Pelvic Shape Research Articles

Individualization of Musculoskeletal Model for Analyzing Pelvic Floor Muscles Activity Based on Gait Motion Features

Stress urinary incontinence (SUI) is a typical quality of life disease in women. The strengthening of the pelvic floor muscle (PFM) is considered effective to prevent this. Specifically, PFM activity is affected by individual pelvic shape and posture. Therefore, it is necessary to analyze muscle activity by considering the individual differences. In this study, individual pelvic alignment was estimated from the feature values of natural gait via multiple regression analysis. In addition, individual pelvic feature points were derived from X-ray images and used to deform the standard model to obtain individual pelvic shapes. Results indicate that the residual averages of the estimated feature angles were less than 2° in most cases. Subsequently, measurements of the pelvis were obtained via MRI to evaluate the estimated pelvis shape. The results indicate that individual adaptation leads to muscle attachment positions, which are important in the muscle activity analysis, and closer to the true MRI value when compared to that of the standard pelvic model.

Sexing Viking Age horses from burial and non-burial sites in Iceland using ancient DNA

Horses are the most common grave goods found in Icelandic Viking Age graves. Horse skeletons have previously been sexed based on pelvis shape and the presence of canine teeth in male horses over 4–5 years of age. Morphological data has shown that all horses from Icelandic burials that were amenable to sexing were male. Yet the use of morphological methods to determine sex is problematic since they rely on finding a well-preserved pelvis and/or robust canine teeth. Furthermore, quantitative data underlying the features of the horse pelvis used for sexing is lacking and canine teeth have been reported to occur in mares. In this study we build upon and extend recently developed methodologies to make use of shotgun sequencing of ancient DNA (aDNA) for molecular sexing of Viking Age horse remains. With minimal sequencing effort we identified the sex of the largest collection (n = 22) of Viking Age Icelandic horses studied to date, sourced from both burial (n = 19) and non-burial (n = 3) sites. Our results revealed a male to female sex bias ratio of 18:1 in burial sites, versus 0:3 in non-burial sites. These findings support the significant over-representation of male horses in Viking Age graves in Iceland, yet show that –albeit rare– mares could also be selected for ritual burial in Viking Age Iceland. This cost-effective method provides statistical confidence to allow for sexing of highly fragmented archaeological specimens with low endogenous DNA content.

Effect of changing femoral head diameter on bony and prosthetic jumping angles.

In THA, using a larger femoral head can increase the oscillation angle and jumping distance. However, there have been no reports which indicate precisely how increasing the jumping distance leads to an increase in the angle from impingement to dislocation (jumping angle). In this study, we clarified the jumping angle of various head diameters and its relationship with pelvic morphology. Using a three-dimensional templating system, virtual THA and ROM simulations were performed in 82 patients. We investigated the distance between bony and prosthetic impingement points and the head centre and calculated the jumping angle for various head diameters. We measured various pelvic shapes and length to clarify the relationship between pelvic morphology and impingement distance. Jumping angles were 7.7° ± 3.2°, 12.1° ± 1.6°, 15.4° ± 2.5° and 10.0° ± 3.0° with flexion, internal rotation with 90° flexion (IR), extension and external rotation (ER), respectively, when we used a 22-mm head diameter. Bony jumping angle increased about 0.5°, 0.8°, 1.0° and 0.7° per 2-mm increase in head diameter with flexion, IR, extension and ER. On the other hand, prosthetic jumping angle remained almost stable at about 31°. Impingement distance was related to pelvic morphology in all directions. Bony jumping angles differed with ROM; the biggest was seen with extension, followed by IR, ER and flexion. On the other hand, bony jumping angle was less than prosthetic jumping angle in all cases. Bony jumping angles differed with ROM; the biggest was seen with extension, followed by IR, ER and flexion. Prosthetic impingement angles were stable. In addition, the bony jumping angle was less than the prosthetic jumping angle in all cases.

Size and shape correlation of birds' pelvis and egg: Impact of developmental mode, habitat, and phylogeny.

