Radiographic study of normal sheep tibial diaphysis for development and testing of new orthopedic design

The article presents the results of a radiographic study of the diaphysis’s middle of tibias of 43 adult mongrel sheep. The following parameters were determined: length (226.12 ± 13.75 mm); outer diameter in the frontal (17.68 ± 2.01 mm) and lateral (14.19 ± 1.07 mm) projections; the diameter of the medullary canal in frontal (8.71±1.72 mm) and lateral (6.43±1.11 mm) projections; the thickness of cortical plate (3.48±0.56 mm). A high correlation was revealed between the outer diameter of diaphysis’s middle and the diameter of medullary canal (in frontal projection); a noticeable correlation between the bone length and the outer diameter (in the frontal and lateral projections); a moderate correlation between the outer diameter and the diameter of medullary canal (lateral projection), the outer diameter and the thickness of cortical plate (in frontal and lateral projections), and between the bone length and the thickness of cortical plate (lateral projection). Sheep are often used in preclinical trials to develop and test implants to replace extensive defects in the diaphysis of long bones. To standardize in vivo experimental conditions, the obtained values for dimensions of anatomical structures of the mid-diaphysis of the sheep tibia allowed us to determine optimal transverse dimensions for the fabrication of the implant prototypes. It was determined that the transverse dimensions of the bone section should be based on X-ray images on the lateral projection. The transverse dimensions of implanted device should not exceed 14.19 ± 1.07 mm and should not be equal to or less than 6.43 ± 1.11 mm. Identified reference values for the mid-diaphysis dimensions of the adult sheep tibia can be used in the development, fabrication and preclinical testing of new implants for filling extensive long bone diaphysis defects in vivo.