Management of the medial canthal tendon in nasoethmoid orbital fractures: the importance of the central fragment in classification and treatment.

The medial canthal tendon and the fragment of bone on which it inserts ("central" fragment) are the critical factors in the diagnosis and treatment of nasoethmoid orbital fractures. The status of the tendon, the tendon-bearing bone segment, and the fracture pattern define a clinically useful classification system. Three patterns of fracture are appreciated: type I--single-segment central fragment; type II--comminuted central fragment with fractures remaining external to the medial canthal tendon insertion; and type III--comminuted central fragment with fractures extending into bone bearing the canthal insertion. Injuries are further classified as unilateral and bilateral and by their extension into other anatomic areas. The fracture pattern determines exposure and fixation. Inferior approaches alone are advised for unilateral single-segment injuries that are nondisplaced superiorly. Superior and inferior approaches are required for displaced unilateral single-segment injuries, for bilateral single-segment injuries, and for all comminuted fractures. Complete interfragment wiring of all segments is stabilized by junctional rigid fixation. All comminuted fractures require transnasal wiring of the bones of the medial orbital rim (medial canthal tendon-bearing or "central" bone fragment). If the fracture does not extend through the canthal insertion, the canthus should not be detached to accomplish the reduction.