Abstract
Obstructive sleep apnoea (OSA) is a serious condition that can be the cause of a number of systemic symptoms and conditions. The diagnosis of OSA is made by clinical and radiological examination, with polysomnography as the gold standard for recording the severity of the disorder. Among the many therapies offered for OSA, maxillomandibular advancement is recognized as a powerful technique for relieving upper airway obstruction. The upper airway may be further opened by an advancement genioplasty, but this may compromise facial aesthetics by over-projecting the chin prominence. To overcome this difficulty, a modified genioplasty is presented. This is designed to enable a rotational repositioning that allows for advancement of the genioglossus attachments but also avoids an excessive projection of pogonion, which would otherwise result in an unfavourable profile.
Obstructive sleep apnoea (OSA) has been reported to affect approximately 4% of men and 2% of women worldwide. It is the cause of a number systemic symptoms and conditions, including excessive daytime sleepiness, fatigue, depression, hypertension, and obesity. In childhood, OSA has been associated with failure to thrive and cardiovascular and neurobehavioural abnormalities.
The diagnosis of OSA is made by clinical and radiological examination, but polysomnography is regarded as the gold standard for the objective recording of data that defines the severity of the disorder. It also helps to identify if the obstruction is peripheral or central in nature. In most cases of upper airway obstruction, the retro-palatal (velopharynx) and retro-glossal (oropharynx) regions are the areas that are most commonly obstructed, causing repetitive apnoeic episodes, as there is narrowing of the upper airway spaces in patients with OSA.
Craniofacial abnormalities such as midfacial hypoplasia, mandibular retrognathia, and macroglossia are known to contribute to OSA. Surgical interventions such as maxillomandibular advancement in combination with chin advancement have been proven to be effective in the relief of upper airway obstruction. Procedures that anteriorly reposition the genial tubercles pull the attachments of the genioglossus and geniohyoid forward and hence increase the airway space by advancing the tongue base.
Various methods of genial advancement have been described in the literature. Advancement of the maxillomandibular complex is a powerful procedure for the relief of upper airway obstruction, and when combined with an advancement genioplasty, complete resolution or a major improvement of OSA may reasonably be anticipated. However, in achieving the maximum possible chin advancement, with or without a maxillary and/or mandibular advancement, it is not always possible to maintain good facial aesthetics, as further chin projection may be detrimental to good facial balance.
A modification to the routine genioplasty has been developed that overcomes this problem by modifying the pattern of osteotomy and the direction of repositioning. It is the purpose of this paper to present this novel technique to demonstrate its advantages.
Surgical technique
Following orthognathic procedures, an incision is made through the lower labial vestibular mucosa from canine to canine, approximately 1 cm from the mucogingival junction and continued down to bone. The anterior mandible is then degloved down to the lower border of the symphysis and just posterior to the region of the mental foramina.
Three vertical bony reference marks are made with a fissure burr, and a horizontal osteotomy finishing at least 6 mm anterior to the mental foramina is performed to avoid injury to the anterior loop of the neurovascular bundle before exiting the foramina ( Fig. 1 ). The height of the osteotomy must be planned to obtain the maximum lingual surface of muscle attachment for advancement yet avoiding potential damage to the apices of the adjacent anterior teeth. A reciprocating bone saw is then used for full thickness bilateral vertical osteotomies from the lower border and these connect to the horizontal osteotomy to mobilize the segment for repositioning.
The segment is then repositioned to the planned advancement to suit the profile with a clockwise rotation, thereby increasing the advancement of the genioglossus muscles ( Fig. 2 ). A 2-mm ‘X-shaped’ plate is adapted and four screws are used to stabilize the segment ( Fig. 3 ). The mentalis muscles are then reattached with 4–0 resorbable sutures and the wound closed with a 3–0 resorbable continuous horizontal mattress suture.
