The anatomy of the sacrococcygeal cornual region and its clinical relevance

Sacral Curvature in Addition to Sacral Ratio to Assess Sacral Development and the Association With the Type of Anorectal Malformations

Introduction: Sacral ratio (SR) is currently the only measurement to quantitatively evaluate sacral development in patients with anorectal malformations (ARM). This study proposes sacral curvature (SC) as a new indicator to qualitatively assess the sacrum and hypothesizes that sacral development, both quantitatively and qualitatively, can be an indicator to predict the type of ARM. The study aims to investigate the difference of SR and SC between ARM types and the association with the type of ARM. Methods and Materials: This study was retrospectively conducted between August 2008 and April 2019. Male patients with ARMs were enrolled and divided into three groups based on the types of ARM: (1) rectoperineal fistulae, (2) rectourethral-bulbar fistulae, and (3) rectourethral-prostatic or rectobladder-neck fistulae. SC was measured in the sagittal views of an MRI or a lateral radiograph of the sacrum. Results: Included in the study were 316 male patients with ARMs. SRs were 0.73 ± 0.12, 0.65 ± 0.12, and 0.57 ± 0.12 in perineal, bulbar, and prostatic/bladderneck fistula, respectively (p < 0.01). The SCs in perineal fistulae and bulbar fistulae were significantly higher than that in prostatic/bladderneck fistulae (0.25 ± 0.04, 0.22 ± 0.14, and 0.14 ± 0.18, p < 0.01). When SR ≥ 0.779, there was an 89.9% of possibility that the child has a perineal fistula. When SR ≤ 0.490 and SC ≤ 0, the possibilities of the child having prostatic/bladderneck fistulae were 91.6 and 89.5%, respectively. SC < 0 was also noted in 27 (27.8%), 19 (10.5%), and no (0%) patients of prostatic/bladderneck, bulbar, and perineal fistulae (p < 0.01), respectively. Sacral defect was noted in 63% of patients with SC ≤ 0, compared to none with SC > 0 (p < 0.01). Conclusions: The higher the rectal level is in an ARM, the lower are the objective measurements of the sacrum. SC ≤ 0 is associated with sacral defects and implies a high likelihood of prostatic/bladderneck fistulae.

A Morphometric and Radiological Study of Sacral Hiatus in Human Adult Sacra and Its Clinical Relevance in Caudal Epidural Anaesthesia

Background: The knowledge of sacral hiatus anatomy is crucial in clinical situations requiring caudal epidural block for various diagnostic and therapeutic procedures of the lumbosacral spine to avoid complications and failure rate. This study was undertaken to compare morphometric characteristics of sacral hiatus in human dry sacra and pelvic radiographs for placing the needle more accurately in the sacral hiatus landmarks to permit correct, painless, and uncomplicated caudal epidural accesses. Materials and methods: The present study was done on 138 human adult dry sacra and 110 anteroposterior lumbosacral spine radiographs of the North Karnataka region of India. Sacral hiatus was evaluated in each sacrum based on its shape, level of its apex, and base according to sacral and coccygeal vertebrae, length, anteroposterior diameter at its apex, and transverse width at its base. Results:The mean length of sacral hiatus in men and women was 27.81+1.17 mm and 24.73+2.21 mm, respectively. The mean anteroposterior diameter of the sacral hiatus at the apex was 6.24+2.73 mm in males and 6.63+2.81 mm in females. The transverse width of the sacral hiatus at the base was 17.56+1.81 mm in males and 17.92+2.59 mm in females. The location of the apex of sacral hiatus was the highest in number at the level of the fourth sacral vertebra (23.63%). The location of apex in radiographs of all lumbosacral spine S3 showed 49.09% maximum. The location of the base of the sacral hiatus was observed in the dry sacra at the level of the fifth sacral vertebra (64.54%). In the present study, different shapes of the sacral hiatus were recorded. The most common shape in males and females was inverted U shape (42.02%), followed by inverted V shape (26.08%) and dumbbell shape (12.31%). The least common shape was observed in the bifid sacra (5.07%). In 2.17% of cases, sacral hiatus was absent. Percentage of absence, agenesis, irregular, and bifid shapes were found rather in female than male sacra. An anteroposterior view of spine radiograph showed sacral hiatus agenesis in both females (7.81%) and males (4.34%). The anatomical knowledge of sacral hiatus and its variations are important in caudal epidural anesthesia, and it may improve the success rate of caudal epidural anesthesia.