Why is a strict liquid diet recommended for patients undergoing maxillomandibular fixation (MMF) for facial fractures?

Why Strict Liquid Diet is Recommended for Maxillomandibular Fixation (MMF)

A strict liquid diet is necessary during MMF because the jaws are physically wired or fixed together, making it mechanically impossible to chew solid foods, while patients still require adequate nutrition (typically 200g carbohydrate/day in divided portions) to support fracture healing and prevent malnutrition-related complications. 1

Mechanical Rationale

The primary reason for a liquid diet during MMF is purely mechanical, not medical:

• MMF involves physically immobilizing the upper and lower jaws together to maintain proper occlusion and alignment during mandibular fracture healing 2, 3
• Patients cannot open their mouths to chew or consume solid foods while the jaws are fixed together 4
• The fixation can be achieved through arch bars, orthodontic brackets, or IMF screws, all of which prevent jaw movement 3, 4

Nutritional Requirements During MMF

Despite the mechanical restriction, nutritional needs remain critical:

• Patients require approximately 200 grams of carbohydrate per day delivered in equally divided amounts at meal and snack times to support healing 1
• Liquids should NOT be sugar-free when nutritional support is needed, as patients require adequate calories and carbohydrates that sugar-free options cannot provide 1
• Small liquid meals consumed 5-6 times per day help patients meet nutritional goals during the fixation period 1, 5

Composition of Appropriate Liquid Diet

The liquid diet should include:

• Clear liquids: water, clear broths, plain gelatin, clear fruit juices without pulp, plain tea and coffee 1
• Full liquids should be added as tolerated: milk, yogurt drinks, nutritional supplements to provide adequate protein and calories 1
• Nutritional supplements may be necessary to prevent the malnutrition that increases postoperative morbidity and mortality in maxillofacial surgery patients 5

Duration and Transition

Modern evidence challenges prolonged MMF:

• A 2014 study of 311 patients with mandibular fractures found no significant difference in complications (wound dehiscence, infection, nonunion, malunion, or malocclusion) between patients maintained in postoperative MMF versus those who were not 2
• When MMF is used alone (without ORIF), the duration is typically several weeks, during which liquid diet must be maintained 2
• Once MMF is removed, patients can advance rapidly from liquids to regular solid food without the traditional stepwise progression through soft diets 1, 6

Critical Pitfall to Avoid

Do not maintain patients on clear liquids alone for extended periods, as this provides inadequate calories and zero protein, which impairs fracture healing and increases complications in maxillofacial surgery patients 1, 5. Progress to full liquids with adequate nutritional content as soon as tolerated while the fixation remains in place.

Alternative Feeding Routes

• Nasogastric tube feeding was historically used but a 2005 study of 111 mandibular fracture patients showed that immediate oral liquid feeding after surgery reduced hospital stay from 7.2 to 2.5 days and decreased complications from 13.6% to 3.3% compared to nasogastric feeding 7
• Enteral or parenteral nutrition should be considered only if oral liquid intake is inadequate to meet nutritional needs for more than 7 days 8

The strict liquid diet is therefore a practical necessity imposed by the mechanical fixation itself, not a medical requirement for healing, and should be as nutritionally complete as possible during the fixation period.