Pelvic Landmarks Research Articles

Radiological bladder characteristics in VCU for young children with high-grade VUR

It has been suggested that infants with dilating vesicoureteral reflux (VUR) often have lower urinary tract (LUT) dysfunction. Signs such as high voiding pressure levels, low bladder capacity and dyscoordination at voiding have previously been thought to be indicative of dysfunction. However, these findings have also been recognised in healthy infants and are, thus, not specific to dysfunction in this age group. The urodynamic findings of interest for LUT dysfunction in children with high-grade VUR have been shown to be high bladder capacity with incomplete emptying, and often with overactivity during filling. Because the bladders in children with VUR are often only investigated with voiding cystourethrography (VCUG) and not urodynamics, the question has arisen as to whether some of the urodynamic findings indicating dysfunction can be recognised as radiological signs. The aim of the present study was to evaluate whether cystometric signs of LUT dysfunction in infants with high-grade VUR could be recognised in VCUG. One hundred and fifteen infants (80 boys) with Grades III-V VUR were included and investigated repeatedly with videocystometry (VCM) at a median age 6, 21 and 39 months. The sign looked for in the VCUG was bladder size (large, normal or small), according to the chosen levels in the bony pelvis. To validate the chosen levels for the different bladder sizes, bladder capacity data from a longitudinal study in healthy children were used. In addition, abnormalities in bladder wall/form and filling of the posterior urethra without voiding, as signs of bladder overactivity and detrusor-sphincter dyscoordination, were evaluated. Bladder size was estimated on VCUG as large, normal or small, according to pelvic landmarks. Large bladder size was mainly seen at the second and third evaluations (64% and 46%), whereas small capacity was mainly seen during the first year (33%). Corresponding cystometric capacities (ml) showed a significant difference between the groups of small, normal and large bladder size. The cystometric capacities of large and small bladder size were also compared with bladder capacity in healthy controls, where large had significantly higher bladder capacity versus age (P = 0.0001) and small had significantly lower (P = 0.011) bladder capacity versus age than in the healthy controls. Bladder shape/wall pathology was mainly seen during the first year (42%), combined with small capacity, and correlated to overactive contractions during filling. Moreover, filling of the posterior urethra without voiding, indicating detrusor/sphincter dyscoordination at voiding, was quite common during the first year (33%), and then successively decreased. The clinical implication from this study of small children with high-grade VUR was that a large bladder on VCUG was synonymous with a high-capacity bladder. According to earlier studies, this is a sign of LUT dysfunction in this age group and should therefore be an indicator for additional studies of bladder function. Overactive contractions could also be recognised in VCUG, but only at the infant evaluation, which should also be regarded as an indicator of LUT dysfunction. All other bladder VCUG signs mainly seen during early infancy were signs of immature bladder function and not a result of VUR dysfunction.

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).

Evaluation of a Novel Method for Determining Transverse Plane Pelvic Obliquity

Study DesignThis was a retrospective review of neuromuscular scoliosis radiographs evaluating interobserver and intra-observer error for a novel method of transverse plane pelvic obliquity. ObjectivesTo evaluate the utility of a previously described method by Lucas et al. of determining transverse plane pelvic obliquity using standard radiographs in patients with cerebral palsy and neuromuscular scoliosis. Summary of Background DataEvaluation of pelvic obliquity in the transverse plane has not been thoroughly studied. The pelvis has been noted to function as intercalary vertebra in neuromuscular scoliosis, resulting in marked obliquity in all 3 planes. MethodsForty radiographs were chosen from 10 patients with cerebral palsy and neuromuscular scoliosis who had had a posterior spine arthrodesis and Galveston spino-pelvic fixation. Four observers independently examined the radiographs at different levels of training on 2 dates 1 week apart. Measurements recorded by each observer were described by Lucas et al.: E (the distance measured on lateral radiographs between the ilium at the inferior part of the sacro-iliac joint and the lateral edge of the anterior superior iliac spine), FR and FL (the coronal plane linear distance between the same 2 landmarks, measured from a posteroanterior radiograph, where F was measured for both the left (FL) and right (FR) sides of the pelvis, respectively), and β (the transverse plane rotation of the pelvis). Reproducibility of the measurements were analyzed using the concordance correlation coefficient (CCC). A CCC of 0.80 or higher was considered excellent agreement. ResultsThe CCC between the first and second sets of measurements was lowest for E and highest for the calculated β, although none of the CCC calculations was statistically significant, demonstrating poor agreement. ConclusionsThe ability to reliably measure and calculate the degree of transverse plane rotation by radiographs in cerebral palsy patients with spino-pelvic deformity by the method described by Lucas et al. is poor, likely because of difficulty in consistently identify pelvic landmarks.

