Pelvic Displacement Research Articles

Radiographic diagnosis of sagittal plane rotational displacement in pelvic fractures: a cadaveric model and clinical case study

Our objective was to measure the sagittal plane rotational (flexion and extension) displacement of hemipelvis radiologically and analyze the ratio of flexion and extension displacement of unstable pelvic fractures. We used 8 cadaveric models to study the radiographic evidence of pelvic fractures in the sagittal plane. We performed pelvic osteotomy on 8 cadavers to simulate anterior and posterior pelvic ring injury. Radiological data were measured in the flexion and extension group under different angles (5°, 10°, 15°, 20°, and 25°). We retrospectively reviewed 164 patients who were diagnosed with a unilateral fracture of the pelvis. Pelvic ring displacement was identified and recorded radiographically in cadaveric models. The flexion and extension displacement of pelvic fractures was measured in terms of the vertical distance of fracture from the top of iliac crest to the pubic tubercle (CD) or from the top of iliac crest to the lowest point of ischial tuberosity (AB). Fifty-seven pelves showed flexion displacement and 15 showed extension displacement. Closed reduction including internal fixation and external fixation was successfully used in 141 cases (86.0%). The success rates of closed reduction in flexion and extension displacement groups were 77 and 73%, respectively, which were lower than in unstable pelvic ring fractures. The sagittal plane rotation (flexion and extension) displacement of pelvic fractures could be measured by special points and lines on the radiographs. Minimally invasive reduction should be based on clearly identified differences between the sagittal plane rotation and the vertical displacement of pelvic fractures.

Gait assessment using the Microsoft Xbox One Kinect: Concurrent validity and inter-day reliability of spatiotemporal and kinematic variables

The revised Xbox One Kinect, also known as the Microsoft Kinect V2 for Windows, includes enhanced hardware which may improve its utility as a gait assessment tool. This study examined the concurrent validity and inter-day reliability of spatiotemporal and kinematic gait parameters estimated using the Kinect V2 automated body tracking system and a criterion reference three-dimensional motion analysis (3DMA) marker-based camera system. Thirty healthy adults performed two testing sessions consisting of comfortable and fast paced walking trials. Spatiotemporal outcome measures related to gait speed, speed variability, step length, width and time, foot swing velocity and medial–lateral and vertical pelvis displacement were examined. Kinematic outcome measures including ankle flexion, knee flexion and adduction and hip flexion were examined. To assess the agreement between Kinect and 3DMA systems, Bland–Altman plots, relative agreement (Pearson's correlation) and overall agreement (concordance correlation coefficients) were determined. Reliability was assessed using intraclass correlation coefficients, Cronbach's alpha and standard error of measurement. The spatiotemporal measurements had consistently excellent (r≥0.75) concurrent validity, with the exception of modest validity for medial–lateral pelvis sway (r=0.45–0.46) and fast paced gait speed variability (r=0.73). In contrast kinematic validity was consistently poor to modest, with all associations between the systems weak (r<0.50). In those measures with acceptable validity, the inter-day reliability was similar between systems. In conclusion, while the Kinect V2 body tracking may not accurately obtain lower body kinematic data, it shows great potential as a tool for measuring spatiotemporal aspects of gait.

Evolutionary allometry of the thoracolumbar centra in felids and bovids.

