Takeshi Arizono

Evaluation of the risk of instrumentation as a foreign body in spinal tuberculosis. Clinical and biologic study.

The risk of persistence and recurrence of infection in posterior spinal instrumentation surgery for spinal tuberculosis was studied clinically and microbiologically. Eleven patients with thoracic, thoracolumbar, and lumbar spinal tuberculosis treated by debridement, anterior fusion, and combined posterior instrumentation surgery were analyzed. Seven patients had tuberculosis in both anterior and posterior spinal elements. There were no cases of persistence or recurrence of infection after surgery, and instrumentation provided immediate stability and protected against development of kyphotic deformity. The adherence properties of Mycobacterium tuberculosis to stainless steel (SUS 316) was evaluated experimentally. The results showed that posterior instrumentation surgery was not a hazard to spinal tuberculosis infection when combined with radical debridement and intensive anti-tuberculosis chemotherapy.

Standing radiographs cannot determine the correction in high tibial osteotomy

The use of standing radiographs to determine correction angles for high tibial osteotomy is not appropriate because the relative angle of the articular surfaces (condylar-plateau angle) in the weight-bearing knee changes after the osteotomy. This may give unpredictable results postoperatively. We found that the condylar-plateau angle in postoperative standing films is very similar to that seen in non-weight-bearing supine views, and suggest that these latter radiographs be used for pre-operative planning. We describe our early results, using a special osteotomy jig, in 140 knees.

Cervical alignment, range of motion, and instability after cervical laminoplasty.

It has been reported that flexibility of the neck decreases after cervical laminoplasty. It also is known that kyphosis can be an unfavorable result after posterior decompression surgery of the cervical spine. To examine whether a decrease in cervical mobility resulting from contracture of the cervical spine helps prevent postoperative kyphotic alignment, changes in radiographic findings after cervical expansive laminoplasty were evaluated. There was a strong correlation postoperatively between range of motion of the cervical spine and cervical lordotic alignment, namely, the more that cervical mobility was maintained, the more that cervical lordosis was preserved. This relationship was not found preoperatively. A postoperative increase in the number of unstable vertebrae was found only in a few patients and was not associated with any deterioration in clinical outcome. The current results suggest that postoperative cervical lordosis is preserved not through intervertebral soft tissue contracture or bony fusion, but through more dynamic factors such as muscles or ligaments, therefore implicating the importance of early removal of cervical orthosis and early postoperative rehabilitation.

Bacterial adherence to bioinert and bioactive materials studied in vitro.

In vitro, bioinert stainless steel and titanium alloy, and bioactive sintered hydroxyapatite and hydroxyapatite-coated titanium materials were exposed to Staphylococcus epidermidis to study bacterial adhesion. Scanning electron microscopy showed that fibrous strands interconnected the adherent bacteria, and that background matrix enclosed bacterial colonies. This adherent mode of growth may reduce the susceptibility of the bacteria to host clearance mechanisms and antibiotic therapy. Adherence assays revealed that bacterial adherence to sintered hydroxyapatite was higher than to the other 3 materials.

Inhibition of bacterial adhesion by tobramycin-impregnated PMMA bone cement.

We investigated the effect of tobramycin-impregnated polymethylmethacrylate (PMMA) bone cement on the adhesion and colonization of Staphylococcus epidermidis. The pattern of colonization was quantitated using plate count techniques and electron microscopy. Colonization of the tobramycin-impregnated disc surface by adhesive bacteria was demonstrated but it was less than in the control disc. This finding suggests that tobramycin may reduce bacterial adherence and proliferation on the PMMA surface.

Increased resistance of bacteria after adherence to polymethyl methacrylate: An in vitro study

The pathobiology of total joint prosthesis infection was investigated in vitro. Discs of polymethylmethacrylate (PMMA) were exposed to a suspension containing cells of 10(8) per mL Staphylococcus epidermidis E-46. After 12 hours, exposed discs were rinsed with phosphate-buffered saline and placed in brain heart infusion broth containing antibiotics (2.5 mg per mL of Cephaloridine). After gentle shaking for 24 hours at 37 degrees C, the bacteria on the PMMA surface were detached and washed with phosphate-buffered saline to remove the antibiotics. Compared with the free bacteria which were detached from the PMMA by sonication immediately after exposure to the antibiotic solution, those allowed to remain adhered to the PMMA surface were more resistant to antibiotics. Scanning electron microscopy showed accumulation of bacteria surrounded by slime on PMMA discs exposed for 12 hours. Our results indicate that resistance of bacteria to antibiotics is increased after adherence to the biomaterial and formation of a slime layer.

A novel technique for surgical resection of spinal meningioma.

