Ella Been

Lumbar lordosis of extinct hominins

The lordotic curvature of the lumbar spine (lumbar lordosis) in humans is a critical component in the ability to achieve upright posture and bipedal gait. Only general estimates of the lordotic angle (LA) of extinct hominins are currently available, most of which are based on the wedging of the vertebral bodies. Recently, a new method for calculating the LA in skeletal material has become available. This method is based on the relationship between the lordotic curvature and the orientation of the inferior articular processes relative to vertebral bodies in the lumbar spines of living primates. Using this relationship, we developed new regression models in order to calculate the LAs in hominins. The new models are based on primate group-means and were used to calculate the LAs in the spines of eight extinct hominins. The results were also compared with the LAs of modern humans and modern nonhuman apes. The lordotic angles of australopithecines (41° ± 4), H. erectus (45°) and fossil H. sapiens (54° ± 14) are similar to those of modern humans (51° ± 11). This analysis confirms the assumption that human-like lordotic curvature was a morphological change that took place during the acquisition of erect posture and bipedalism as the habitual form of locomotion. Neandertals have smaller lordotic angles (LA = 29° ± 4) than modern humans, but higher angles than nonhuman apes (22° ± 3). This suggests possible subtle differences in Neandertal posture and locomotion from that of modern humans.

Geometry of the vertebral bodies and the intervertebral discs in lumbar segments adjacent to spondylolysis and spondylolisthesis: pilot study

The objective is to evaluate the geometric parameters of vertebral bodies and intervertebral discs in spinal segments adjacent to spondylolysis and spondylolisthesis. This pilot cross-sectional study was an ancillary project to the Framingham Heart Study. The presence of spondylolysis and spondylolisthesis as well as measurements of spinal geometry were identified on CT imaging of 188 individuals. Spinal geometry measurements included lordosis angle, wedging of each lumbar vertebra and intervertebral disc. Last measurements were used to calculate ΣB, the sum of the lumbar L1–L5 body wedge angles; and ΣD, the sum of the lumbar L1–L5 intervertebral disc angles. Using Wilcoxon–Mann–Whitney test we compared the geometric parameters between individuals with no pathology and ones with spondylolysis (with no listhesis) at L5 vertebra, ones with isthmic spondylolisthesis at L5–S1 level, and ones with degenerative spondylolisthesis at L5–S1 level. Spinal geometry in individuals with spondylolysis or listhesis at L5 shows three major patterns: In spondylolysis without listhesis, spinal morphology is similar to that of healthy individuals; In isthmic spondylolisthesis there is high lordosis angle, high L5 vertebral body wedging and very high L4–5 disc wedging; In degenerative spondylolisthesis, spinal morphology shows more lordotic wedging of the L5 vertebral body, and less lordotic wedging of intervertebral discs. In conclusion, there are unique geometrical features of the vertebrae and discs in spondylolysis or listhesis. These findings need to be reproduced in larger scale study.

The Neandertal vertebral column 1: The cervical spine

This paper provides a metric analysis of the Neandertal cervical spine in relation to modern human variation. All seven cervical vertebrae have been analysed. Metric data from eight Neandertal individuals are compared with a large sample of modern humans. The significance of morphometric differences is tested using both z-scores and two-tailed Wilcoxon signed rank tests. The results identify significant metric and morphological differences between Neandertals and modern humans in all seven cervical vertebrae. Neandertal vertebrae are mediolaterally wider and dorsoventrally longer than modern humans, due in part to longer and more horizontally oriented spinous processes. This suggests that Neandertal cervical morphology was more stable in both mid-sagittal and coronal planes. It is hypothesized that the differences in cranial size and shape in the Neandertal and modern human lineages from their Middle Pleistocene ancestors could account for some of the differences in the neck anatomy between these species.

Association between computed tomography–evaluated lumbar lordosis and features of spinal degeneration, evaluated in supine position