Occiput posterior position diagnosis: vaginal examination or intrapartum sonography? A clinical review

The occiput posterior (OP) position is one of the most frequent malposition during labor. During the first stage of labor, the fetal head may stay in the OP position in 30% of the cases, but of these only 5–7% remains as such at time of delivery. The diagnosis of OP position in the second stage of labor is made difficult by the presence of the caput succedaneum or scalp hair, both of which may give some problem in the identification of fetal head sutures and fontanels and their location in relationship to maternal pelvic landmarks. The capability of diagnosing a fetus in OP position by digital examination has been extremely inaccurate, whereas an ultrasound approach, transabdominal, transperineal and transvaginal, has clearly shown its superior diagnostic accuracy. This is true not only for diagnosis of malpositions, detected in both first and second stage of labor, but also in cases of marked asynclitism.

Dosimetric coverage of anal sphincter by 3D conformal fields in patients undergoing neoadjuvant chemoradiation for rectal cancer: An implication in the concept of sphincter-preserving radiation therapy.

558 Background: Functional impact related to dosimetric coverage of the anal sphincter in rectal cancer patients treated with neoadjuvant chemoradiation (NCRT) remains unknown. We evaluated the anatomic location of the anal sphincter to pelvic bony landmarks related to 3D conformal radiotherapy (3DRT) and studied the dosimetric coverage of the anal sphincter in patients undergoing NCRT for rectal cancer. Methods: Between June 2006 and March 2012, 64 patients with rectal cancer treated with NCRT were included. All patients were treated in prone position on a bellyboard by 3DRT with 3 or 4-field setup up to 5,040 (86%) or 5,400 (14%) cGy. The inferior borders of the RT fields used were the lower of either at 3-5 cm inferior to the lowest gross tumorous volume (GTV) or at the inferior border of the obturator foramina (IBOF). The anal sphincters were contoured retrospectively and dose distributions were determined using dose volume histograms. Results: The mean anal sphincter volume was 5.1 cm3 (range, 1.3 – 11.2 cm3). On average, the center of anal sphincter was 18.6 mm inferior to the IBOF. In 53 cases (82.8%), the anal sphincter was completely inferior to the IBOF. In the remaining 11 cases (17.2%), the anal sphincter was either overlapping the IBOF (10 cases; 15.6%), or completely superior to the IBOF (1 case; 1.7%). On average, the center of anal sphincter was 39 mm inferior to the lowest edge of GTV. In 19 cases (30%), the anal sphincter was completely outside of the inferior border of the RT fields. In another 10 cases (16%), the sphincter was more than 4 cm away from the GTV inferior border but was partially treated. The mean dose delivered to anal sphincter was 2795 cGy (range, 245–5441 cGy). Lower mean doses delivered to the anal sphincters were noted for larger distances from the center of the anal sphincter to the GTV. Conclusions: Minimizing dose delivered to anal sphincter is possible, especially for upper or mid rectal cancer. However, meticulous planning to define the inferior border of RT fields is necessary. Future studies will focus on the correlation between RT dose distribution to the anal sphincter and anal-rectal dysfunction.

An Automated Pelvic Bone Geometrical Feature Measurement Utilities on Ct Scanning

An accurate depth location of pelvic land mark could be affected by the acoustic properties of the penetrated tissues and improper depth estimation could lead to a miscalculation of the acetabular cup implant. In the case of obese patient it is very difficult to locate the place of damage. Errors in land mark location leads to the improper treatment by orthopedic surgeons. The aim of this system is to determine pelvic orientation from CT scan images based on patch statistical shape model multilevel measurement utility tools by image calibration system; by applying a hierarchical registration scheme. Here a plastic bones and cadaveric specimen are used. Many approaches have been proposed in the literature to replace the percutanesous digitization, Involvement of the experts in the system to give the solution or conclusion.

Le suivi échographique de la deuxième partie du travail

In the second stage of labor, fetal head rotation and fetal head position are determinant for the management of labor to attempt a vaginal delivery or a cesarean section. However, digital examination is highly subjective. Nowadays, delivery rooms are often equipped with compact and high performance ultrasound systems. The clinical examination can be easily completed by quantified and reproducible methods. Transabdominal ultrasonography is a well-known and efficient way to determine the fetal head position. Nevertheless, ultrasound approach to assess fetal head descent is less widespread. We can use translabial or transperineal way to evaluate fetal head position. We describe precisely two different types of methods: the linear methods (3 different types) and the angles of progression (4 different types of measurement). Among all those methods, the main pelvic landmarks are the symphysis pubis and the fetal skull. The angle of progression appears promising but the assessment was restricted to occipitoanterior fetal position cases. In the coming years, ultrasound will likely play a greater role in the management of labor.

