Residency · Residency · Oral Maxillofacial Surgery

Mandible Fractures: Principles of Management

Overview

The mandible is the second most commonly fractured facial bone after the nasal bones. As a ring-shaped bone, it often fractures in two places (contrecoup). Management depends on fracture location, displacement, dentition status, and the presence of complicating factors. The goals are to restore pre-injury occlusion, achieve anatomic reduction, provide stable fixation, and enable return to function.

Epidemiology

Mandible fractures show a male predominance of 3:1 to 4:1 with peak incidence between 20 and 30 years of age. Causes include interpersonal violence (most common in urban settings), motor vehicle collisions, falls, sports, and pathologic fractures. Associated injuries include other facial fractures (25-50%), C-spine injury (1-6%), and TBI.

Anatomy Relevant to Fracture Management

Fracture Distribution (Approximate)

The condyle and subcondylar region account for 25-35% of fractures, the angle for 20-25%, the body for 15-25%, the symphysis and parasymphysis for 15-20%, the ramus for 3-5%, the coronoid for 1-2%, and the alveolar process for 2-5%.

Biomechanics

The mandible has zones of tension at the superior (alveolar) border and zones of compression at the inferior border. During function, the alveolar border is under tension (teeth act as tensile elements) and the inferior border is under compression. Champy's ideal lines of osteosynthesis describe miniplate placement along the tension band of the mandible: two miniplates for the symphysis and parasymphysis (one at the inferior border for torsional resistance), one miniplate along the external oblique ridge for the body, and one miniplate along the external oblique ridge for the angle (the Champy technique). Fractures are classified as favorable or unfavorable based on the relationship between muscle pull and fracture line direction -- favorable fractures are compressed by muscle forces, while unfavorable fractures are distracted or displaced.

Muscles of Mastication and Their Effect

The elevator muscles (masseter, medial pterygoid, temporalis) pull the posterior mandible superiorly and anteriorly. The depressor muscles (suprahyoid group including geniohyoid, mylohyoid, and digastric) pull the anterior mandible inferiorly and posteriorly. The lateral pterygoid pulls the condyle anteriorly and medially. These forces determine fracture displacement patterns and guide fixation strategy.

<image>Anatomical diagram of the mandible showing the common fracture sites with their relative frequencies, Champy's ideal lines of osteosynthesis marked along the tension band, and the vectors of muscle forces (elevators posteriorly, depressors anteriorly) that determine fracture displacement patterns</image>

Classification

By Location

Fractures are classified by location as condylar (intracapsular, subcondylar/neck, or base of condyle), coronoid, ramus, angle, body (canine to third molar), parasymphysis (canine to canine), symphysis (midline), or alveolar process.

By Condition

Simple (closed) fractures have no communication with the external environment. Compound (open) fractures communicate with skin or mucosa -- all fractures in the tooth-bearing area communicating with the oral cavity are compound. Comminuted fractures have multiple fragments. Greenstick fractures are incomplete and occur in pediatric patients. Pathologic fractures occur through diseased bone (cyst, tumor, osteomyelitis, MRONJ).

By Dentition Status

Dentate fractures have teeth present on both sides, allowing MMF for reduction. Partially dentate fractures have some teeth present that may be sufficient for MMF. Edentulous fractures have no teeth in one or both segments, requiring alternative fixation strategies.

Diagnosis

Clinical findings include pain, swelling, malocclusion, step deformity, mobility at the fracture site, numbness (IAN), sublingual hematoma, gingival tears, and ecchymosis. Panoramic radiograph provides excellent screening. CT face with 3D reconstruction is the gold standard for complex fractures. PA mandible and Towne views supplement evaluation of condylar fractures.

Principles of Management

Goals

The goals are to restore pre-injury occlusion (the patient's occlusion serves as the template), achieve anatomic reduction of fracture segments, provide stable fixation to allow primary bone healing, minimize complications (infection, nonunion, malunion, nerve injury), and enable early return to function.

