Scammell B E, Roach H I
Academic Orthopaedic Unit, Southampton General Hospital, United Kingdom.
J Bone Miner Res. 1996 Jun;11(6):737-45. doi: 10.1002/jbmr.5650110604.
We studied the endochondral ossification that occurs during the transition of soft to hard callus during fracture healing in the rabbit. During this process, parts of the cartilaginous soft callus are invaded by capillaries, and new bone is laid down onto the central unresorbed cartilage struts. We found that the chondrocytes within these cartilage struts changed phenotype and became bone-forming cells which directly replaced the central cartilage core with bone matrix. We have termed this bone "lacunar" bone to distinguish it from the "vascular" bone laid down by osteoblasts. With time the lacunar bone spread beyond the confines of the lacunae and gradually replaced all the cartilage matrix that was originally present in the early endochondral spicules. The lacunar bone could still be distinguished from the vascular bone as follows: (1) it was woven bone, whereas vascular bone was lamellar bone; (2) it contained acid phosphatase activity, whereas vascular bone did not; and (3) it had strong antigenicity for bone sialoprotein, whereas this noncollagenous protein was undetectable in vascular bone. Eventually the hard callus was resorbed and remodeled, but at an interim period of endochondral ossification the direct replacement of cartilaginous callus by the formation of lacunar bone is a rapid mechanism by which the mechanical strength of fracture callus is increased.
我们研究了兔骨折愈合过程中软骨痂向硬骨痂转变期间发生的软骨内成骨。在此过程中，部分软骨性软骨痂被毛细血管侵入，新骨沉积在中央未吸收的软骨支柱上。我们发现这些软骨支柱内的软骨细胞改变了表型，变成了成骨细胞，直接用骨基质替代了中央软骨核心。我们将这种骨称为“腔隙性”骨，以区别于成骨细胞形成的“血管性”骨。随着时间的推移，腔隙性骨扩展到腔隙范围之外，并逐渐替代了软骨内骨针最初存在的所有软骨基质。腔隙性骨仍可通过以下方式与血管性骨区分开来：（1）它是编织骨，而血管性骨是板层骨；（2）它含有酸性磷酸酶活性，而血管性骨没有；（3）它对骨唾液蛋白具有强抗原性，而这种非胶原蛋白在血管性骨中无法检测到。最终，硬骨痂被吸收并重塑，但在软骨内成骨的中间阶段，通过形成腔隙性骨直接替代软骨痂是一种快速增加骨折痂机械强度的机制。
