Fifty-eight patients, all less than 25 years of age, underwent multilevel laminectomy for conditions that in themselves do not usually cause spinal deformity. Spinal deformity developed in 46% (12 of 26) of the patients who were less than 15 years of age, but in only 6% (two of 32) of the patients aged 15 to 24 years. Spinal deformity developed in all (100%) patients who had cervical laminectomy, in 36% of those who had thoracic laminectomy, and in none (0%) of those who had lumbar laminectomy. There was no correlation between the occurrence of deformity and sex, number of laminae removed, neurological conditions after laminectomy, or length of time after surgery.

The pathogenesis of postlaminectomy spinal deformity and instability in children was evaluated by reviewing appropriate roentgenographic findings. First, we reviewed spine roentgenograms of patients below 40 years of age who underwent spinal fusion for deformity and instability of the spine developing after a multiple level laminectomy. Two types of deformity were recognized on the roentgenograms: increased mobility between the vertebral bodies and wedging deformity of the ventral aspect of the vertebral bodies. Second, we did a follow-up study of another group of patients who had undergone laminectomy. We found the same two types of deformity in children, but not in adult patients. The incidence of deformity was higher after laminectomies of the cervical or cervicothoracic region than after lumbar laminectomies. Our data suggest that postlaminectomy spinal deformity can develop in children without irradiation or facet injury. The deformity is due to a wedging change in the cartilaginous portion of the vertebral body and to the viscoelasticity of ligaments in children. When treatment of this complication becomes necessary, anterior fusion may be effective in arresting progression. Prophylactic measures against the development of deformity are discussed. Our hypothesis concerning the mechanism of development of this complication supports the rationale of osteoplastic laminar resection and reconstruction instead of laminectomy, particularly in the management of children.

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This study involved 57 patients with benign extramedullary tumors of the foramen magnum (19 neurinomas, 37 meningiomas, and one teratoma), who were operated on between 1957 and 1976. The 37 meningiomas represented 3.2% of 1139 meningiomas of the neuraxis. The initial neurological examinations of about half of these patients were unremarkable. The clinical presentation of tumors of the foramen magnum frequently mimics multiple sclerosis, cervical spondylosis, intramedullary tumor, syrinx, carpal tunnel syndrome, and even normal-pressure hydrocephalus. All operations were performed through a posterior approach, and two surgical deaths (3.5%) were recorded. No surgery for recurring of tumor was recorded. The follow-up review of 56 patients (98.2%) showed good functional results if the tumor was detected before severe neurological deficits occurred. The possible mechanism of the sensory symptoms and muscle atrophy of the hands is discussed, and the electromyographic findings are reviewed.

Influence of low-level (810nm, Ga-Al-As semiconductor) laser on bone and cartilage during joint immobilization was examined with rats' knee model. Materials and Methods:The hind limbs of 42 young Wistar rats were operated on in order to immobilize the knee joint. One week after operation they were assigned to three groups; irradiance 3.9W/cm 2 , 5.8W/cm 2 , and sham treatment. After 6 times of treatment for another 2 weeks both hind legs were prepared for 1) indentation of the articular surface of the knee (stiffness and loss tangent), and for 2) dual energy X-ray absorptiometry (bone mineral density) of the focused regions. Results and Conclusions:The indentation test revealed preservation of articular cartilage stiffness with 3.9 and 5.8W/cm 2 therapy. Soft laser treatment has a possibility for prevention of biomechanical changes by immobilization.