Yu Yamato

Distribution of Longitudinal Wave Velocities in Bovine Cortical Bone in vitro

The distribution of longitudinal wave velocities and longitudinal moduli in a bovine femoral cortical bone was experimentally investigated. In all parts of the long cylindrical bone, the velocities and longitudinal moduli in the axial direction were the highest. In the anterior (A) part, the velocities in the axial direction were high and almost constant, whereas the velocities in the proximal postero medial (PM) and distal postero lateral (PL) parts markedly decreased. Classifying the cortical bone into three structures (plexiform, Haversian, and porotic), we clarify the velocity distributions in the bone with discussion from an anatomical point of view.

Craniopelvic alignment in elderly asymptomatic individuals: analysis of 671 cranial centers of gravity.

Study Design. Prospective radiographical analysis using the cranial center of gravity (CCG) of sagittal vertical axis (SVA) in elderly asymptomatic individuals. Objective. To determine sex differences and age-related correlations of CCG and relationships between CCG and other spinopelvic parameters/health-related quality of life (HRQOL) measures. Summary of Background Data. Few studies have investigated CCG in a relatively large sample of elderly asymptomatic individuals. Methods. Six hundred seventy-one healthy participants older than 50 years (mean age, 72.9 yr; range, 50–92 yr) were enrolled. Whole-spine standing radiographs were obtained. The following radiographical measurements were obtained: (1) CCG–C7 SVA, (2) C7–SVA, (3) CCG–SVA, (4) C2–C7 lordosis angle, (5) thoracic kyphosis, (6) lumbar lordosis, (7) pelvic incidence, and (8) sacral slope. HRQOL measures included the EuroQol-5D and Oswestry Disability Index. Pearson product-moment correlation coefficients were calculated between pairs of radiographical measures and HRQOL. Results. Sex differences were observed in CCG–C7 SVA, CCG–SVA, C2–C7 Cobb angle, thoracic kyphosis, and pelvic incidence. Three SVA parameters (CCG–C7 SVA, C7–SVA, CCG–SVA) rapidly increased between seventh and ninth decades and were approximately 40, 80, and 120 mm, respectively, in the ninth decade. Age-related correlations were observed for all parameters without pelvic incidence, and the CCG measurement correlated the most with age. Furthermore, CCG–SVA correlated with other spinopelvic measurements and HRQOL. Conclusion. Age-related changes and sex difference in craniopelvic alignment were analyzed. Craniopelvic alignment became rapidly positive with age, particularly in the eighth decade. The CCG measurement correlated the most with age and may be a useful index marker of global spinal balance in decision making for surgical treatment of adult deformity involving cervical and thoracolumbar lesions. Level of Evidence: 4

Correlation between Hydroxyapatite Crystallite Orientation and Ultrasonic Wave Velocities in Bovine Cortical Bone

The mineral component of bone is mainly composed of calcium phosphate, constituting 70% of total bone mass almost entirely in the form of hydroxyapatite (HAp) crystals. HAp crystals have a hexagonal system and uniaxial elastic anisotropy. The objective of this study was to investigate the effect of HAp crystallite preference on macroscopic elasticity. Ultrasonic longitudinal wave velocity and the orientation of HAp crystallites in bovine cortical bone are discussed, considering microstructure, density, and bone mineral density (BMD). Eighty cube samples of cortical bone were made from two bovine femurs. The orientation of HAp crystallites was evaluated by integrated intensity ratio of (0002) peak using an X-ray diffractometer. Ultrasonic longitudinal wave velocity was investigated with a conventional pulse system. The intensity ratio of HAp crystallites and velocity were measured in three orthogonal directions; most HAp crystallites aligned in the axial direction of the femurs. Our results demonstrate a linear correlation between velocity and intensity ratio in the axial direction. Significant correlation between velocity and BMD values was observed; however, the correlation disappeared if we focused on the identical type of microstructure. In conclusion, differences in microstructure type have an impact on density and BMD, which clearly affects the velocity. In addition, at the nanoscopic level, HAp crystallites aligned in the axial direction also affected the velocity and anisotropy.

The Influence of Age and Sex on Cervical Spinal Alignment Among Volunteers Aged Over 50