While eggs shapes and sizes have been subject of many studies, we still know little about factors affecting these characteristics of birds' eggs. We revealed that shapes of pelvis and egg correlated less than their respective sizes. Egg measurements (length or diameter) scaled with negative allometry against pelvis size, that is, eggs become relatively larger with decreasing pelvis size. Studied birds with altricial developmental mode had on average the smallest pelvic dimensions and the largest relative size of eggs. However, this is due to the effect of small pelvis size (and body as a whole) of most altricials. At the similar size of the pelvis, birds with altricial developmental mode had a smaller relative size of eggs than their precocial counterparts. Correlation between the shape of egg and pelvis is affected by habitat. Narrow pelvis with an elongated postacetabular region correlated with elongated eggs in diving waterfowl. In raptorial birds, the relatively wide pelvis with the shortened postacetabular region correlated with the nearly rounded shape of eggs.

Ancient pelvis reconstruction from collapsed component bones using statistical shape models

We propose a new method for recovering the pelvis of an ancient skeleton from its three component bones with collapsed surfaces. The proposed method uses four types of statistical shape models (SSMs) for the bones. The SSM for each bone describes the mean shape and shape variations of a class of bones. The SSMs for the three component bones are employed to restore the shapes of the component bones. The SSM for the whole pelvis provides the natural anatomical shape of the pelvis and the spatial relationship among the sacrum and the hip bones. Therefore, the three component bones are aligned by using the SSM for the pelvis. The experimental results show that our method achieves reliable reconstruction of the ancient pelvis shape despite having collapsed surfaces in its component bones.

Anatomical features of the pelvis in Azerbaijani women according to osteometry

The purpose of the study was to identify morphological features of the pelvis of Azerbaijani women. Material and methods. The osteological collection from the museum of the anatomy department of the human anatomy department of the Azerbaijan Medical University (total 78 female pelvis, aged 16 to 60) was studied. On each anatomic preparation of the bone pelvis 15 pelviometric signs were studied according to the standard standard procedure. The results were recorded in an electronic database in Microsoft Excel (version 2007), where the necessary statistical calculations were performed. Results. According to the results of osteometry, three forms of the pelvis are distinguished: normal shape, uniformly dense shape, and transversely restricted pelvic shape. Parameters of 42 objects were assigned to the normal form. Basins with a transverse diameter of less than 11.8 cm. and the transverse diameter of the exit of the small pelvis is less than 10.5 cm. were assigned to the transversalized forms of the pelvis; There were 18 such objects in the collection. The remaining objects had osteometric characteristics that differed from the average values were attributed to the uniformly constricted forms of the pelvis. The maximum parameters of the parameters were noted in the group of normal cans, and the minimum ones in the group of uniformly-compressed pelvis. The narrow pelvic forms were characterized by low values of pelviometric traits, and for normal ones - high indices. Conclusions. The revealed features of the pelvic dimensions are planned to be used for the development of appropriate anthropometric standards.

Reducing Cesarean Delivery Rates and Length of Labor by Addressing Pelvic Shape.

Reducing Cesarean Delivery Rates and Length of Labor by Addressing Pelvic Shape.

Association Between Lumbar Spinal Degeneration and Anatomic Pelvic Parameters.

