Inter-rater Reliability of Sacral Ratio Measurements in Patients with Anorectal Malformations.

BACKGROUND: Anorectal malformations (ARMs) are a spectrum of congenital anomalies with varying prognosis for fecal continence. The sacral ratio (SR) is a measure of sacral development that has been proposed as a method to predict future fecal continence in children with ARM. The aim of this study was to quantify the inter-rater reliability (IRR) of SR calculations by radiologists at different institutions. MATERIALS AND METHODS: x-Rays in the anteroposterior (AP) and lateral planes were reviewed by a pediatric radiologist at each of six different institutions. Subsequently, images were reviewed by a single, central radiologist. The IRR was assessed by calculating Pearson correlation coefficients and intraclass correlation coefficients from linear mixed models with patient and rater-level random intercepts. RESULTS: Imaging from 263 patients was included in the study. The mean inter-rater absolute difference in the AP SR was 0.05 (interquartile range, 0.02-0.10), and in the lateral SR was 0.16 (interquartile range, 0.06-0.25). Overall, the IRR was excellent for AP SRs (intraclass correlation coefficient [ICC], 81.5%; 95% confidence interval, 75.1%-86.0%) and poor for lateral SRs (ICC, 44.0%; 95% CI, 29.5%-59.2%). For both AP and lateral SRs, ICCs were similar when examined by the type of radiograph used for calculation, severity of the ARM, presence of sacral or spinal anomalies, and age at imaging. CONCLUSIONS: Across radiologists, the reliability of SR calculations was excellent for the AP plane but poor for the lateral plane. These results suggest that better standardization of lateral SR measurements is needed if they are going to be used to counsel families of children with ARM.

Cost Analysis of Magnet-driven Growing Rods for Early-onset Scoliosis at 5 Years.

STUDY DESIGN: Prospective case series of nine children with early-onset scoliosis (EOS) treated by a single surgeon with a novel implant, the magnet-driven growing rod (MdGR) in a publicly funded health care service accounting for "payer costs" (PC) incurred. OBJECTIVE: The aim of this study was to compare the cost-effectiveness of MdGR versus conventional growing rods (CGRs) with respect to the PC incurred for treating EOS at 5 years. SUMMARY OF BACKGROUND DATA: Cost estimate and mathematical modeling study projections of MdGR have shown despite high insertional costs, it breaks even with CGR by 3 to 4 years. However, no clinical study to date exists either supporting or refuting this hypothesis. METHODS: Nine patients with EOS secondary to idiopathic (two), congenital (one), syndromic (three), and neuromuscular (three) etiologies treated by submuscular insertion of MdGR against stringent inclusion criteria formed the study cohort. We collected costs incurred with all aspects of care over the lifetime of device (or at least 5 years) from payers' perspective to compute and report average PC incurred per patient. We performed this cost analysis by comparing the MdGR PC against literature reported PC for CGR at 5 years. RESULTS: There were five single rod (SR) and two dual rod (DR) de novo MdGR insertions, while two patients had conversion of CGR to MdGR. MdGR alone accounted for at least 50% of overall budget. The MdGR was at least 40% more cost-effective in comparison to the CGR (£34,741 vs. £52,293) and there were seven MdGR graduates. CONCLUSION: The first study reporting direct PC incurred in EOS treated by MdGR that is devoid of any mathematical modeling and deterministic sensitivity analysis is presented. The true societal/human cost savings taking into consideration indirect costs are likely to be significantly higher. MdGR is a promising novel implant that may eventually become the "standard of care" for certain EOS etiologies. LEVEL OF EVIDENCE: 4.

Patterns of growth in the presacral vertebral column of the leopard gecko (Eublepharis macularius).

