Geometry of the Intervertebral Volume and Vertebral Endplates of the Human Spine

Replacement of a degenerated vertebral disc with an artificial intervertebral disc (AID) is currently possible, but poses problems, mainly in the force distribution through the vertebral column. Data on the intervertebral disc space geometry will provide a better fit of the prosthesis to the vertebrae, but current literature on vertebral disc geometry is very scarce or not suitable. In this study, existing CT-scans of 77 patients were analyzed to measure the intervertebral disc and vertebral endplate geometry of the lumbar spine. Ten adjacent points on both sides of the vertebrae (S1-superior to T12-inferior) and sagittal and transverse diameters were measured to describe the shape of the caudal and cranial vertebral planes of the vertebrae. It was found that the largest endplate depth is located in the middle or posterior regions of the vertebra, that there is a linear relationship between all inferior endplate depths and the endplate location (p < 0.0001) within the spinal column, and that the superior endplate depth increases with age by about 0.01 mm per year (p < 0.02). The wedge angle increases from T12-L1 to L5-S1. The results allow for improvement of the fit of intervertebral disc-prostheses to the vertebrae and optimized force transmission through the vertebral column.     

Structural and functional characteristics of the thoracolumbar multifidus muscle in horses

The multifidus muscle fascicles of horses attach to vertebral spinous processes after crossing between one to six metameres. The fascicles within one or two metameres are difficult to distinguish in horses. A vertebral motion segment is anatomically formed by two adjacent vertebrae and the interposed soft tissue structures, and excessive mobility of a vertebral motion segment frequently causes osteoarthropathies in sport horses. The importance of the equine multifidus muscle as a vertebral motion segment stabilizer has been demonstrated; however, there is scant documentation of the structure and function of this muscle. By studying six sport horses postmortem, the normalized muscle fibre lengths of the the multifidus muscle attached to the thoracic (T)4, T9, T12, T17 and lumbar (L)3 vertebral motion segments were determined and the relative areas occupied by fibre types I, IIA and IIX were measured in the same muscles after immunohistochemical typying. The values for the normalized muscle fibre lengths and the relative areas were analysed as completely randomized blocks using an anova (P ≤ 0.05). The vertebral motion segments of the T4 vertebra include multifidus bundles extending between two and eight metameres; the vertebral motion segments of the T9, T12, T17 and L3 vertebrae contain fascicles extending between two and four metameres The muscle fibres with high normalized lengths that insert into the T4 (three and eight metameres) vertebral motion segment tend to have smaller physiological cross‐sectional areas, indicating their diminished capacity to generate isometric force. In contrast, the significantly decreased normalized muscle fibre lengths and the increased physiological cross‐sectional areas of the fascicles of three metameres with insertions on T9, T17, T12, L3 and the fascicles of four metameres with insertions on L3 increase their capacities to generate isometric muscle force and neutralize excessive movements of the vertebral segments with great mobility. There were no significant differences in the values of relative areas occupied by fibre types I, IIA and IIX. In considering the relative areas occupied by the fibre types in the multifidus muscle fascicles attached to each vertebral motion segment examined, the relative area occupied by the type I fibres was found to be significantly higher in the T4 vertebral motion segment than in the other segments. It can be concluded that the equine multifidus muscle in horses is an immunohistochemically homogeneous muscle with various architectural designs that have functional significance according to the vertebral motion segments considered. The results obtained in this study can serve as a basis for future research aimed at understanding the posture and dynamics of the equine spine.     

Differentiation and classification of thoracolumbar transitional vertebrae

The literature states that transitional vertebrae at any junction are characterized by features retained from two adjacent regions in the vertebral column. Currently, there is no published literature available that describes the prevalence or morphology of thoracolumbar transitional vertebrae (TLTV). The aim of this study was to identify the qualitative characteristics of transitional vertebrae at the thoracolumbar junction and establish a technique to differentiate the various subtypes that may be found. A selection of vertebral columns from skeletal remains (n = 35) were evaluated in this study. Vertebrae were taken based on features that are atypical for vertebrae in each relative region. The transitional vertebrae were qualitatively identified based on overlapping thoracic and lumbar features of vertebrae at the thoracolumbar junction. The following general overlapping characteristics were observed: aplasia or hypoplasia of the transverse process, irregular orientation on the superior articular process and atypical mammillary bodies. The results show that the most frequent location of the transitional vertebrae was in the thoracic region (f = 23). The second most frequent location was in the lumbar region (f = 10). In two specimens of the selection (f = 2), an additional 13th thoracic vertebra was present which functioned as a transitional vertebra. This study concluded that one can accurately identify the characteristics of transitional vertebrae at the thoracolumbar junction. In addition, the various subtypes can be differentiated according to the region in the vertebral column the vertebra is located in and the relative number of vertebral segments in the adjacent regions of the vertebral column. This provides a qualitative tool for researchers to differentiate the transitional vertebrae from distinctly different typical thoracic or lumbar vertebrae at the thoracolumbar junction.     

