Morphometric study of sacral hiatus in adult human Egyptian sacra: Their significance in caudal epidural anesthesia

Evaluation of the Level of Dural Sac Tip in Saudi Population: A Magnetic Resonance Imaging Study

Background For the success of procedures such as caudal block, craniospinal irradiation (CSI), and management of lower back pain and to minimize the risk of dural puncture the exact level of dural sac (DS) termination should be known. Objective The evaluation of DS tip location in the Saudi population and exploring possible significant factors that could be used as predictors in clinical prognosis. Methods A total of 200 patients' lumbar sagittal Weighted T2 Magnetic Resonance Imaging (MRI) study were randomly selected from a single-center hospital in-between 2020 and 2021. The DS tip location was determined by generating a perpendicular line from the longitudinal axis of its termination to the corresponding level. Then naming it after an intervertebral disk or a corresponding vertebrate that is divided into three thirds (upper, middle, and lower). Results In most cases, the level of DS termination is at the middle part of S2 (26.5%), followed by the upper part of S2 (25.1%), and the lower part of S2 (20%). In Saudi nationals, the DS tip was in the middle S2 level at 21.5%, upper S2 level at 19.1%, and lower S2 level at 17%. Factors such as age, sex, cause of referral, and nationality had no statistical significance in relation to DS tip location. Conclusion The DS termination level in the Saudi population ranges from disk between L5-S1 to the lower third of S3. Moreover, nationality, age, and cause of referral were not significant in determining the DS termination level. Therefore, it is still important to individualize patients' treatment by using MRI for each case that requires it.

Is "Trigonum sacrale" a real equilateral triangle? Anatomic consideration of sacral hiatus in adult: A three-dimensional CT study for reliable caudal access

This study is the first attempt to examine anatomical characteristics using three-dimensional computed tomography (3DCT) bone images with some parameters, in order to achieve correct and uncomplicated accesses. In addition, the study addresses a long-standing problem in the field and evaluates whether the trigonum sacrale forms an equilateral triangle or not. A detailed anatomic study of the sacral region was carried out on 91 patient 3DCT images. The CT data, in DICOM format, was read into VINCENT software from Fuji Film, with a slice thickness of 0.5 mm. The average length of sacral hiatus was 28.6 ± 8.4 (range 13.8-45.2 mm). The average width of sacral hiatus at the level of sacral cornua was 10.9 ± 2.7 (range 3.8-16.5 mm). The ratio between the length of the oblique and base line formed by the sacral triangle was 0.81 ± 0.12 (range 0.54-1.00). Using 3DCT images translated by the volume rendering technique, we can remove soft tissue from bones virtually. A slice thickness of 0.5 mm makes it a fine image, and permits meticulous measurement, which is different from previous cadaveric studies. Interestingly, our data showed that the ratio between oblique and base line on sacral triangle was <1.0, average 0.81. Findings demonstrated that the trigonum sacrale is not an equilateral triangle. This is useful information for the identification of the sacral hiatus when the landmark-based technique is employed.

Morphometric Study of Sacral Hiatus in Dry Adult Human Sacra: Its Clinical Relevance in Caudal Epidural Block

Introduction: Correct localization of the sacral hiatus is essential for administering a successful caudal epidural block. The present study was undertaken to find out the anatomical variations of sacral hiatus by a metrical method so that it could help anaesthesiologists in the clinical field.

Materials and methods: The study was performed on 140 (83 male and 57 female) adult human sacra. Various parameters of the sacrum studied were as follows: the shape of the hiatus, length of the sacral hiatus, transverse width at the base and anteroposterior diameter at the level of the apex. For each parameter, the mean value (calculated in mm), standard deviation, range and percentage of bones identified correctly were calculated.

