Maxillomandibular advancement (MMA) is an alternative therapeutic option that is highly effective for treating obstructive sleep apnoea (OSA). MMA provides a solution for OSA patients that have difficulty accepting lifelong treatments with continuous positive airway pressure or mandibular advancement devices. The goal of this study was to investigate the different characteristics that determine OSA treatment success/failure after MMA. The apnoea–hypopnoea index (AHI) was used to determine the success or failure of OSA treatment after MMA. Sixty-two patients underwent MMA for moderate and severe OSA. A 71% success rate was observed with a mean AHI reduction of 69%. A statistically significant larger neck circumference was measured in patients with failed OSA treatments following MMA ( P = 0.008), and older patients had failed OSA treatments with MMA: 58 vs. 53 years respectively ( P = 0.037). Cephalometric analysis revealed no differences between successful and failed OSA treatment outcomes. There was no difference in maxillary and mandibular advancements between success and failed MMA-treated OSA patients. The complications most frequently reported following MMA were sensory disturbances in the inferior alveolar nerve (60%) and malocclusion (24%). The results suggest that age and neck girth may be important factors that could predict susceptibility to OSA treatment failures by MMA
Obstructive sleep apnoea (OSA) is a chronic sleep breathing disorder that is becoming a major problem in national and international healthcare. For example in the United States the prevalence of OSA in general population is estimated between 9–38% and is higher in men, in older patients, and in patients with high body mass index (BMI) . OSA severity is classified using the apnoea–hypopnoea index (AHI; events/hour), which is assessed using a polysomnography (mild OSA, AHI >5–15; moderate OSA, AHI >15–30; severe OSA, AHI >30). The present treatment guidelines may include a mandibular advancement device (MAD) and continuous positive airway pressure (CPAP) for treating patients with OSA . Maxillomandibular advancement (MMA) is an alternative therapeutic option that is highly effective for treating patients with OSA and is currently performed on a relatively small scale. Our first 10 patients were described in a report in 2013 . MMA provides a solution for OSA patients that have difficulty accepting lifelong treatments with CPAP or MAD. The combination of a Le Fort I osteotomy with a bilateral sagittal split osteotomy (BSSO) creates significant enlargement of the pharyngeal airway space . Therapeutic success is defined according to Sher et al. as postoperative AHI changes that decreased beyond 50% and <20 events/hour. MMA has demonstrated satisfactory reductions in mean AHI from 63.9 to 9.5 events/hour with a pooled surgical success rate of 86% and an OSA cure rate of 43% . However, whether MMA is a success depends on more than just a decrease in AHI. For physicians working in the field of OSA, MMA is regarded as a very invasive procedure and is therefore only indicated as a last resort.
Detailed information regarding the advantages of MMA procedures is available but not on the disadvantages and complications; it is therefore unknown which variables are of influence in patient selection and what complications and side effects should be considered for predicting success or predisposition to failure in relation to OSA therapy. This investigation aims to identify which variables could influence the rate of OSA treatment failure after MMA procedures. It seems that in approximately 10–20% of OSA cases treated with MMA that AHI was not successfully decreased after surgery . It is currently unknown which preoperative patient-related factors could be of importance in the selection of adequate patients for achieving OSA treatment success. Recently Zaghi et al. showed that the pre-operative severity of OSA was the most reliable predictor of outcome. More specifically, the most severe cases of OSA tend to benefit most after MMA in decreasing AHI, but the cure rate was only 20% among patients with a preoperative AHI of >90 events/hour. Patients with a preoperative AHI of <30 events/hour showed cure in 56% and thus showed a higher chance for success.
MMA is a routine procedure performed in many centres in patients without OSA. In those patients the most common complications and side effects are well known (e.g. sensory disturbances from the inferior alveolar nerve) and the risk for developing complications are discussed in detail with these patients to ensure adequate patient information briefing. Studies that present large cohorts of patients treated with MMA for OSA show detailed polysomnographic results and symptom relief measured by the Epworth Sleeping Scale (ESS) or the Functional Outcome Sleep Questionnaire (FOSQ), but are inadequate in providing data on side effects and complications after MMA . This lack of information makes evidence-based decision-making difficult in patients with OSA and it is relatively unclear what role MMA has in the guideline for OSA treatment.
