Experimental Study On Bone Regeneration After Laminectomy And The Establishment Of The Lumbar Spinal Stenosis Animal Models

It has been more than 120 years since the laminectomy being used in the clinic and the spinal stenosis after the laminectomy has already been observed and reported. However, the mechanism of this phenomenon is not known as much as the people think. Seldom experiment on this problem was carried out and there was dispute between the correlated researchers. The mechanism of the bone regeneration after laminectomy is important to the understanding of pathological progress and the treatments. And the bone regeneration could be take advantage in establishing the degenerative spinal stenosis animal models, supporting the study of that very disease as well. Besides, when study the spinal stenosis the actuary measurement of the spinal area was essential. This essay also explode how to use Photoshop to do those jobs such as measuring the area, angles and distance.1. The application of Photoshop to medical image measurementObjective: To apply Photoshop to the measurement of the medical images, and test its accuracy.Methods: 50 lumbar spinal CT and 50 kyphosis X-ray were measured by the traditional manual way, Photoshop CS2 and Image-Pro Plus 6.0 separately. Sagittal diameters of vertebral canals (L4/5) and kyphosis angles gained by the 3 methods were compared with two way ANOVA using SAS8.02 to study is there any Besides, the 2 software were used to measure the areas of the vertebral canals (L4/5) and the results were paired and carried out t test, to study is there any obvious statistical difference between the results. Results: No obvious statistical difference was found in the measurements of distance and angle between the 3 methods (P>0.05) ; No obvious statistical difference was found in the measurements of area between the 2 software (P>0.05) .Conclusion: It is an easy and accurate way to apply Photoshop to the medical image measurements, it also provides a new idea and choice.2. Experimental study on bone regeneration after laminectomyObjective: To explore the mechanism and aftereffects of bone regeneration after laminectomy in the rats.Methods: The SD rats receiving L₅ laminectomy as the experimental group were evaluated by examinations of sensory and motorial functions as well as radiological and pathological methods with those of the control group. The results were analyzed by computer.Results: The pathological examination showed that fibrous tissue appeared at the defect after laminectomy firstly, then the cancellous bone regenerated in the form of endochondral ossification while the cortical bone in intramembranous ossification from the resection margins, besides, chondral bone islands emerged in the fibrous tissue and then ossificated and formed laminae. The measurement of L₅ spinal canal area 16 weeks post the operation showed that the regeneration had the spinal canal area diminished by 15.6% (P<0.05) , meanwhile, obvious intermittent claudication occurred in the experimental group (P<0.05) . SEP latent periods increased and amplitudes decreased obviously in the experimental group (both P<0.05) , showing damage to the sensory function of the lower limbs.Conclusion: The bone regeneration resulting in stenosis after laminectomy consists of both bone regeneration from the defect margins and the chondral islands ossification in the fibrous tissue. 3. The establishment of the lumbar spinal stenosis animal models by laminectomy and bone particles replanting in-situObjective: To explore a simple and effective method of making the animal models of lumbar spinal stenosis.Methods: Took SD rats as experimental animals, group B were performed laminectomy on L₅, group A received autogeneic bone transplantation in-situ after L₅ laminectomy. All these rats together with control group(group C) were evaluated by examinations of motorial functions ( BBB score and the distance before the intermittent claudication) and SEP to observe the evidence of stenosis as well as radiological and pathological examination to observe and measure the stenosis. The data was analyzed statistically to examine the effect of the models.Results: Both group A and B showed obvious bone regeneration and stenosis, especially group A. The BBB scores of group A and B recovered to normal level 2 and 1 week after the operation (P>0.05) . Group A had the shortest mean distances (P<0.05) before intermittent claudication 16 weeks after the operation, decreasing by 42.9% while group B decreasing by 17.1% in contrast with group C (P<0.05) . Both SEP of group A and B was damaged obviously (P<0.05) with decreased sensory function of the hints. And group A was the worst (P<0.05 ) . Besides, the L₅ vertebral canal cross-sectional mean area of group A was the smallest (P<0.05) in the 3 groups, decreasing by 34.1% while group B decreasing by 18.2% compared with that of group C (P<0.05) according to the pathology, meanwhile, the X-ray, CT and MR of L₅ also showed bone regeneration and stenosis in group A and B.Conclusions: The laminectomy and bone particles replanting in-situ is an easy and effective method of making the animal models of lumbar spinal stenosis.