Pelvis feature extraction and classification of Cardiff body match rig base measurements for input into a knowledge-based system

The purpose of this paper is to determine whether it is possible to use an automated measurement tool to clinically classify clients who are wheelchair users with severe musculoskeletal deformities, replacing the current process which relies upon clinical engineers with advanced knowledge and skills. Clients’ body shapes were captured using the Cardiff Body Match (CBM) Rig developed by the Rehabilitation Engineering Unit (REU) at Rookwood Hospital in Cardiff. A bespoke feature extraction algorithm was developed that estimates the position of external landmarks on clients’ pelvises so that useful measurements can be obtained. The outputs of the feature extraction algorithms were compared to CBM measurements where the positions of the client’s pelvis landmarks were known. The results show that using the extracted features facilitated classification. Qualitative analysis showed that the estimated positions of the landmark points were close enough to their actual positions to be useful to clinicians undertaking clinical assessments.

Reliability of plain radiographic parameters for developmental dysplasia of the hip in children

Few studies have evaluated the reliability and reproducibility of the femoral neck-shaft angle (NSA), center-edge angle (CEA), and acetabular index (AI) in young children with developmental dysplasia of the hip (DDH). We wanted to determine whether these parameters could be used reliably by practitioners. Fifty radiographs from 21 children with DDH were reviewed. Analysis was performed by three observers, at two time periods. The intra- and inter-observer reliability for each measure was assessed. At time period one, we noted a "high" level of agreement between observers when measuring the NSA, a "low" level when measuring the CEA, and a "moderate" level when measuring the AI. At time period two, we noted a "very high" level of agreement between observers when measuring the NSA and a "high" level when measuring the CEA and AI. When comparing the measurements of observer 1 at the two different time periods, we noted nearly "very high" agreement when measuring the NSA, a "moderate" agreement when measuring the CEA, and a "high" agreement for the AI. In comparing the measurements of observer 2, we noted "very high" agreement for the NSA and "high" agreement for the CEA and AI. In comparing the measurements for observer 3, we noted nearly "very high" agreement for the NSA, nearly "high" agreement for the CEA, and "high" agreement for the AI. It is difficult to reliably measure three-dimensional pelvic morphology on a frontal plane radiograph, especially when important pelvic landmarks have yet to ossify.

MO-A-217A-02: Prostate and Pelvic Lymph Node Anatomy for Contouring.

1. Know the common anatomical landmarks in pelvis used for contouring. 2. Know the contouring guidelines used in published contouring atlas. 3. Know how to use the contouring guidelines in the clinic.

Bedside ultrasound diagnosis of atraumatic bladder rupture in an alcohol-intoxicated patient: a case report

Most commonly, patients who present to the emergency department with a history and physical examination suggestive of urinary bladder rupture report a preceding traumatic event. Spontaneous atraumatic bladder rupture is relatively uncommon, but can occur in the context of a recent alcohol binge. The alcohol-intoxicated patient presents diagnostic and therapeutic challenges to the emergency physician (EP) that take on additional urgency given the high mortality of unrecognized bladder rupture. This case report reviews bladder anatomy, the unique physiological changes in the alcohol-intoxicated patient, and the high mortality rate of a ruptured urinary bladder. We review the historical diagnostic imaging options followed by a discussion of how bedside ultrasound could expedite diagnosis and management. We present the case of a patient with spontaneous atraumatic rupture of the urinary bladder after a recent alcohol binge. Bedside ultrasound was utilized by the EP to determine the need for emergent surgical consultation and intervention. We recommend that EPs consider bladder rupture in their initial evaluation of patients presenting with nonspecific abdominal pain in the context of recent alcohol intoxication. When using bedside ultrasound to evaluate the pelvis, the presence of anterior or posterior vesicular fluid collections, the loss of normal pelvic landmarks, or irregularities in the bladder wall may increase the EPs suspicion for this disease entity and expedite time-sensitive management.

