Lag Screw Fixation in Maxillofacial Trauma

Abstract

The use of lag screws provides maximum compression with a minimal amount of implant- able material. Because of anatomic considerations, lag screws cannot always be utilized in the management of maxillofacial trauma. However, when appropriately used, lag screw fixation provides a predictable and versatile means of stabilization. The following important principles must be adhered to if lag screw fixation is to be successful: 1. Any screw that is to traverse a fracture must be inserted as a lag screw. 2. Any cortical screw can be used as a lag screw provided the receptor site is prepared properly. 3. Proper receptor site preparation requires that the gliding hole be equivalent to the thread diameter of the screw and the traction hole be equivalent to the core diameter of the screw. 4. The receptor site should be aligned so that it is the bisector of the perpendicular to the fracture and the perpendicular to the long axis of the bone. 5. The traction hole and the gliding hole must be drilled coaxially. 6. When a lag screw is placed through a stabilization plate, the remainder of the screws must be placed in the neutral position. 7. When lag screws are used as the sole fixators for a mandibular fracture, a minimum of three screws must be used in order to ensure adequate stabilization. If only one lag screw can be placed, then it must be protected by a stabilization plate. Although at first glance the insertion of a lag screw may seem a technically demanding and complex method of fixation, when properly utilized, lag screw fixation provides the surgeon with a reliable method of restoring function to the injured patient rapidly.