Study Design. A technical note. Objectives. To describe and discuss a novel technique for surgical resection of spinal meningioma. Summary of Background Data. With conventional methods for surgical resection of isolated intradural spinal meningioma, there are two ways of dealing with the dural attachment of the tumor. One is complete resection of the involved dura together with the tumor, and the other is coagulation only of the tumor base of the dura. In the case of the novel technique herein described, the dura mater is preserved in a new manner. Methods. In the surgical procedure a small incision is made in the surface of the dura mater after the conventional laminectomy. The spinal dura can be easily divided into two layers, comprising inner and outer layers. The outer layer is stripped away from the inner layer surrounding the tumor base. The tumor is then resected together with the inner layer alone outside the arachnoid membrane, and finally the outer layer is simply closed. Results. This method has been applied to three cases. The preserved outer layer of the dura mater did not demonstrate the existence of tumor cells histologically. Neither complications nor tumor recurrence have been experienced. Conclusion. The authors introduced a novel technique for surgical resection of isolated intradural spinal meningioma. Using this simple procedure the outer part of the dura mater, which is not involved by the tumor, can be preserved and complicated dural reconstruction is not necessary. Furthermore, there is less risk of postoperative cerebrospinal fluid fistulas than when the dura is completely resected together with the tumor. However, long-term observation as a result of the possibility of local recurrence is strongly recommended.

Ethylene oxide sterilization of bone grafts Residual gas concentration and fibroblast toxicity

We examined the concentration of ethylene oxide in bone allografts after gas sterilization. Chips of the human femoral head were investigated. Residual gas concentration was determined by gas chromatography after the bone chips had been subjected to defatting and freeze-drying, followed by ethylene oxide gas sterilization. Bones were prepared in various ways in an attempt to reduce the concentration of residual ethylene oxide. The concentration was higher when gas sterilization was performed before freeze-drying than when it was done afterwards. An experiment performed with fibroblasts showed the high toxicity of residual ethylene oxide in bone chips, even when the concentration was very low. The growth of fibroblast was reduced more in medium which had been shaken with bones sterilized with ethylene oxide before freeze-drying than in medium which had been shaken with bones sterilized after freeze-drying. The higher residual ethylene oxide concentrations resulted in a decrease in fibroblastic culture activity. Our experiment showed the importance of reducing the residual ethylene oxide gas concentration. Defatting and freeze-drying result in lower residual ethylene oxide concentrations.

Spontaneous hemarthrosis of the knee in the elderly: Etiology and treatment

The etiology of spontaneous hemarthrosis of the knee in elderly patients with osteoarthritis is still unknown. This report discusses six cases, one that was managed with conservative measures and five in which arthroscopic evaluation and treatment were performed. These patients were elderly individuals whose chief complaint was knee pain and swelling about the joint, without an obvious history of trauma. Each of the five operative patients underwent arthroscopic surgery after repeated hemorrhage into the joint that did not respond to serial aspirations of large amounts of blood and immobilization, using a knee immobilizer. The roentgenograms of each involved knee demonstrated lateral compartment osteoarthritis. Arthroscopic examination revealed a degenerative flap tear of the posterior horn of the lateral meniscus in the five operative cases. These patients underwent arthroscopic resection of the injured lateral meniscus and did not experience a recurrence of the hemarthrosis. The origin of the bleeding was most likely from the peripheral arteries of the posterior horn of the lateral meniscus.

Degenerative Change in the Adjacent Segments to the Fusion Site after Posterolateral Lumbar Fusion with Pedicle Screw Instrumentation : A Minimum 4-Year Follow-up

BACKGROUND Controversy remains regarding the subsequent degeneration of adjacent segments, and little reliable information could be found in the literature regarding long-term clinical results and adjacent segment degeneration. The objective of this study is to investigate the degenerative change of adjacent segments to the fusion site and clinical outcome after posterolateral lumbar fusion with pedicle screw instrumentation and identify the risk factors in degenerative change at adjacent segments. METHODS Thirty-two patients who underwent posterolateral lumbar fusion and were able to be followed over four years were evaluated in this study. The intervertebral disc height, percent of slip, lumbosacral joint angle, lumbar lordosis and disc angle were all examined. The postoperative progression of degeneration at adjacent segments were defined as more than a 50 % narrowing in the adjacent disc height or more than a 5 % slip in adjacent segments in comparison to the preoperative neutral lateral radiographs. The clinical results were assessed using an evaluation scores for lumbar lesions proposed by the Japanese Orthopedic Association. RESULTS Fifteen (46.8%) of the 32 patients had adjacent segment degeneration including slip or narrowing. No significant correlation was found between the adjacent segment degeneration and the recovery rate at the final follow-up. In addition, no significant correlation was observed between the adjacent segment degeneration at the lastest follow-up and postoperative radiographic measurements. CONCLUSIONS The rate of radiographic degeneration at the adjacent segments was 46.8%. No significant correlation was found between degenerative change in the adjacent segments and the clinical results. We could not identify any preoperative radiographic factors which might have influenced the segments adjacent to the fusion.