Kazuhiro Ido

Development of bioactive bone cement and its clinical applications

This paper is a summary of already published papers on the bioactive bone cement (BA cement) which consists of CaO-SiO2-P2O5-MgO-CaF2 (AW glass-ceramic) powder and bisphenol-a-glycidyl methacrylate (Bis-GMA) resin. Two types of BA cement, dough and injection type, were prepared by changing their chemical compositions slightly. They harden in a few minutes exhibiting much lower curing temperature than PMMA cement. They have significantly higher compressive, bending, and tensile strengths than PMMA cement and have a character of bonding directly with bone in 4-8 weeks in vivo. Intercalary prosthetic replacement of the femur and total prosthetic replacement of the hip were performed in dogs using either PMMA cement or BA cement. Mechanical tests demonstrated that fixation strengths of these prostheses with BA cement increased with time and were significantly greater than those with PMMA cement tested at any time. Results of histological examinations showed direct bonding between BA cement and bone, and that the bone trabeculae around BA cement mantle grew with time, while with PMMA cement an intervening soft tissue layer was always observed at the cement-bone interface. BA cement was used in a few aged patients to install a hip prosthesis either in cases of revision or femoral neck fracture. The longest follow-up period of the patient is 4 yrs. The patients have been doing well with no adverse effect of the cement to date.

Multiple thoracic disc herniations: case report and review of the literature

The incidence of intervertebral disc herniation in the thoracic region of the spine is much less than in the cervical or lumbar areas, and multiple thoracic disc herniations are rare. We described a 33-year-old man with two-level thoracic disc herniation, who exhibited features of spinal cord compression. Magnetic resonance imaging and computed tomographic myelography demonstrated anterior compression of the spinal cord due to disc herniation at T4/5 and T7/8 levels. Through an anterolateral approach, these discs were removed and interbody fusion was performed using autogenous bone grafts. Excellent results were obtained.

Ependymoma of the spinal cord and the cauda equina region.

Ependymomas are the most common glial tumors of the spinal cord, including the conus medullaris, filum terminale, and cauda equina. This study involved eight ependymomas of the spinal cord encountered during a 29-year period (1968-1996). The male:female ratio was 1:1.7, and the mean age at diagnosis was 33.7 years (range, 13-55 years). The outcome was studied in relation to initial presentation, initial therapy, location of tumor, histology of tumor, and gender after a follow-up period ranging from 2-16 years (mean, 113 months). Complete removal was achieved in six patients. Two patients received postoperative irradiation after partial removal. Histological examination revealed a benign ependymoma in all patients. Patients undergoing gross total excision at initial operation had excellent or good outcomes. We conclude that ependymomas of the spinal cord should be removed completely, if possible. Spine surgeons should be aware of the disease, and magnetic resonance imaging should be used in its detection.

Cementless total hip replacement. Bio-active glass ceramic coating studied in dogs.

We studied 2 types of a cementless total hip prosthesis in dogs. Both were coated with titanium plasma-spray. In both components, the pores in the deep layer of 1 group were further coated with apatite and wollastonite containing glass-ceramic (AW glass-ceramic). 50 dogs underwent unilateral total hip replacements, and were killed at 1, 3, or 6 months postoperatively. We evaluated the femoral and the acetabular components mechanically and histologically. At 1 month, the detaching load and bone ingrowth of the AW glass-ceramic-coated femoral and acetabular components were higher than those of the control implants. At 3 and 6 months there were no differences between the 2 types of components. Thus, AW glass-ceramic enhanced the early phase of cementless implant fixation.

Chylous leakage after circumferential thoracolumbar fusion for correction of kyphosis resulting from fracture. Report of three cases.

