Medpor Motility Coupling Post: a rabbit model.

PURPOSE: To verify if a Medpor porous polyethylene orbital implant (PPOI) (Porex Surgical, Atlanta, GA, U.S.A.), once vascularized, will tolerate a partially exposed titanium screw on its anterior surface. METHODS: Ten New Zealand white rabbits were enucleated and given Medpor PPOIs. Eight weeks postoperatively, Medpor Motility Coupling Posts (MCPs) (Porex Surgical) were placed into the orbital implants. Clinical tissue tolerance and histologic response to the new device were noted. RESULTS: The titanium screws were well tolerated by the animals. No case of post-operative infection, conjunctival inflammation, conjunctival erosion, MCP dislocation, or PPOI fragmentation was noted. A fibrous tissue growth over the titanium head was noted in all screws with a head height of 2.5 mm. The fibrous tissue overgrowth was not observed in screws with a head height of 4 mm or more. CONCLUSION: During the 6-month observation period, all implanted Medpor MCPs demonstrated favorable tissue tolerance and stable interfaces between the MCP and the conjunctiva and between the MCP and the PPOI.

Porous polyethylene sheet implant with a barrier surface: a rabbit study.

Soft tissue adhesion to the porous polyethylene sheet implant (PPSI) raises the concern of postoperative extraocular motility disturbance after orbital blowout fracture repairs using PPSI. A PPSI with a barrier surface (PPSI-B) has been developed to reduce adhesion between soft tissue and the implant. Six PPSI-B and six conventional PPSI were implanted under the scalps of three New Zealand white rabbits. The implants were harvested at 2-, 4-, and 20-week intervals. Clinical and histologic comparisons were made between PPSI-B and PPSI with regard to adhesion at the soft tissue-implant interface. Clinically, PPSI-B demonstrated less adhesion between soft tissue and implant compared with the conventional PPSI. Both types of implants demonstrated a complete fibrovascular ingrowth by 2 weeks. Because PPSI-B causes less adhesion at the soft tissue-implant interface, consideration should be given to the use of PPSI-B in repairs of orbital blowout fractures in which extraocular muscle is exposed to the implant surface.