Load-Sharing vs. Load-Bearing Fixation

Load-Sharing (Functionally Stable)

In load-sharing fixation, the hardware shares functional loads with the bone, which provides inherent stability. It is indicated for simple fractures with good bone-to-bone contact, minimal comminution, and minimal gaps. Hardware consists of miniplates (2.0 mm system) with monocortical screws. Examples include the Champy technique at the angle and a single miniplate at the body along the oblique ridge. Advantages include less dissection, less hardware, periosteum preservation, and avoidance of the IAN.

Load-Bearing (Rigid Fixation)

In load-bearing fixation, the hardware bears all functional loads and is used when bone cannot contribute to stability. Indications include comminuted fractures, fractures with gaps or bone loss, atrophic edentulous mandible, and pathologic fractures. Hardware consists of reconstruction plates (2.4 mm) with locking screws and bicortical fixation. An example is a 2.4 mm reconstruction plate at the inferior border for a comminuted angle fracture. This provides immediate rigid stability regardless of bone contact but requires more dissection, larger hardware, and carries risk of IAN injury if screws are placed in the canal area.

Intermaxillary Fixation (MMF)

MMF is used for reduction (temporary) or treatment (extended). Methods include arch bars (Erich arch bars, the gold standard), IMF screws (faster placement, less gingival trauma), Ivy loops, and dental wiring. When used as primary treatment, the duration is 4-6 weeks. MMF alone (closed reduction) has limited indications in modern practice, primarily for favorable nondisplaced fractures, condylar fractures, and pediatric fractures.

Management by Fracture Site

Symphysis and Parasymphysis

Two-plate fixation following the Champy principle places one plate at the inferior border for torsional resistance and one along the external oblique ridge or subapical area. An alternative is a single lag screw with a superior miniplate. An associated condylar fracture (contrecoup) should always be checked for. Bilateral parasymphysis fractures pose an airway risk from loss of genioglossus support.

Body

A single miniplate along the external oblique ridge (Champy) is used for simple fractures. Two miniplates (tension and compression band) provide increased stability. A reconstruction plate is used for comminuted fractures. The IAN must be preserved, with screws avoided in the canal.

Angle

The angle is the most debated fracture site regarding fixation method. The Champy technique uses a single 2.0 mm miniplate along the external oblique ridge with monocortical screws and is excellent for favorable fractures. The two-miniplate technique places plates at both the superior and inferior borders, providing more stability but requiring more dissection. A lag screw (transbuccal or intraoral, single bicortical screw) is technically demanding. A reconstruction plate is reserved for comminuted or unfavorable fractures. Regarding the third molar in the fracture line, it should be removed if fractured, carious, infected, or preventing reduction, but retained if removal would further destabilize the fracture.

Condylar Fractures

Classification

Condylar fractures are classified as intracapsular (condylar head, within the capsule), condylar neck (the narrow area below the head), or subcondylar (base, below the sigmoid notch).

Open vs. Closed Treatment -- The Controversy

Closed treatment (MMF plus guiding elastics) is indicated for intracapsular fractures, nondisplaced or minimally displaced fractures, pediatric fractures, and medically compromised patients. The protocol involves 1-2 weeks of MMF followed by 4-6 weeks of guiding elastics and physiotherapy. Advantages include avoidance of surgical risks (facial nerve injury, scarring), while disadvantages include risk of malocclusion, shortened ramus height, and TMJ dysfunction.

Open treatment (ORIF) is indicated for displaced fractures with ramus shortening, lateral extracapsular displacement, bilateral condylar fractures, fracture-dislocation into the middle cranial fossa, and inability to achieve occlusion with MMF. Approaches include preauricular, retromandibular (transparotid), submandibular, and endoscopic-assisted transoral. Fixation uses two miniplates or one trapezoidal plate. Advantages include anatomic reduction, early function, and avoidance of MMF. Disadvantages include facial nerve risk and surgical scarring.

Ramus

Ramus fractures rarely require ORIF because they are protected by the masseter and medial pterygoid. They are usually managed with MMF or observation, with open treatment reserved for significantly displaced fractures.