Study Design. A description of the clinical picture of chylous leakage after spinal surgery. Objectives. To present the clinical course of three cases of chylous leakage after spinal surgery and to discuss the pathogenesis of the disease. Summary of Background Data. Chylous leakage is a rare complication after spinal surgery. It has been attributed to direct injury of a lymphatic trunk or one of its major tributaries by surgical maneuver. Methods. Three cases of chylous leakage after circumferential thoracolumbar fusion for correction of kyphosis resulting from fracture were reported. Results. All of the three cases were managed successfully; two cases of chyloretroperitoneum detected within 4 days after surgery were healed conservatively, but one case of chylothorax, of which the onset was noticed 5 weeks after spinal surgery, required surgical ligation of the thoracic duct and pleurodesis. Conclusion. Early detection of this disease is important for a good prognosis. Retroperitoneal drainage is necessary for the detection and management of chyloretroperitoneum. The pathogenesis and management of the chylous leakage are discussed in this report.

Suction/irrigation for deep wound infection after spinal instrumentation: a case study

Deep wound infection after spinal instrumentation is a serious complication that is difficult to treat without removing the instruments and bone graft. Debridement and suction/irrigation is an effective method of treatment in these cases. It was performed on six patients in our department who developed this complication between 1985 and 1994. Four patients with early post-operative infection were cured by this method without removing the instruments and bone graft, and two patients with delayed post-operative infection were cured by this method with instrument removal. Debridement and suction/irrigation is a useful method of treatment for both groups of deep wound infection and gives good results when performed soon after infection onset together with additional antibiotic therapy.

Correction of kyphotic deformity of the cervical spine in ankylosing spondylitis using general anesthesia and internal fixation

Surgical correction of kyphotic deformity of the cervical spine caused by ankylosing spondylitis is usually done using local anesthesia to prevent undue spinal cord compression and paralysis followed by a sudden-extension maneuver. We report a case of kyphotic deformity that was corrected while the patient was under general anesthesia. To prevent cord compression and paralysis and to obtain an accurate and gradual correction, we used a Hartshill rod prebent to the desired angle, and correction was done by tightening sublaminar wires on the rod until the lamina made full contact with it. Somatosensory evoked potential and wake-up tests were also performed. Our successful result shows that correction of kyphotic deformity of the cervical spine in ankylosing spondylitis can be done more accurately and without discomfort using the present method.

Anterior Decompression and Fusion for Ossification of Posterior Longitudinal Ligament in the Thoracic Spine

Twelve cases are reviewed of ossification of posterior longitudinal ligament (OPLL) in the thoracic spine for which anterior decompression and fusion were performed. A transthoracic approach was used in 10 patients, and median sternotomy and a transsternal approach were used in one each. The clinical symptoms and the Japanese Orthopaedic Association (JOA) score improved in 10 patients, whereas they were unchanged in two patients who underwent a revision operation for a previous laminectomy. An anterior procedure that results in adequate decompression of the spinal cord and good spinal stability is recommended for anterior lesions, such as OPLL, which compress the anterior spinal cord at each level of the thoracic spine.

Surgical treatment for ossification of the posterior longitudinal ligament and the yellow ligament in the thoracic and cervico-thoracic spine.

This study analyzed the postoperative results of surgical treatment for thoracic and cervico-thoracic myelopathy caused by ossification of the posterior longitudinal ligaments (OPLL) or ossification of the yellow ligaments (OYL) in 22 patients using magnetic resonance imaging (MRI), myelography and computed tomography (CT).Anterior procedures were performed in 11 patients for OPLL, while posterior approaches were adopted for the management of 11 patients for both OYL and OPLL combined with OYL lesions. Clinical symptoms were improved using both anterior and posterior techniques.MRI and myelo-CT studies, which show the direction of cord compression, the form and extent of the lesion, and the degree of thoracic kyphosis, are very useful when the surgical procedure for OPLL and OYL in the thoracic and cervico-thoracic spine is selected.

Considerations for surgical treatment of patients with upper lumbar disc herniations

Nine patients treated by surgery for upper lumbar disc herniations were reviewed. Of nine patients with upper lumbar disc herniations at the L1-L2 or L2-L3 level, five were treated by anterior procedures, whereas four underwent posterior procedures. Four of the five patients on whom anterior procedures were performed underwent additional spinal instrumentation using the Kaneda device and Z-plate system. Clinical symptoms improved in all nine patients. Confirmation of the type and level of disc herniation and increased thoracolumbar kyphosis must be taken into consideration when the optimal surgical procedure and spinal instrumentation method are selected.