David C. Stanton, D.M.D., M.D.
Therese DiFlorio Brennan, D.M.D., M.D.
Kae S.C. Cheng, D.M.D., M.D.
The University of Pennsylvania Medical Center Department of Oral and Maxillofacial Surgery
Case History
A 25 year-old male presented to the emergency room after an assault during which he incurred several blows to the face. His resulting injuries were a left subcondylar fracture, a mandibular symphysis fracture, and a comminuted right mandibular angle fracture with tooth number 32 in the line fracture (Figure 1 and 2). His past medical history was significant for a two-story fall in 1993 in which he sustained head trauma, blindness of left eye, and fracture of his left hip.
Treatment Options
Treatment options for the right mandibular angle fracture included:
1) Closed reduction and maxillomandibular fixation for six to eight weeks
2) Open reduction and internal fixation with lag screws and reconstruction
plate
3) External biphasic pin fixation
Treatment options for the mandibular symphysis fracture included:
1) Closed reduction for six to eight weeks
2) Open reduction and internal fixation with a dynamic compression plate
3) Open reduction and internal fixation with lag screws
4) Open reduction and internal fixation with monocortical plating
5) External biphasic pin fixation
All treatment options included removing tooth number 32 which was in the line of the mandibular angle fracture. In addition, the nondisplaced left subcondylar fracture was treatment planned for a closed reduction with two weeks of maxillomandibular fixation.
Operative Stabilization
After a thorough history and physical examination, it was determined that the patient's injuries were limited to the stated mandibular fractures. The patient was brought to the operating room and under general anesthesia, extraction of tooth number 32 was performed. A bridle wire was then placed prior to placement of Erich arch bars to assist in reducing the mandibular symphysis fracture.
Next, the patient was placed in maxillomandibular fixation, which reestablished the patient's natural occlusion. The right mandibular angle fracture was then approached by a modified Risdon incision. A comminuted fracture was appreciated. Appropriate reduction of both the distal and proximal segments of the fracture was achieved with two Kocher clamps (Figure 3). An eight-hole reconstruction plate was fitted and secured with 2.4 mm bicortical screws.
Next, a separate large sagital comminuted bone fragment was fixated with a 2.4 mm lag screw. (Figure 4) Finally, the mandibular symphysis was approached intraorally via a genioplasty incision. The fracture was repaired using the lag screw technique. A 2.4 mm lag screw measuring 38 mm was placed superiorly, and 2.4 mm lag screw measuring 32mm was placed inferiorly (Figure 5).
The non-displaced left subcondylar fracture was treated conservatively by two weeks of maxillomandibular fixation. Post-operative x-rays demonstrated appropriate reduction of the fracture sites (Figure 6 and 7).
Summary
This case demonstrates the versatility of lag screws in the repair of complex mandibular fractures. In this case, the lag screw technique served to achieve primary dynamic compression of the symphysis fracture and also as an adjunct for stabilization of a separate free bone segment not engaged by the reconstruction plate.
When using reconstruction plates to stabilize a comminuted fracture, dynamic compression is not employed and a separate tension band is not necessary. Traditionally, mandible fractures of this nature would have been treated with at least six weeks of maxillomandibular fixation. However, by applying the AO/ASIF principles of internal fixation, our patient was able to return to relatively normal masticatory function after a shorter period of maxillomandibular fixation.