Kinematics of the lumbar spine in elderly subjects with decreased bone mineral density

Lumbar spine kinematics was studied in subjects with normal bone mineral density, osteopenia and osteoporosis to determine the effect of bone mineral density and morphology on the flexion–extension movement patterns of the lumbar spine. Lateral radiographs and skin-mounted electromagnetic motion tracking sensors were employed to study lumbar spine kinematics using a Bayesian Belief Network model. The predicted angular displacement of the vertebrae had a high correlation (r = 0.91, p < 0.001) with the actual movements. The overall mean error was −0.51° ± 3.11°. Intervertebral angular displacement and velocity consistently increased from L1/L2 to L5/S1. Differences were observed in the movement pattern between normal subjects and those with decreased bone density. In normal subjects, vertebral angular acceleration consistently decreased from the upper to the lower vertebrae but the same consistent predictable pattern was not observed in the subjects with decreased bone mineral density. It is possible that these changes in kinematic behaviours are related to morphological changes as well as altered neuromuscular functions.     

C7 vertebra homeotic transformation in domestic dogs – are Pug dogs breaking mammalian evolutionary constraints?

The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic ‘screw‐tailed’ breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco‐lumbar vertebra (P = 0.041) and a pre‐sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and the Pug dog appears to be a good naturally occurring model to further investigate the aetiology of cervical ribs, other congenital vertebral anomalies and numerical alterations.     

Common Variable Immunodeficiency in Horses is Characterized by B Cell Depletion in Primary and Secondary Lymphoid Tissues

Introduction  Common variable immunodeficiency (CVID) in horse patients is characterized by late-onset B cell lymphopenia or depletion, hypo- or agammaglobulinemia, impaired humoral response to tetanus toxoid vaccination, and recurrent fevers and bacterial infections. Discussion  This study describes the clinical and immunologic findings of 14 affected horses (average age 10.7 ± 4.4 years) of both genders (six females, eight males) and different breeds (eight Thoroughbreds, four Quarter Horses, one Warmblood, one Pony). Serial immunological testing in peripheral blood revealed persistent, severe B cell lymphopenia (mean 1.3 ± 2.3% positive cells) in all patients. Serum IgG (range <200 to 800 mg/dL) and IgM (≤25.0 mg/dL) deficiency was common to all horses. Serum IgA concentrations declined with time. Histopathology and immunohistochemistry revealed absence of lymphoid follicles and B cells in primary and secondary lymphoid tissues. CVID is a cause of recurrent pneumonia, septicemia, and meningitis in adult horses and has a grave prognosis for clinical management and survival.     

Perinatal factors associate with vertebral size and shape but not lumbar lordosis in 10‐year‐old children

The intrauterine environment is known to influence foetal development and future health. Low birthweight has been linked to smaller vertebral canals in children and decreased adulthood spine bone mineral content. Perinatal factors affecting lumbar spine curvature have not yet been considered but could be important for adult spinal health, as lumbar movement during lifting, a risk factor for backpain, is associated with lordosis. To investigate this, lumbar spine magnetic resonance images at age 10 years and perinatal and maternal data (birthweight, placental weight, gestation length, crown‐heel length, maternal age, height, weight and smoking status) from 161 children born in Aberdeen in 1988–1989 were acquired. Statistical shape modelling, using principal component analysis, quantified variations in lumbar spine shape and resulting modes of variation were assessed in combination with perinatal data using correlations and analyses of covariance, adjusted for potential confounders. Spine modes 1–3 (SM1–SM3) captured 75% of the variation in lumbar spine shape. The first and third modes described the total amount (SM1) and evenness of curvature distribution (SM3). SM2 accounted for variations in antero‐posterior vertebral diameter relative to vertebral height, increasing positive scores representing a larger relative diameter. Adjusting for gestation length and sex, SM2 positively correlated with birthweight (r = 0.25, P < 0.01), placental weight (r = 0.20, P = 0.04), crown‐heel length (r = 0.36, P < 0.001) and maternal weight (r = 0.19, P = 0.04), and negatively with maternal age (r = ?0.22, P = 0.02). SM2 scores were lower in girls (P < 0.001) and in the low birthweight group (P = 0.02). There were no significant differences in SM1 and SM3 scores between birthweight groups, boys and girls or children of smokers (31%) and non‐smokers (69%). In conclusion, s ome perinatal factors were associated with vertebral body morphology but had little effect on lumbar curvature.     

