Abstract
Abstract: :
Purpose: To evaluate the surgical technique and potential morbidity related to secondary stainless steel posting of a previously implanted microporous implant and the enhanced motility associated with magnetic coupling of the prosthetic and the implant in an animal model. Methods: Eighteen New Zealand white rabbits underwent primary enucleation surgery of one eye with implantation of a 12 mm microporous polyethylene scleral wrapped implant (Medpor). In twelve rabbits, at 6 weeks post-surgery, a small bi-leveled incision was made in the conjunctiva and Tenon's capusule. A 2 x 4 mm stainless steel post was inserted underlying the scleral wrapped surface and embedded flush with the anterior surface of the implant. Six rabbits served as controls. Animals were evaluated weekly for complications. Four weeks after the second surgery, rabbits were fitted with a magnet-embedded, porcelain prosthesis. Eye motility was measured in lateral excursion using a photographic model. Magnetic coupling forces were determined with a hanging block technique. Rabbits were euthanized at 1 week, 1, 2, 3, 4 or 6 months after the second surgery. The integrated implant and surrounding tissues were obtained for histopathologic examination. Results: Secondary embedding of the stainless steel post within the microporous implant was accomplished without difficulty or compromise of the implant. Gross clinical evaluation showed no signs of extrusion, erosion, or infection. Orbital histopathologic features at 1,2,3,4 and 6 months disclosed no evidence of conjunctival thinning or other signs of orbital toxicity. Clinical grading documented increased movement when compared with magnetically non-integrated controls. Magnetic coupling forces were noted maximally at 0.47 Newtons. Conclusion: This study establishes the surgical technique, feasibility and safety of secondary stainless steel posting into microporous implants in the rabbit model. Cosmetic enhancement of motility is documented using this magnetically integrated model. These results will provide the basis for further investigation of the potential of this technique in improving long-term motility and cosmesis in patients with previously implanted microporous implants.
Keywords: 501 orbit • 496 oncology • 610 tumors