Retrospective cohort study. The objective was to prove the association between anatomic pelvis parameters and specific types of lumbar spinal degeneration. Different spinopelvic sagittal profile types are suggested to be associated with specific degenerative lumbar spine pathologies. Because pelvic morphology plays a key role defining the spinal shape as well as its load and function it thereby potentially predisposes the development of spinal degeneration. Patients with symptomatic lumbar spinal degeneration who were surgically treated in 2 spine departments from March 2011 until August 2016 were included in this retrospective analysis. Single-level degenerative pathologies were classified as lumbar disc herniation (LDH), degenerative disc disease (DDD), lumbar spinal stenosis (LSS), and degenerative spondylolisthesis (DSPL). The constant anatomic pelvic parameters pelvic incidence (PI), pelvic radius (PR), and sacral table angle (STA) were assessed in lateral radiographs of the lumbar spine and compared between the pathologies. In total, 249 patients were assigned to the LDH (n=73), DDD (n=67), LSS (n=42), and DSPL (n=67) groups. Group comparisons revealed significant differences in the anatomic pelvic parameters PR (LDH, 139.5±10.8 mm; DDD, 135.9±14.0 mm; LSS, 127.8±14.3 mm; DSPL, 135.8±12.7 mm; P<0.001), PI (LDH, 53.1±10.0 degrees; DDD, 50.0±9.9 degrees; LSS, 54.5±9.6 degrees; DSPL, 57.1±10.8 degrees; P=0.001), and STA (LDH, 95.3±12.7 degrees; DDD, 105.4±9.0 degrees; LSS, 105.9±11.5 degrees; DSPL, 98.6±9.5 degrees; P<0.001). Post hoc tests indicated significant differences between the PR of the LSS group and that of all other subgroups (P<0.012), the PI of the DDD group and that of DSPL (P<0.001), and the STA of the LDH/DSPL groups and that of the LSS/DDD group (P<0.005). We found all the constant anatomic parameters to be specific for distinct types of degeneration, suggesting pelvis shape is a predisposing factor for their development. Level III.

Computed tomographic pelvimetry in English bulldogs

English bulldogs have been reported to have a high incidence of dystocia and caesarean section is often performed electively in this breed. A narrow pelvic canal is the major maternal factor contributing to obstructive dystocia. The objective of this cross-sectional study was to assess the pelvic dimensions of 40 clinically healthy English bulldogs using computed tomography pelvimetry. A control group consisting of 30 non-brachycephalic dogs that underwent pelvic computed tomography was retrospectively collected from the patient archive system. Univariate analysis of variance was used to compare computed tomography pelvimetry of both groups and the effects of weight and gender on the measurements. In addition, ratios were obtained to address pelvic shape differences. A significantly (P = 0.00) smaller pelvic size was found in English bulldogs compared to the control group for all computed tomography measurements: width and length of the pelvis, pelvic inlet and caudal pelvic aperture. The pelvic conformation was significantly different between the groups, English bulldogs had an overall shorter pelvis and pelvic canal and a narrower pelvic outlet. Weight had a significant effect on all measurements whereas gender that only had a significant effect on some (4/11) pelvic dimensions. Our findings prove that English bulldogs have a generally reduced pelvic size as well as a shorter pelvis and narrower pelvic outlet when compared to non-brachycephalic breeds. We suggest that some of our measurements may serve as a baseline for pelvic dimensions in English bulldogs and may be useful for future studies on dystocia in this breed.

Investigations of the relation between birth trauma and pelvic size in females from a medieval gravesite from Lübeck.

This study proposes that female pelvises showing no birth traumata may have had ideal child-bearing bone constitutions, differing significantly in size and shape from those with severe traumata, resulting in advantages during parturition. Based on this assumption, the female pelvises of a late medieval mass grave from Lübeck have been examined in terms of pelvic osteometric standards in obstetrics, morphological aspects, the degree of birth trauma lesions, and the possible effect of age at death on trauma mark severity. The results imply much wider pelvises (up to 1 cm) in the historical population and a shift in pelvic shape appearances from gynaecoid and platypelloid forms toward android and anthropoid shapes, compared with modern European populations. Furthermore, a significant relation between the appearances of lesions and the age at death was found, while the relations between pelvic size and shape and birth trauma appearances is not significant in this historical skeletal series.

Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins

The evolutionary emergence of humans' remarkably economical walking gait remains a focus of research and debate, but experimentally validated approaches linking locomotor capability to postcranial anatomy are limited. In this study, we integrated 3D morphometrics of hominoid pelvic shape with experimental measurements of hip kinematics and kinetics during walking and climbing, hamstring activity, and passive range of hip extension in humans, apes, and other primates to assess arboreal-terrestrial trade-offs in ischium morphology among living taxa. We show that hamstring-powered hip extension during habitual walking and climbing in living apes and humans is strongly predicted, and likely constrained, by the relative length and orientation of the ischium. Ape pelves permit greater extensor moments at the hip, enhancing climbing capability, but limit their range of hip extension, resulting in a crouched gait. Human pelves reduce hip extensor moments but permit a greater degree of hip extension, which greatly improves walking economy (i.e., distance traveled/energy consumed). Applying these results to fossil pelves suggests that early hominins differed from both humans and extant apes in having an economical walking gait without sacrificing climbing capability. Ardipithecus was capable of nearly human-like hip extension during bipedal walking, but retained the capacity for powerful, ape-like hip extension during vertical climbing. Hip extension capability was essentially human-like in Australopithecus afarensis and Australopithecus africanus, suggesting an economical walking gait but reduced mechanical advantage for powered hip extension during climbing.

Corrigendum: Human Variation in Pelvic Shape and the Effects of Climate and Past Population History.

Corrigendum: Human Variation in Pelvic Shape and the Effects of Climate and Past Population History.

Pelvic inlet shape measured by three-dimensional pelvimetry is a predictor of the operative time in the anterior resection of rectal cancer.

We evaluated pelvic shape as a predictor of the surgical outcome of anterior resection in patients with rectal cancer. In total, 228 patients who had undergone anterior resection (R0 resection and double-stapling anastomosis) for rectal cancer from 2005 to 2014 were included in this study. The anteroposterior (AP) and transverse (T) diameters of the pelvic inlet and outlet and pelvic depth were analyzed on three-dimensional volume-rendered images, and the AP/T ratio was calculated. Univariate and multivariate analyses were performed to determine the predictive significance of the operative time and intraoperative blood loss as surgical outcomes. No difference was observed between the inlet AP/T and patient sex ratios, but the other pelvic dimensions were significantly shorter in males than in females. The univariate analysis revealed that the operative time was significantly correlated with the inlet T diameter and that it tended to be correlated with the outlet T diameter and the inlet AP/T ratio. A multivariate analysis adjusted for operation-related factors revealed that the inlet AP/T ratio was the only independent risk factor for an extended operative time (p=0.036). None of the pelvic dimensions were independent risk factors for increased blood loss. The shape of the pelvic inlet may be useful for predicting the operative time.

Sexual dimorphism, asymmetry, and the effect of reproduction on pelvis bone in the bank vole, Myodes glareolus

Sexual dimorphism in anatomical traits has been widely studied in animals. Although pelvis dimorphism was mostly studied in humans, it occurs also in many other mammalian species. Here, we investigated sexual dimorphism in the pelvis of the bank vole Myodes glareolus using individuals with known sex and reproductive status of females (parous vs nulliparous). The analyses revealed that the size and shape of pelvis differed significantly between sexes, as well as between nulliparous and parous females. In comparison with males, females had a significantly longer pelvis and pubis bones and a longer obturator foramen length, but a smaller pubis width. Interestingly, the difference between parous and nulliparous females resembles that between females and males: parous females had bigger pelvis, which probably resulted from changes during pregnancy and after birth. Left bones were on average larger than right ones, but the magnitude of directional asymmetry was not different between sex and reproduction group. Moreover, we noticed that fluctuating asymmetry of pelvis and pubis length was higher in females than in males and higher in parous than in nulliparous females, what is presumably associated with locomotor performance. A discriminant function analysis performed for the four bone size traits showed that the traits can be effectively used for a nearly perfect recognition of sexes and also a quite reliable recognition of the reproductive status of females.