Study Design. Large cohort study of volunteers aged over 50. Objective. To investigate influence of age and sex on cervical sagittal alignment among volunteers aged over 50. Summary of Background Data. Few large-scale studies have described normative values in cervical spine alignment regarding age and sex among volunteers aged over 50. Methods. The study cohort included 656 volunteers aged 50 to 89 years. Pelvic tilt, sacral slope, pelvic incidence, lumbar lordosis, pelvic incidence−lumbar lordosis, thoracic kyphosis, T1 slope (T1S), cervical lordosis (CL), C7 sagittal vertical axis (C7 SVA), C2−C7 SVA, and T1S−CL were measured using whole spine and pelvic radiographs taken in the standing position. Health-related quality of life was assessed using the EuroQOL (EQ-5D) standardized instrument for measurement of health outcome and Oswestry Disability Index. Results. There were 36 subjects aged 50 to 59 years, 174 aged 60 to 69 years, 311 aged 70 to 79 years, and 135 aged 80 to 89 years. Average T1S for each decade was 32°, 31°, 33°, and 36° for males, and 28°, 29°, 32°, and 37° for females, respectively. Average C2–C7 SVA was 25, 28, 34, and 35 mm for males, and 20, 21, 22, and 28 mm for females, respectively. C2–C7 SVA 40 mm or more, T1S 40° or more, and T1S–CL 20° or more pertaining to EQ-5D were significantly worse in other cases. Conclusion. C2–C7 SVA was significantly greater in males among all age groups, particularly among those with C2–C7 SVA of 40 mm or more [males, 69% (82/118) vs. females, 33% (36/118)]. Sagittal parameters of cervical spine were significantly worse in males than females. C2–C7 SVA, T1S, and T1S–CL negatively influenced EQ-5D. These results help to explain the greater prevalence of cervical spondylotic myelopathy among elderly males. Level of Evidence: 3

Blockade of IL-6 signaling by MR16-1 inhibits reduction of docosahexaenoic acid-containing phosphatidylcholine levels in a mouse model of spinal cord injury

The interleukin (IL)-6 pathway plays an important role in recovery after spinal cord injury (SCI). The anti-IL-6 receptor antibody MR16-1 has been shown to suppress inflammation after SCI and promote recovery of motor function. The purpose of this study was to analyze the effects of MR16-1 on the expression patterns of phospholipids in the spinal cord in a mouse model of SCI. Eight-week-old C57BL/6JJmsSlc mice were used in this study. Laminectomy was performed at the ninth and tenth thoracic levels (T9-T10), and contusion injury of the spinal cord was induced at level T10. Immediately after SCI, mice were intraperitoneally injected with a single dose of MR16-1 (MR16-1 group) or a single dose of phosphate-buffered saline of the same volume (control group). Imaging mass spectrometry was performed to visualize phosphatidylcholine (PC) expression in the spinal cord 7 days after SCI. We found that MR16-1 treatment suppressed the infiltration of immune cells after SCI, and was able to increase the locomotor function post-injury. Phospholipid imaging revealed that the MR16-1 was able to prevent the reduction of docosahexaenoic acid (DHA)-containing PC in comparison with the control group. We also observed high levels of glial fibrillary acidic protein (GFAP) at the site of DHA-containing PC expression in the MR16-1 group. These results suggest that MR16-1 treatment influences the DHA-containing PC composition of GFAP-positive cells at the injury site as early as 7 days post-SCI.

Ultrasonic Wave Properties in Bone Axis Direction of Bovine Cortical Bone

Quantitative ultrasonography (QUS) is a good method for measuring elastic properties of bone in vivo. Bovine cortical bone has two typical microstructures, plexiform and Haversian. In this study, the relationship between the speed of sound (SOS) and the hydroxyapatite (HAp) crystallite orientation in the axial direction was investigated in two different aged bovine cortical bones. The dependence of attenuation on anatomical position was also investigated. Two ring-permanent hyphen shaped cortical bone samples were obtained from 36- and 24-month-old bovine femurs. SOS was measured with a conventional ultrasonic pulse system. The integrated intensity of the (0002) peak obtained by X-ray diffraction was determine to evaluate the amount of preferred orientation. Regardless of the age of the bovine femurs, a significant correlation between SOS and the preferred orientation of HAp crystallites was observed in parts of the plexiform structure, and the gradient of the relationship showed a similar tendency. Attenuation seemed to depend on bone microstructure.

Calculation of the Target Lumbar Lordosis Angle for Restoring an Optimal Pelvic Tilt in Elderly Patients With Adult Spinal Deformity.

Study Design. This investigation consisted of a cross-sectional study and a retrospective multicenter case series. Objective. This investigation sought to identify the ideal lumbar lordosis (LL) angle for restoring an optimal pelvic tilt (PT) in patients with adult spinal deformity (ASD). Summary of Background Data. To achieve successful corrective fusion in ASD patients with sagittal imbalance, it is essential to correct the sagittal spinal alignment and obtain a suitable pelvic inclination. We determined the LL angle that would restore the optimal PT following ASD surgery. Methods. The cross-sectional study included 184 elderly volunteers (mean age 64 years) with an Oswestry Disability Index score less than 20%. The relationship between PT or LL and the pelvic incidence (PI) in normal individuals was investigated. The second study included 116 ASD patients (mean age 66 years) who underwent thoracolumbar corrective fusion at 1 of 4 spine centers. The postoperative PT values were calculated using the parameters measured. On the basis of these studies, an ideal LL angle was determined. Results. In the cross-sectional study, the linear regression equation for the optimal PT as a function of PI was “optimal PT = 0.47 × PI – 7.5.” In the second study, the postoperative PT was determined as a function of PI and corrected LL, using the equation “postoperative PT = 0.7 × PI – 0.5 × corrected LL + 8.1.” The target LL angle was determined by mathematically equalizing the PTs of these 2 equations: “target LL = 0.45 × PI + 31.8.” Conclusion. The ideal LL angle can be determined using the equation “LL = 0.45 × PI + 31.8,” which can be used as a reference during surgical planning in ASD cases. Level of Evidence: 4

Feasibility of a novel diagnostic chart of intramedullary spinal cord tumors in magnetic resonance imaging.