Coronoid

Coronoid fractures are usually nondisplaced and managed with observation. Displaced fractures interfering with opening are treated with reduction or excision (coronoidectomy).

Alveolar Process

Alveolar process fractures are reduced and stabilized with an arch bar or miniplate, with management of associated dental injuries (splinting, endodontics).

<image>Intraoperative photographs demonstrating different fixation techniques for mandibular fractures: Champy single miniplate along the external oblique ridge for an angle fracture, two-plate fixation of a parasymphysis fracture, and a 2.4 mm reconstruction plate for a comminuted body fracture with a load-bearing construct</image>

Special Situations

Edentulous Mandible Fractures

The atrophic mandible (less than 20 mm height) has compromised blood supply and poor healing potential. Closed treatment with dentures or Gunning splints and circumandibular wires is used for minimally displaced fractures. ORIF with a load-bearing reconstruction plate is standard for displaced fractures. Periosteal stripping should be avoided because the atrophic mandible depends on periosteal blood supply.

Pediatric Mandible Fractures

A conservative approach is preferred due to developing tooth buds and growth centers. Closed reduction with short-term MMF (7-10 days) is standard. Acrylic splints are used for young children without teeth suitable for arch bars. ORIF with resorbable plates and screws is used when operative management is needed. Condylar fractures are managed conservatively as the remodeling potential is excellent.

Pathologic Fractures

Pathologic fractures occur through cysts, tumors, or MRONJ. The underlying pathology is addressed at the time of fracture repair, and load-bearing fixation (reconstruction plate) is required because diseased bone cannot share loads.

Infected/Contaminated Fractures

Management involves irrigation, debridement, reduction, and fixation along with antibiotic therapy. Grossly mobile teeth and sequestra are removed. Hardware is left in place unless infection is refractory.

Complications

Infection occurs in 5-15% of cases, with higher rates at the angle, with teeth in the fracture line, and with delayed treatment. Malunion and malocclusion result from inadequate reduction or premature mobilization. Nonunion is rare (less than 2%), with risk factors including infection, mobility, and devascularized fragments. Nerve injury (IAN or mental nerve) produces temporary paresthesia commonly, with permanent injury in 1-5%. Hardware failure includes plate fracture or screw loosening. Tooth injury may occur during screw placement or fracture reduction. TMJ dysfunction is particularly associated with condylar fractures.

Clinical Pearls

The patient's occlusion is the single most important guide to adequate reduction, and occlusion should always be checked after fixation. A second fracture site should always be sought because the mandible is a ring and often breaks in two places. The Champy technique at the angle is elegant, effective, and time-tested -- one miniplate along the oblique ridge with monocortical screws is sufficient for most favorable angle fractures. The third molar in the fracture line should be removed if it prevents reduction or is a source of infection, but retained if it is intact and contributes to fracture stability. For condylar fractures, the decision between open and closed treatment should be individualized, as neither approach is universally superior. Sublingual hematoma in a patient with bilateral mandibular fractures is an airway warning sign because the tongue can prolapse posteriorly. Postoperative elastics are as important as the fixation, as they guide the occlusion during healing. Edentulous mandible fractures in atrophic bone require load-bearing fixation -- miniplates should not be used on a paper-thin mandible.

References

• Champy M, et al. Mandibular osteosynthesis by miniature screwed plates via a buccal approach. J Maxillofac Surg. 1978.
• Ellis E III, Miles BA. Fractures of the mandible: a technical perspective. Plast Reconstr Surg. 2007.
• Zide MF, Kent JN. Indications for open reduction of mandibular condyle fractures. J Oral Maxillofac Surg. 1983.
• Gear AJ, et al. Treatment modalities for mandibular angle fractures. J Oral Maxillofac Surg. 2005.
• Nasser M, et al. Interventions for the management of mandibular fractures. Cochrane Database Syst Rev. 2013.
• Pickrell BB, et al. Management of mandibular condylar fractures. Facial Plast Surg. 2017.

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