Magnesium is a highly promising candidate with respect to its future use as a material
for resorbable implants. When magnesium degrades, hydrogen gas is released. High doses
of gas emergence are reported to impair osseointegration and may therefore lead to
fixation failure. The successful delay and reduction of the degradation rate by applying
plasma electrolytic oxidation (PEO) as a post processing surface modification method
for magnesium alloy has recently been demonstrated. The aim of this study was thus
to compare the degradation behavior of a WE43-based plate system with and without
respective PEO surface modification and to further investigate osseointegration, as
well as the resulting effects on the surrounding bony tissue of both variants in a
miniature pig model. WE43 magnesium screws and plates without (WE43) and with PEO
surface modification (WE43-PEO) were implanted in long bones of Go spacing diaeresis
ttingen Miniature Pigs. At six and twelve months after surgery, micro-CT and histomorphometric
analysis was performed. Residual screw volume (SV/TV; WE43: 28.8 +/- 21.1%; WE43-PEO:
62.9 +/- 31.0%; p = 0.027) and bone implant contact area (BIC; WE43: 18.1 +/- 21.7%;
WE43-PEO: 51.6 +/- 27.7%; p = 0.015) were increased after six months among the PEO-modified
implants. Also, surrounding bone density within the cortical bone was not affected
by surface modification (BVTV; WE43: 76.7 +/- 13.1%; WE43-PEO: 73.1 +/- 16.2%; p =
0.732). Intramedullar (BV/TV; WE43: 33.2 +/- 16.7%; WE43-PEO 18.4 +/- 9.0%; p = 0.047)
and subperiosteal (bone area; WE43: 2.6 +/- 3.4 mm2; WE43-PEO: 6,9 +/- 5.2 mm2; p
= 0.049) new bone formation was found for both, surface-modified and nonsurface-modified
groups. After twelve months, no significant differences of SV/TV and BV/TV were found
between the two groups. PEO surface modification of WE43 plate systems improved osseointegration
and significantly reduced the degradation rate within the first six months in vivo.
Osteoconductive and osteogenic stimulation by WE43 magnesium implants led to overall
increased bone growth, when prior PEO surface modification was conducted.
