Blow-in and blow-out fractures of the orbit: clinical correlations and proposed mechanisms.

Various theories have been proposed regarding the exact etiology of blow-out fractures of the orbital floor and blow-in fractures of the orbital roof. These include the role of increased intraorbital pressure causing a downward fracture of the orbital floor, and the role of a buckling force transmitted by the orbital rim to the thinner orbital walls. This paper presents two case histories that illustrate the roles of these mechanisms in the production of such fractures. One is a classic blow-out fracture while the other is a unique case of orbital roof blow-in fracture which may shed additional light on the role of buckling forces in the creation of these fractures. A review of experimental and clinical data supporting these mechanisms is presented and suggests that more than one factor may be involved in the production of such orbital fractures.