Magnetic resonance imaging of abdominal versus vaginal prolapse surgery with mesh

We compared two surgical approaches in patients with symptomatic prolapse of the vaginal apex with normal controls by analyzing pelvic landmark relationships measured using magnetic resonance imaging (MRI) before and after surgery. In this prospective multicenter pilot study involving 16 participants, nulliparous controls (n = 6) were compared with ten parous (3.0 ± 1.0) women with uterine apical prolapse equal to or greater than stage 2. Group A (n = 5) underwent abdominal sacral colpopexy with monofilament polypropylene mesh and group B (n = 5) with vaginal mesh kit repair (Total ProLift). Subtotal hysterectomy was performed in all group A and no group B women. All patients underwent preoperative and 3-month postoperative Pelvic Organ Prolapse Quantification (POP-Q) and dynamic MRI. Comparison of MRI pelvic angles and distances was performed and analyzed by Mann-Whitney rank sum test and chi-square test. Vaginal apical support is similar at 3 months for abdominal sacral colpopexy (ASCP) and ProLift by POP-Q examination and MRI analysis. In both treatment groups, the postoperative POP-Q point C and MRI parameters were similar to nulliparous controls at 3 months. Anatomic outcomes for ASCP compared with ProLift were similar at 3 months in terms of vaginal apical support by POP-Q and MRI analysis. Continued comparative analysis of postoperative support with objective imaging seems warranted.

Inter-tester reliability of non-invasive technique for measurement of innominate motion

Although the complex anatomical orientation and position of the sacroiliac joints (SIJ) has rendered their 3D kinematic evaluation difficult, recent techniques of palpation–digitization of pelvic landmarks using electromagnetic tracking device have been able to accurately and non-invasively quantify the subtle SIJ kinematics. While this technique demonstrates radiographic validity and high test-retest reliability, it is yet to be assessed with regards to inter-tester and trial-to-trial reliability. A single-group repeated measure design using 4 testers was conducted to evaluate the inter-tester and trial-to-trial reliability of palpation–digitization technique for innominate vector length measurements using the Polhemus electromagnetic tracking device. Fourteen young, healthy adults between the ages of 18–40 years participated in the study. The innominate vector length was calculated from 3D co-ordinates of palpated and digitized pelvic landmarks in two test positions of hip. A sensitivity analysis was conducted to determine how palpation–digitization errors for pelvic landmarks impacts on innominate angle calculation. Reliability indexes of Intraclass correlation coefficient (ICC) (≥0.97) and Standard error of measurement (SEM) (≤2.02 mm) demonstrated very high inter-tester and trial-to-trial reliability and accuracy of palpation–digitization technique for innominate vector length measurements, irrespective of the two test positions. A higher consistency of measurements was obtained within-testers as compared to between testers, and sensitivity analysis demonstrated a negligible influence of palpation–digitization errors on the innominate angle measurements. The results support clinical and research utility of this technique for non-invasive kinematic evaluation of SIJ motion for this population. Further research on the use of this palpation–digitization technique in symptomatic population is warranted.

Sacro-femoral-pubic angle: a coronal parameter to estimate pelvic tilt

Pelvic tilt is an established measure of position which has been tied to sagittal plane spinal deformity. Increased tilt is noted in the setting of the aging spine and sagittal malalignment syndromes such as flatback (compensatory mechanism). However, the femoral heads are often poorly visualized on sagittal films of scoliosis series in adults, limiting the ability to determine pelvic incidence and tilt. There is a need to establish a coronal plane (better visualization) pelvic parameter which correlates closely with pelvic tilt. This is a retrospective review of 71 adult patients (47 females and 24 males) with full-length standing spine radiographs. Visualization of all spinal and pelvic landmarks was available coronally and sagittally (including pelvis and acetabuli). Pelvic tilt was calculated through validated digital analysis software (SpineView(®)). A new parameter, the sacro-femoral-pubic angle (midpoint of S1 endplate to centroid of acetabuli to superior border of the pubic symphysis) was analyzed for correlation (and predictive ability) with sagittal pelvic tilt. The sacro-femoral-pubic angle (SFP angle) was highly correlated to PT, and according to this analysis, pelvic tilt could be estimated by the formula: PT=75-(SFP angle). A Pearson's correlation coefficient of 0.74 (p<0.005) and predictive ability of 76% accuracy was obtained (±7.5°). The correlation and predictive ability was greater for males compared to females (male: r=0.87 and predictive model=93%; female: r=0.67 and predictive model=67%). The pelvic tilt is an essential measure in the context of radiographic evaluation of spinal deformity and malalignment. Given the routinely excellent visibility of coronal films this study established the SFP as a coronal parameter which can reliably estimate pelvic tilt. The high correlation and predictive ability of the SFP angle should prompt further study and clinical application when lateral radiographs do not permit assessment of pelvic parameters.