Postnatal growth patterns within the vertebral column may be informative about body proportions and regionalization. We measured femur length, lengths of all pre-sacral vertebrae, and lengths of intervertebral spaces, from radiographs of a series of 21 Eublepharis macularius, raised under standard conditions and covering most of the ontogenetic body size range. Vertebrae were grouped into cervical, sternal, and dorsal compartments, and lengths of adjacent pairs of vertebrae were summed before analysis. Femur length was included as an index of body size. Principal component analysis of the variance-covariance matrix of these data was used to investigate scaling among them. PC1 explained 94.19% of total variance, interpreted as the variance due to body size. PC1 differed significantly from the hypothetical isometric vector, indicating overall allometry. The atlas and axis vertebrae displayed strong negative allometry; the remainder of the vertebral pairs exhibited weak negative allometry, isometry or positive allometry. PC1 explained a markedly smaller amount of variance for the vertebral pairs of the cervical compartment than for the remainder of the vertebral pairs, with the exception of the final pair. The relative standard deviations of the eigenvalues from the PCAs of the three vertebral compartments indicated that the vertebrae of the cervical compartment were less strongly integrated by scaling than were the sternal or dorsal vertebrae, which did not differ greatly between themselves in their strong integration, suggesting that the growth of the cervical vertebrae is constrained by the mechanical requirements of the head. Regionalization of the remainder of the vertebral column is less clearly defined but may be associated with wave form propagation incident upon locomotion, and by locomotory changes occasioned by tail autotomy and regeneration. Femur length exhibits negative allometry relative to individual vertebral pairs and to vertebral column length, suggesting a change in locomotor requirements over the ontogenetic size range.

Ontogeny of the Postcranial Axial Skeleton of Melanosuchus niger (Crocodylia, Alligatoridae).

This study proposes the description of the development of the postcranial axial skeleton, including vertebrae, gastralium, ribs, sternum, and interclavicle, in Melanosuchus niger. Six nests were marked and two eggs removed from each nest at 24-hr intervals until hatching. For posthatching evaluation, 30 hatchlings were kept in captivity and one exemplar was euthanized at three-day intervals. Samples were diaphanized using potassium hydroxide (KOH), alizarin red S, and Alcian blue. A routinely generally used method was applied for histological evaluation. It was difficult to define in which vertebrae the development of cartilaginous centers began, but it was possible to observe that this condensation advanced in the craniocaudal direction. The condensation started in the vertebral arches and was visibly stronger in the cervical and dorsal regions, advancing to the lumbar, sacral and, last, to the caudal region. The atlas showed a highly different morphology compared with the other cervical vertebrae, with a short intercenter, two neural arches, and a proatlas. The ossification process began in the body of cervical vertebrae III to VIII and alizarin retention decreased in the last vertebrae, indicating a craniocaudal direction in bone development, similar to cartilage formation. In the histological sections of gastralium and interclavicles of M. niger at several development stages, it was possible to observe that these elements showed intramembranous development. Anat Rec, 301:607-623, 2018. © 2017 Wiley Periodicals, Inc.

Finding sacral: Developmental evolution of the axial skeleton of odontocetes (Cetacea).

Axial morphology was dramatically transformed during the transition from terrestrial to aquatic environments by archaeocete cetaceans, and again during the subsequent odontocete radiation. Here, we reconstruct the sequence of developmental events that underlie these phenotypic transitions. Archaeocete innovations include the loss of primaxial/abaxial interaction at the sacral/pelvic articulation and the modular dissociation of the fluke from the remainder of the tail. Odontocetes subsequently integrated lumbar, sacral, and anterior caudal vertebrae into a single torso module, and underwent multiple series-specific changes in vertebral count. The conservation of regional proportions despite regional fluctuations in count strongly argues that rates of somitogenesis can vary along the column and that segmentation was dissociated from regionalization during odontocete evolution. Conserved regional proportions also allow the prediction of the location and count of sacral homologs within the torso module. These predictions are tested with the analysis of comparative pudendal nerve root location and geometric morphometrics. We conclude that the proportion of the column represented by the sacral series has been conserved, and that its vertebrae have changed in count and relative centrum length in parallel with other torso vertebrae. Although the sacral series of odontocetes is de-differentiated, it is not de-regionalized.

Effect of growing rod on sagittal and spinopelvic parameters in early-onset scoliosis patients.