Mammals have evolved a remarkable range of body sizes, yet their overall body plan remains unaltered. One challenge of evolutionary biology is to understand the mechanisms by which this size diversity is achieved, and how the mechanical challenges associated with changing body size are overcome. Despite the importance of the axial skeleton in body support and locomotion, and much interest in the allometry of the appendicular skeleton, little is known about vertebral allometry outside primates. This study compares evolutionary allometry of the thoracolumbar centra in two families of quadrupedal running mammals: Felidae and Bovidae. I test the hypothesis that, as size increases, the thoracolumbar region will resist increasing loads by becoming a) craniocaudally shorter, and b) larger in cross-sectional area, particularly in the sagittal plane. Length, width, and height of the thoracolumbar centra of 23 felid and 34 bovid species were taken. Thoracic, prediaphragmatic, lumbar, and postdiaphragmatic lengths were calculated, and diameters were compared at three equivalent positions: the midthoracic, the diaphragmatic and the midlumbar vertebra. Allometric slopes were calculated using a reduced major axis regression, on both raw and independent contrasts data. Slopes and elevations were compared using an ANCOVA. As size increases the thoracolumbar centra become more robust, showing preferential reinforcement in the sagittal plane. There was less allometric shortening of the thoracic than the lumbar region, perhaps reflecting constraints due to its connection with the respiratory apparatus. The thoracic region was more robust in bovids than felids, whereas the lumbar region was longer and more robust in felids than bovids. Elongation of lumbar centra increases the outlever of sagittal bending at intervertebral joints, increasing the total pelvic displacement during dorsomobile running. Both locomotor specializations and functional regionalization of the axial skeleton appear to have influenced its response to increasing size.

Correlation between balance and gait according to pelvic displacement in stroke patients.

[Purpose] The purpose of this study was to investigate the correlations of balance and gait according to pelvic displacement in stroke patients. [Subjects] The subjects of this study were 58 stroke patients who had been admitted to a hospital. [Methods] A Global Postural System was used to measure pelvic displacement. To measure the balance ability, a Tetrax balance system was used to measure the weight distribution index and stability index. Gait ability was measured during the 10-Meter Walking Test and Figure-of-8 Walk Test. [Results] The results of this study showed that was significant positive correlation between the anterior superior iliac spine height difference in pelvic displacement and the weight distribution index and significant positive correlation between the posterior superior iliac spine height difference and the stability index in the normal position with the eyes closed. Statistically significant positive correlation also was found between the anterior superior iliac spine height difference and the straight and curved gait ability. [Conclusion] The increased pelvic displacement in stroke patients results in a decrease in balance ability and gait speed. This suggests that control of pelvic displacement is necessary before functional training for patients with stroke.

Cardiorespiratory and Biomechanical Responses to Simulated Recreational Horseback Riding in Healthy Children

Purpose: The purpose of this study was to determine the reliability of cardiorespiratory and pelvic kinematic responses to simulated horseback riding (SHBR) and to characterize responses to SHBR relative to walking in apparently healthy children. Method: Fifteen healthy children (Mage = 9.5 ± 2.6 years) completed SHBR on a commercially available simulator at low intensity (0.27 Hz) and high intensity (0.65 Hz) during 3 sessions on different occasions. Heart rate (HR), blood pressure, and respiratory gases were measured at rest and during steady-state exercise at both intensities. Pelvic displacement was measured during steady-state exercise. Rate of energy expenditure, mean arterial pressure, and rate pressure product (RPP) were calculated. Participants also walked on a treadmill for 26.8 m/min to 80.5 m/min in 13.4-m/min increments at 0% grade during 1 session to compare cardiorespiratory responses with those of SHBR. Results: Physiological variables across all 3 SHBR sessions were similar at both intensities (p>.05 for all). Intraclass correlation coefficients (ICCs) and coefficients of variation indicate good to modest reliability of cardiorespiratory measures during SHBR (ICCs = .542–.996 for oxygen consumption, energy expenditure, and RPP). Cardiorespiratory variables, except for HR, were 2% to 19% greater, and pelvic displacement was up to 37% greater with high-intensity riding. Treadmill walking at all speeds elicited greater physiological responses compared with SHBR (p < .05). Conclusion: Cardiorespiratory responses and pelvic kinematics are reproducible with SHBR in young children, and these responses were lower than those elicited by slow treadmill walking.