The aims of this study were to identify factors that could predispose MMA failure in OSA patients and to present the findings of our centre’s experience regarding complications and assessments of factors that could elicit surgical failures in relation to MMA surgery. In order to identify factors that determine the success or failure of OSA patient treatment by MMA a detailed preoperative work-up including AHI, cephalometric analysis, physical examination including neck girth measurements, as well as postoperative information on AHI, complications and side effects were analysed.
Materials and methods
The data for this single-centre observational study was obtained from patients admitted between 2011 and 2015 for elective MMA therapy for moderate and severe OSA. The institutional medical ethics review board of the Academic Medical Centre of the University of Amsterdam reviewed the research proposal and study procedures and granted permission to collect data and questionnaires (Project no. W16_006). All participants registered in this investigation’s database received a detailed explanation of the study guidelines and procedures and written informed consent was obtained. This investigation was conducted in accordance with the principles established in the Declaration of Helsinki (Fortaleza, October 2013).
Patients with moderate or severe OSA referred to the Department of Oral & Maxillofacial Surgery of the Academic Medical Centre of the University of Amsterdam for elective MMA reconstruction procedures were eligible for participation in this study. Preoperative (baseline) patient data included gender, age, BMI (kg/m 2 ), neck circumference (cm), AHI, and comorbidities (e.g. diabetes mellitus, smoking) represented through ASA-score.
Preoperative (baseline) and postoperative cephalometric analysis was performed using skeletal landmarks that include the sella (S), nasion (N), A-point (A), B-point (B), and posterior airway space (PAS; distance between the base of the tongue and the posterior pharyngeal wall, derived from a line connecting B-point to gonion in millimetres). The following reference lines were placed on all cephalometric tracings to create descriptive linear measurements of interest, a constructed horizontal plane (S–N line, 7 ° ) and x -axis (vertical at S, perpendicular to constructed horizontal plane). Using points S, N, A, and B, the maxilla mandible and the skeletal relationship between maxilla and mandible was computed. SNA indicates whether or not the maxilla is normal, prognathic, or retrognathic. SNB assesses the mandible in a similar way (normal, prognathic, and retrognathic) and ANB defines the skeletal relationship as a class I (+2 degrees), class II (+4 degrees or more) or class III (0 or negative). The distance between points A and B was measured with respect to the x -axis (Ax and Bx) to assess the horizontal movement of the maxilla and the mandible. Similarly, the distance of points A and B to the constructed horizontal plane was measured (Ax′) to assess the vertical movement of the maxilla (see Fig. 1 ).
Standard polysomnographic evaluation pre- (baseline) and postoperative was based on electroencephalography, electro-oculography, chin and leg electromyography, and electrocardiography. Respiration was assessed through oronasal airflow, thoracic and abdominal movements (inductive plethysmography), and peripheral capillary oxygen saturation measurements (pulse oximetry). Polysomnographic variables were integrated into the AHI, because the scope of this article is on the technical considerations of the MMA.
Maxillomandibular advancement (MMA) procedure
A Le Fort I osteotomy and a BSSO was performed to advance the maxillary and mandibular facial skeleton. The maxilla was advanced to the preoperatively planned position (∼8–10 mm anteriorly) and an intermediate splint was installed to immobilize the advanced maxilla. After fixation of the maxilla with osteosynthesis, the mandible was repositioned using a final splint and fixated with osteosynthesis. Postoperatively, elastics were used for guiding the occlusion. Intra-operative information such as surgical time, admission time, and blood loss were recorded. Potential complications associated with the MMA procedure were assessed for each patient and included malocclusion, sensory disturbances of the IAN, symptomatic ostheosynthesis requiring hardware removal, and malunion of the maxilla or mandible.
