CF RoundsMandible FRACTURES

PRINCIPLES OF FIXATIONApril 21 2011

URGENT not EMERGENT

• Compound #’s need early antibiotics as proven to reduce the number of postoperative infections

• May need bedside temporary fixation of mobile segments for pain or hemorrhage

• Surgical repair early but no evidence to suggest complications related to increased injury to repair times

Fixation

• Primary goal• Restore pre-injury occlusion

• Secondary goal– Anatomic reduction of fracture

• Tertiary goal– Attain pre-injury mobility and function

Determine fixation requirements• Determine the strength of the host mandible

preoperatively– Load bearing• Comminution, Atrophic mandibles, Segmental loss• Hardware bears entire masticatory load during healing• Reconstruction plates with 3 points fixation either side

of the fracture

Determine fixation requirements

• Load sharing– Simple fractures– Requires adequately apposed bony cortices– Masticatory load shared between host bone and

hardware

Load sharing fixation

• Non-rigid fixation• Application of hardware that does not prevent

micromotion across the fracture site• Two points of fixation on either side of the

fracture sufficient• Example Champy technique– Placement of smaller plates in biomechanically

favorable locations

Approach

• Pre-operative assessment of fracture

• Selection of hardware influenced by– Fracture location– Fracture type

Mandibular Symphysis & Body

• Vestibular approach– Expose #– Protect mental nerves– Temporary MMF– Bone clamp to aid with reduction

Mandibular Symphysis & Body

• Selection of hardware– Isolated fractures with sound teeth• 2mm miniplate with monocortical screws (5-6mm)

below tooth roots• Arch bars act as 2nd point of fixation

– Isolated fractures with missing dentition• Unable to secure arch bars• 2mm locking plate with bicortical screws• (alternately) Two 2mm miniplates with monocortical

screws

Symphysis v.s. Body

• Differences between body and symphysis– Inferior alveolar nerve travels in the body

– Shorter distance from tooth roots to inferior border in body

– Bone is much thicker in symphysis

Lag screws

• Very stable fixation• Useful for oblique fractures in body• Must be able to place two screws• Most often for symphyseal/parasymphyseal

• Lag technique allows compression of the fracture• First cortex drilled to the screw diameter and

perpendicular to fracture• Lag screws are contraindicated in comminuted

fractures• A single lag screw does not give 3D stability and

needs a second point of fixation

Postoperative management

• MMF should not be required if appropriate fixation is achieved

• Early ROM should be encouraged

• If arch bar used as second point of fixation should be maintained 5 weeks

• No evidence to support post-op antibiotics