Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA.
J Morphol. 2024 Jan;285(1):e21660. doi: 10.1002/jmor.21660.
Sesamoid bones are ossified structures that are embedded in tendons near articulation. They consist of an inner trabecular bone architecture surrounded by a thin cortical shell. While the formation of sesamoid bones is probably mainly controlled by genetic factors, the proper development and mineralization of a sesamoid bone depends also on mechanical stimulation. While most sesamoid bones are not loaded directly by other bones during locomotion, they still experience forces directed from the tendon in which they are embedded. In cases when the sesamoid bone is experiencing forces only from a single tendon, such as the cyamella in the rabbit, this may give us a tool to study bone functional adaptation in a relatively simple loading setting. This study investigates the internal trabecular architecture of the popliteal sesamoid bone (cyamellae) in New Zealand white (NZW) rabbits (Oryctolagus cuniculus). Five hind limbs of NZW rabbits were micro-computed tomography scanned and the cortical and trabecular architectures of the cyamellae were evaluated. The results revealed that similar to the patella, the cyamella has a thin cortex and a high trabecular bone volume fraction (BV/TV), which is derived mostly from the high trabecular thickness (Tb.Th). Trabecular BV/TV and Tb.Th were not distributed homogeneously, but they were lower at the periphery and higher closer to the proximal and middle of the cyamella, near the musculotendinous junction. The results also demonstrated that trabeculae tend to align along two recognizable orientations, one with the direction of tensile stresses, in line with the popliteal tendon, and the second bridging the narrow space between the cranial and caudal cortical faces of the bone.
籽骨是嵌入关节附近肌腱中的骨化结构。它们由内部的小梁骨结构组成，周围是一层薄的皮质壳。虽然籽骨的形成可能主要受遗传因素控制，但籽骨的适当发育和矿化也依赖于机械刺激。虽然在运动过程中大多数籽骨不会直接受到其他骨骼的负荷，但它们仍然会受到来自嵌入其中的肌腱的力的作用。在籽骨仅受到来自单个肌腱的力的情况下，例如兔子的籽骨，这可能为我们提供了一种在相对简单的加载环境中研究骨骼功能适应的工具。本研究调查了新西兰白兔（Oryctolagus cuniculus）的腘籽骨（籽骨）的内部小梁骨结构。对 5 只新西兰白兔的后肢进行了微计算机断层扫描，并对籽骨的皮质和小梁骨结构进行了评估。结果表明，与髌骨相似，籽骨具有薄的皮质和高的小梁骨体积分数（BV/TV），这主要来自高的小梁厚度（Tb.Th）。小梁 BV/TV 和 Tb.Th 分布不均匀，但在籽骨的外围较低，在靠近肌-腱连接的籽骨近端和中部较高。结果还表明，小梁倾向于沿着两个可识别的方向排列，一个与拉伸应力的方向一致，与腘肌腱一致，另一个则在骨的颅侧和尾侧皮质面之间的狭窄空间中形成桥接。