Results: Various shapes of sacral hiatus were observed, including inverted “U” in 73 (52.14%), inverted “V” in 33 (23.57%), irregular in 10 (7.14%), elongated in 10 (7.14%) and dumbbell-shaped in 12 (8.57%). Absent sacral hiatus was observed in two (1.43%) specimens. The mean value for the length of sacral hiatus from the apex to the midpoint of the base was found to be 23.26 mm in males and 22.38 mm in females. However, the parameter was found to be statistically not significant. The mean value for transverse width at the base of hiatus was found to be 14.19 mm in males and 13.54 mm in females. The mean value for the anteroposterior diameter of the sacral canal at the apex was found to be 4.57 mm in males and 4.32 mm in females. Both the above parameters were found to be statistically not significant.

Summary and conclusion: The anatomical knowledge of sacral hiatus and its variations are important in caudal epidural anaesthesia, and it may improve the success rate of caudal epidural anaesthesia.

Sacralization of Coccygeal Vertebra: A Descriptive Observational Study in Bangladesh

Background: In the sacrococcygeal region, anatomical variation is due to the sacralization of the coccygeal vertebra, which is the due union of/fusion of the fifth sacral with the first coccygeal vertebra of five couples of sacral foramina under-detected or asymptomatic beyond radiological assessment. That is why it is challenging to know the cause of coccydynia, caudal block failure, the difficult second stage of labor, and perineal tears. The present study aims to improve knowledge about the anatomical variation of sacralization of the coccygeal vertebra. Additionally, to find the prevalence of sacralization of coccygeal vertebra in Sylhet, Bangladesh.

Methods: This study was performed on 60 parched, totally calcified, typical sacra of mature-age individuals of undetermined sexes, fulfilling the inclusion criteria from the bone bank of the osteology museum of the Department of Anatomy, Sylhet MAG Osmani Medical College, Sylhet, Bangladesh, from July 2017 to June 2018. Sex determination of the collected unknown sacra was conducted using discriminant function analysis. It was found that 50% (30) were male and 50% (30%) were female. The unpaired t-tests and chi-square were utilized to determine the statistical significance.

Results: Out of 60 sacra, eight (13.33%) samples presented with sacralization. This study found that males had significantly higher straight (p=0.05) and curved (p=0.05) lengths of sacrococcygeal vertebrae. The sacrococcygeal curvature index (SCI) showed statistically significant (p=0.05) differences between the sexes.

Conclusion: Sacralization may exert an impact on the caudal block. It could extend the second stage of the labor process with perineal tears. Therefore, knowledge about the anatomical variation of the coccygeal vertebra is essential.

Estimation of the relationship between the sacral hiatus and other dorsal sacral parameters using principle component analysis

PURPOSE

Correct localization of the sacral hiatus is essential for administering a successful caudal epidural block. The purpose of this study is to create a statistical model of sacral hiatus from dorsal sacral parameters to improve the location of the hiatus and thus, reduce the failure rate. The aim of this investigation was to examine the relationship of sacral hiatus morphology and dimension with sacral curvature. This study further examines the dorsal sacral parameters that could affect the sacral hiatus dimension.

METHODS

Adult, human, dry sacra and three-dimensionally reconstructed sacra from computed tomography imaging of normal subjects were included in the study and measured using digital Vernier calipers of 0.01 mm accuracy and Geomagic freeform plus software, respectively.

RESULT

The most frequent shape of the sacral hiatus was an inverted V (48%) followed by inverted U shape (32%), an irregular shape (12.3%), an M shape (4.7) and an A shape (2.8%). The data were represented by mean and standard deviation. Sacra with M-shaped hiatus had the lowest hiatal length (14.21 ± 5.44 mm), whereas sacra with an inverted V-shaped hiatus had the highest length (25.41 ± 11.3 mm). The anteroposterior diameter of the sacral hiatus at the base in males and females was found to be 3.46 ± 1.48 mm and 2.79 ± 0.83 mm, respectively (P < 0.001). The distance between the caudal end of the median sacral crest and the apex of the sacral hiatus (7.90 ± 6.74 mm, 4.4 ± 5.86 mm) also revealed sexual dimorphism (P < 0.001).

