Tomoyuki Takigawa

ADAMTS1, ADAMTS5, ADAMTS9 and aggrecanase-generated proteoglycan fragments are induced following spinal cord injury in mouse

ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) proteinases are involved in a variety of biological processes such as angiogenesis, cancer and arthritis. ADAMTSs appears to be responsible for the cleavage of proteoglycans in several tissues including brain and cartilage. Chondroitin sulfate proteoglycans (CSPGs) maintains the integrity of the brain extracellular matrix and major inhibitory contributors for glial scar and neural plasticity. The activity of aggrecanases in the central nervous system (CNS) has been reported. ADAMTSs are an enzyme degrading CSPGs in the brain. However, there is a little knowledge regarding ADAMTSs in the CNS. We investigated the expression levels of ADAMTSs mRNAs by RT-PCR after spinal cord injury in mouse. Transcripts encoding 4 of the 19 known ADAMTSs were evaluated in the mouse spinal cord following injury. ADAMTS1, -5 and -9 expression levels were found to be upregulated. No change was observed in ADAMTS4 expression. By means of immunohistochemistry, ADAMTSs were detected in the astrocytes implying its cellular source in SCI. Western blot analyses indicated that aggrecanase-generated proteoglycan fragments are produced after SCI.

Type IV collagen induces expression of thrombospondin‐1 that is mediated by integrin α1β1 in astrocytes

Following brain injury, thrombospondin‐1 (TSP‐1) is involved in angiogenesis and synaptic recovery. In this study, we used a cold injury‐model and found that TSP‐1 mRNA was markedly upregulated after brain injury. Immunohistochemistry showed that TSP‐1 was upregulated in both the core of the lesion and in the perilesional area of injured brain tissue. Numerous astrocytes immunopositive for glial fibrillary acidic protein (GFAP) were found in the perilesional area, and TSP‐1 was also expressed in almost all astrocytes surrounding blood vessels at 4 days after injury. Next, we examined the influence of vascular basement membrane components on TSP‐1 expression. When astrocytes were cultured on type IV collagen, TSP‐1 was significantly upregulated compared with the expression when cells were grown on laminin, fibronectin, or poly‐L‐lysine. This increase occurred exclusively when astrocytes were grown on the native form of type IV collagen but not on the heat‐denatured form or the non‐collagenous 1 domain. Further, integrin α1 and β1 mRNAs were upregulated concomitantly with GFAP mRNA, and integrin α1 protein was localized to the endfeet of astrocytes that surrounded blood vessels in the injured brain. Using function‐blocking antibodies, we found that the effectof type IV collagen was attributed to integrin α1β1 in primary astrocytes. Collectively, our results suggest that vascular basement membrane components substantially impact gene expression in astrocytes during brain tissue repair.

Comparative biomechanical analysis of an improved novel pedicle screw with sheath and bone cement.

Study Design A human cadaveric biomechanical study of fixation strength of an improved novel pedicle screw (NPS) with cement and a conventional screw. Objective To clarify whether the NPS has adequate fixation strength without leakage in vertebrae with low bone quality. Summary of Background Data The fixation strength of pedicle screws decreases in frail spines of elderly osteoporotic patients. Augmentation of screw fixation with bone cement must be balanced against increased difficulty of screw removal and risk of cement leakage. We developed the NPS consisting of an internal screw and an outer sheath to mitigate the disadvantages of cement augmentation. Methods The T12 and L1 vertebrae obtained from 18 formalin preserved cadavers (11 males and 7 females; mean age, 82.7 y) were used. The mean bone mineral density was 0.39±0.14 g/cm2. The NPS was inserted into one pedicle of each vertebra and the control screw, a Compact CD2 screw, was inserted into the contralateral pedicle. Both screws were 6 mm in diameter and 40 mm in length. Pull-out tests were performed at a crosshead speed of 10 mm/min. Cyclic loading tests were performed with a maximum 250 N load at 2 Hz until 30,000 cycles. Results Cement leakage did not occur in any of the specimens tested. The mean maximum force at pull-out was 760±344 N for the NPS and 346±172 N for the control screw (P<0.01). Loosening of 50% of the screws was observed after 17,000 cycles of the NPS and after 30 cycles of the control screw. The hazard ratio of loosening was 19.6 (95% confidence interval 19.3-19.9) (P<0.001). Conclusions The NPS showed a significantly higher mechanical strength than the control screw in both pull-out tests and cyclic loading tests. The NPS showed more than adequate strength without cement leakage.