Effect of two synthetic peptides mimicking conserved regions of equine infectious anemia virus proteins gp90 and gp45 upon cytokine mRNA expression

Gp90 and gp45 synthetic peptides, which mimic conserved sequences of native viral proteins, are recognized by antibodies to equine infectious anemia virus (EIAV) in asymptomatic carrier horses and generate humoral and cellular responses in immunized mice. Cytokine mRNA levels were evaluated in equine peripheral blood mononuclear cells (PBMCs) after in vitro stimulation with gp90 and gp45 with the aim of determining the cytokine profile associated with the proliferative response. Stimulation index (SI) values indicate that 100 and 60% of EIAV-infected horses recognized gp90 and gp45, respectively. A strong positive correlation was found between IL-12p40 and SI, IFN-γ and SI, and IL-12p40 and IFN-γ (p < 0.001). These results suggest the presence of specific memory cells that would contribute to maintain reinfection resistance and that conserved viral regions represented by gp90 and gp45 synthetic peptides may be good candidates for inclusion in vaccine strategies against EIAV.     

Expression of Runx2 and Type X Collagen in Vertebral Growth Plate of Patients with Adolescent Idiopathic Scoliosis

The different expression of type X collagen and Runx2 between the convex and concave side of vertebral growth plate in scoliosis may help to improve our understanding of the role that growth plate tissue play in the development or progression of idiopathic scoliosis. In this investigation, there were significant differences of the total expression of type X collagen, Runx2 protein, and Runx2 mRNA between convex side and concave side growth plates of the apex vertebrae (p < 0.05). The total expression of type X collagen in the concave side growth plates of the lower end vertebrae was higher than that in the same side growth plates of apex (p < 0.05). The total expression of Runx2 in the concave side growth plates in the upper and lower end vertebrae were higher than that in the concave side growth plates of apex (p < 0.05). The expression of type X collagen, Runx2, and Runx2 mRNA, the cell density of type X collagen and Runx2 positive chondrocytes, and histological changes between convex side and concave side of the vertebral growth plate indicated that the vertebral growth plate was affected by mechanical forces, which was a secondary change and could contribute to progression of adolescent idiopathic scoliosis.     

The diameter of the vertebral canal in dogs in cases of lumbosacral transitional vertebrae or numerical vertebral variations

From Th1 to L7 midsagittal and interpedicular vertebral canal diameters were measured in macerated spines of 162 dogs to determine, whether the presence of lumbosacral transitional vertebrae or numerical vertebral variations are associated with dislocation of the maximal enlargement of the lumbar vertebral canal. Relative to dogs with a regular number of 27 presacral vertebrae (C7/Th13/L7), the maximal enlargement of the lumbar vertebral canal was more frequently ( P < 0.05) located at vertebra 24 in dogs with 26 presacral vertebrae (C7/Th13/L6), and more frequently at vertebra 25 in dogs with 28 presacral vertebrae (C7/Th13/L8). However, in dogs with 26 presacral vertebrae, maximal agreement in the spinal position of maximal lumbar vertebral canal diameters was achieved relative to dogs with 28 presacral vertebrae by adding one additional thoracic (Th6, 7, or 8) segment. Therefore, the present findings strongly suggest that relative to the regular (C7/Th13/L7) condition, decrease in the number of presacral vertebrae (C7/Th13/L6) is associated with incorporation of a midthoracic segment, whereas increase in the number of presacral vertebrae (C7/Th13/L8) is not related to the presence of an additional vertebral segment. When using Th1 as landmark, the difference in the position of the maximal enlargement of the lumbar vertebral canal between dogs with 26 and dogs with 28 presacral vertebrae in average was only one segment. It is known from previous reports that the maximal enlargement of the lumbar vertebral canal corresponds with the maximal enlargement of the lumbar spinal cord. When using S1 or the transitional vertebra as the landmark for determination of the appropriate site for subarachnoid cannulation, this site is expected to range within the same limits regardless of the vertebral formula.     