Compensation of Sound Speed Deviations in 3-D B-Mode Ultrasound for Intraoperative Determination of the Anterior Pelvic Plane

An accurate determination of the pelvic orientation is inevitable for the correct cup prosthesis placement of navigated total hip arthroplasties. Conventionally, this step is accomplished by percutaneous palpation of anatomic landmarks. Sterility issues and an increased landmark localization error for obese patients lead to the application of B-mode ultrasound imaging in the field of computer-assisted orthopedic surgery. Many approaches have been proposed in the literature to replace the percutaneous digitization by 3-D B-mode ultrasound imaging. However, the correct depth localization of the pelvic landmarks could be significantly affected by the acoustic properties of the penetrated tissues. Imprecise depth estimation could lead to a miscalculation of the pelvic orientation and subsequently to a misalignment of the acetabular cup implant. But so far, no solution has been presented, which compensates for acoustic property differences for correct depth estimation. In this paper, we present a novel approach to determine pelvic orientation from ultrasound images by applying a hierarchical registration scheme based on patch statistical shape models to compensate for differences in speed of sound. The method was validated based on plastic bones and a cadaveric specimen.

Stapler access and visibility in the deep pelvis: A comparative human cadaver study between a computerized right angle linear cutter versus a curved cutting stapler

PurposeDistal rectal stapling is often challenging because of limited space and visibility. We compared two stapling devices in the distal rectum in a cadaver study: the iDrive™ right angle linear cutter (RALC) (Covidien, New Haven, CT) and the CONTOUR® curved cutter (CC) (Ethicon Endo-Surgery, Cincinnati, OH).MethodsTwelve male cadavers underwent pelvic dissection by 4 surgeons. After rectal mobilization as in a total mesorectal excision, the staplers were applied to the rectum as deep as possible in both the coronal and sagittal positions. The distance from the pelvic floor was measured for each application. A questionnaire rated the visibility and access of the stapling devices. Measurements were taken between pelvic landmarks to see what anatomic factors hinder the placement of a distal rectal stapler.ResultsThe median (range) distance of the stapler from the pelvic floor in the coronal position for the RALC was 1.0 cm (0-4.0) vs. 2.0 cm (0-5.0) for the CC, p = 0.003. In the sagittal position, the median distance was 1.6 cm (0-3.5) for the RALC and 3.3 cm (0-5.0) for the CC, p < 0.0001. The RALC scored better than the CC in respect to: 1. interference by the symphysis pubis, 2. number of stapler readjustments, 3. ease of placement in the pelvis, 4. impediment of visibility, 5. ability to hold and retain tissue, 6. visibility rating, and 7. access in the pelvis. A shorter distance between the tip of the coccyx and the pubic symphysis correlated with a longer distance of the stapler from the pelvic floor (p = 0.002).ConclusionsThe RALC is superior to the CC in terms of access, visibility, and ease of placement in the deep pelvis. This could provide important clinical benefit to both patient and surgeon during difficult rectal surgery.

The assessment of pelvic landmarks using palpation: A reliability study of undergraduate students

Background The use of palpation to diagnose the movement and positional components of sacroiliac joint (SIJ) dysfunction is commonly taught within osteopathy. However, concerns have been raised about the reliability of such protocols. Objective The aim of this study was to investigate the inter-rater reliability of four traditional static palpation tests based upon the Frank Mitchell Sr biomechanical model of pelvic movement as taught and used to diagnose and treat positional pelvic joint dysfunction. Design A small scale inter-rater reliability study. Methods Twenty third-year students with similar levels of training in the Mitchell Model examined and scored four asymptomatic subjects for positional and movement dysfunctions. The examiners were blinded to each other and performed all four diagnostic tests. Scores were recorded and analysed for inter-rater reliability using Fleiss’ Kappa (F k ), Agreement Coefficient 1 (AC1) and Kendall’s coefficient of concordance. Results All SIJ test scores produced F k results below 0.4 (−0.0476 to 0.0330), indicating “Poor” inter-rater reliability; values of F k ≥ 0.4 are considered to be clinically reliable. In addition, AC1 results ranged from −0.04 to 0.189. Kendall’s coefficients of concordance were not significant for inter-rater agreement ( p = 0.06 to p 0.89). Conclusion This small study demonstrated “Poor” inter-rater reliability of the Mitchell Model used to diagnose pelvic SIJ dysfunction. These findings are consistent with other studies in this field. It is suggested that the inclusion of this osteopathic model within curricula be reviewed forthwith.

