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. 2025 Nov 11:13:1675881.
doi: 10.3389/fbioe.2025.1675881. eCollection 2025.

Calcium hydroxide coating for orthopedic implants: evaluation of osseointegrative and antibacterial properties in vivo

Sebastian Philipp von Hertzberg-Boelch #  1 , Andrea Ewald #  2 , Markus Meininger  2 , Julia Ludwig  2 , Fabian Vogt  2 , Jürgen Groll  2 , Maximilian Rudert  1
Affiliations

Calcium hydroxide coating for orthopedic implants: evaluation of osseointegrative and antibacterial properties in vivo

Sebastian Philipp von Hertzberg-Boelch et al. Front Bioeng Biotechnol. .

Abstract

Purpose: We evaluated the osseointegrative and antibacterial properties of calcium hydroxide-coated titanium implants in this study and compared them to uncoated implants in a rabbit model.

Methods: Coated and uncoated implants were implanted into both femora of 19 New Zealand white rabbits. After retrieval, the osseointegrative properties were compared via quantification of bone-implant contact and proportion of unmineralized bone around the implant; further, the antibacterial properties were assessed using a Staphylococcus aureus infection model. The bacterial burden on and around the implants as well as the immunoreactions of the hosts were quantified using the neutrophil percentage in the tissue and effusion from the affected knees.

Results: The bone-implant contact was significantly higher (p < 0.000) around the coated implant, whereas the proportion of osteoids was significantly higher around the uncoated implant (p = 0.001). The antibacterial effects of the coated implants were not significant. However, bacterial presence on the implant was observed in only 20% of the coated but 75% of the uncoated implants. The overall infection score indicated lower infection activities at joints with coated implants.

Conclusion: Calcium hydroxide is a promising coating for titanium implants. Our animal study demonstrates the improved osseointegrative properties and evidences the topical antibacterial effects of coated implants.

Keywords: antibacterial implant coating; bone–implant contact; implant osseointegration; infection model; periprosthetic infection.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
(A) Surgical situs directly after introduction of the implant. (B) X-ray after euthanasia showing the implant localization in the bone. The implants are indicated by the black arrows.
FIGURE 2
FIGURE 2
Overview of animal allocation for the experiments.
FIGURE 3
FIGURE 3
Trichrome Masson–Goldner staining of the histological sections to evaluate bone–implant contact (BIC). Overview of a slice with (A) an uncoated implant and (B) a coated implant. Magnified images of the (C) uncoated and (D) coated implants showing areas of not-yet-calcified bone (osteoid, orange) and close contact between the bone tissue (dark green, orange) and implant. Scale bars: 1 mm (A,B), 500 µm (C,D).
FIGURE 4
FIGURE 4
Distribution of neutrophil percentages observed in the tissue sections of the control knees; the vertical green line indicates the 0.35 mark, while the vertical red line indicates the derived cutoff value of 0.7.
See this image and copyright information in PMC

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