What is the Maxillomandibular Advancement (MMA) procedure?

What is the Maxillomandibular Advancement (MMA) Procedure?

MMA is a major orthognathic surgical procedure that simultaneously advances both the maxilla (upper jaw) and mandible (lower jaw) forward by 10-15mm through bilateral sagittal split ramus osteotomies and Le Fort I osteotomy, both with rigid internal fixation, primarily used to treat obstructive sleep apnea by physically expanding the upper airway skeletal framework. 1

Surgical Technique

The classical MMA procedure consists of two main components 1:

• Le Fort I osteotomy with rigid internal fixation - cuts and advances the maxilla (upper jaw) forward
• Bilateral sagittal split ramus osteotomies with rigid internal fixation - cuts and advances the mandible (lower jaw) forward
• Advancement distance: 10-15mm is necessary when there is no pre-existing maxillomandibular abnormality; more pronounced advancement is required if skeletal abnormalities exist 1

Surgical Variations

Some surgeons use a staged approach 1:

• Phase I: Pharyngoplasty with or without hyoid myotomy suspension performed first
• Phase II: MMA performed only if Phase I fails, particularly for moderate OSA cases to avoid unnecessary high-risk surgery 1
• Alternative approach: Other surgical teams proceed directly to MMA without staging 1

For difficult cases requiring larger advancements, mandibular elongation using osseous distraction followed by Le Fort I advancement osteotomy can achieve 12-14mm advancement in 3 weeks, requiring close orthodontist collaboration 1

Primary Indication: Obstructive Sleep Apnea

MMA specifically addresses hypopharyngeal or tongue base obstruction to enlarge the retrolingual and retropalatal airway 1:

• Used for patients who refuse or cannot tolerate CPAP therapy 2
• Most effective in younger patients without excessive BMI 2
• Success rates range from 67% to 100% depending on polysomnographic techniques used 1
• As effective as CPAP in appropriately selected patients 2

Clinical Outcomes

Based on 12 case series (298 patients) published 1989-2006 1:

• Mean AHI reduction: -47.8 events/hour (80.1% reduction) 3
• Surgical success rate: 85.5% (defined as >50% AHI reduction to <20 events/h) 3
• Cure rate: 38.5% (defined as post-operative AHI <5 events/h) 3
• Oxygen saturation nadir improvement: 70.1% to 87.0% 3
• Epworth Sleepiness Scale improvement: 13.5 to 3.2 3
• 98.8% of patients showed improvement 3

Cardiovascular Benefits

MMA demonstrates potential cardiovascular improvements 1:

• Lowering of systolic and diastolic blood pressure (associated with weight loss) 1
• >50% of patients no longer require antihypertensive medications post-operatively 1

Patient Selection Criteria

Pre-operative Evaluation Requirements

All patients must undergo 1:

• Full in-laboratory overnight polysomnography (home monitoring without EEG is insufficient due to inadequate detection of hypopneas and central events) 1
• Complete clinical and cephalometric examination evaluating three major anatomic regions: nose, palate (oropharynx), and base of tongue (hypopharynx) 1
• Multidisciplinary team evaluation including maxillofacial surgeon, neurophysiologist, and pulmonologist in some centers 1

Ideal Candidate Profile

Selected patients typically meet these criteria 1:

• Male patients (most common)
• AHI >30 events/hour
• Age <60 years
• BMI <30 kg/m² (though success rates of 81% reported even with BMI ≥40) 4
• No significant cardiovascular or pulmonary comorbidities
• Failed or intolerant to CPAP therapy 2

Anatomic Findings

Common anatomic patterns in surgical candidates 1:

• Hypertrophic tonsils (40% of candidates)
• Hypopharyngeal obstruction at tongue base (80% of candidates) - typically from small oral cavities with normal tongue size
• Pharyngeal narrowing at basal lingual level, sometimes with retrognathia
• Shorter anterior floor of cranial base, smaller mandible, and retro-positioned mandible in patients with BMI <30 kg/m² (predicts better surgical success) 1

Complications and Recovery

Common Complications

All patients experience 1:

• Transient anesthesia of cheek and chin area (universal)
• Residual neurosensitive deficit (hypoesthesia of lower lip) - most common complication, does not affect quality of life 1

Serious but Rare Complications

Reported complications include 1:

• Cardiac arrest without sequelae and dysrhythmia
• Local infection
• Perforation of the palate
• Maxillary pseudarthrosis
• Malocclusion and dysgnathia due to mandibular deficiencies
• Temporary postoperative velar insufficiency (phonetic deficit and liquid regurgitation) in patients with prior pharyngoplasty, improved with speech therapy 1

Recovery Timeline

• Average postoperative off-work time: 2-10 weeks 1
• Most patients accept changes in facial appearance, which can be predicted by preoperative computer imaging 1

Post-operative Follow-up

Full in-laboratory polysomnography should be performed 2-6 months after surgery to assess effectiveness 1, 2

Long-term Outcomes

• Long-term skeletal stability confirmed at 12 months based on cephalometric analysis 1
• Long-term success rates approximately 60% with some deterioration over time 1, 5
• MMA has been shown to be effective over the long term 1

Critical Success Factors

Successful surgery depends on three key elements 1:

1. Proper patient selection - matching anatomic findings to surgical approach
2. Proper procedure selection - choosing appropriate technique and advancement distance
3. Experience of the surgeon - technical expertise in performing complex orthognathic procedures

Important Caveat

**Preoperative AHI <60 events/h is the factor most strongly associated with highest surgical cure rates**; however, patients with AHI >60 still experience large and substantial net improvements despite modest cure rates 3