Study of Osteoplastic Laminectomy with Lag Screws

The purpose of this study is to evaluate the clinical outcome of osteoplastic laminectomy applied to space occupying lesions in the spinal canal. Osteoplastic laminectomy was performed in 14 patients, of which 4 were diagnosed with spinal cord tumor, 3 with cauda equina tumor, 3 with lumbar disc herniation, 1 with extradural arachnoid cyst, 1 with extradural granulation, 1 with arterio-venous malformation, and 1 with L3 burst fracture. Operative procedures were 1) osteotomy of the bilateral interarticular parts and spinous processes using a threadwire saw, 2) removal of the lamina, 3) resection of the intracanal lesion, and 4) fixation of the posterior element with lag screws.The average recovery rate of the clinical score was 29% in 2 cases of thoracic myelopathy, and 67% in 12 cases of lumbar symptoms. The lesions expanding up to 107% of the longitudinal diameter or 123% of the lateral diameter in the spinal canal could be resected under an excellent visual field. Oblique radiographs of the lag screws showed that congruity of the osteotomy site strongly correlated (p=0.03) to positioning all threads in the anterior part. The screw tips in L5 were loosened because of osteoporosis and the lowest mobile segment.