Application of laminar screws to posterior fusion of cervical spine: Measurement of the cervical vertebral arch diameter with a navigation system

Study Design. Morphometric analysis. Objective. For safe and solid fixation, it is necessary to measure the diameter of the vertebral arch to ascertain whether or not screws can be used and if so, the appropriate size of screws to be used. Summary of Background Data. Cervical pedicle screws are the most biomechanically stable screws. However, their use carries a high risk of neurovascular complications during screw insertion. In 2004, a new method to avoid such vertebral artery injuries was reported by insertion of screws with crosswise to the lamina of C2. For safe and solid fixation, it is necessary to measure the diameter of the vertebral arch to ascertain whether or not screws can be used and if so, the appropriate size of screws to be used. There is no report of the diameter of the vertebral arch by a navigation system. Methods. Morphometric analysis was performed on 42 patients who had undergone a CT scan of the cervical spine for either surgery or diagnostic purposes. To examine the possibilities to insert laminar screws, the diameter of the vertebral arch was measured using a navigation system. Results. The diameter of the vertebral arch in C2 was the largest in the cervical spine, individual differences ranging between 0.8 and 8.4 mm. In C2, insertion of screws with a diameter of 3 mm was possible in 80% of males and 63% of females. As for screws with a diameter of 4 mm, insertion was possible in 50% of the males and 24% of the females in C2. In C2, gender had a significant effect, but left-right differences and height did not. Conclusion. Laminar screws are useful as they can prevent vascular injuries, but a preoperative evaluation is necessary.

SAPHO syndrome associated spondylitis.

The concept of synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome has been well clarified, after Chamot et al. suggested this peculiar disorder in 1987. The most commonly affected site in SAPHO syndrome is the anterior chest, followed by the spine. However, the clinical course and taxonomic concept of SAPHO spinal lesions are poorly understood. This study was performed to analyze: (1) the detailed clinical course of spinal lesions in SAPHO syndrome, and (2) the relationship between SAPHO syndrome with spinal lesions and seronegative spondyloarthropathy. Thirteen patients with spondylitis in SAPHO syndrome were analyzed. The features of spinal lesions were a chronic onset with a slight inflammatory reaction, and slowly progressing non-marginal syndesmophytes at multi spinal levels, besides the coexistence of specific skin lesions. SAPHO syndrome, especially spinal lesions related to palmoplantar pustulosis, can be recognized as a subtype of seronegative spondyloarthropathy.

Separation of the Perivascular Basement Membrane Provides a Conduit for Inflammatory Cells in a Mouse Spinal Cord Injury Model

Spinal cord injury results in disruption of the cord microstructure, which is followed by inflammation leading to additional deterioration. Perivascular basement membranes are a component of the spinal cord microstructure that lies between blood vessels and astrocytes. The impact of disrupting the basement membrane structure on the expansion of inflammation has not been fully examined. The objective of this study was to clarify the relationship between damage to basement membranes and inflammation after spinal cord injury. Immunohistochemical analyses of the perivascular extracellular matrix were performed in a mouse spinal cord injury model. In normal tissue, the perivascular basement membrane was a single-layer structure produced by both endothelial cells and surrounding astrocytes. After spinal cord injury, however, the perivascular basement membrane often separated into an inner endothelial basement membrane and an outer parenchymal basement membrane. The altered basement membranes formed during the acute phase (within 7 days after spinal cord injury). During the subacute phase of injury, numerous monocytes and macrophages accumulated in the space between the separated basement membranes and infiltrated into the parenchyma where astrocytic endfeet were displaced. Infiltration of inflammatory cells from the injury core was attenuated coincident with the appearance of the glia limitans and glial scar. Furthermore, the outer parenchymal basement membrane was connected to the basement membrane of the glia limitans surrounding the injury core. Our data suggest that structurally altered basement membranes facilitate expansion of secondary inflammation during the subacute phase of spinal cord injury.