Evaluation of the Rigo classification system for brace design

Methods The inter-observer reliability of the classification was testing, in every case individually by an orthopaedic surgeon with CPO degree and a Physiotherapist (Schroth and SEAS certified). The total of the cases for the purpose of this paper was checked again by the same team. The patients were visited every 3 months, checking posture and Cobb angle with Formetric 4D, as well the adequacy of the brace. The patients have had also an in brace x-Ray, about three months after bracing. Results From the 243 patients we had 13 patients A1, 9 A2, 41 A3, 66 B1, 28 B2, 20 C1, 26 C2, 22 E1 and 18 E2, according the Rigo classification. The in brace x-rays have shown a correction from 2/3 to 1/3 of the initial Cobb angle, depending on the skeletal maturity, as well as the compliance of the patient. All the patients out of the brace had a better balance and aesthetics (Scapular symmetry, waist triangles, humps and pelvic displacement), almost from the first visit after 3 months.

Posterior iliac offset

The purpose of this study was to describe the radiological characteristics of a previously unreported finding: posterior iliac offset at the sacroiliac joint and to assess its association with pelvic instability as measured by initial displacement and early implant loosening or failure. Radiographs from 42 consecutive patients with a mean age of 42 years (18 to 77; 38 men, four women) and mean follow-up of 38 months (3 to 96) with Anteroposterior Compression II injuries, were retrospectively reviewed. Standardised measurements were recorded for the extent of any diastasis of the pubic symphysis, widening of the sacroiliac joint, static vertical ramus offset and a novel measurement (posterior offset of the ilium at the sacroiliac joint identified on axial CT scan). Pelvic fractures with posterior iliac offset exhibited greater levels of initial displacement of the anterior pelvis (anterior sacroiliac widening, pubic symphysis diastasis and static vertical ramus offset, p < 0.001,0.034 and 0.028, respectively). Pelvic fractures with posterior ilium offset also demonstrated higher rates of implant loosening regardless of fixation method (p = 0.05). Posterior offset of the ilium was found to be a reliable and reproducible measurement with substantial inter-observer agreement (kappa = 0.70). Posterior offset of the ilium on axial CT scan is associated with greater levels of initial pelvic displacement and early implant loosening.

Pelvic Lymph Nodes Displacement in High-Risk Prostate Cancer Patients Treated With Image-Guided IMRT With 2 Independent Target Volumes

Purpose/Objective(s): To report initial experience of biochemical outcomes and the acute and late toxicity in 200 patients with clinically localized prostate cancer treated with volumetric modulated arc therapy (VMAT). Materials/Methods: Between November 2007 and September 2011, 200 patients with clinically localized prostate cancer were treated with VMAT using daily cone-beam computed tomography acqusition. Treatment planning systems used were avoidance conformal-based in 77 patients and multileaf collimator-based in 123 patients. All plans were generated on an inverse-planning approach. A total of 182 patients (91%) were treated to 76 Gy, and 18 patients (9%) were treated to Z < 72 Gy. Acute and late toxicities were scored according to CTCAE grading scales. PSA relapse was defined according to Phoenix definition. The mean follow-up time was 50 months (range: 7-85 months). Results: Two patients (1%) developed acute Grade 2 or worse GI toxicity. Thirty-nine patients (19%) developed acute Grade 2 GU symptoms, and no one experienced Grade 3 GU toxicity. Six patients (3%) developed late Grade 2 rectal bleeding. Two patients (1%) experienced Grade 3 rectal toxicity requiring either one or more transfusions or a laser cauterization procedure. No Grade 4 rectal complications have been observed. The 5year actuarial likelihood of late Grade 2 or higher rectal bleeding was 3.4%. Twenty patients (10%) experienced late Grade 2 GU toxicity, and no one developed Grade 3 GU toxicity. The 5-year actuarial likelihood of late Grade 2 or higher GU toxicity was 11.6%. The 5-year actuarial PSA relapse-free survival rates for low-, intermediate-, and high-risk group patients stratified according to NCCN criteria, were 100%, 91,8%, and 85.3%, respectively. Conclusions: Our initial data demonstrate the feasibility of VMAT in patients with localized prostate cancer. Acute and late rectal toxicities seem to be dramatically reduced compared with what has been observed with conventional radiation therapy techniques. Short-term PSA control rates were excellent. Based on our promising initial experiences, VMAT is an established novel conformal radiation delivery method for localized prostate cancer at our institution. Further studies in a larger population are required to determine long-term results in VMAT. Author Disclosure: K. Shiraishi: None. K. Yamamoto: None. A. Haga: None. A. Sakumi: None. K. Nakagawa: None.

