Morphometric description of the feline tibia using three-dimensional CT

Objectives The aim of the study was to characterise the three-dimensional external and internal morphology of the feline tibia, including bone length, external and internal diameters, cortical thickness, cancellous bone volume and mechanical joint angles using CT. Methods Eight paired tibiae from adult domestic feline cadavers were evaluated using CT imaging. Morphometric parameters – including bone length, external and internal diameters, cortical thickness, cancellous bone volume and mechanical joint angles – were measured in triplicate for each bone. The mean of each set of triplicate measurements was recorded for analysis. Results Overall tibia length measured 111.61 mm (95% confidence interval [CI] 107.89–115.53). The narrowest internal bone diameter mediolaterally was at 50% tibial length (4.23 mm, 95% CI 4.05–4.42) and craniocaudally at 75% tibial length (3.77 mm, 95% CI 3.57–3.97). The cranial and caudal cortex was thickest at 50% of tibial length. The proximal tibia had a mean cancellous bone volume of 12.45 mm 3 (95% CI 11.4–13.49). The distal tibia had a mean cancellous bone volume of 2.09 mm 3 (95% CI 1.62–2.55). Mean mechanical joint angles were as follows: tibial plateau angle 31.42° (95% CI 30.09–32.75); mechanical medial proximal tibia angle 95.15° (95% CI 94.63–95.68); mechanical medial distal tibia angle 94.08° (95% CI 93.36–94.79); mechanical cranial distal tibia angle 88.68° (95% CI 87.04–90.32); mechanical caudal proximal tibia angle 58.53° (95% CI 57.20–59.86); and sagittal plane alignment 30.16° (95% CI 28.47–31.84). Conclusions and relevance The use of CT allowed for the estimation of internal bone morphometry and joint geometry in feline tibiae. This provided data that may be valuable in planning and developing new techniques for internal fracture fixation in cats.