Inferior meatal antrostomy impairs dynamic stability of the orbital walls

Tensile modulus of human orbital wall bones cut in sagittal and coronal planes

In the current research, 68 specimens of orbital superior and/or medial walls taken from 33 human cadavers (12 females, 21 males) were subjected to uniaxial tension untill fracture. The samples were cut in the coronal (38 specimens) and sagittal (30 specimens) planes of the orbital wall. Apparent density (ρ_app), tensile Young’s modulus (E-modulus) and ultimate tensile strength (UTS) were identified. Innovative test protocols were used to minimize artifacts and analyze the obtained data: (1) grips dedicated to non-symmetrical samples clamping were applied for mechanical testing, (2) non-contact measuring system of video-extensometer was employed for displacement registration, (3) ink imprint technique coupled with CAD analysis was applied to precisely access the cross-sectional areas of tested samples. With regard to a pooled group, apparent density for the coronal and sagittal cut plane was equal 1.53 g/cm³ and 1.57 g/cm³, tensile Young’s modulus 2.36 GPa and 2.14 GPa, and ultimate tensile strength 12.66 MPa and 14.35 MPa, respectively. No significant statistical differences (p > 0.05) were found for all the analyzed parameters when comparing coronal and sagittal plane cut groups. These observations confirmed the hypothesis that direction of sample cut does not affect the mechanical response of the orbital wall tissue, thus suggesting that mechanical properties of orbital wall bone show isotropic character.

Biomechanical analysis of likelihood of optic canal damage in peri-orbital fracture

PURPOSE

Detection of optic canal fractures is often difficult because of the subtleness of the fracture. If we could clarify impact on which region around the orbit is likely to accompany the fracture of the optic canal, the knowledge should be useful to make early diagnosis of optic canal fractures. The present study was conducted to elucidate this issue.

METHODS

Ten finite element models were produced simulating the skulls of ten humans (8 males and 2 females; 43.8 ± 10.2 y/o). The peri-orbital area of each of the ten models was divided into eight regions in a clockwise fashion per 45 degrees. These regions were defined as Superior-Medial (0-45 degrees), Medial-Superior (45-90 degrees), Medial-Inferior (90 to 135 degrees), Inferior-Medial (135 to 180 degrees), Inferior-Lateral (180-225 degrees), Lateral-Inferior (225 to 270 degrees), Lateral-Superior (270-315 degrees), and Superior-Lateral regions (315-360 degrees), respectively. Dynamic simulation of applying traumatic energy on each of these regions was conducted. Resultant fracture patterns were evaluated using finite element analyses. Thereafter, frequencies of fracture involvement of the optic canal were evaluated for each of the eight regions.

RESULTS

The involvement of the optic canal was most frequent for the Superior-Medial region (7/10), followed by the Medial-Superior region (5/10).

CONCLUSION

Optic canal fracture is likely to occur when the area between the supra-orbital notch and the medial canthus are strongly impacted. When evident fracture or serious damage of soft tissue is observed in this area, occurrence of optic canal fracture should be suspected.

Posttraumatic orbital emphysema: a numerical model

Orbital emphysema is a common symptom accompanying orbital fracture. The pathomechanism is still not recognized and the usually assumed cause, elevated pressure in the upper airways connected with sneezing or coughing, does not always contribute to the occurrence of this type of fracture. Observations based on the finite model (simulating blowout type fracture) of the deformations of the inferior orbital wall after a strike in its lower rim. Authors created a computer numeric model of the orbit with specified features—thickness and resilience modulus. During simulation an evenly spread 14400 N force was applied to the nodular points in the inferior rim (the maximal value not causing cracking of the outer rim, but only ruptures in the inferior wall). The observation was made from 1 · 10⁻³ to 1 · 10⁻² second after a strike. Right after a strike dislocations of the inferior orbital wall toward the maxillary sinus were observed. Afterwards a retrograde wave of the dislocation of the inferior wall toward the orbit was noticed. Overall dislocation amplitude reached about 6 mm. Based on a numeric model of the orbit submitted to a strike in the inferior wall an existence of a retrograde shock wave causing orbital emphysema has been found.

[Pathologies of lateral nasal wall in children with diagnosed antrochoanal polyps]

Antrochoanal polyps are more frequent in children than in adults. Patomechanism of their development is still unclear. New diagnostic methods allow precise examination of lateral nasal wall pathologies.

AIM OF THE STUDY

Aim of the study is an evaluation of endoscopic examinations and CT scans of lateral walls in 15 children with chronic sinusitis and diagnosed antrochanal polyps.

MATERIAL AND METHODS

Both groups of children, those with chronic sinusitis and those with diagnosed antrochoanal polyps, were compared according to the results of the endocopies and CT scans.

RESULTS

Unilateral pathologies of lateral nasal wall, like notable widening of natural ostium in 4 children and additional ostium in 7 children with antrochoanal polyps were noted. In children with chronic sinusitis pathologies were observed bilaterally, in none of them additional ostia were observed and pathologies of lateral nasal wall were typical for chronic inflammatory process or trauma.

CONCLUSION

Diagnosed pathologies of lateral nasal wall in both children are different and need further studies, which may lead to explanation of antrochoanal polyps development.