Hip joint centre position estimation using a dual unscented Kalman filter for computer-assisted orthopaedic surgery.

In computer-assisted knee surgery, the accuracy of the localization of the femur centre of rotation relative to the hip-bone (hip joint centre) is affected by the unavoidable and untracked pelvic movements because only the femoral pose is acquired during passive pivoting manoeuvres. We present a dual unscented Kalman filter algorithm that allows the estimation of the hip joint centre also using as input the position of a pelvic reference point that can be acquired with a skin marker placed on the hip, without increasing the invasiveness of the surgical procedure. A comparative assessment of the algorithm was carried out using data provided by in vitro experiments mimicking in vivo surgical conditions. Soft tissue artefacts were simulated and superimposed onto the position of a pelvic landmark. Femoral pivoting made of a sequence of star-like quasi-planar movements followed by a circumduction was performed. The dual unscented Kalman filter method proved to be less sensitive to pelvic displacements, which were shown to be larger during the manoeuvres in which the femur was more adducted. Comparable accuracy between all the analysed methods resulted for hip joint centre displacements smaller than 1 mm (error: 2.2 ± [0.2; 0.3] mm, median ± [inter-quartile range 25%; inter-quartile range 75%]) and between 1 and 6 mm (error: 4.8 ± [0.5; 0.8] mm) during planar movements. When the hip joint centre displacement exceeded 6 mm, the dual unscented Kalman filter proved to be more accurate than the other methods by 30% during multi-planar movements (error: 5.2 ± [1.2; 1] mm).

Can external lateral stabilization reduce the energy cost of walking in persons with a lower limb amputation?

The aim of this study was to examine whether impaired balance control is partly responsible for the increased energy cost of walking in persons with a lower limb amputation (LLA). Previous studies used external lateral stabilization to evaluate the energy cost for balance control; this caused a decrease in energy cost, with concomitant decreases in mean and variability of step width. Using a similar set-up, we expected larger decreases for LLA than able-bodied controls.Fifteen transtibial amputees (TT), 12 transfemoral amputees (TF), and 15 able-bodied controls (CO) walked with and without external lateral stabilization provided via spring like cords attached to the waist. Effects of this manipulation on energy cost, step parameters, and pelvic motion were evaluated between groups.TT (−5%) and CO (−3%) showed on average a small reduction in energy cost when walking with stabilization, whereas TF exhibited an increase in energy cost (+6.5%) The difference in the effect of stabilization was only significant between TT and TF. Step width, step width variability, and medio-lateral pelvic displacement decreased significantly with stabilization in all groups, especially in TT.Contrary to expectations, external lateral stabilization did not result in a larger decrease in the energy cost of walking for LLA compared to able-bodied controls, suggesting that balance control is not a major factor in the increased cost of walking in LLA. Alternatively, the increased energy cost with stabilization for TF suggests that restraining (medio-lateral) pelvic motion impeded necessary movement adaptations in LLA, and thus negated the postulated beneficial effects of stabilization on the energy cost of walking.

Application of the Lumped-Parameter Model in Concept Design Phase of Side Impact Safety Development

In the process of side impact, the door was directly contacted with the chest, abdomen and pelvis of dummy and its movement has a large effect upon dummy injury. A evaluation about dummy injury influenced by the velocity and displacement of chest, abdomen and pelvis in dummy was proposed. A rapid forward development strategy which is applied in forward development was presented. A new type side impact LPM (Lumped-Parameter Model) was established. The stiffness of critical area in vehicle body was optimized by LPM which used the intrusive velocity and displacement of chest, abdomen and pelvis in dummy as design object. The example showed that the safety performance was improved obviously and the development period was shortened in some extent.

