Postoperative long-term follow-up studies were conducted on patients with cervical myelopathy. We described clinical observations on operated 135 cases and computed-assisted myelographycal observations on 98 cases who were followed for more than 6 months. The final follow-up results were excellent in 34%, good in 33%, fair in 23%, poor in 4%, unchanged and worsened in 6%. Long-term results were influenced by the factors including the duration of the history and progression type of the disease, but not by spinal cord area measured from preoperative computed-assisted myelography.
Postoperative evaluation was performed on fifty-two patients with the ossification of the posterior longitudinal ligament (OPLL) after decompressive laminectomy or anterior decompression and fusion. OPLLs with cervical cord trauma showed poor results, thus these cases had better be excluded.Twenty-one cases with posterior approach gained 48.4% recovery rate, and eigteen cases with anterior approach 51.7%.In severe narrow cases (narrow ratio>40%), posterior decompressive laminectomy was performed on eighteen cases and anterior decompression under microscopy on four cases.Four anterior cases gained 58.5% recovery rate, whereas 18 posterior cases 48.7%.Anterior resection of OPLL and fusion was a good procedure for compressive myelo pathy due to OPLL, especially cases with kyphosis or cases with locally located big OPLL.In order to perform this operation safely, it is essential to use the microscopy during operation.
Retrospective review.To describe a safe and effective surgical procedure for old distractive flexion (DF) injuries of the subaxial cervical spine.Surgical treatment is required in old cases when a progression of the kyphotic deformity and/or persistent neck pain and/or the appearance of new neurological symptoms are observed. Since surgical treatment is more complicated and dangerous in old cases than in acute distractive-flexion cases, the indications for surgery and the selection of the surgical procedure must be carefully conducted.To identify a safe and effective surgical procedure, the procedure selected, reason(s) for its selection, and associated neurological complications were investigated in 13 patients with old cervical DF injuries.No neurological complications were observed in nine patients (DF stage 2 or 3) who underwent the anterior-posterior-anterior (A-P-A) method and two patients (DF stage 1) who underwent the posterior method. It was initially planned that two patients (DF stage 2) who underwent the P-A method would be treated using the Posterior method alone; however, anterior discectomy was added to the procedure after the development of a severe spinal cord disorder.The A-P-A method (anterior discectomy, posterior release and/or partial facetectomy, reduction and instrumentation, anterior bone grafting) is considered to be a suitable surgical procedure for old cervical DF injuries.
Laminoplasty by splitting the spinous process is an established treatment procedure for patients with cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL). We have used a hydroxyapatite spacer as an intraspinous spacer since February, 1991 and evaluated its bonding to the split lamina by computed tomography. Sixty patients (47 men, 13 women) underwent laminoplasty by splitting the spinous process. Their mean age at the time of surgery was 60 years, and the follow-up period ranged from 4 to 28 months (mean 15 months). The spacer has a hole and was fixed to the spinous process using two silk threads. Approximately 10% of spacers showed ossification and 20% showed sclerotic changes between the spacer and lamina. Only three cases showed obvious displacement of the spacer but they had no problems clinically. All other cases had a stable fixation.
In the case of ultrasonic welding of metal specimens, the vibration direction of welding tip is parallel to specimen surfaces.The weld strength by ultrasonic welding is directly affected by specimens vibration characteristics.The purpose of the study is to measure directly the vibration distribution of welding specimens, and to show clearly the effects of specimens vibration and fatigue fracture by vibration on the weld strength.The automatic vibration amplitude and phase distribution measuring equipment with X-tal cartridge is used. The vibration amplitude and phase distributions are measured with aluminum specimens (thickness=0.5 & 1.0 mm), and welding tip amplitude 0.5, u is used.The results obtained are as follows;1) Specimen length has direct affects on the weld strength, when the specimens are at anti-resonance condition of longitudinal vibration and the weldment is a vibration node.2) The vibration distributions of welding specimens measured are complex and with rather small vibration amplitude, except the case at resonance or anti-resonance condition of longitudinal and bending vibration of specimens with large amplitude.3) The vibration amplitude of longitudinal and bending mode at welding becomes so large as to cause vibration fatigue fracture of specimens.
The authors have devised an original type of ultrasonic power accumulator using a directional converter which has a two-or three-dimensional coupling mode of vibration. We experimented with this ultrasonic power accumulator using an R-L type directional converter. We then conducted experiments to determine the accumulation characteristics of ultrasonic power. We have confirmed that this ultrasonic power accumulator can produce a large quantity of ultrasonic power by summarizing the output power of several transducers.
In order to obtain an ultrasonic power propagating through an ultrasonic transmission line, standing wave ratios of the longitudinal vibration are measured with a toroidal magnetic type vibration detector. A new power measurement technique is also proposed in which the particle velocity and the force at a nodal point are measured with the same detector. These results are compared with the powers measured by the power meter method. An ultrasonic power propagating in a bending vibration bar is also measured.
This is a clinical study of the surgical treatment of tuberculous spondylitis in the past ten years. In principle, radical debridement and anterior spinal fusion with bone grafting has been done in our center; but as circumstances demand, posterior fixation with instrumentation was combined. We consider that the combined surgical method is effective for the facilitation of bone fusion and the stabilization of anterior spinal fusion in cases of more than 3 vertebral bodies involved, for the maintenance of corrected angle in cases of high degree kyphosis, and for the early start of rehabilitation in cases of paresis.