Growing rod is a commonly used surgery for early-onset scoliosis (EOS). However, the effect of growing-rod lengthening on the spinopelvic alignment is unclear. In this study, 21 EOS patients treated by growing rod were evaluated retrospectively and thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI) , sacral slope (SS), pelvic tilt (PT), and sagittal vertical axis (SVA) were measured. Preoperatively, the mean TK, LL, PI, PT, SS, and SVA were 27.4°, 35.2°, 43.8°, 7.5°, 33.8°, and 47.7 mm respectively. After the last lengthening, TK, LL, PI, PT, SS, and SVA were 28.3°, 28.06°, 41.4°, 7°, 5.2°, and 42.6 mm, respectively. The sagittal plane parameters in our EOS patients were not significantly altered during the lengthening period.

Distraction magnitude and frequency affects the outcome in juvenile idiopathic patients with growth rods: finite element study using a representative scoliotic spine model.

BACKGROUND CONTEXT: Growth rods are used to limit the progression of scoliosis without restraining the opportunity for the spine to grow. However, major complications like rod breakage, screw loosening, and altered sagittal contour have been encountered. OBJECTIVE: To analyse the effect of the magnitude of distraction forces on the T1-S1 growth, maximum von Mises stresses on the rods, sagittal contours, and load at the pedicle screw-bone interface and quantify the maximum stresses on the rod for a period of 24 months using different frequencies of distraction in a representative scoliotic spine model. STUDY DESIGN: A representative finite element model of a juvenile scoliotic spine was used to study the effect of magnitude and frequency of distraction on growth rods. METHODS: A representative scoliotic model was developed and instrumented using proximal foundation, distal foundation, and rods. Part 1: simulation steps comprised 6 months of growth under various distraction forces to analyze effects of distraction force on the biomechanics of the spine and instrument. Part 2: simulation steps comprised 24 months of growth under various intervals of distraction to analyze effects of distraction interval on the propensity of rod fracture. RESULTS: Part 1: an optimal distraction force exists for which the growth is sustained with minimum stress on the rod, lower loads at screw-bone interface, and unaltered sagittal contours. Part 2: the stresses on the rods were highest for 12-month distraction (2 distractions in 2 years) and lowest for 2-month distraction (12 distractions in 2 years). CONCLUSIONS: The data and trend suggest that as the distraction forces vary so do the effects on spinal growth. The results of this study also signify the importance of shorter distraction period in reducing the stresses on the rods.

Where is the apex of the sacral hiatus for caudal epidural block in the pediatric population? A radio-anatomic study.

PURPOSE: Caudal epidural block (CEB), administered through the sacral hiatus, is a regional anesthetic technique commonly used in children. To facilitate and optimize pediatric CEB, morphometric data that may be important for the sacral hiatus have been obtained using multidetector computed tomography (MDCT). METHODS: This study is the first radio-anatomic study designed to address this topic in children. Images of 79 children (39 girls and 40 boys between 1 and 9 years old) were divided into three groups according to age [group I (ages 1-3), group II (ages 4-6), and group III (ages 7-9)] and were retrospectively examined. Data were gathered via 3D volume-rendered images. Measurements included the height and width of the sacral hiatus, S2-S4 (sacral vertebra) distance, the distances between the poles of the unfused spinous process of each sacral vertebra, and the dimensions of an imaginary triangle formed between the right and left posterior superior iliac spines (PSIS) and the apex of the sacral hiatus. RESULTS: The most frequently fused spinous process was at S2 level. The mean S2-S4 distance was 1.36 cm for group I, 1.78 cm for group II, and 2.17 cm for group III. There was not the imaginary equilateral triangle used in the method of finding the sacral hiatus for CEB, and the apex of this triangle did not occur at the standard level (S4) in most of the children. It was observed that the apex deriving from the most distal fused spinous process was at the level of S2 in one of two children. CONCLUSION: Dural puncture is inevitable for CEB applied at the S2 level. Consequently, CEB should be applied below this level (range, 1.36-2.17 cm) from the midpoint of the interspinous distance between the PSIS (at the same level with S2) in children aged 1-9 years.

Ossification timing of sacral vertebrae by ultrasound in the mid-second trimester of pregnancy.