CONCLUSION

The correlations between most of the dorsal sacral parameters and length of the sacral hiatus are significant. The intercornual distance is also moderately correlated with the distance between right and left lateral sacral crest S1 level. Dorsal sacral parameters predicts variance of the sacral hiatus dimension from 40 to 73% and this could be utilized for statistical model of the sacral hiatus.

Assessment of Morphological and Morphometrical Variations of Sacral Hiatus in Dry Human Sacrum in Ethiopia

Background

The sacral hiatus is an opening present at the lower end of the sacral canal. The anatomy of the sacral hiatus and its variations are clinically important during administration of caudal epidural block (CEB) in obstetrics and gynecology, orthopedic, urology and general surgical practices. The success and reliability of CEB depends upon the sound knowledge of anatomical variations of the sacral hiatus.

Objective

The aim of this study was to assess the morphological and morphometric variation of the sacral hiatus in dry human sacrum.

Methods

An institution-based observational cross-sectional study design was conducted to assess morphological and morphometric variations of the sacral hiatus in 61 dry human sacrum specimens at the anatomy departments of Gondar, Addis Ababa, Hawassa and Jimma universities and Hayat and Korea Medical Colleges in Addis Ababa. Descriptive analysis was applied to analyze the data.

Results

The most commonly recorded shape of the sacral hiatus is inverted-V (41%) followed by inverted-U (37.7%). The least common was complete bifida (1.6%). The apex of the sacral hiatus is mostly seen at the level of the 4th sacral vertebra (60.7%), while the base is commonly located at the level of the 5th sacral vertebra (78.7%). The mean length of the sacral hiatus is 22.67 ± 11.84 mm. The mean transverse width and mean anteroposterior diameter of the sacral hiatus at the apex are 13.14 mm ± 2.85 mm and 5.57 mm ± 1.53 mm, respectively.

Conclusion

The sacral hiatus has anatomical variations. These variations should be kept in mind during administration of caudal epidural anesthesia and analgesia.

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.

Anatomical Evaluation of the Sacral Hiatus Using Ultrasound Imaging: Factors That Inhibit Needle Insertion During Caudal Epidural Block Procedures

OBJECTIVE

Caudal epidural blocks often fail due to the difficulty of appropriate needle insertion. This study aimed to evaluate the anatomy of the sacral hiatus using ultrasound imaging.

METHODS

This was a retrospective study involving 76 patients with spinal disorders. The following factors were analyzed to see if they affected the palpability of the sacral hiatus: sex, body mass index (BMI), and the morphology of the sacral hiatus on ultrasound imaging. The difficulty of needle insertion and the factors that influenced it were investigated in 28 of the 76 patients, who underwent landmark-based caudal epidural block procedures performed by the same doctor.

RESULTS

Among the 76 patients, the mean length of the sacral hiatus was 21.3 ± 5.6 mm, the mean distance from the skin to the sacral cornua was 5.2 ± 3.4 mm, and the mean angle of the sacral hiatus was 16.4 ± 5.5 degrees. Sacral base protrusion was present and absent in 35 and 41 cases, respectively. The sacral hiatus exhibited good and poor palpability in 53 and 23 cases, respectively. The mean distance from the skin to the sacral cornua and BMI were found to significantly influence the palpability of the sacral hiatus. Only sacral base protrusion significantly influenced the difficulty of needle insertion.

CONCLUSION

The mean distance from the skin to the sacral cornua and BMI were found to be associated with the palpability of the sacral hiatus, and sacral base protrusion was demonstrated to be associated with the difficulty of needle insertion into the sacral hiatus.