BACKGROUND CONTEXT Few studies have directly evaluated the association of lumbar lordosis and segmental wedging of the vertebral bodies and intervertebral discs with the prevalence of spinal degenerative features. PURPOSE To evaluate the association of computed tomography (CT)-evaluated lumbar lordosis as well as segmental wedging of the vertebral bodies and that of the intervertebral discs with various spinal degenerative features. STUDY DESIGN This cross-sectional study was a nested project to the Framingham Heart Study. PATIENT SAMPLE A random consecutive subset of 191 participants chosen from the 3,590 participants enrolled in the Framingham Heart Study who underwent multidetector CT to assess aortic calcification. OUTCOME MEASURES Dichotomous variables indicating the presence of intervertebral disc narrowing, facet joint osteoarthritis, spondylolysis, spondylolisthesis and spinal stenosis, and density (in Hounsfield units) of multifidus and erector spinae muscles were evaluated on supine CT, as well as the lordosis angle (LA) and the wedging of the vertebral bodies and intervertebral discs. The sum of vertebral bodies wedging (ΣB) and sum of intervertebral discs wedging (ΣD) were used in the analyses. METHODS Mean values (±standard deviation [SD]) of LA, ΣB, and ΣD were calculated in males and females and compared using the t test. Mean values (±SD) of LA, ΣB, and ΣD in four age groups (<40, 40-49, 50-59, and 60+ years) were calculated. We tested the linear relationship between LA, ΣB, and ΣD and age groups. We evaluated the association between each spinal degenerative feature and LA, ΣB, and ΣD using multiple logistic regression analysis where studied degenerative features were the dependent variable and all LA, ΣB, and ΣD (separately) as well as age, sex, and body mass index were independent predictors. RESULTS Lordosis angle was slightly lower than the normal range for standing individuals, and no difference was found between males and females (p=.4107). However, the sex differences in sum of vertebral bodies wedging (ΣB) and sum of intervertebral discs wedging (ΣD) were statistically significant (.0001 and .001, respectively). Females exhibit more dorsal wedging of the vertebral bodies and less dorsal wedging of the intervertebral discs than do males. All these parameters showed no association (p>.05) with increasing age. Lordosis angle showed statistically significant association with the presence of spondylolysis (odds ratio [95% confidence interval]: 1.08 [1.02-1.14]) and with the density of multifidus (1.06 [1.01-1.11]) as well as a marginally significant association with isthmic spondylolisthesis (1.07 [1.00-1.14]). ΣB showed a positive association with degenerative spondylolisthesis and disc narrowing (1.14 [1.06-1.23] and 1.04 [1.00-1.08], correspondingly), whereas ΣD showed a negative one (0.93 [0.87-0.98] and 0.93 [0.89-0.97], correspondingly). CONCLUSIONS Significant associations were found between lumbar lordosis evaluated in supine position and segmental wedging of the vertebral bodies and intervertebral discs and the prevalence of spondylolysis and spondylolisthesis. Additional studies are needed to evaluate the association between spondylolysis, isthmic and degenerative spondylolisthesis and vertebral and disc wedging at the segmental level.

Vertebral Bodies or Discs: Which Contributes More to Human-like Lumbar Lordosis?

BackgroundThe attainment of upright posture, with its requisite lumbar lordosis, was a major turning point in human evolution. Nonhuman primates have small lordosis angles, whereas the human spine exhibits distinct lumbar lordosis (30°–80°). We assume the lumbar spine of the pronograde ancestors of modern humans was like those of extant nonhuman primates, but which spinal components changed in the transition from small lordosis angles to large ones is not fully understood.Questions/PurposesWe wished to determine the relative contribution of vertebral bodies and intervertebral discs to lordosis angles in extant primates and humans.MethodsWe measured the lordosis, intervertebral disc, and vertebral body angles of 100 modern humans (orthograde primates) and 56 macaques (pronograde primates) on lateral radiographs of the lumbar spine (humans–standing, macaques–side-lying).ResultsThe humans exhibited larger lordosis angles (51°) and vertebral body wedging (5°) than did the macaques (15° and −25°, respectively). The differences in wedging of the intervertebral discs, however, were much less pronounced (46° versus 40°).ConclusionsThese observations suggest the transition from pronograde to orthograde posture (ie, the lordosis angle) resulted mainly from an increase in vertebral body wedging and only in small part from the increase in wedging of the intervertebral discs.

Morphology and Function of the Lumbar Spine of the Kebara 2 Neandertal

The morphology of the lumbar spine is crucial for upright posture and bipedal walking in hominids. The excellent preservation of the lumbar spine of Kebara 2 provides us a rare opportunity to observe a complete spine and explore its functionally relevant morphology. The lumbar spine of Kebara 2 is analyzed and compared with the lumbar spines of modern humans and late Pleistocene hominids. Although no size differences between the vertebral bodies and pedicles of Kebara 2 and modern humans are found, significant differences in the size and orientation of the transverse processes (L(1)-L(4)), and the laminae (L(5), S(1)) are demonstrated. The similarity in the size of the vertebral bodies and pedicles of Kebara 2 and modern humans suggests similarity in axial load transmission along the lumbar spine. The laterally projected (L(2)-L(4)) and the cranially oriented (L(1), L(3)) transverse processes of Kebara 2 show an advantage for lateral flexion of the lumbar spine compared with modern humans. The characteristic morphology of the lumbar spine of Kebara 2 might be related to the wide span of its pelvic bones.

