pages devoted to surgery on deformities following clefts are less than two or three percent probably representing their smaller numbers. One reason could be that when such deformities were very common, sometimes even grotesque, orthagnathic surgery was in a stage of early development. On the other hand as clefts came to be treated with fewer raw areas following surgery and orthodontic treatment improved the incidence of major deformities may have fallen. It is generally accepted that both orthognathic slow distraction as well as orthognathic surgery with immediate movement of the bone, should be undertaken around 18 years of age when facial growth is complete. Only when the deformity is severe and has a functional element, for example difficulty in swallowing, chewing, breathing (sometimes mild sleep apnea) or when the deformity is so severe that it leads to psycho-social problems should these procedures be undertaken during the growing years, after advising the parents that the procedure might have to be repeated. Unlike orthognathic surgery of the facial skeleton in non-cleft patients deformities in patients with clefts have some special features.
a) The soft tissue envelope of the face may stretch with distraction or surgery but might shrink after the final orthodontic appliance to maintain the correction is removed.
b) At least part of the bony envelope, mostly mucoperiosteal, is inevitably scarred following repair of the cleft leading to difficulty in moving the bone.
c) Such scarring or repair might have compromised vascular environment of the bone which may compel a change of design from Le Forte 1 osteotomy to Le Forte 2 osteotomy (please see arrow in figures).
d) Fistulae between the oral and the nasal cavity might need import of tissue but even here a part of the cover or lining may have been borrowed from the local area leading to shortage
e) Alveolar bone grafting, a procedure with a fickle outcome, might mean that the maxillary segment might not be firmly united; not an ideal situation while moving the bone ‘en block’. Fresh bone grafting might have to be done at the time of surgery
f) And lastly the other features of the face which accompany a repaired cleft such as nasal deformity or hypoplasia on the affected side unless corrected will mar the final result and may have to be performed separately particularly because almost all orthognathic surgery is done with nasal intubation.
7. The modern orthognathic surgeon carries out a number of different surgical procedures for dento-facial deformities. There is little doubt however that the three most commonly used techniques are the Le Forte 1 maxillary osteotomy, the bilateral sagittal split ramus osteotomy of the mandible and the sliding genioplasty particularly in cases for deformities in patients with clefts. (see figures following para 10).
8. The history of orthognathic surgery began strangely when Obwegeser, a German plastic surgeon observed a sagittal fracture of the mandible in which the anterior fragment had displaced posteriorly on the medial side of the vertical ramus. A recent clinical case similar to what Obwegeser might have seen is presented below.
9. From then onwards, it was realized that both the maxilla as well as the mandible could be osteotomised at strategic points in order to achieve favourable displacement of the two osteotomised segments to achieve improvement of function, better dental occlusion and an improved appearance.
10. In clefts of the maxillary bone the commonest deformity that is encountered is a relatively posterior position of the maxilla due to inherent deficiency as well as the iatrogenic assault following surgery and subsequent scarring. A standard case of maxillary advancement is presented below. In the mandible this maxillary retrusion results in what is called a relative mandibular prognathism because it continues to grow unhindered compared to the maxilla and in fact it might rotate upwards naturally in order to occlude the maxillary dentition (Sometimes there is a true mandibular prognathism in addition to the maxillary retrognathism because the mandible growth is unimpeded due to a negative vertical overbite). In the mandible therefore, as opposed to the maxilla, surgery is undertaken to effect a setback so that it will match the maxilla which has already been moved forwards but not enough to match its mandibular counterpart (see figures).
The following illustrations show the steps of a bilateral sagittal split-osteotomy of the mandible.
A clinical series of a patient with a standard deformity in a case of unilateral cleft of the lip and palate with a retruded maxilla and a somewhat prominent mandible who required both, maxillary advancement and a mandibular setback is shown in the following figures.
All cases of orthognathic surgery courtesy Ashok Dabir, Oro-maxillofacial surgeon, Mumbai
- Surgical distraction involves an ostetomy or corticotomy in situ followed by application of an appliance which opens or widens slowly. It is usually accompanied by osteogenesis in the bony gap that forms slowly but simultaneously as distraction progresses, a principle that Ilizarov demonstrated in the long bones. Several examples of maxillary or mandibular distractions are illustrated below.
- However in exceptional circumstances when a maxillofacial deformity endangers life for example in Pierre Robin syndrome, after conservative treatment fails distraction of the short mandible remains the only viable option and can be undertaken even in small babies.
All case illustrations of post-surgical distraction courtesy Nitin Mokal, craniofacial and plastic surgeon, Mumbai.
Nisheet Agni, a maxillofacial surgeon from Mumbai, one of the reviewers of this chapter, adds the following:
Conventional Orthognathic surgery for management of cleft maxillary hypoplasia largely corrects the dental discrepancy (reverse overjet). However, it has a tendency to cause some deleterious effects on the speech of the patient. To avoid it recently a procedure termed as ANTERIOR MAXILLARY DISTRACTION is being done. The anterior maxillary segment is osteotomized and an intra-oral distraction device which is custom made using an orthodontic expansion screw is employed to distract the osteotomized segment and correct the reverse overjet. Like conventional Lefort I advancement, it also effectively corrects the dental discrepancy. Since it doesn’t move the posterior aspect of the maxilla and the soft palatal musculature it doesn’t cause any worsening of speech. In fact it does improve speech to an extent because it creates additional space for the tongue movements (please refer to the chapter, Cleft Palate and Speech).
This case was operated by Dr. Sunil Richardson, Maxillofacial Surgeon, Nagercoil, Tamil Nadu and was assisted by Nisheet Agni while he did a fellowship under Dr. Richardson.