Design of a fixture for precise perpendicular cuts in bone-implant sample preparation

Accurate specimen preparation is essential for biomechanical push-out testing of bone–implant interfaces. A common source of error arises when implants such as pins or screws are not cut exactly perpendicular to their axis. This results in oval or irregular cross-sections that compromise the validity of mechanical testing. In this study, we present a newly developed holder designed to ensure perpendicular sectioning of bone-anchored implants. Titanium pins coated with tricalcium phosphate (TCP) and GB14 were implanted in rabbit condyles and prepared for thin-section analysis using the Donath method. The roundness of implant cross-sections was quantitatively assessed with ImageJ (FIJI 1.53t) based on circularity and aspect ratio parameters. Compared with conventional freehand sectioning techniques, which exhibited a roundness of 0.83 ± 0.06 and an aspect ratio of 1.22 ± 0.09, the novel holder achieved markedly improved geometrical accuracy, with a roundness of 0.99 ± 0.002 and an aspect ratio of 1.003 ± 0.002. This difference was statistically significant (p < 0.01). These results demonstrate that the device effectively minimizes geometric artifacts during sample preparation, thereby enhancing reproducibility and reliability in subsequent biomechanical testing. Although the validation was limited to rabbit condyles, the holder is a simple and versatile instrument with the potential for application across different implant types and experimental models.