Primary outcome was defined as surgical success or failure according to the criteria by Sher et al. for surgical treatment of OSA (AHI <20 and >50% reduction). Secondary outcomes were specific patient characteristics like age, gender, ASA score, BMI, neck circumference, and pre- and postoperative AHI and cephalometric variables.
All datasets were analysed with SPSS ® (IBM ® SPSS ® Statistics version 21, IBM Corp., Armonk, NY, USA). Descriptive statistics were assessed on normality and were analysed and expressed as median (interquartile range) or mean ± standard deviation. All presented variables were tested for their influence on postoperative surgical success or failure using the Fisher exact test for categorical variables and the Mann–Whitney U test for continuous variables. We describe associations between continuous variables using Spearman’s Rho correlation. Strength of correlation was categorized as either being absent (<0.20), poor (0.20–0.34), moderate (0.35–0.50) or strong (>0.50) . A P -value <0.05 was considered statistically significant.
Sixty-two consecutive patients (87% male) were treated with a MMA for OSA. Baseline characteristics showed a median age of 54 (47–61) years, BMI was 29 (27–33) kg/m 2 and median neck circumference was 43 (40–45) cm. Polysomnographic parameters showed a median AHI preoperative of 52 (36–67). Only 19 patients (31%) had a medical history coinciding with ASA I, 35 patients (57%) with ASA II, and eight patients (13%) with ASA III. The primary outcome formulated as surgical success or failure showed a 71% success rate in our population after MMA when applying the success formula according to Sher.
Secondary outcome was defined as a reduction of the AHI after MMA showed a 69% decrease in AHI in our patient population. A statistically significant difference between patient age and neck circumference was found when comparing success vs. failed therapeutic outcomes ( P = 0.037 and P = 0.008, respectively). There were no significant differences observed between gender, BMI, and ASA scores. A comparison of BMI separations of obesity (BMI >30) vs. non-obesity (BMI <30) showed no significant difference between the MMA success and failed outcomes. A reduction of AHI was higher in the obese patients 82% (49–90) than in the non-obese patients 73% (53–87). A summary of each parameter separated as successful and failed outcomes is presented in Table 1 .
|Age (years)||53 (43–60)||58 (52–62)||0.037|
|BMI||29 (27–33)||30 (28–33)||0.609|
|Neck circ. a (cm)||42 (40–44)||44 (43–48)||0.008|
|AHI preop||51 (35–67)||56 (37–74)||0.515|
|ODI preop||38 (26–52)||49 (26–65)||0.223|
|PAS preop (mm)||7 (5–10)||8 (6–10)||0.365|
|SNA preop (degrees)||81 (79–83)||80 (78–85)||0.739|
|SNB preop (degrees)||76 (73–78)||77 (73–82)||0.299|
|ANB preop (degrees)||5 (3–7)||4 (−1–7)||0.480|
The reoperative skeletal profile (ANB) was class I in 21 patients (34%), class II (retrognathism) in 34 patients (56%), and class III (prognathism) in six patients (10%). Baseline and postoperative differences in skeletal relationships represented by SNA, SNB, and ANB are shown in Table 2 . The advancement of the maxillomandibular complex sets the maxilla in a prognathic position, the mandible is within normal range, and the skeletal relationship between maxilla and mandible was retrognathic in most cases. The PAS showed a significant increase from the preoperative median of 7 (5–10) to 14 (11–17) postoperatively ( P < 0.001). In this population the median advancement of the maxilla was 7 (5–8) mm in the success cases and 8 (7–10) mm in the patients with failure in decrease of OSA. The mandible also had an advancement of a median 7 (5–10) mm in patients with success OSA decrease, the failure cases showed an advancement of 6 (4–6) mm. The advancement of the maxilla and mandible and the enlargement in PAS were not different when comparing therapeutic success cases with failures. Table 3 summarizes baseline and postoperative maxillary and mandibular skeletal dimensional relationships. Maxillary and mandibular advancement were not correlated with the decrease in AHI, −0.147 ( P = 0.265) and 0.117 ( P = 0.378) respectively. Only the enlargement of the PAS and the advancement of the mandible (B) were positively correlated 0.439 ( P < 0.001).