Hiroaki Matsumori

Revision surgery after cervical laminoplasty: report of five cases and literature review

BACKGROUND CONTEXT Revision surgery after laminoplasty is rarely performed, and there are few reports of this procedure in the English literature. PURPOSE To evaluate the reasons why patients underwent revision surgery after laminoplasty and to discuss methods of preventing the need for revision surgery. A literature review with a comparative analysis between previous reports and present cases was also performed. STUDY DESIGN Case report and literature review. PATIENT SAMPLE Five patients who underwent revision surgery after laminoplasty. OUTCOME MEASURES Diagnosis was based on the preoperative computed tomography and magnetic resonance imaging findings. Neurologic findings were evaluated using the Japanese Orthopedic Association score. METHODS A total of 237 patients who underwent cervical laminoplasty for cervical spondylotic myelopathy from 1990 to 2010 were reviewed. Patients with ossification of the posterior longitudinal ligament, renal dialysis, infection, tumor, or rheumatoid arthritis were excluded. Five patients who underwent revision surgery for symptoms of recurrent myelopathy or radiculopathy were identified, and the clinical courses and radiological findings of these patients were retrospectively reviewed. RESULTS The average interval from the initial surgery to revision surgery was 15.0 (range 9-19) years. The patients were four men and one woman with an average age at the time of the initial operation of 49.8 (range 34-65) years. Four patients developed symptoms of recurrent myelopathy after their initial surgery, for the following reasons: adjacent segment canal stenosis, restenosis after inadequate opening of the lamina with degenerative changes, and trauma after inadequate opening of the lamina. One patient developed new radiculopathy symptoms because of foraminal stenosis secondary to osteoarthritis at the Luschka and zygapophyseal joints. All patients experienced resolution of their symptoms after revision surgery. CONCLUSIONS Revision surgery after laminoplasty is rare. Inadequate opening of the lamina is one of the important reasons for needing revision surgery. Degenerative changes after laminoplasty may also result in a need for revision surgery. Surgeons should be aware of the degenerative changes that can cause neurologic deterioration after laminoplasty.

Spectrocolorimetric evaluation of repaired articular cartilage after a microfracture

BackgroundIn clinical practice, surgeons differentiate color changes in repaired cartilage compared with surrounding intact cartilage, but cannot quantify these color changes. Objective assessments are required. A spectrocolorimeter was used to evaluate whether intact and repaired cartilage can be quantified.FindingsWe investigated the use of a spectrocolorimeter and the application of two color models (L* a* b* colorimetric system and spectral reflectance distribution) to describe and quantify articular cartilage. In this study, we measured the colors of intact and repaired cartilage after a microfracture. Histologically, the repaired cartilage was a mixture of fibrocartilage and hyaline cartilage. In the L* a* b* colorimetric system, the L* and a* values recovered to close to the values of intact cartilage, whereas the b* value decreased over time after the operation. Regarding the spectral reflectance distribution at 12 weeks after the operation, the repaired cartilage had a higher spectral reflectance ratio than intact cartilage between wavelengths of 400 to 470 nm.ConclusionThis study reports the first results regarding the relationship between spectrocolorimetric evaluation and the histological findings of repair cartilage after a microfracture. Our findings demonstrate the ability of spectrocolorimetric measurement to judge the repair cartilage after treatment on the basis of objective data such as the L*, a* and b* values and the SRP as a coincidence index of the spectral reflectance curve.

Raloxifene: its ossification-promoting effect on female mesenchymal stem cells

BackgroundRaloxifene acts like estrogen in preventing bone loss in postmenopausal women, but it selectively activates biological responses in bone tissue. It has a direct effect on osteoblasts’ differentiation and bone formation in bone marrow culture. However, the point at which raloxifene has an effect on bone marrow-derived mesenchymal stem cells (MSCs), regardless of sex difference, is not known. The purpose of this study was to examine the osteogenic effect of raloxifene on MSCs derived from female and male rats and to assess the sex difference of raloxifene with or without osteogenic supplements (OSs) in the regulation of bone formation.MethodsFemale and male rat bone marrow cells were cultured with or without OSs. In each experimental group, 10-6 M or 10-8 M raloxifene was added. As a control, cells were cultured without raloxifene. Histologically, mineralization was assessed by alizarin red S staining. Biochemically, alkaline phosphatase (ALP) activity, calcium content, and osteocalcin content were assessed.ResultsOn histological analysis, mineralized nodules were seen on alizarin red S staining in the groups treated with OS. On the biochemical analysis, OS increased ALP activity, calcium content, and osteocalcin content. Among female groups with OSs, 10-6 M raloxifene significantly increased ALP activity, calcium content, and osteocalcin content compared with the controls. Among male groups, raloxifene had negligible effects.Conclusions10-6 M Raloxifene had no ossification-inducing effect on female MSCs, but it had an ossification-promoting effect; it had no osteogenic effect on male MSCs. Therefore, raloxifene has a sex difference with regard to its osteogenic effect on MSCs. Moreover, combined treatment with raloxifene plus OS has an effect on female MSCs. These results provide a useful insight into the possible influence of raloxifene after MSC transplantation in clinical practice.

Temporal changes in the tensile strength of ultra-high-molecular-weight polyethylene cable embedded in muscle tissue

BACKGROUND Wires and cables have been used extensively for spinal sublaminar wiring, but damages to the spinal cord due to compression by metal wires have been reported. We have used more flexible ultra-high-molecular-weight polyethylene cable (Tekmilon tape) instead of metal wires since 1999 and have obtained good clinical outcomes. Although the initial strength of Tekmilon tape is equivalent to metal wires, the temporal changes in the strength of Tekmilon tape in the body should be investigated to show that sufficient strength is maintained over time until bone union is complete. METHODS Tekmilon tape was embedded into the paravertebral muscle of 10-week-old male Japanese white rabbits. Samples were embedded for 0, 1, 3, 6 or 12 months. At the end of each period, sequential straight tensile strength and sequential knot-pull tensile strength were measured. FINDINGS The initial strength of Tekmilon tape in muscle tissue was maintained over time, with 92% straight tensile strength and 104% knot-pull tensile strength at 6months, and values of 77% and 100% at 12 months, respectively. Since single knot is clinically relevant, it is very important that the knot-pull tensile strength did not decrease over a 12-month period. This suggests that temporal changes in the tensile strength of Tekmilon tape are negligible at 1 year. INTERPRETATION Tekmilon tape maintains sufficient strength in vivo until bone union has occurred. It is useful for sublaminar wiring instead of metal materials due to its flexibility and strength and may reduce the risk of neurological damage.