Midterm results of prostaglandin e1 treatment in patients with lumbar spinal canal stenosis accompanied by intermittent claudication

Study Design. The midterm results of prostaglandin E1 (PGE1) treatment in patients with lumbar spinal canal stenosis, and discuss the factors influencing the improvement rate by using multivariable analysis. Objective. We report the clinical results of PGE1 treatments in patients with lumbar spinal canal stenosis. Summary of Background Data. Neurogenic intermittent claudication, a prominent symptom of lumbar spinal canal stenosis, poses a substantial impairment of quality of life in patients. A variety of approaches to treatment for lumbar spinal canal stenosis have been reported. However, general systemic complications make it difficult for many elderly people to undergo surgical treatment. Sometimes the only reasonable option is to receive conservative treatment. Methods. The subjects were 63 patients with lumbar spinal canal stenosis. After admission, patients were given an intravenous infusion of PGE1 (60 &mgr;g/d) for approximately 2 weeks. To obtain the spinal canal stenosis rate, the area of the dural canal observed on magnetic resonance imaging and CT myelography was measured by using image analysis software (NIH image). The correlation of improvement rates to ages, JOA scores, claudication distances, and stenosis rate obtained through magnetic resonance imaging was evaluated using multivariable analysis. Results. Regardless of stenosis type, JOA scores significantly improved after PGE1 administration (the mixed type: P < 0.0001, the nerve root type: P < 0.01, and the cauda equina type: P < 0.01), and claudication distance was significantly improved. Multivariable analysis showed that JOA scores before PGE1 administration significantly contributed to the improvement rates. Conclusion. Our midterm results showed that PGE1 was useful for treating intermittent claudication in patients with lumbar spinal canal stenosis. The effect of PGE1 was not related to the degree of stenosis obtained with images, age, or claudication distance, but was correlated with baseline disease severity (JOA scores before administration).

Assessing the range of cervical rotation in patients with rheumatoid arthritis after atlantoaxial screw fixation using axial CT.

Study Design. Case-series study. Objective. To assess range of cervical rotation possible after atlantoaxial fixation in rheumatoid arthritis (RA) patients using axial CT. Summary of Background Data. The atlantoaxial complex is primarily responsible for rotation, and the percentage of global cervical rotation dependent on C1–C2 is 60%. Fusion of C1–C2 was expected to cause a loss of almost half the normal cervical rotation. However, some authors had reported that cervical rotation in RA patients increased after atlantoaxial fixation because of pain relief. Methods. Nineteen consecutive patients with atlantoaxial instability secondary to RA who had undergone transarticular fixation were included in our study. Visual analog scale was used for assessment of neck pain. We recorded functional CTs to assess C1 to T1 rotation angles before surgery and 6 months after surgery. The patient actively rotated his neck toward right as far as possible, taking care that the shoulders remained in the horizontal plane. Results. The average visual analog scale for neck pain decreased significantly from 7 (range, 4–9) before surgery to 3 (range, 0–5) at 6 months after surgery. The average preoperative C1–T1 rotation angles that were measured using axial CT were 80° in total. C1–T1 rotation angle significantly decreased (55% decrease) after surgery, but there was no difference between right and left motion. Average subaxial rotation (C2–T1) was 31° before surgery and did not increase after surgery. Conclusion. All 19 patients with RA and atlantoaxial instability in our study had relief of pain and a significant decrease in the C1–T1 rotation angle after atlantoaxial fixation. Subaxial rotation did not change from before to after the operation.