腰椎椎基静脉孔的解剖学观测及其临床意义

目的　通过对腰椎椎基静脉孔（BVF）的观测,为临床脊柱外科手术提供解剖学数据。  方法　(1)测量115块成人腰椎观测BVF的数目、面积、与椎体上下缘距离、与左右椎弓根最短距离。(2)解剖成人尸体13具,观察BVF的形态结构。  结果　(1) BVF以椭圆形多见,不同人体BVF数目有差异（P<0.05）,分布集中。(2) BVF与椎体上缘及左右椎弓根最短距离在不同人体间有差异（P<0.05）,与椎体上下缘距离、左右椎弓根最短距离在同一人体不同腰椎间有差异（P<0.05）。(3)尸体解剖见血管出入BVF,并有脂肪组织等软组织填充。  结论　腰椎BVF是腰椎椎体后壁面积较大的骨质缺损区。该区域与左右椎弓根之间以及与椎体上下缘之间有一无血管出入骨质的区域,为临床脊柱外科手术提供参考。     

Posterior distraction forces of the posterior longitudinal ligament stratified according to vertebral level

Introduction Although considered significant in resisting midline intervertebral disc herniation, the posterior longitudinal ligament (PLL) has had relatively few studies performed regarding its morphology and function. We performed the present experiment to discern the amount of posterior tensile force necessary to disrupt the PLL at each vertebral level. Materials and methods Twenty-five adult cadavers underwent laminectomies of vertebrae C1 to S1. After removal of the spinal cord, nerve roots, and dura mater, the PLL was identified for each vertebral level and a steel wire placed around its waist in the midline and a tensile gauge attached and posterior tension applied perpendicular to the spine. Forces necessary to failure of the PLL were noted for each vertebral level. Results The PLL was found to be stronger in the thoracic spine compared to the cervical and lumbar vertebrae (P < 0.05). Dividing the vertebral levels in this manner, we found an average posterior distraction force to failure of 48.3 N in the cervical region, 61.3 N in the thoracic region, and 48.8 N in the lumbar region. Conclusions These findings support clinical observations that thoracic disc herniation is rare. We hypothesize that this clinical observation is partially due to a stronger PLL in the thoracic spine.     

Damage to the human lumbar cartilage endplate and its clinical implications

The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage, and plays an important role in the diffusion of nutrients into the intervertebral discs. Its damage may seriously affect the disc degeneration, and result in low back pain (LBP). However, the structural features of damaged CEPs have not been well characterized, and this hinders our understanding of the etiology of disc degeneration and pain. To present the structural features of micro-damaged CEPs in patients with disc degeneration and LBP that might even be regarded as an initial factor for disc degeneration, we performed a histological study of micro-damaged CEPs harvested from human lumbar intervertebral discs and analyzed its clinical implications. Human lumbar CEPs were excised from 35 patients (mean age 60.91 years) who had disc degeneration and LBP. Control tissue was obtained from 15 patients (mean age 54.67 years) with lumbar vertebral burst fractures. LBP and disability were assessed clinically, and all patients underwent anterior vertebral body fusion surgery. CEPs together with some adjacent nucleus pulposus (NP) were sectioned at 4 µm, and stained using H&E, Safranin O/Fast Green, and Alcian Blue. Immunostaining and PCR were used to identify various markers of degeneration, innervation, and inflammation. Histology demonstrated physical micro-damage in 14/35 CEPs from the disc degeneration group. Six major types of damage could be distinguished: fissure, traumatic nodes, vascular mimicry, incorporation of NP tissue within the CEP, incorporation of bone within the CEP, and incorporation of NP and bone within the CEP. Pain and disability scores (ODI: p = 0.0190; JOA: p = 0.0205; JOABPEQ: p = 0.0034) were significantly higher in those with micro-damaged CEPs (N = 14) than in those with non-damaged CEPs (N = 21). CEP damage was significantly associated with elevated MMP3 (p = 0.043), MMP13 (p = 0.0191), ADAMTS5 (p = 0.0253), TNF-α (p = 0.0011), and Substance P (p = 0.0028), and with reduced Sox9 (p = 0.0212), aggrecan (p = 0.0127), and type II collagen (p = 0.0139). In conclusion, we presented a new classification of human lumbar micro-damaged CEPs. Furthermore, we verify disc degeneration, innervation, and discogenic pain in micro-damaged CEPs.     

