1. CF Rounds Mandible FRACTURES PRINCIPLES OF FIXATION April 21 2011

2. 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

3. Fixation Primary goal Restore pre-injury occlusion Secondary goal – Anatomic reduction of fracture Tertiary goal – Attain pre-injury mobility and function

4. 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

5. Determine fixation requirements Load sharing – Simple fractures – Requires adequately apposed bony cortices – Masticatory load shared between host bone and hardware

6. 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

7. Approach Pre-operative assessment of fracture Selection of hardware influenced by – Fracture location – Fracture type

8. Mandibular Symphysis & Body Vestibular approach – Expose # – Protect mental nerves – Temporary MMF – Bone clamp to aid with reduction

9. 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 2 nd 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

11. 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

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

13. 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

14. 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