Korean J Ophthalmol.  2005 Mar;19(1):9-17. 10.3341/kjo.2005.19.1.9.

Fibrovascularization of Intraorbital Hydroxyapatite-Coated Alumina Sphere in Rabbits

• Chung WS
• Song SJ
• Lee SH
• Kim EA

• KMID: 1099079
• DOI: http://doi.org/10.3341/kjo.2005.19.1.9

Abstract

We investigated the fibrovascular ingrowth and fibrovascular tissue maturation of hydroxyapatite-coated, porous alumina sphere (Alumina sphere) in comparison with the hydroxyapatite sphere (HAp sphere) in rabbits. Alumina spheres and HAp spheres were implanted in the left orbits of 42 New Zealand white rabbits after enucleation. Fibrovascular ingrowth and maturation were graded from 1 to 5 at postoperative 1, 2, 3, 4, 8, 12 and 24 weeks. We defined 4 phases: postoperative 1-2 weeks as phase I, 3-4 weeks as phase II, 8-12 weeks as phase III, and 24 weeks as phase IV. The grade was analyzed at each phases. There was no significant difference in fibrovascular ingrowth and maturation between the two groups at all 4 phases, except phase II at which the Alumina sphere showed significantly lower maturation grade (p< 0.05). We concluded that the Alumina sphere is an ideal orbital implant material and an ideal substitute for the HAp sphere in clinical practice.

Keyword

Alumina sphere; Fibrovascularization; Hydroxyapatite; Hydroxyapatite-coated alumina sphere; Orbital implant material

MeSH Terms

*Aluminum Oxide
Animals
*Coated Materials, Biocompatible
*Durapatite
Eye Enucleation
Female
Fibroblasts/cytology/physiology
Microscopy, Electron, Scanning
Neovascularization, Physiologic/*physiology
*Orbital Implants
Prosthesis Implantation
Rabbits
Research Support, Non-U.S. Gov't

Figure

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  Fig. 1 Scanning electron micrograph of hydroxyapatite-coated alumina sphere and hydroxyapatite sphere. (A) Hydroxyapatite-coated alumina sphere shows porosity of 90% and pore size of 500-600 µm. (B) Hydroxyapatite sphere shows porosity of 60-70% and pore size of 300-500 µm.

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  Fig. 2 Schematic diagram for grading of fibrovascular ingrowth.

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  Fig. 3 Fibrovascular maturation grades of the hydroxyapatite-coated alumina sphere. (A) Maturation grade 1 shows edematous young granulation tissue and little fibroblast proliferation (Toluidine blue stain, ×200). (B) Maturation grade 2 shows moderate fibroblast proliferation and decreased edema. (Toluidine blue stain, ×400). (C) Maturation grade 3 shows early stage of collagen fiber lay-down. (Toluidine blue stain, ×200). (D) The granulation tissue is composed of collagen fibers in almost all areas in grade 5. (Toluidine blue stain, ×200).

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  Fig. 4 Fibrovascular maturation grades of the hydroxyapatite sphere (hematoxylin-eosin stain, ×200). (A) Maturation grade 2 shows fibroblast proliferation and capillary development in the edematous stroma. A few neutrophils are present. (B) Collagen fiber lay-down is initiated in grade 3. (C) Marked increase of collagen is noted in grade 4. (D) In grade 5, there is compact growth of collagen fibers.

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  Fig. 5 Hydroxyapatite-coated alumina sphere at postoperative 1 week. (A) Fibrovascular ingrowth accounts for about 20% of the radius of implant in grade 1 (periphery of the implant, Toluidine blue stain, ×40). (B) Fibroblasts begin to proliferate in grade 1 (Toluidine blue stain, ×200).

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  Fig. 6 Hydroxyapatite-coated alumina sphere at postoperative 2 weeks. (A) Fibrovascular ingrowth accounts for about 40% of the radius of implant in grade 2 (periphery of the implant, Toluidine blue stain, ×40). (B) Fibroblast proliferation is considered as grade 2 (Toluidine blue stain, ×200).

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  Fig. 7 Hydroxyapatite-coated alumina sphere at postoperative 3 weeks. (A) Fibrovascular proliferation reaches the central portion of the implant (center of the implant, Toluidine blue stain, ×40). (B) The implant shows initial stage of collagen lay-down, representing maturation grade 3 (Toluidine blue stain, ×200).

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  Fig. 8 Hydroxyapatite sphere at postoperative 1 week. (A) Fibrovascular ingrowth accounts for about 20% of the radius of implant in grade 1 (periphery of the implant, Hematoxylin-eosin stain, ×40). (B) Moderate fibroblast proliferation and considerable capillary proliferation indicates grade 2 (Hematoxylin-eosin stain, ×200).

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  Fig. 9 Hydroxyapatite sphere at postoperative 2 weeks. (A) Fibrovascular ingrowth accounts for about 60% of the radius of implant in grade 3 (periphery of the implant, Hematoxylin-eosin stain, ×40). (B) The implant shows the initial stage of collagen fiber lay-down, representing grade 3 maturation (Hematoxylin-eosin stain, ×200).

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  Fig. 10 Hydroxyapatite sphere at postoperative 3 weeks. (A) The central portion of the implant is filled with fibrovascular proliferation, representing grade 5 (center of the implant, Hematoxylin-eosin stain, ×40). (B) The granulation tissue is composed of collagen fibers in almost all areas in grade 5 (Hematoxylin-eosin stain, ×200).

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