Vertebral pattern variation in the North Sea harbor porpoise (Phocoena phocoena) by computed tomography

Vertebral series in the harbor porpoise (Phocoena phocoena) include cervical, thoracic, lumbar, and caudal. In contrast to studying skeletons from museums, in which small bones can be missed, evaluation of full body computed tomography (CT) scans provides an overview of the vertebral column, while maintaining interrelationship of all structures. The aim of this study was to document variations in vertebral patterning of the harbor porpoise via evaluation of CT images of intact stranded harbor porpoises. The harbor porpoises were divided into age classes, based on developmental stage of reproductive organs on postmortem examination and closure of proximal humeral physis on CT. Numbers of vertebrae per series, fusion state of the syncervical, type of first hemal arch, number of double articulating ribs, and floating ribs were recorded based on CT images. Included in the study were 48 harbor porpoises (27 males and 21 females), which were divided in two age classes (27 immatures and 21 adults). Total vertebral count varied from 63 to 68 with vertebral formula range C7T12-14L12-16Cd29-33. Twenty-five different vertebral formulas were found, of which C7T13L14Ca30 was the most common (n = 8, 17%). Thoracic vertebrae with six, seven, or eight double articulating ribs and zero, one, or two vertebrae with floating ribs were seen. Four different fusion states of the syncervical and four types of hemal arches were recognized. This study showed a great variation in vertebral patterning in the harbor porpoise, with homeotic and meristic variation in the thoracic, lumbar, and caudal vertebral series.     

Functional adaptations of facet geometry in the canine thoracolumbar and lumbar spine (Th10-L6).

The shape, size and transverse distance between contralateral caudal articular processes of caudal thoracic and lumbar vertebrae were evaluated in a sample of 140 macerated canine spines to contribute to the understanding of the development of vertebral misalignment. Dogs were grouped as large, chondrodystrophic, and small breeds. In large dogs, caudal articular surfaces were adapted to higher body-weight by the presence of larger articular surfaces. Additionally, caudal articular surfaces not only covered the lateral, but also the ventral (i.e. ventral facet) and/or caudal aspects (i.e. caudal facet) of the caudal articular processes. Ventral facets, which increase loading capacity of the zygapophyseal joints in normally aligned vertebrae, were more frequently observed in large breeds (p < 0.001) than in small and chondrodystrophic breeds. With some exceptions, caudal facets primarily were present in large dogs, especially at the vertebral levels L3-L5. Their formation is induced by extension of the normal lykphotic thoracic and lumbar spine causing lumbar lordosis and denotes loss in elasticity of the bow-and-string-construction of the trunk. Because ventral and caudal facets are consistent with convexity of the caudal articular surfaces, which to a great degree was noted to result in formation of ball-and-socket joints, spinal stability is supposed to be decreased under such conditions.     

Radiographic and Magnetic Resonance Imaging Identification of Thoracolumbar Spine Variants with Implications for the Positioning of the Conus Medullaris in Rhesus Macaques

The anatomy of the vertebral column in mammals may differ between species and between subjects of the same species, especially with regards to the composition of the thoracolumbar spine. We investigated, using several noninvasive imaging techniques, the thoracolumbar spine of a total of 44 adult rhesus macaques of both genders. Radiographic examination of the vertebral column showed a predominant spine phenotype with 12 rib‐bearing thoracic vertebrae and 7 lumbar vertebrae without ribs in 82% of subjects, whereas a subset of subjects demonstrated 13 rib‐bearing thoracic vertebrae and 6 lumbar vertebrae without ribs. Computer tomography studies of the thoraco‐lumbar spine in two cases with a pair of supernumerary ribs showed facet joints between the most caudal pair of ribs and the associated vertebra, supporting a thoracic phenotype. Magnetic resonance imaging (MRI) studies were used to determine the relationship between the lumbosacral spinal cord and the vertebral column. The length of the conus medullaris portion of the spinal cord was 1.5 ± 0.3 vertebral units, and its rostral and caudal positions in the spinal canal were at 2.0 ± 0.3 and 3.6 ± 0.4 vertebral units below the thoracolumbar junction, respectively (n = 44). The presence of a set of supernumerary ribs did not affect the length or craniocaudal position of the conus medullaris, and subjects with13 rib‐bearing vertebrae may from a functional or spine surgical perspective be considered as exhibiting12 thoracic vertebrae and an L1 vertebra with ribs. Anat Rec, 300:300–308, 2017. © 2016 Wiley Periodicals, Inc.     

