Force Necessary to Fracture the Orbital Floor

Indications for repositioning of blow-out fractures of the orbital floor based on new objective criteria - tissue protrusion volumometry

“…In anteroposterior fractures (76% of which required operating) we recommend surgery in prolapse greater than 1400 mm 3 , and in anterior (operated only in 11% of cases ) and posterior fracture types (operated in 46% of cases) in prolapse over 500 mm 3 after remission of acute swelling, if no urgent (Table 4, Fig. 4).…”

The effects of the extraocular muscles on eye impact force–deflection and globe rupture response

“…This is due to the fact that other injuries, such as hyphema, lens damage, and retinal damage cannot be assessed on post-mortem eyes. Therefore, in a similar manner to other reported studies (Weidenthal, 1964;Green et al, 1990;Vinger et al, 1999;Bass et al, 2002;Stitzel et al, 2002;Kennedy et al, 2006), globe rupture was the only eye injury that was evaluated in conjunction with the impact response. Current computational models of the eye for impact scenarios do not model the interface between the sclera and the retina, or ciliary body/zonules/lens interfaces (Kisielewicz et al, 1998;Uchio et al, 1999Uchio et al, , 2001Power et al, 2002;Stitzel et al, 2002Stitzel et al, , 2005Hansen et al, 2003), but may be useful to compare stress distributions including extraocular muscle insertion points, and common sites of retinal or lens injuries.…”

“…2). The impactor energy level of 4 J was selected to be approximately twice the energy level of previously reported blunt impact studies investigating globe rupture which used similarly sized impactors (Weidenthal, 1964;Green et al, 1990). The 19 mm diameter of the blunt impactor corresponds to a nominal 25 mm average diameter of the eye and was selected to maximize the anterior translation of the whole eye in order to fully engage the extraocular muscles.…”

“…Previous studies have been performed to determine the injury tolerance of the eye to globe rupture from blunt impact (Weidenthal, 1964;Green et al, 1990;Vinger et al, 1999;Bass et al, 2002;Stitzel et al, 2002;Kennedy et al, 2006); however, nearly all of the reported tests were conducted using enucleated eyes mounted in a gelatin solution without the extraocular muscles intact. No known prior study has investigated the effects of the extraocular muscles on the impact response of the eye.…”

What happens between pure hydraulic and buckling mechanisms of blowout fractures?

“…For the prevention and effective treatment of blowout fractures, it is essential to understand the aetiology of blowout fractures. A number of studies have been performed to elucidate the biomechanical mechanisms of blowout fractures (Jones and Evans, 1967;Green et al, 1990;Waterhouse et al, 1999). Two mechanismsdhydraulic and bucklingdare generally believed to cause blowout fractures (Warwar et al, 2000;Ahmad et al, 2003;Ahmad et al, 2006).…”