[Evaluation of peribulbar soft tissue reactions to titanium mesh in experimental tests in animals]

Orbital fractures are often accompanied by periosteal rupture and oculomotor muscle injury from the orbital fissure (blowout fracture). During reconstruction, substitute material (biomaterial) restoring the orbit is placed on a bony shelf and brought into direct contact with muscles and indirect contact with the eyeball, optic nerve and lacrimal gland. Histological examination of orbital tissues following reconstruction with titanium mesh, not possible in humans, can be performed in a rat model. In spite of different anatomy, the rats orbit was found satisfactory for the purpose of this study. The eyeball is supported by oculomotor muscles, lying partly on the malar bone. The aim was to follow the reaction of periorbital soft tissues to titanium mesh in a rat model of inferior orbital wall injury simulating orbital muscle lesions in man caused by blowout fracture. Insertion of titanium mesh directly in contact with muscles reproduced the situation in the human orbit. The following soft tissues and organs were studied: striated oculomotor muscle (inferior rectus), sclera, choroid, optic nerve and lacrimal gland. The results were compared with sham-operated animals (titanium mesh not implanted). Two questions were addressed: Is the process of healing of orbital muscle injury affected by the titanium mesh? Is there any evidence of adverse effect on periorbital soft tissues or eye of titanium wear particles produced by contraction of orbital muscles? Buffalo rats of the 38th generation and smooth titanium mesh (Ti-6AI-4V alloy) measuring 0.2 x 8 x 8 mm were used.