Variations in the anatomy of the celiac trunk: A systematic review and clinical implications

The normal pattern of the celiac trunk (CT) implies its bifurcation to three branches, the common hepatic, the splenic and the left gastric artery. According to the available literature the CT presents several anatomical variations. The purpose of our study is to investigate the different types of these variations, the corresponding incidences and the probable influence of genetic factors, as they are presented in the existing literature. Four databases were searched for eligible articles for the period up to January 2013 and a total of 36 studies were collected. The CT was trifurcated into the three basic branches in the 89.42% (10,906/12,196) of the cases. Bifurcation of the CT occurred in the 7.40% of the pooled samples (903/12,196). Absence of the CT was the rarest variation with a percentage of 0.38% (46/12,196), hepatosplenomesenteric trunk was found in 49 out of the 12,196 cases (0.40%) and the celiacomesenteric trunk presented an incidence of 0.76% (93/12,196). Other variations of the CT were detected in the 1.64% of the pooled cases (199/12,196). The 14.9% of the cases in the cadaveric series (489/3278 specimens), the 10.5% in the imaging series (675/6501 specimens) and the 4.6% (104/2261) in the liver transplantation series presented variations. These differences are statistically significant (p < 0.001). The Japanese and Korean populations presented more variations in the CT than Caucasians (p < 0.05 and p < 0.001). Negro, colored and black populations presented more variations of the CT than Indian ones (p > 0.05).Using those data, a novel classification of CT variations is proposed.     

A new method for determining lumbar spine motion using Bayesian belief network

A Bayesian network dynamic model was developed to determine the kinematics of the intervertebral joints of the lumbar spine. Radiographic images in flexion and extension postures were used as input data for modeling, together with movement information from the skin surface using an electromagnetic motion tracking system. Intervertebral joint movements were then estimated by the graphic network. The validity of the model was tested by comparing the predicted position of the vertebrae in the neutral position with those obtained from the radiographic image in the neutral posture. The correlation between the measured and predicted movements was 0.99 (p < 0.01) with a mean error of less than 1.5°. The movement sequence of the various vertebrae was examined based on the model output, and wide variations in the kinematic patterns were observed. The technique is non-invasive and has potential to be used clinically to measure the kinematics of lumbar intervertebral movement. This work was supported by the Hong Kong Research Grant Council (Competitive Earmarked Research Grant CERG CUHK5251/04E).     

Morphometric study of the equine navicular bone: variations with breeds and types of horse and influence of exercise

Navicular bones from the 4 limbs of 95 horses, classified in 9 categories, were studied. The anatomical bases were established for the morphometry of the navicular bone and its variations according to the category of horse, after corrections were made for front or rear limb, sex, weight, size and age. In ponies, navicular bone measurements were smallest for light ponies and regularly increased with body size, but in horses, navicular bone dimensions were smallest for the athletic halfbred, intermediate for draft horse, thoroughbreds and sedentary halfbreds and largest for heavy halfbreds. The athletic halfbred thus showed reduced bone dimensions when compared with other horse types. Navicular bones from 61 horses were studied histomorphometrically. Light horses and ponies possessed larger amounts of cancellous bone and less cortical bone. Draft horses and heavy ponies showed marked thickening of cortical bone with minimum intracortical porosity, and a decrease in marrow spaces associated with more trabecular bone. Two distinct zones were observed for the flexor surface cortex: an external zone composed mainly of poorly remodelled lamellar bone, disposed in a distoproximal oblique direction, and an internal zone composed mainly of secondary bone, with a lateromedial direction for haversian canals. Flexor cortex external zone tended to be smaller for heavy ponies than for the light ponies. It was the opposite for horses, with the largest amount of external zone registered for draft horses. In athletic horses, we observed an increase in the amount of cortical bone at the expense of cancellous bone which could be the result of reduced resorption and increased formation at the corticoendosteal junction. Cancellous bone was reduced for the athletic horses but the number of trabeculae and their specific surfaces were larger. Increased bone formation and reduced resorption could also account for these differences.     

Study on risk factors and serologic prevalence of antibodies against equine influenza virus in the south of Iran

Six hundred horse serum samples were analyzed for equine influenza virus-specific antibodies using competitive ELISA in Fars Province (south of Iran) (2011–2012). In our study, 2.5 % of horses had a positive reaction which was proved to be due to natural exposure to equine influenza virus. Of the horses, 1.94 % were positive in autumn and 5.47 % were positive in winter. No significant difference was found among the prevalences of the disease in different breeds. It was concluded that the seroprevalence of equine influenza is quite low in the south of Iran. In view of no vaccination coverage for equine influenza in the country, the necessity of surveillance should be considered.