The Molteno M-Sphere.
OBJECTIVE
To analyze a mammalian hydroxyapatite (HA) implant known as the Molteno M-Sphere, recently approved by the Food and Drug Administration of the United States.


METHODS
The authors examined the implant macroscopically, with chemical analysis (x-ray powder diffraction, x-ray fluorescence spectrophotometry), and microscopically with scanning electron microscopy. Animal implantation of six Molteno M-Spheres was carried out in six adult male New Zealand albino rabbits. Implant vascularization was evaluated by means of magnetic resonance imaging and histopathologic sectioning.


RESULTS
The M-Sphere was found to have multiple interconnected pores throughout with an average pore size of 300 microm to 600 microm. This implant was very light-weight (0.31 g) and fragile. It was made up of pure HA. Magnetic resonance imaging studies showed implant enhancement to its center by 4 weeks after implantation. Histopathologically, fibrovascularization occurred uniformly throughout the 4, 8, and 12-week rabbit implants.


CONCLUSIONS
The M-Sphere is an alternative type of HA implant that recently has been reintroduced into the United States for use after enucleation, evisceration, or as a secondary implant. It has multiple interconnected pores allowing central fibrovascularization as early as 4 weeks in a rabbit model. Its light weight and fine trabecular framework, however, are associated with increased implant fragility when compared with other available HA implants (BioEye and FCI3 synthetic HA). The implant requires careful handling because routine handling may damage the implant. The implant is currently approved by the United States Food and Drug Administration.
Jordan
D R
DR
Department of Ophthalmology, University of Ottawa Eye Institute, Ontario, Canada.
Hwang
I
I
Brownstein
S
S
McEachren
T
T
Gilberg
S
S
Grahovac
S
S
Mawn
L
L
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D018795:Device Approval; D017886:Durapatite / Q000737:chemistry; D015353:Eye Enucleation; D008279:Magnetic Resonance Imaging; D008297:Male; D008855:Microscopy, Electron, Scanning; D018919:Neovascularization, Physiologic; D009915:Orbit / Q000098:blood supply* / Q000473:pathology / Q000601:surgery; D020273:Orbital Implants; D019919:Prosthesis Implantation; D011817:Rabbits; D013052:Spectrometry, X-Ray Emission; D014481:United States; D014486:United States Food and Drug Administration; D014961:X-Ray Diffraction
D001672:Biocompatible Materials; D017886:Durapatite