OBJECTIVES: The aim of the study was to establish the ossification timing of sacral vertebrae by ultrasonography in the second trimester of pregnancy, for the diagnosis of caudal regression syndrome with isolated sacral agenesis. METHODS: The study was carried out on 77 normal single pregnancies, at gestational ages ranging from 15 to 21 weeks, using high-resolution transabdominal echography. The sacral region was visualized in a coronal plane, when the fetus was in anterodorsal position. The level of ossification of sacral vertebrae (S1 to S5) at each gestational age was recorded. Each sacral region was examined three times by the same observer and the nucleus was considered as present when it was visualized at least two times out of three. Blind assessment was performed three times by a second observer, who was not present at the previous examination, for interobserver and intraobserver error analysis. RESULTS: Interobserver and intraobserver error calculation demonstrated the reproducibility of the method. Concordance between the two observers as evaluated by Cohen Kappa index was 0.77 (C.I. 95%, 0.69-0.85).S1 ossification nuclei were visualized in all fetuses at 15 weeks and S2 nucleus was found in all fetuses within 17 weeks. S3 nucleus was detected in 45% of fetuses by the beginning of the 16th week. S4 was visualized in 55% of the cases at 18 weeks and progressively in a higher percentage of cases during the following weeks of gestation. CONCLUSION: The data obtained showed that the sequence of development of sacral region ossification was related to gestational age. This observation allows clinicians to accurately exclude isolated sacral agenesis at 16 to 17 weeks of gestation, when the S1-S2 ossification nuclei are visualized. This opportunity may be of particular value in the offspring of diabetic mothers.

Fetal bony pelvis in the bladder exstrophy complex: normal potential for growth?

OBJECTIVES: To provide the first look at the bony histologic features of fetuses with the exstrophy complex, specifically evaluating the endochondral ossification, stage of development, and microscopic potential for normal growth. METHODS: Three fetuses between 28 and 30 weeks of gestation, one with classic bladder exstrophy, one with cloacal exstrophy, and one control, were obtained from France. The bony pelves were dissected and preserved in formalin, and multiple representative sections were sliced from all pelvic areas: pubis, ischium, ilium, and sacrum. These slices were sequentially processed as slides, stained with hematoxylin-eosin, and evaluated microscopically for histologic changes, developmental stage, and degree of endochondral ossification. RESULTS: All slides from the three specimens showed cartilage analogue with endochondral ossification. Histologically the exstrophy specimens were identical to the control and appeared completely normal; bone development was occurring at an expected rate with the potential for continued normal growth. CONCLUSIONS: These new findings illustrate that fetal bone in the exstrophy complex displays normal microscopic growth patterns and unhindered endochondral ossification at 28 weeks of gestation, well beyond the embryologic period. With no evident microscopic bony defect, the gross bony anomalies in exstrophy should be surgically correctable, leading us to conclude that early reapproximation of the physiologic shape of the pelvis could lead to more normal gross bone growth, decreased shortage of bone, and a more appropriate distribution of the mechanical and developmental forces on a closed, normally functioning pelvic ring.

Anatomy of the sacrum.

One of the basic tenets of performing surgery is knowledge of the relevant anatomy. Surgeons incorporate this knowledge along with factors, such as biomechanics and physiology, to develop their operative approaches and procedures. In the diagnosis and management of sacral tumors, the need to be familiar with the anatomy of the sacrum is no less important than knowledge of the pathological entity involved. This article will provide an overview of the embryology and anatomy of the sacrum, along with concepts as applied to surgical intervention.

Human foetal sacral length measurement for the assessment of foetal growth and development by ultrasonography and dissection.