Spinal kinematics and facet load transmission after total disc replacement.

Study Design. In vitro human cadaveric biomechanical study. Objective. The objectives were to determine the effect of total disc replacement (TDR) on kinematics, especially range of motion (ROM), helical axis of motion (HAM), and facet joint contact force. Summary of Background Data. Ball-and-socket type artificial discs are designed to mimic normal motion, but the biomechanical effect on kinematics has not been thoroughly clarified. Methods. Fourteen human cadaveric L4–L5 units were tested before and after TDR. In 7 specimens, facet contact forces were directly measured with thin-film piezoresistive load transducers inserted in the facet joints. In the other 7 specimens, the facet joint capsules were kept intact. Moments (±7.5 Nm) were applied in flexion/extension, lateral bending, and axial rotation motion, with and without an axial compressive preload of 400 N. Three-dimensional motion was recorded, and each angular ROM and HAM were calculated. Results. Without axial compressive preload, the TDR did not produce significant differences in ROMs in all cases. However, under compressive preload, the TDR produced significantly larger ROMs for flexion (4.0° and 8.7°) and lateral bending (2.4° and 5.6°) (intact state and TDR, respectively). The TDR did not alter the HAM significantly except the location in lateral bending without compressive preload and the orientation in flexion/extension against horizontal plane. The location of HAM was slightly shifted caudally by the compressive preload in intact and TDR states. Despite the increased ROMs, the facet contact forces were not significantly altered by the TDR either with or without compressive preload (26 N and 27 N in extension, 41 N and 41 N in lateral bending, 117 N and 126 N in axial rotation). Conclusion. TDR using a ball-and-socket type artificial disc significantly increased ROM under axial load and maintained the HAM with similar facet contact forces to the intact state.

Predicting Intraoperative Vertebral Rotation in Patients With Scoliosis Using Posterior Elements as Anatomical Landmarks

Study Design. A retrospective study. Objective. o predict intraoperative vertebral rotation in patients with scoliosis using posterior elements as anatomic landmarks. Summary of Background Data. In patients with scoliosis, accurate intraoperative vertebral rotation measurements are needed to avoid spinal cord injury caused by pedicle screw misplacement. Generally, we predict vertebral rotation by anatomic landmarks, that is, posterior elements that can be seen during surgery, such as spinous processes, transverse processes, or laminae. However, correlation between vertebral rotation and these anatomic landmarks is unclear. Methods. eventy-six vertebrae (T4–T12) of 17 patients with thoracic scoliosis were measured. Patients who had severe scoliosis (>90° Cobb angle) were excluded from this study. We assessed apex and adjacent vertebrae using axial computed tomography scans taken with patients in a supine position. We measured the angle between the vertebral reference line (Ve), defined as the midline of the vertebral body, and various lines based on the following anatomic landmarks of posterior elements of the vertebrae: (a) The Spinous qprocess line (Sp), defined as the midline of the spinous process; (b) A bisector (Bi) of the bilateral lines that pass the depressions in the laminae to the medial apex of the transverse processes; (c) a line (Tr) perpendicular to a line which passes the bilateral transverse processes; and (d) a line (La) perpendicular to the line which passes the bilateral depressions in the laminae. Results. The average Cobb angle in A-P radiographs was 68°. The average angles between Sp, Bi, Tr, and La and the vertebral reference line were 13.6° (range 0°–29.2°), 3.0° (range 0°–9.0°), 2.5° (range 0°–8.1°), and 4.4° (range 0°–11.9°), respectively. Conclusion. The line Tr, (runs perpendicular to the line which passes the bilateral transverse processes) had the greatest correlation to the rotation of a vertebra. On the other hand, the line Sp (defined as the midline of the spinous process) was not sufficient for predicting rotation of a vertebra and can be disregarded during the intraoperative analysis and screw placement.