Study design:Retrospective chart review.Objectives:Each type of intramedullary spinal cord tumor (IMSCT) has specific anatomical and pathological features visible on magnetic resonance (MR) imaging. The purpose of this study was to investigate the accuracy of preoperative IMSCT diagnosis using our diagnostic chart of tumor-specific MR imaging findings.Setting:Hamamatsu, Japan.Methods:From 2009 to 2013, 28 consecutive patients with IMSCT who underwent surgery in our university hospital were included in this study. There were 17 men and 11 women with an average age of 49 years (12–81). The pathological diagnoses were hemangioblastoma (12), ependymoma (11), astrocytoma (4) and squamous cell carcinoma (1). Tumor-specific MR imaging findings were as follows: ependymoma ((a) spinal cord swelling, (b) contrast effect with necrosis, (c) tumor in the center of the spinal cord), hemangioblastoma ((a) spinal cord swelling, (b) homogeneous contrast effect) and astrocytoma ((a) spinal cord swelling, (b) contrast effect is either, (c) eccentric tumor). Based on these features, we generated a diagnostic chart to investigate the MR imaging diagnosis accuracy for IMSCTs.Results:The accuracy of preoperative diagnosis was 89% (25/28 cases). Correct diagnoses were made in 100% of hemangioblastomas (12/12 cases), 90% of ependymomas (9/11 cases) and 100% of astrocytomas (4/4 cases).Conclusions:Different types of IMSCTs exhibit unique MR imaging characteristics. These features can be used to preoperatively diagnose IMSCTs with high accuracy.

Distribution of hydroxyapatite crystallite orientation and ultrasonic wave velocity in ring-shaped cortical bone of bovine femur

At the nanoscopic level, bone consists of calcium phosphate, which forms incomplete hydroxyapatite (HAp) crystals. The preferred orientation of the c-axis of HAp crystallites induces anisotropy and inhomogeneity of elastic properties in bone. In this study, the effect of the preferred orientation of HAp crystallites on the spatial distribution of ultrasonic wave velocity was experimentally investigated, considering bone mineral density (BMD) and microstructure. Three ring-shaped cortical bone samples were made from a 36-month-old bovine femur. Longitudinal wave velocity was measured by a conventional ultrasonic pulse system, using self-made polyvinylidene fluoride transducers. The integrated intensity of the (0002) peak obtained using X-ray diffraction was estimated to evaluate the amount of preferred orientation. The velocity distribution pattern was similar to the distribution of integrated intensity of (0002). The effect of the preferred orientation of HAp crystallites on velocity was clearly observed in the plexiform structure, despite the fact that the BMD value was almost independent of the preferred orientation of HAp crystallites. Velocity measurement of cortical bone can reveal information about HAp crystallite orientation.

Relationships between the anisotropy of longitudinal wave velocity and hydroxyapatite crystallite orientation in bovine cortical bone.

Quantitative ultrasound (QUS) is now widely used for evaluating bone in vivo, because obtained ultrasonic wave properties directly reflect the visco-elasticity. Bone tissue is composed of minerals like hydroxyapatite (HAp) and a collagen matrix. HAp crystallites orientation is thus one parameter of bone elasticity. In this study, we experimentally investigated the anisotropy of ultrasonic wave velocity and the HAp crystallites orientation in the axial-radial and axial-tangential planes in detail, using cylindrical specimens obtained from the cortical bone of three bovine femurs. Longitudinal bulk wave propagation was investigated by using a conventional ultrasonic pulse system. We used the one cycle of sinusoidal pulse which was emitted from wide band transmitter. The nominal frequency of the pulse was 1MHz. First, we investigated the anisotropy of longitudinal wave velocity, measuring the anisotropy of velocity in two planes using cylindrical specimens obtained from identical bone areas. The wave velocity changed due to the rotation angle, showing the maximum value in the direction a little off the bone axis. Moreover, X-ray pole figure measurements also indicated that there were small tilts in the HAp crystallites orientation from the bone axis. The tilt angles were similar to those of the highest velocity direction. There were good correlations between velocity and HAp crystallites orientation obtained in different directions. However, a comparatively low correlation was found in posterior bone areas, which shows the stronger effects of bone microstructure. In the radial-tangential plane, where the HAp crystallites hardly ever align, weak anisotropy of velocity was found which seemed to depend on the bone microstructure.