Genetic mapping of principal components of canine pelvic morphology

BackgroundConcentrated breeding effort to produce various body structures and behaviors of dogs to suit human demand has inadvertently produced unwanted traits and diseases that accompany the morphological and behavioral phenotypes. We explored the relationship between pelvic conformation and canine hip dysplasia (HD) because purebred dogs which are predisposed, or not, to HD share common morphologic features, respectively. Thirteen unique bilateral anatomical features of the pelvis were measured on 392 dogs of 51 breeds and 95 mixed breed dogs. Principal components (PCs) were derived to describe pelvic morphology. Dogs were genotyped at ~183,000 single nucleotide polymorphisms and their hip conformation was measured by the Norberg angle and angle of inclination between the femoral neck and diaphysis.ResultsNo associations reached genome wide significance for the Norberg angle when averaged over both hips. PC1 was negatively correlated with the Norberg angle (r = -0.31; P < 0.05) but not the angle of inclination (r = -0.08; P > 0.05). PC1, 2, 4, and 5 differed significantly between male and female dogs confirming pelvic sexual dimorphism. With sex as a covariate, the eigenvector contribution to PC1 reflected the overall size of the pelvis and was significantly associated with the IGF-1 locus, a known contributor to canine body size. PC3, which represented a tradeoff between ilial length and ischial length in which a longer ischium is associated with a shorter ilium, was significantly associated with a marker on canine chromosome 16:5181388 bp. The closest candidate gene is TPK1, a thiamine-dependent enzyme and part of the PKA complex. Associations with the remaining PCs did not reach genome wide significance.ConclusionIGF-1 was associated with the overall size of the pelvis and sex is related to pelvic size. Ilial/ischial proportion is genetically controlled and the closest candidate gene is thiamine-dependent and affects birth weight and development of the nervous system. Dogs with larger pelves tend to have smaller NAs consistent with increased tendency toward HD in large breed dogs. Based on the current study, pelvic shape alone was not strongly associated with canine hip dysplasia.

Female pelvic synthetic CT generation based on joint intensity and shape analysis

Using MRI for radiotherapy treatment planning and image guidance is appealing as it provides superior soft tissue information over CT scans and avoids possible systematic errors introduced by aligning MR to CT images. This study presents a method that generates Synthetic CT (MRCT) volumes by performing probabilistic tissue classification of voxels from MRI data using a single imaging sequence (T1 Dixon). The intensity overlap between different tissues on MR images, a major challenge for voxel-based MRCT generation methods, is addressed by adding bone shape information to an intensity-based classification scheme. A simple pelvic bone shape model, built from principal component analysis of pelvis shape from 30 CT image volumes, is fitted to the MR volumes. The shape model generates a rough bone mask that excludes air and covers bone along with some surrounding soft tissues. Air regions are identified and masked out from the tissue classification process by intensity thresholding outside the bone mask. A regularization term is added to the fuzzy c-means classification scheme that constrains voxels outside the bone mask from being assigned memberships in the bone class. MRCT image volumes are generated by multiplying the probability of each voxel being represented in each class with assigned attenuation values of the corresponding class and summing the result across all classes. The MRCT images presented intensity distributions similar to CT images with a mean absolute error of 13.7 HU for muscle, 15.9 HU for fat, 49.1 HU for intra-pelvic soft tissues, 129.1 HU for marrow and 274.4 HU for bony tissues across 9 patients. Volumetric modulated arc therapy (VMAT) plans were optimized using MRCT-derived electron densities, and doses were recalculated using corresponding CT-derived density grids. Dose differences to planning target volumes were small with mean/standard deviation of 0.21/0.42 Gy for D0.5cc and 0.29/0.33 Gy for D99%. The results demonstrate the accuracy of the method and its potential in supporting MRI only radiotherapy treatment planning.

Allometry and Sexual Dimorphism in the Human Pelvis.

Sexual dimorphism in the human pelvis has evolved in response to several jointly acting selection regimes that result from the pelvis' multiple roles in locomotion and childbirth, among others. Because human males are, on average, taller than females, some aspects of sexual dimorphism in pelvis shape might result from allometry, the association between stature and pelvis shape across individuals. In this study, they aimed to disentangle and quantify the two components contributing to pelvic sex differences: the allometric component, which emerges as a consequence of dimorphism in stature, and the remaining non-allometric sexual dimorphism component. A geometric morphometric analysis of a dense set of 3D landmarks, measured on 99 female and male adult individuals was conducted. While pelvis size was similar in both sexes, the average differences in pelvis shape reflected the well-documented pattern of sexual dimorphism. There was almost no overlap between females and males in shape space. Their analysis showed that pelvis size and shape were similarly associated with stature in both sexes. It was found that dimorphism in the height-to-width ratio of the pelvis and in the orientation of the iliac blades was largely allometric, whereas dimorphism in the subpubic angle and the relative size and distance of the acetabula was largely non-allometric. It was concluded that, in contrast to the overall pelvic proportions, sexual dimorphism in the birth-relevant pelvic dimensions was mainly of non-allometric origin and was presumably mediated via steroid hormone secretion during puberty. Anat Rec, 300:698-705, 2017. © 2017 Wiley Periodicals, Inc.