This study investigated the value of prenatal ultrasonographic measurements of sacrum as a predictor of in utero development and gestational age (GA), and to make a comparison between the data obtained by ultrasonography and dissection. A prospective cross-sectional study of ultrasonography was conducted in 186 pregnant women with uneventful single pregnancies. GA ranged from 14 to 40 weeks, and the relationships of sacrum length (SL) with GA, femur length (FL), biparietal diameter (BPD), head circumference (HC) and abdominal circumference (AC) were evaluated. In addition, the sacral bones of 101 spontaneously aborted foetuses aged from 13 to 39 weeks were dissected and measured. The relationship of the results with GA was investigated. There was a linear relationship between the ultrasonographic measurements of the SL and the GA (R2 = 0.93, P < 0.001), the FL (R2 = 0.93, P < 0.001), the BPD (R2 = 0.93, P < 0.001), the HC (R2 = 0.92, P < 0.001) and the AC (R2 = 0.90, P < 0.001). The rate of increase of SL was significantly higher before 28 weeks of gestation than in later pregnancy, with a correlation coefficient between SL and GA of 0.96 and 0.88, respectively. The SL measurements obtained by dissection were similar to those of ultrasonography. There was a linear relationship between the SL and the GA (R2 = 0.96, P < 0.001) and the correlation coefficients between SL and GA were 0.97 before 28 weeks of gestation, and 0.94 in later weeks. In conclusion, this study demonstrates a high correlation between the SL, GA and other standard measurements of foetal growth, and suggests that SL measurement is a valuable predictor of GA in the foetuses with normal growth.

Postnatal maturation of the sacrum and coccyx: MR imaging, helical CT, and conventional radiography.

OBJECTIVE: The purpose of this paper is to provide a detailed radiologic description of the postnatal developmental anatomy of the sacrum and coccyx as revealed by MR imaging, helical CT, and conventional radiography. MATERIALS AND METHODS: One hundred ten imaging examinations of the sacrococcygeal spine were performed in patients who were newborn to 30 years old. Imaging included conventional radiography (n = 63), three-dimensional gradient-recalled echo MR imaging (n = 10), and helical CT with sagittal and angled coronal reformations (n = 37). A detailed analysis was performed of the ossification and fusion of the primary and secondary ossification centers. RESULTS: The sacrum and coccyx were noted to develop from 58 to 60 sacral ossification centers and eight coccygeal centers, respectively. These centers were noted to ossify and fuse in an organized temporal pattern from the fetal period to the age of 30. CONCLUSION: The sacrum and coccyx are formed by a complex process that fuses primary and secondary ossification centers. Because the maturation process can be asymmetric, an understanding of this process may prove useful for distinguishing physeal plates from fracture lines.

Study of the course of the incidence angle during growth.

Standing posture is made possible by hip extension and lumbar lordosis. Lumbar lordosis is correlated with pelvic parameters, such as the declivity angle of the upper surface of the sacrum and the incidence angle, which determine the sagittal morphotype. Incidence angle, which is different for each individual, is known to be very important for up-right posture, but its course during life has not yet been established. Incidence angle was measured on radiographs of 30 fetuses, 30 children and 30 adults, and results were analysed using the correlation coefficient r and Student's t test. A statistically significant correlation between age and incidence angle was observed. Incidence angle considerably increases during the first months, continues to increase during early years, and stabilizes around the age of 10 years. Incidence is a mark of bipedism, and its role in sagittal balance is essential.

Natural selection and developmental sexual variation in the human pelvis.

