Experimental study of osteoplastic laminectomy in the lumbar spine of rabbits.

Osteoplastic laminectomy has been used to treat lumbar canal stenosis and to prevent postoperative lumbar spinal instability by reconstructing the posterior element of the lumbar spine, which has been documented in many clinical studies. However, the biological sequence of repairing the posterior lumbar element, which is replaced at the time of surgery, has not yet been made clear. An in vivo rabbit study was designed to observe the biological sequence of repairing the replaced posterior element of the lumbar spine. Twenty-one adult rabbits underwent osteoplastic laminectomy at the L6. Animals were killed at 2, 4, 8, 12, 26, and 52 weeks after surgery. The samples of the L6 vertebra, which contained the replaced lamina and spinous process, were analyzed by radiography, computed tomography (CT), and a histological method. Overall, radiograms demonstrated clearly the union of interarticular osteotomized sites from 4 to 8 weeks. CT findings revealed that the union of interarticular osteotomized sites could be confirmed beginning at 12 weeks, and that postoperative narrowing of the lumbar spinal canal had not occurred in the rabbit model. The biological sequence of repairing the replaced lamina and spinous process was characterized by slowly progressive creeping substitution, with continuous remodeling.