Anatomy of the sacral hiatus and its clinical relevance in caudal epidural block

PURPOSE

Caudal epidural anesthesia (CEB) is widely used for the prevention of chronic lower back pain, the control of intraoperative analgesia such as genitourinary surgery and labor pain cases in sacral epidural space approach for the implementation of analgesia. CEB is an anesthetic solution used into the sacral canal via sacral hiatus (SH). For optimal access into the sacral epidural space, detailed anatomical landmarks of SH are required. This study aims at exploring the anatomical structures and differences of the SH by using the sacral bone as a guide point to failure criteria for reviewing the caudal epidural anesthesia and improving the criteria for success in practice.

MATERIALS AND METHODS

Detailed morphometric measurements of orientation points of the SH were taken in 87 sacral bones. The measurements were taken using digital calipers and calculated with photogrammetric methods using Image J program.

RESULTS

Most commonly encountered shape of the SH was inverted U (33.33%), while 6.9% 3.45% often lack SH and bifida shape were found. The average length of the SH was 28.7 ± 7.1 mm, the average distance of the intercornual distance was 13.48 ± 2.69 mm, the average of the apex of SH and S2 sacral foramen was 34.68 ± 7.09 mm. There was no statistically significant difference determined in bilateral measurements (p > 0.05). Apex and base of SH were most commonly observed against S4 and S5 vertebrae, respectively. The level of maximum curvature of sacrum was S3 in 62.07% and S4 in 28.78%. Findings of spina bifida level were found 16.13% often in L5-S1 segment. Sacral cornua were marked by their bilateral presence in 55.26% and impalpable in 21.05% cases. Minimum distance between the S2 and the apex of the SH was 7.25 mm which suggested that it would not be safe to push the needle beyond 7 mm into the sacral canal so as to avoid dural puncture. In 8.77% cases, the depth of hiatus was less than 3 mm.

CONCLUSIONS

Single bony landmark may not help in locating the SH because of the anatomical variations. Important anatomical landmarks of the CEB are the sacral cornu, lateral sacral crests, the apex of the SH, the base of the SH, the top portion of the median sacral crest, anteroposterior distance of the sacral canal, intercornual distance, distance of the apex of the SH to the S2 foramina. Depth of hiatus less than 3 mm may be one of the causes for the failure of needle insertion. Surrounding bony irregularities, different shapes of hiatus and defects in dorsal wall of sacral canal should be taken into consideration before undertaking CEB so as to avoid its failure. This guide can be done by considering the points and securing a successful venture.

Ultrasound as a screening tool for performing caudal epidural injections

Background:

The caudal approach to the epidural space has been used for decades to treat low back pain caused by lumbosacral root compression. The use of fluoroscopy during epidural steroid injection is the preferred method for placing the needle more accurately in the sacral hiatus, but it carries the risk of radiation hazard.

Objectives:

The aim of the study was to assess the anatomical structure of the sacral hiatus and the feasibility of caudal epidural injections under ultrasound guidance.

Patients and Methods:

Two hundred and forty patients (male = 100, female = 140) with low back pain and sciatica who were candidates for caudal epidural injection were enrolled into this study. Ultrasound images of the sacral hiatus and bilateral cornua were obtained by a real-time linear array ultrasound transducer. The distance between bilateral cornua and the anterior and posterior wall of the sacrum were measured at the base (sacral hiatus). Under the guide of ultrasonography, we defined the injection successful if turbulence of medication fluid was observed in the sacral canal, but correct placement of the needle and injectant was confirmed on fluoroscopic view as the gold standard technique.

Results:

The epidurogram showed that the injection was successful in 230 of the 240 patients (95.8%). In eight patients, the injection was not in the correct place in the sacral canal. The sacral hiatus could not be identified by ultrasound images in only two patients who had a closed sacral hiatus identified by fluoroscopy. The mean distance of the sacral hiatus was 4.7 ± 1.7 mm and the mean distance between bilateral cornua was 18.0 ± 2.8 mm. The mean duration of the procedure was 10.8 ± 6.8 minutes. No major complication was observed in the next month.

Conclusions:

In conclusion, ultrasound could be used as a safe, fast and reliable modality to observe the anatomic variation of the sacral hiatus and to perform caudal epidural injections.