[Experimental study on ossification of spinal ligaments in the rabbit under influence of bone morphogenetic protein]

Bone morphogenetic protein (BMP) is known to induce cartilage from mesenchymal cells in organ culture. The purpose of the present study was to determine whether spinal ligaments differentiate into cartilage when cultured with BMP. Implantation of BMP into the yellow ligament was also done to make a model of the ossification of yellow ligament. The rabbit was employed as an experimental animal. In organ culture, BMP induced new cartilage from the posterior longitudinal ligament, the yellow ligament and the supraspinous ligament. This indicates that spinal ligaments have the potential to ossify, and bone or periosteum may not have a direct relationship with spinal ligament ossification. Ossification of the yellow ligament was produced by implantation of BMP. Blood vessels are thought to have some role in the ossification of spinal ligaments. The spinal cord was compressed posteriorly by the ossified yellow ligament. This ossification of the yellow ligament resembled that of human beings and may be regarded as a useful experimental model.