論文

The authors placed titanium mesh cages to achieve posterior atlantoaxial fixation in five patients with atlantoaxial instability caused by rheumatoid arthritis or os odontoideum. A mesh cage packed with autologous cancellous bone was placed between the C-1 posterior arch and the C-2 lamina and was tightly connected with titanium wires. Combined with the use of transarticular screws, this procedure provided very rigid fixation. Solid fusion was achieved in all patients without major complications. The advantages of this method include more stable fixation, better control of the atlantoaxial fixation angle, and reduced donor-site morbidity compared with a conventional atlantoaxial arthrodesis in which an autologous iliac crest graft is used.

We fabricated the Hydroxyapatite(HAp)-PMMA hybrid material having mechanical properties similar to those of the cortical bone, using porous HAp ceramics with well-controlled pore sizes and bulk polymerization of MMA monomer without solvents. The histological results showed that the present hybrid material bonded directly to bone without intervening fibrous tissue between hybrid material and newly formed bone, and that a large amount of new bone was formed around the hybrid material. In addition, the results of in vitro evaluation also showed that the hybrid material in the present investigation has good biocompatibility.

We retrospectively analyzed neurological signs of 106 patients with cervical myelopathy caused by single-level soft disc herniation. Neurological signs that were intensively analyzed were deep tendon reflexes, the uppermost level of impaired pinprick sensation, the uppermost weak muscle, and region of numbness in the bands. Characteristic signs for each intervertebral level were deduced, and sensitivity, specificity, and accuracy of these signs were calculated. Deep tendon reflexes were specific signs for each intervertebral level, although not as sensitive as the neurological signs. Muscle weakness and pinprick sensation were neither sensitive nor specific. Hand numbness was moderately sensitive and specific. On the whole, there was no neurological sign that was both highly sensitive and specific for an intervertebral level, and therefore, neurological level diagnosis in cervical myelopathy should be performed comprehensively according to more specific signs, i.e., deep tendon reflexes and hand numbness.