Vertical Displacement of the Equine Pelvis When Trotting on an Aqua Treadmill

IntroductionHydrotherapy is increasingly applied within the equine industry for rehabilitation and therapy. Substantial anecdotal evidence exists suggesting the benefits of its application but while there is extensive literature on the use of aqua‐treadmills in humans and canines there is comparatively little in equines. Therefore, limited research exists supporting the role of the aqua‐treadmill in current therapy practices. This study aimed to investigate the effect of water depth on pelvic movement during aqua‐treadmill exercise.MethodsEight horses were trotted on an aqua‐treadmill at four water depths specifically measured to individual horses (P3, fetlock, MC3, carpus). Pelvic displacement was recorded using an optical motion capture system to collect coordinates from markers placed on the tuber sacrale, tuber coxae, withers and lumbar spine. Data were processed using custom written scripts (Matlab®) and ANOVA was performed.ResultsAll subjects demonstrated a significant increase in vertical displacement of the pelvis as water depth increased from P3 to carpus while displacement symmetry was not significantly altered with a change in water depth.ConclusionsThe common practice of increasing water depth to intensify the physical demands of the exercise while maintaining the desired movement symmetry is supported. Having knowledge of how a horse moves on an aqua‐treadmill is vital for tailoring specific therapy in order to most successfully rehabilitate the horse from injury. Investigation of the effects of increasing water depth on asymmetric horses should be carried out to further support its application as a tool for rehabilitation.Ethical Animal ResearchEthical approval was obtained from the Ethics Review Committee at Moulton College. Owner consent was granted for all subjects and all horses were handled in compliance with British Horse Society standards throughout the trials. Sources of funding: Thomas Harrison Trust at Moulton College. Competing interests: none.

FRI0586-HPR Three Dimensional Evaluation of Pelvic Posture in Adolescents with A History of Low Back Pain

BackgroundIt is known that adolescent low back pain (LBP) is a significant public health problem and 29-71% of the adolescents suffer from LBP in a period of their lives (1)....

Neurobiological Degeneracy and Affordance Perception Support Functional Intra-Individual Variability of Inter-Limb Coordination during Ice Climbing

This study investigated the functional intra-individual movement variability of ice climbers differing in skill level to understand how icefall properties were used by participants as affordances to adapt inter-limb coordination patterns during performance. Seven expert climbers and seven beginners were observed as they climbed a 30 m icefall. Movement and positioning of the left and right hand ice tools, crampons and the climber’s pelvis over the first 20 m of the climb were recorded and digitized using video footage from a camera (25 Hz) located perpendicular to the plane of the icefall. Inter-limb coordination, frequency and types of action and vertical axis pelvis displacement exhibited by each climber were analysed for the first five minutes of ascent. Participant perception of climbing affordances was assessed through: (i) calculating the ratio between exploratory movements and performed actions, and (ii), identifying, by self-confrontation interviews, the perceptual variables of environmental properties, which were significant to climbers for their actions. Data revealed that experts used a wider range of upper and lower limb coordination patterns, resulting in the emergence of different types of action and fewer exploratory movements, suggesting that effective holes in the icefall provided affordances to regulate performance. In contrast, beginners displayed lower levels of functional intra-individual variability of motor organization, due to repetitive swinging of ice tools and kicking of crampons to achieve and maintain a deep anchorage, suggesting lack of perceptual attunement and calibration to environmental properties to support climbing performance.

