Our results suggest that the bone mineral distribution of the proximal tibia is directly affected but lumbar BMD is not influenced by the local mechanical stress around the knee with medial compartment OA.

We investigated lordotic alignment and posterior migration of the spinal cord following en bloc open-door laminoplasty for cervical myelopathy. Fifty-five patients (32 men and 23 women) were studied, with an average follow-up of 2.4 years. Radiological examination included evaluation of lordosis of the cervical spine and spinal cord, degree of enlargement of bony spinal canal, and the magnitude of posterior cord migration. We also correlated these changes with neurological improvement. Postoperatively, there was an average of 5% loss of cervical spine lordosis (P > 0.01) on radiographs and 12% reduction in the lordotic alignment of the spinal cord (P > 0.05) on magnetic resonance imaging. Postoperatively, the size of the bony spinal canal increased by 48%. Posterior cord migration showed a significant correlation with the preoperative cervical spine and spinal cord lordosis (P < 0.05). Thirty-seven (67%) patients with neurological improvement exceeding 50% showed significant posterior cord migration following laminoplasty compared with those demonstrating less than 50% improvement (P = 0.01). Our results suggest that a significant neurological improvement is associated with posterior cord migration after cervical laminoplasty.

This paper describes 27 patients who had a spinal fracture and underwent an anterior or a posterior spinal decompression, with or without spinal instrumentation, for late neuro logical compromise secondary to post-traumatic vertebral collapse associated with osteo porosis. Five males and 22 females were studied, with an average follow-up of 3.7 years. The patients developed delayed neurological compromise due to osteoporotic vertebral collapse 1 month to 1. 5 years following insignificant spinal fractures. Abnormal hypermo bility at the collapsed spinal level with gradual retropulsion of fracture fragments into the spinal canal appeared to contribute to late paralysis. This pathology is treated surgically either anteriorly or posteriorly, but we recommend transpedicular posterolateral decom pression and stabilization with a screw-rod construct because of technical ease and minimum invasion.

The long term effects of laminoplasty on cervical movement and alignment were investigated by radiography and CTscans in a study of 56 patients with multisegmental myelopathy who had undergone a C3 to C7 open-door laminoplasty. Follow up averaged 5.8 years. Satisfactory neurological improvement occurred in 73%. Cervical flexion decreased by 35% and extension by 57%; the decrease of both movements was statistically significant. Decreased vertebral slip, as well as slightly reduced lordosis, was seen after operation. Increase in measured canal size after operation and at follow up was 48% and 40%; 8% of the expanded canal size was lost at the last follow up. Expansive open-door laminoplasty leads to a better neurological prognosis in this group of patients, while maintaining an increase in canal size and preserving spinal stability. R6sum& Les effets gt long terme de la laminoplastie sur la mobilitd et l'alignement du rachis cervical ont dtg dtudids par radiographie et tomodensitomitrie. Le travail a portd sur 56 patients atteints de myilopathie spondylitique multisegmentaire, ayant subi une laminoplastie ouverte C 3 -C 7 avec une greffe osseuse rdalisant un espaceur autogkne. Le recul est en moyenne de 5.8 ans (de 2 ~ 10.4) et les rdsultats ont montrd une amdlioration neurologique satisfaisante darts 73% des cas. La flexion itait diminude de 35% et l'extension de 57%. Cette diminution de la mobiReprint requests to: H. Baba lit~ dtait statistiquement significative. On a dgalement observd une rdduction du glissement vertebral et une ldg~re rdduction de la lordose. L'augmentation de la taille du canal apr~s l'intervention chirurgicale dtait de 48% et de 40% au dernier examen; glce moment elle avait disparu dans 8% des cas. Les laminoplasties ouvertes dtendues assurent un meilleur pronostic neuroIogique chez les patients atteints de spondylite multisegmentaire en maintenant la taille du canal et en prdservant la stabilit~ vert~brale.

We investigated quantitative changes in spinal cord motoneurons following chronic compression using a mouse model of cervical cord compression. Twenty-five tip-toe-walking Yoshimura (twy) mice with calcified mass lesions compressing the spinal cord posterolaterally at the C1-C2 vertebral levels were compared with five Institute of Cancer Research (ICR) mice that served as controls. Spinal cord motoneurons in the anterior grey horn between the C1 and C3 spinal cord segments were Nissl-stained and counted topographically and then analysed in relation to the extent of spinal cord compression. The number of motoneurons in C1-C3 spinal cord segments decreased significantly with a linear correlation with the transverse area of the spinal cord when the cord was compressed to 50-70% of control values. A significant reduction in the number of motoneurons occurred at the C2-C3 spinal cord segment compressed at the C1-C2 vertebral level. In contrast, at the level rostral to the C1 vertebra, the number of motoneurons increased significantly in proportion to the magnitude of compression. The current study demonstrates that a number of neurons, morphologically consistent with anterior horn cells, were observed at a rostral site absolutely free of external compression where no such cells normally exist.

No abstract

We examined the morphology of spinal accessory motoneurons and immunoreactivity to neurotrophins, brain-derived neurotropic factor (BDNF) and neurotrophin (NT)-3, as well as the presence of reactive astrocytosis in 70 tiptoe walking Yoshimura (twy) mice that develop calcification at C1-C2 vertebral level compressing the spinal cord. At the level of compression, the area of neuronal soma and total length of dendrites of wheat germ agglutinin-horseradish peroxidase (WGA-HRP)-labelled accessory motoneurons in the medial cell pool decreased significantly with decrement in motoneuron population, relative to the control. In contrast, at sites rostral to the compressive lesion, a significant enlargement of the neuron soma and dendritic elongation were noted, associated with increased motoneuron population and decreased transverse area of the cord at the level of compression. At this site, enhanced BDNF and NT-3 immunoreactivities were evident in the anterior horn cells. In mice with a more severe degree of compression, astrocyte-like cells showing BDNF immunoreactivity became abundant and axons in the anterior column demonstrated a marked NT-3 immunoreactivity. Our results suggest increased functional activity of anterior horn cells at levels rostra] to the site of compression. We speculate that the presence of BDNF and NT-3 in neurons and astrocyte-like cells is proportionate to the severity of chronic mechanical compression and may contribute to the heterotropic neuronal reserve and survival.

We describe a technique for microsurgical widening of the nerve root canal in the lumbosacral spine. We also report our early results in 31 patients (19 men and 12 women; average follow up, 3.2 years) with such foraminal stenosis but without osseous defects in the pars interarticularis and/or spondylolisthesis. The affected nerve root was decompressed by interlaminar medial foraminotomy followed by lateral laminotomy and foraminotomy using a microsurgical technique. The procedure aimed at preserving bony continuity of the pars interarticularis and segmental motion. Neurological results showed a favourable improvement of radicular symptoms and of intermittent claudication. The need for segmental fusion at the operated segment was excluded in 30 patients, but one patid.t subsequently required a transpedicular screw procedure with bone grafting. We recommend the present technique for effective decompression of the nerve root within the neural foramen, simultaneously maintaining lumbar spine mobile function.