Human Variation in Pelvic Shape and the Effects of Climate and Past Population History.

The human pelvis is often described as an evolutionary compromise (obstetrical dilemma) between the requirements of efficient bipedal locomotion and safe parturition of a highly encephalized neonate, that has led to a tight fit between the birth canal and the head and body of the foetus. Strong evolutionary constraints on the shape of the pelvis can be expected under this scenario. On the other hand, several studies have found a significant level of pelvic variation within and between human populations, a fact that seems to contradict such expectations. The advantages of a narrow pelvis for locomotion have recently been challenged, suggesting that the tight cephalo-pelvic fit might not stem from the hypothesized obstetrical dilemma. Moreover, the human pelvis appears to be under lower constraints and to have relatively higher evolvability than other closely related primates. These recent findings substantially change the way in which we interpret variation in the human pelvis, and help make sense of the high diversity in pelvic shape observed within and among modern populations. A lower magnitude of covariance between functionally important regions ensured that a wide range of morphological variation was available within populations, enabling natural selection to generate pelvic variation between populations living in different environments. Neutral processes such as genetic drift and differential migration also contributed to shaping modern pelvic diversity during and after the expansion of humans into and across the various continents. Anat Rec, 300:687-697, 2017. © 2017 Wiley Periodicals, Inc.

Development of Modular Organization in the Chimpanzee Pelvis.

The bony pelvis of primates is a composite structure serving a variety of functions, and exhibiting a complex pattern of modularity and integration. Still little is known, however, about how patterns of modularity and integration arise, and how they change throughout ontogeny. Here we study the ontogeny of modularity and integration in developmental and functional units of the pelvis of our closest living relatives, the chimpanzees. We use methods of biomedical imaging and geometric morphometrics to quantify pelvic shape change from late fetal stages to adulthood, and to track changes in patterns of covariation within and among pelvic regions. Our results show that both developmental and functional units of the pelvis exhibit significant levels of modularity throughout ontogeny. Modularity of developmental units (ilium, ischium, and pubis) decreases with increasing age, whereas modularity of functional units tends to increase. We suggest that the decreasing modularity and increasing integration of developmental units reflects their gradual fusion. In contrast, increasing modularity of functional pelvic units likely reflects changing functional demands during an individual's lifetime. Overall, ontogenetic changes in patterns of modularity and integration imply that natural selection could act differently on each module, either developmental or functional, at different stages of ontogeny. This further implies that adult patterns of covariation in the pelvis provide only limited information about its evolvability. Anat Rec, 300:675-686, 2017. © 2017 Wiley Periodicals, Inc.

Predicting the location of the hip joint centres, impact of age group and sex.

Clinical gait analysis incorporating three-dimensional motion analysis plays a key role in planning surgical treatments in people with gait disability. The position of the Hip Joint Centre (HJC) within the pelvis is thus critical to ensure accurate data interpretation. The position of the HJC is determined from regression equations based on anthropometric measurements derived from relatively small datasets. Current equations do not take sex or age into account, even though pelvis shape is known to differ between sex, and gait analysis is performed in populations with wide range of age. Three dimensional images of 157 deceased individuals (37 children, 120 skeletally matured) were collected with computed tomography. The location of the HJC within the pelvis was determined and regression equations to locate the HJC were developed using various anthropometrics predictors. We determined if accuracy improved when age and sex were introduced as variables. Statistical analysis did not support differentiating the equations according to sex. We found that age only modestly improved accuracy. We propose a range of new regression equations, derived from the largest dataset collected for this purpose to date.