The effect of polyethylene orbital implant(Medpor(R)) pretreated with autogenous fibrovascular tissues in rabbits

PURPOSE: The purpose of this study is to determine whether partially neovascularized Medpor(R) by preplacement of implant to buttock area for one month before secondary orbital insertion demonstrates earlier refibrovascular ingrowth into implant than that in primary orbital placement. METHODS: Thirty-five rabbits were divided into two groups: Group A (15 rabbits) ; primary orbital implantation of Medpor(R)(nonvascularized) after enucleation, Group B (15 rabbits) ; secondary orbital implantation of implant (vascularized) after enucleation after harvesting implants from buttock area, inserted for one month prior to orbital implantation. Five neovascularized implants by preplacement of implant to buttock area for one month were sectioned and investigated for the fibrovascular ingrowth, expression of bFGF, and CD-31 to evaluate the influence of pretreatment. Implants from group A and B were harvested from the orbit at 1, 2, 4, 6, and 8 weeks postoperatively. The implants were sectioned and studied grossly and histopathologically. Immunohistochemical study on bFGF and CD-31 were conducted to detect the angiogenetic factor and degree of angiogenesis in both group A and B. RESULTS: The fibrovascular ingrowth and expression of bFGF and degree of angiogenesis in group B were higher than those in group A. The degrees of angiogenesis were well correlated with bFGF expression. CONCLUSIONS: This animal model may provide the basis for the future investigation of agents and structural modifications directed towards optimization of fibrovascular ingrowth into porous anophthalmic socket implants and clinically apply to enucleation for the vascular compromised patients such as in the settings of postirradiation, diabetes.

Clinical Outcome and Complications of Medpor(R) Orbital Implant

PURPOSE: This study was to observe the clinical outcome and complications of Medpor(R) orbital implant. METHODS: The clinical outcome and complications were studied retrospectively in 64 eyes with Medpor(R) implantation. Evisceration was done in 34 cases, enucleation in 19 cases, and secondary implantation in 11cases. Mean follow up period was 16 months(4~30 months) and mean age of the participants was 34.9(1~79). RESULTS: Implant infection developed in one case, implant exposure developed in four cases and superior sulcus deformity developed in two cases. Motility Coupling Post(MCP) was inserted in 26 eyes. Motility of the prosthesis was good in most cases. CONCLUSIONS: Medpor(R) orbital implant is being widely used currently. Complications or motility of the prosthesis showed no significant difference from those of Hydroxyapatite. But low cost and its handiness in operation makes it a desirable orbit implant.

Clinical Evaluation of Medpor(r) Orbital Implant

Recently the high-density porous polyethylene[Medpor(r)]has been used as a new orbital implant for the reconstruction after enucleation or evisceration to reduce the implant exposure and migration, and to increase the prosthesis motility. We performed 16 cases of Medpor(r) orbital implantation combined with enucleation, evisceration or secondary orbital implantation between November 1997 and December 1998. Then, we investigated the postoperative complication, prosthesis motility, fibrovascular ingrowth pattern into the implant and MCP[Medpor(r) Coupling Post]insertion to increase the prosthesis motility for the average of 10 months [range, 6 to 18 months]. We performed a total of 16 cases of implantation :10 cases after evisceration, 5 cases after enucleation and 1 case as secondary implantation. There were 3 cases of conjunctival dehiscence, 1 case of retrobulbar hemorrhage and 1 case of superior sulcus deformity. There were no implant exposure, migration or severe inflammation. Postoperative prosthesis motility was found in 13 cases as good, 2 cases as fair and 1 case as poor. After enucleation or evisceration, Medpor(r) orbital implantation showed no significant difference from the previous porous orbital implants in postoper ative complication, prosthesis motility and fibrovascular ingrowth into the implant. It appears to be a good orbital implant because of the lower material cost, convenience in the operative procedure and other advantages. But long-term follow-up may be necessary for the detection of clinical change, the complication of MCP insertion and for the evaluation of the fibrovascular ingrowth pattern after Medpor(r) implantation.

Clinical Effect of Porous Polyethylene (Medpor(r))Orbital Implant

Porous polyethylene (Medpor(r))implant offers several advantages over other implant materials. Its porosity allows fibrovascular ingrowth which promotes host integration, prevents migration and reduces the likelihood of opportunistic infections. The authors used the porous polyethylene (Medpor(r)) as a central orbital implant in 36 eyes of the 36 patients. They underwent enucleation (17 cases), evisceration (16 cases), and a secondary implantation (1 cases)between November 1997 and June 1999. A mean follow-up period was 8.9 months (range, 3 to 17 months). There were 5 cases of implant exposure and 4 cases of superior sulcus deformity. There were no infection of implant, implant migration, or extrusion of motility coupling post. Postoperatively, all sockets showed good to excellent motility of prosthesis. Porous polyethylene (Medpor(r))can be used successfully as an orbital implant in anophthalmic socket surgery. Its advantages over other similar implants include a significantly lower material cost and the ability to suture the extraocular muscles directly to it without the need for a covering material such as fascia or sclera.