Establishment Of Orbital Hypertelorism Models In Rabbit And Effect Of Para-orbital Soft-tissue Expansion Technique On Orbital Medial Translocation

Objective1 To establish the correction models of orbital hypertelorism in rabbit. Give para-orbital osteotomies and medial translocation. Interorbital distanse (IOD) and Healing of the bone between orbital were studied with gross measurement and X-ray examination before and after operation and 12 weeks later.2 Investigate the effect of para-orbital soft-tissue expansion before orbital osteotomies and medial translocation by combined intracranial-extracranial approach. IOD and healing of the bone between orbital were studied with gross measurement, X-ray, and histological examination before and after operation and 12 weeks later. Methods and Results1 16 New Zealand rabbits were given para-orbital osteotomies and medial translocation by combined intracranial-extracranial approach. The coronary, palpebral.and nasofrontal incisions are necessary to expose the craniofacial skeleton. Leaving the periosteum intact in the frontal area as far as 5-10 mm from the orbital rim and continuing underthe periosteum in the orbital and malar regions. The bone blocks to be resected can be performed by an ethmoidofrontal resection with a frontal crown to provide a base for bone graftfixation. A resection of the ethmoid cells leaving a central T shape in the nasofrontal area to rebuild the dorsum of the nose, and 5mm bone graft were resected beside the T shape. Osteotomies separate the whole orbit from the skull and facial bones in order to mobilize the orbit medially. Finally, fix these bone graft with steel wire. IOD and Healing of the bone between orbital were studied with gross measurement and X-ray examination before and after operation and 12 weeks later.IOD were measured by vernier caliper before and after operation, IOD is the distance between lacrimonasal. Excute the rabbits 12 weeks after operation, and measure IOD again. Give X-ray examination before and after operation and 12 weeks later.The average IOD of the rabbits is 17.2mm before operation and 8.4mm after operation. 12 weeks after operation, the average IOD of the rabbits recurred to 9.6mm. the relapse is significant. (P<0.01). 2 16 New Zealand rabbits were divided into two groups randomly. In experimental group, para-orbital soft-tissue expansion were given before orbital osteotomies and medial translocation; in the contrast experimental group without soft-tissue expansion. 12 weeks after the correction operation, IOD and healing of the bone between orbital were studied with gross measurement, X-ray, and histological examination before and after operation and 12 weeks later.In experimental group, para-orbital soft-tissue expansion were given before orbital osteotomies and medial translocation. 30ml tissue expanders with remote reservoir domes were used in all instances. Put the expanders under periosteum around the orbit. Inflation begins after operation, the amount of fluid injected is individualized about 30 ml. Orbital osteotomies and medial translocation 2 weeks after the last inflation.The interorbital distance were decreased 14.6 nm on average. At the 12th week after correction operation, the IOD of the para-orbital soft-tissue expansion group were 15.3mm and were 18.5 mm in the other group on average. There is significant difference in statistics (P<0.01). More new bone were observed in the non-soft-tissue-expansion group. Conclusion1 There is significant relapse of the IOD after the orbital osteotomies and medial translocation by combined intracranial-extracranial approach in rabbit models.2 The para-orbital soft-tissue expansion technique may be an effective technique for the stability of the corrected IOD in orbital hypertelorism.Lack of soft tissue around orbit can result in relapse after hypertelorism correction. The para-orbital soft-tissue expansion technique may help prevent the relapse of orbital hypertelorism after correction.