A New Look at the Geometry of the Lumbar Spine

Study Design. A retrospective cohort study of the relationship between the structures that form the lumbar spine in humans. Objective. To investigate the relationship between the segmental wedging of the vertebral bodies and that of the intervertebral discs, and between the overall lordosis angle and each of the 5 lumbar segments. Summary of Background Data. Little attention has been paid to the internal relationship between the structures that form the lumbar spine. Understanding these relationships is instrumental to our ability to restore and rehabilitate the lordotic curvature. Methods. Lateral radiographs of 101 adult lumbar spines were examined in patients at spinal clinics. The patients had no history of spinal surgery and no radiographic abnormality. The radiologic parameters are the lordosis angle (LA), the body wedge angle (B), the total segmental angle (S), and the intervertebral disc angle (D). Measurements B, S, and D were taken for each of the 5 lumbar segments. Measurements B and D were used to calculate &Sgr;B, the sum of the B, and &Sgr;D, the sum of the D. Results. The LA correlates with the sum of the vertebral body angles and with the sum of the intervertebral disc angles. Vertebral body wedging is negatively correlated with intervertebral disc wedging. The middle 3 lumbar segments are moderately-to-poorly correlated, among themselves and with the LA, while the upper and lower lumbar segments are poorly correlated with the LA and not correlated with any lumbar segment. Conclusion. Three parts of the lumbar lordosis were identified: the upper part, formed by the first lumbar segment; the middle part, formed by the middle 3 segments; and the lower part, formed by the fifth lumbar segment. The statistical study shows an inverse relationship between vertebral body and intervertebral disc wedging.

Brief Communication: Lumbar lordosis in extinct hominins: Implications of the pelvic incidence

Recently, interest has peaked regarding the posture of extinct hominins. Here, we present a new method of reconstructing lordosis angles of extinct hominin specimens based on pelvic morphology, more specifically the orientation of the sacrum in relation to the acetabulum (pelvic incidence). Two regression models based on the correlation between pelvic incidence and lordosis angle in living hominoids have been developed. The mean values of the calculated lordosis angles based on these models are 36°-45° for australopithecines, 45°-47° for Homo erectus, 27°-34° for the Neandertals and the Sima de los Huesos hominins, and 49°-51° for fossil H. sapiens. The newly calculated lordosis values are consistent with previously published values of extinct hominins (Been et al.: Am J Phys Anthropol 147 (2012) 64-77). If the mean values of the present nonhuman hominoids are representative of the pelvic and lumbar morphology of the last common ancestor between humans and nonhuman hominoids, then both pelvic incidence and lordosis angle dramatically increased during hominin evolution from 27° ± 5 to 22° ± 3 (respectively) in nonhuman hominoids to 54° ± 10 and 51° ± 11 in modern humans. This change to a more human-like configuration appeared early in the hominin evolution as the pelvis and spines of both australopithecines and H. erectus show a higher pelvic incidence and lordosis angle than nonhuman hominoids. The Sima de los Huesos hominins and Neandertals show a derived configuration with a low pelvic incidence and lordosis angle.

New method for predicting the lumbar lordosis angle in skeletal material.

Reconstructing the lordotic curvature of the lumbar spine in humans is essential for understanding their posture and locomotion. To date there is still no reliable method for predicting the lordotic curvature of disarticulated spines (in the absence of intervertebral disks). This article examines two possible methods for predicting the lordotic curvature of the lumbar spine. The first—the traditional method—is based on the degree of wedging of the vertebral bodies, and the second—the suggested new method—is based on a lateral view of the orientation of the inferior articular processes. We propose a linear regression model for predicting the lordotic curvature of the lumbar spine (lordosis angle) in disarticulated human spines. This model, derived directly from our new method, is a more reliable predictor of the lumbar lordosis angle in disarticulated spines. Anat Rec, 2007.

Sacral orientation and spondylolysis.

Study Design. A descriptive study (based on skeletal material) was designed to measure sacral anatomic orientation (SAO) in individuals with and without spondylolysis. Objective. To test whether a relationship between SAO and spondylolysis exists. Summary of Background Data. Spondylolysis is a stress fracture in the pars interarticularis (mainly of L5). The natural history of the phenomenon has been debated for years with opinions divided, i.e., is it a developmental condition or a stress fracture phenomenon. There is some evidence to suggest that sacral orientation can be a “key player” in revealing the etiology of spondylolysis. Methods. The pelvis was anatomically reconstructed and SAO was measured as the angle created between the intersection of a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis (PUBIS). SAO was measured in 99 adult males with spondylolysis and 125 adult males without spondylolysis. The difference between the groups was tested using an unpaired t test. Results. Spondylolysis prevalence is significantly higher in African-Americans compared to European-Americans: 5.4% versus 2.04% in males (P < 0.001) and 2.31% versus 0.4%, P < 0.001 in females. SAO was significantly lower in the spondylolytic group (44.07° ± 11.46°) compared to the control group (51.07° ± 8.46°, P < 0.001). Conclusion. A more horizontally oriented sacrum leads to direct impingement on L5 pars interarticularis by both L4 inferior articular facet superiorly and S1 superior articular facet inferiorly. Repetitive stress due to standing (daily activities) or sitting increases the “pincer effect” on this area, and eventually may lead to incomplete synostosis of the neural arch.