Quantification of equine sacral and iliac motion during gait: A comparison between motion capture with skin‐mounted and bone‐fixated sensors

Information regarding movement at the ilium and sacrum in nonlame horses during normal gait may assist in understanding the biomechanics of the equine sacroiliac joint. To determine the amount and direction of motion at the ilium and sacrum using 3D orientation sensors during walk and trot in sound Thoroughbreds. To compare results from sensors fixed to the skin with results from sensors fixed to bone-implanted pins. Three 3D wireless orientation sensors were mounted to the skin over the tuber sacrale (TS) and sacrum of 6 horses and motion at the ilium and sacrum was recorded for lateral bending (LB) flexion-extension (F-E) and axial rotation (AR) during walk and trot. This process was repeated with the orientation sensors mounted to the same pelvic landmarks via Steinmann pins. Mean walk values were greater than trot values using pin-mounted sensors for all planes of movement (P < 0.05). Walk had 1.64 ± 0.22° (mean ± s.e.) more LB than trot (pin-mounted) yet 0.68 ± 0.22° less than trot when skin-mounted; 3.45 ± 0.15° more F-E (pin- and skin-mounted), and 4.99 ± 0.4° more AR (pin-mounted), but trot had 3.4 ± 0.40° more AR than walk with skin mounting. Using pinned sensors for trot resulted in less LB (2.47 ± 0.22°), F-E (1.12 ± 0.15°) and AR (10.62 ± 0.40°); and for walk less F-E (1.12 ± 0.15°) and AR (2.15 ± 0.40°) compared to skin-mounted. Poor correlation existed between mean values for skin- and pin-mounted data for walk and trot, for all planes of motion. Movements were smaller at trot with bone-fixated sensors compared to walk, suggesting increased muscular control of movement at the trot. The apparent increase in skin motion at the trot and no clear correlation between skin- and bone-mounted sensors indicates inaccuracies when measuring sacral and iliac movement with skin mounting.

MRI pelvic landmark angles in the assessment of apical pelvic organ prolapse

The aim of the study was to evaluate the utility of magnetic resonance imaging (MRI) pelvic landmark angles and lines in the assessment of apical vault prolapse. Seventeen women were evaluated as part of a prospective surgical trial. Baseline data are presented as a pilot study of the utility of MRI in addition to this evaluation of 6 nulliparous volunteers without prolapse and 11 parous women with symptomatic ≥ stage II uterine prolapse. Each patient underwent assessment for pelvic organ prolapse quantification (POPQ) and pelvic MRI. Pelvic landmark angles and lines were measured. Mann-Whitney Rank sum test and Spearman's Rank order correlation test were used to assess agreement. Women with prolapse had a significantly larger h angle, g angle, and e angle at rest than those without prolapse. Correlation between apical vault descent was measured clinically by POPQ point C with MRI measurements: h angle (r = 0.61, p = 0.01), g angle (r = 0.64, p = 0.005), and e angle (r = 0.62, p = 0.007). MRI measurements of pelvic landmark angles reliably differentiate between women with and without uterine prolapse and correlate best with POPQ point C.

Robust Pelvic Coordinate System Determination for Pose Changes in Multidetector-row Computed Tomography Images

For developing navigation system of total hip arthroplasty (THA) and evaluating hip joint kinematics, 3-D pose position of the femur and acetabulum in the pelvic coordinate system has been quantified. The pelvic coordinate system is determined by manually indicating pelvic landmarks in multidetector-row computed tomography (MDCT) images. It includes intra- and inter-observer variability, and may result in a variability of THA operation or diagnosis. To reduce the variability of pelvic coordinate system determination, this paper proposes an automated method in MDCT images. The proposed method determines pelvic coordinate system automatically by detecting pelvic landmarks on anterior pelvic plane (APP) from MDCT images. The method calibrates pelvic pose by using silhouette images to suppress the affect of pelvic pose change. As a result of comparing with manual determination, the proposed method determined the coordinate system with a mean displacement of <TEX>$2.6\;{\pm}\;1.6$</TEX> mm and a mean angle error of <TEX>$0.78\;{\pm}\;0.34$</TEX> deg on 5 THA subjects. For changes of pelvic pose position within 10 deg, standard deviation of displacement was 3.7 mm, and of pose was 1.28 deg. We confirmed the proposed method was robust for pelvic pose changes.