Femur performed better than tibia in autologous transplantation during hemipelvis reconstruction

BackgroundPelvic reconstruction after hemipelvectomy can greatly improve the weight-bearing stability of the supporting skeleton and improve patients’ quality of life. Although an autograft can be used to reconstruct pelvic defects, the most suitable choice of autograft, i.e., the use of either femur or tibia, has not been determined. We aimed to analyze the mechanical stresses of a pelvic ring reconstructed using femur or tibia after hemipelvectomy using finite element (FE) analysis.MethodsFE models of normal and reconstructed pelvis were established based on computed tomography images, and the stress distributions were analyzed under physiological loading from 0 to 500 N in both intact and restored pelvic models using femur or tibia.ResultsThe vertical displacement of the intact pelvis was less than that of reconstructed pelvis, but there was no significant difference between the two reconstructed models. In FE analysis, the stress distribution of the intact pelvic model was bilaterally symmetric and the maximum stresses were located at the sacroiliac joint, arcuate line, ischiatic ramus, and ischial tuberosity. The maximum stress in each part of the reconstructed pelvis greatly exceeded that of the intact model. The maximum von Mises stress of the femur was 13.9 MPa, and that of the tibia was 6.41 MPa. However, the stress distribution was different in the two types of reconstructed pelvises. The tibial reconstruction model induced concentrated stress on the tibia shaft making it more vulnerable to fracture. The maximum stress on the femur was concentrated on the connections between the femur and the screws.ConclusionsFrom a biomechanical point of view, the reconstruction of hemipelvic defects with femur is a better choice.

Accuracy in Radiographic Assessment of Pelvic Ring Fracture Deformity

To our knowledge, measuring pelvic ring displacement on plain radiographs has not been scientifically evaluated. This study aims to assess the validity and reliability of existing measurement systems utilizing plain radiographs. A Sawbones model, validated as part of this study, was fractured in a controlled fashion to simulate known pelvic ring fracture patterns. Computed tomographic scans with 2- and 3-dimensional reconstructions of intact and injury models were obtained to measure the "true" displacement of anterior and posterior disrupted surfaces. The computed tomographic data set was used to create computer-reconstructed radiographs (CRR) simulating standard anteroposterior, inlet and outlet views. Currently described measurement techniques were utilized by 8 senior orthopaedic residents and 3 fellowship-trained orthopaedic trauma surgeons on the computer-reconstructed radiograph of each model. These measurements were than assessed for interobserver reliability and validity. Average observer measurements of anterior symphysis diastasis and vertical translation had good validity and reliability with each having an average confidence interval of 4.6 mm. The observer measurements of sacroiliac (SI) joint displacement were significantly less reliable with average confidence interval of 5.8 mm. Kappa correlation calculations for whether the SI joint was displaced more than 1 cm showed an overall agreement of 0.702 and kappa coefficient of 0.404. Computer-reconstructed radiographic, and thus plain radiographic, assessments of deformity at the SI joint have poor reliability and accuracy. Clinicians should recognize these limitations when measuring pelvic displacement of the SI joint and cautiously interpret clinical results of treatment of SI joint injuries where displacement is measured on plain radiographs.

Posture class prediction of pre-peak height velocity subjects according to gross body segment orientations using linear discriminant analysis

Measurement and classification of standing posture in the sagittal plane has important clinical implications for adolescent spinal disorders. Previous work using cluster analysis on three gross body segment orientation parameters (lower limbs, trunk, and entire body inclination) has identified three distinct postural groups of healthy subjects before pubertal peak growth: "neutral", "sway-back", and "leaning-forward". Although accurate postural subgrouping may be proposed to be crucial in understanding biomechanical challenges posed by usual standing, there is currently no objective method available for class assignment. Hence, this paper introduces a novel approach to subclassify new cases objectively according to their overall sagittal balance. Postural data previously acquired from 1,196 pre-peak height velocity (pre-PHV) subjects were used in this study. To derive a classification rule for assigning a class label ("neutral", "sway-back", or "leaning-forward") to any new pre-PHV subjects, linear discriminant analysis was applied. Predictor variables were pelvic displacement, trunk lean and body lean angle. The performance of the newly developed classification algorithm was verified by adopting a cross-validation procedure. The statistical model correctly classified over 96.2% of original grouped subjects. In the cross-validation procedure used, over 95.9% of subjects were correctly assigned. Based on three angular measures describing gross body segment orientation, our triage method is capable of reliably classifying pre-PHV subjects as either "neutral", "sway-back", or "leaning-forward". The discriminant prediction equations presented here enable a highly accurate posture class allocation of new cases with a prediction capability higher than 95.9%, thereby removing subjectivity from sagittal plane posture classification.

