Skeletal Stability of Patients Undergoing Maxillomandibular Advancement for Treatment of Obstructive Sleep Apnea

Orthognathic surgical procedures to advance the maxilla and mandible in patients with obstructive sleep apnea (OSA) are the same as those used for dentofacial deformities (DFD) in patients without upper airway obstruction. Long-term stability of skeletal movements has been studied after orthognathic surgery for DFD but there are few such reports after MMA, despite the importance of advancement magnitude as a predictor of success. The purpose of this study is to determine the long-term skeletal stability of maxillomandibular advancement (MMA) for OSA.  

This is a retrospective cohort study of adult patients evaluated for  OSA in the Department of Oral and Maxillofacial Surgery at Massachusetts General Hospital between 2003 and 2012.  Patients were included if they: had a diagnosis of OSA based on overnight polysomnogram; were treated by MMA and there was adequate radiographic documentation at least 11 months after operation.  Patients were excluded if they had any previous maxillofacial surgery. Predictor variables were the presence of OSA and treatment by MMA. Outcome variable was skeletal stability based on serial cephalometric tracings.

LeFort I and bilateral sagittal split osteotomies were carried out in standard fashion and rigidly fixed with Synthes plates and screws (Synthes CMF, Westchester PA).

Standardized digital lateral cephalograms on a Planmeca Dimax 2 Ceph (Planmecam Helsinki, Finland) at Time 0 (preoperative), Time 1 (immediate postoperative) and Time 2 (at least 11 months postoperative) were analyzed with Dolphin software (version 10.0 Premium) by a single examiner. Parameters examined were maxillary relationship to cranial base (SNA), mandibular relationship to cranial base (SNB and Mn Pl to SN), maxillomandibular relationship (ANB), maxillary length (ANS-PNS and Co-ANS), mandibular length (Co-Gn), and incisal relationship (overbite and overjet).

Bivariate statistics were computed to compare change in variables at T1 and T2 time points. Parametric methods were used to evaluate the changes of cephalometric parameters at T2 (paired t test).   Correlation between length of follow up and amount of advancement with change of cephalometric variables between T1 and T2 were analyzed by Pearson's correlation. For all analyses, p< .05 was considered statistically significant.

There were 120 patients evaluated and 25 patients (M:F; 17:8) met  inclusion criteria. Maxillary fixation was achieved with miniplates;the mandible was fixed with bicortical screws (n=2) and/or miniplates (n=5 ). Eleven patients had preoperative orthodontic treatment. Mean follow up was 27.84 ± 19.96 months (range, 11-85 months).  No patients were bone grafted. Mean  maxillary advancement measured at upper incisor tip and A point was 9.26 ± 3.06 mm and 9.48 ± 3.02 mm respectively; mean mandibular advancement calculated at lower incisor tip was 10.85 ± 2.36 mm.

At T2, mean SNA and ANB decreased significantly;the other mean cephalometric variables did not change significantly in whole sample analysis compared to T1.  Subgroup analysis failed to demonstrate differences in stability between patients who had and those who did not have orthodontic treatment. There was no relationship between the follow up period and change in cephalometric parameters.  No patients developed a malocclusion.

The results from this study indicate that despite statistically significant cephalometric changes between T1 and T2 possibly due to maxillary relapse, the mean difference was ≤1 degree and no patients developed a malocclusion. Large advancement of the maxillomandibular complex for treatment OSA remains stable at greater than 2 years follow up and preoperative orthodontic treatment does not appear to influence skeletal stability.

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Holty JE, Guilleminault C: Maxillomandibular advancement for the treatment of obstructive sleep apnea: a systematic review and meta-analysis. Sleep Med Rev 14:287, 2010