This research examines ontological patterns of change in variation of the human pelvis as a means of identifying regions of differential growth, growth canalization and evidence of selection. Data were derived from pelvic radiogrammetry of 180 8-year-olds and 89 subjects at age 18 who were part of the Fels Longitudinal Growth Study. Coefficients of variation (CVs) and total growth increments were compared between sexes and between ages 8 and 18 for 14 pelvic measures. Sex-specific comparisons of mean size were tested per age using Student's t, whereas coefficients of variation were calculated and compared using the methods suggested by Sokal and Braumann ([1980] Syst. Zool. 29:50-66). The Mann-Whitney U-test was used to test median growth increments between ages 8 and 18. Results of these comparisons show significant sex differences in breadth of the ischium and acetabular regions among 8-year-olds. Most of the sexual dimorphism in the pelvis at age 18, however, develops during the adolescent growth period, during which both male and female pelves undergo growth remodeling of the pelvic cavity. Over the same time period, males show significantly greater incremental growth in the acetabulum, and females show differentially greater growth in the pelvic cavity. At age 18, the pelvis demonstrates a posterior-to-anterior gradient of increasing dimorphism within the inlet and midplane of the pelvic birth canal. As a means of interpreting the effects of natural selection on the pelvis, it is argued that appropriate comparisons are within-sample comparisons of CVs over time, rather than comparisons between sexes of adult coefficients as has been argued by others (Meindl et al. [1985] Am. J. Phys. Anthropol. 68:79-85). Analyses of change in coefficients of variation over time show evidence of concordantly reduced within-sample variation in 7 pelvic dimensions indicating canalization of growth. These results are attributed to the effects of stabilizing selection operating on both males and females and include transverse diameters of the sacrum, inlet, anterior inferior iliac spines, and breadths of the ilium and ischium. Six pelvic dimensions show evidence of increased total sample CVs and discordant change in within-sex comparisons of CVs as well as differential growth between sexes over time. This pattern is indicative of the effects of disruptive selection on the pelvis for interacetabular diameter, breadths of the anterior superior and posterior inferior iliac spines, public length, and ilium height.

[Measurement data of the lateral lumbosacral region in healthy subjects during the growth period]. / Messwerte der seitlichen Lumbosakralregion bei Normalpersonen im Wachstumsalter.

The following measurement data were obtained to characterise the healthy lumbosacral profile, via lateral x-rays taken of 90 female and 90 male patients between 8 and 17 years of age: Degree of slip 0%, slip angle -21.3 degrees, sacral inclination 45.5 degrees, posterior lumbosacral angle 140.5 degrees. These measurement data are independent of age and sex. If an adolescent suffers from lumbosacral spondylolisthesis, they will quantify the process of slip that has taken place, more accurately than the conventional method after Meyerding. If the shape of the sacral vertebra is considered at the same time, these parameters will also enable to assess the risk of progression of spondylolisthesis to a degree that is satisfactorily accurate in clinical practice.

[Pelvic abnormalities affecting the statics of the vertebral column]. / Beckenfehlbildungen mit Auswirkungen auf die Statik der Wirbelsäule.

Of all the bony anomalies of the pelvis, unilateral developmental disturbances of the body of the iliac bone and the lateral parts of the os sacrum mainly affect the statics of the vertebral column. After a short description of the normal development of the os coxae and os sacrum, an attempt is made to systematize these anomalies and explain them from a developmental point of view. This is achieved by studying anatomical specimens and clinical cases. Primary disturbances concerning the growing of the cartilaginous epiphysis itself or secondary disturbances, which result from unilateral muscular palsy, can be responsible for retarded development of the body of the iliac bone. Unilateral dysplasia of the lateral part of the os sacrum could be based on disturbances of the precartilage. This is also thought to be the reason for asymmetrical formations of so-called transitional vertebrae.

Posterior widening of the S1-S2 interspace in children: a normal variant of sacral development.

A lucency in the posterior S1-S2 area of the sacrum was seen in two pediatric patients. Bone scans in both and a myelogram in one case were normal. Follow-up has failed to show any clinical evidence of pathology. The lucencies are felt to represent normal variations in the development of the sacrum. A series of radiographs at different ages is presented to illustrate how normal developmental progresses in this area.

[Progression of untreated idiopathic scoliosis up to the end of growth]. / Die Progredienz der unbehandelten idiopathischen Skoliose bis Wachstumsabschluss

110 patients with idiopathic scoliosis are reported on, who had no treatment for 2 years or more before growth stopped. Another 36 patients untreated for 1 year could be observed. The changes in the scoliotic angle were followed up radiologically and entered into a diagram. The average progression of these scolioses during one year were calculated. Progression was always most pronounced between the 10th and 15th year and coincided with the prepubertal increase in growth. This has to be expected 2 years later in boys than in girls. The degree of progression definitely depended on the site of the primary curve. Thoracic and S scoliosis showed most pronounced progression, followed by thoracolumbar and lumbar scoliosis. Progression was worse the earlier scoliosis was diagnosed.