Radiological measurement and diagnosis of rotation displacement of pelvic fractures

Objective To measure the sagittal rotation displacement of hemipelvis for determining the rotation displacement of pelvis on three dimensional section and further instructing closed reduction of pelvis fractures.Methods Sagittal rotation degree of hemipelvis was calculated by measuring the special radiological points and lines of a rational mathematical model created according to anatomic structure of pelvis and peri-and intra-operative pelvic frontal X-ray view.Ten cadaver pelvises without bony structure abnormality were selected and marked by lead line in bilateral anterior superior iliac spine and exterior edge of pubic symphysis.Hemipelvic rotation displacement in sagittal plane was simulated and modified pelvic frontal view was obtained in X-ray projection.Radiological data was measured and calculated by using radiological measuring software.Thereafter,feasibility and accuracy of the method discussed in the study were verified by statistical analysis.Results Distance of ipsilateral anterior superior iliac spine to exterior edge of ipsilateral pubic symphysis was measured and presented no statistical difference in both sides (P ＞0.05).As compared with the models of 20 degree of rotation of hemipelvis in sagittal plane desgined in this study,the calculated rotation degree presented no significant difference (P ＞ 0.05).Conclusion Quantified indicators of pelvic spatial displacement measured by special points and lines on X-ray films of modified pelvic frontal view put forwarded in study of pelvic anatomic structure and radiographic features guides reduction operation and effect judgment and benefits closed reduction of pelvic fractures. Key words: Pelvis; Fractures; Closed reduction

A biomechanical approach on the optimal stance of Anhanguera piscator (Pterodactyloidea) and its implications for pterosaur gait on land

The stance of pterosaurs on land is traditionally a controversial question. Here, we show that pterosaurs like Anhanguera piscator were quadrupeds. An osteological model of A. piscator was three-dimensionally built in digital space. The reconstructed muscles of its pelvic girdle were then placed on their points of origin and insertion to allow the biomechanical calculations to find the most efficient stance on land to be performed. The hindlimb readjustment (i.e. the repositioning of the hindlimb according to the achieved results) led to a pelvic counterclockwise displacement at 10°, which means that the ilium previously placed at 0° regarding an axis parallel to the ground was moved (and so the whole pelvis) 10° up from the preacetabular process. This new position prevents A. piscator from having a fully upright stance. A 10° displacement of the pelvic girdle would compel the forelimbs to be highly sprawled. Therefore, this study affords A. piscator having a quadrupedal gait and demonstrates that a bipedal stance is not viable once the lever arm values decrease abruptly both for extensor and flexor muscles during the femoral extension. This is the first time this approach is used to shed light on this question.

Gender differences in trunk, pelvis and lower limb kinematics during a single leg squat

The relationship between trunk and lower limb kinematics in healthy females versus males is unclear since trunk kinematics in the frontal and transverse planes have not been systematically examined with lower limb kinematics. The aim of this study was to investigate the existence of different multi-joints movement strategies between genders during a single leg squat. We expected that compared to males, females would have greater trunk and pelvis displacement due to less trunk control and display hip and knee movement consistent with medial-collapse (i.e. greater hip adduction, hip medial rotation, knee abduction, and knee lateral rotation) on the weight-bearing limb.Nine females and 10 males participated in the study. Kinematic data were collected using an 8-camera, 3D-motion-capture-system. Trunk relative to pelvis, pelvis relative to the laboratory, hip and knee angles in three planes (sagittal, frontal and transverse) were examined at two time events relevant to knee joint mechanics: 45° of knee flexion and peak knee flexion.Females flexed their trunk less than males and rotated their trunk and pelvis toward the weight-bearing limb more than males. Females also displayed greater hip adduction and knee abduction than males.Taken together these results suggest that females and males used different movement strategies during a single leg squat. Females displayed a trunk and pelvic movement pattern that may put them at risk of knee injury and pain.