A Morphometric study of the Sacrum and Its Clinical Significance

Priyanka Clementina, Stephen (2020) A Morphometric study of the Sacrum and Its Clinical Significance. Masters thesis, Christian Medical College, Vellore.


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INTRODUCTION: The sacrum is found at the caudal end of the vertebral column, between the two hip bones. On the dorsal aspect of the sacrum, is an inverted v-shaped opening, the sacral hiatus (SH). It is formed due to failure of fusion of laminae of the fifth sacral vertebrae. The sacral cornua, which are the remnants of the inferior articular processes of the fifth sacral vertebra are important landmarks while performing caudal epidural block (CEB). Caudal epidural block (CEB) is widely used for intraoperative and postoperative analgesia as well as various diagnostic and therapeutic procedures on the lower back. A knowledge of the level of termination of dural sac is required to prevent injury to duramater or surrounding structures. The duramater and the arachnoid mater of spinal cord end at the level of the second piece of sacrum within the vertebral canal but varies between the lower border of the S1 foramen in adults to S3 in children. The space below the spinal cord contains fat and the lower sacral nerve roots. A successful CEB can be performed upon accurate localization of sacral hiatus and gaining entry into the epidural space. Anatomic variations of SH may contribute to failure of caudal epidural block. The complications that can occur when CEB is not performed properly are injury to the spinal cord and spinal nerves, tears of the dura, epidural hematoma, epidural abscess and anterior spinal syndrome. OBJECTIVES: 1. To determine the morphometric characteristics of adult dry sacra. 2. To determine the morphometry of the sacral hiatus (SH) in lumbosacral spine radiographs. 3. To determine the morphometry of the posterior sacral foramina in cadavers. 4. To classify the dry sacra according to the number of segments and position of the auricular surface. METHODS: Fifty dry sacra, 95 lumbosacral spine radiographs and 10 cadavers were used for the study. In the dry sacra, parameters like the length, width, sacral indices, shape of sacral hiatus, level of apex and base of sacral hiatus were determined. Linear distances of the apex of sacral hiatus from adjacent bony landmarks were measured. In the radiographs, the sacral hiatus and in the cadavers, the posterior sacral foramina were studied. The dry sacra were grouped into different groups based on specific criteria. RESULTS: The maximum length and width of the sacrum were 100.6 ±13.8 mm and 102.7 ±7.1 mm respectively. The midventral curved length of the sacrum was 108.7 ±15.1 mm and the maximum curvature of the sacrum was at S3. The sacral and curvature indices were 103.2 ±11.9 and 92.5 ±3.9 respectively. The most common shape of the sacral hiatus (SH) in the dry sacra was the inverted U shape (70%). The apex was commonly seen at S4 (46%) and base at S5 (76%) levels. The mean distance between the caudal end of the median sacral crest and the apex of the sacral hiatus was 8.9 ± 3.8 mm and the mean distance between SH apex and S2 foramen was 28.7 ± 11.8 mm. The most common type of sacral hiatus was Type A (86%) and 64% of sacra belonged to group IA. In the radiographs, the most common shape of SH seen was the inverted U shape in males (45.5%) and the inverted V shape in females (44.4%). The apex of the sacral hiatus in radiographs was commonly seen at S4 in males (50%) and at S3 level in females (51.9%), whereas the base was seen at S5 in males (70.6%) and females (51.9%). The diameter of the posterior sacral foramina were S2 - 6.4±1.5 mm, S3 - 6.7± 1 mm and S4 - 7 ±1.4 mm. The vertical distance between S2 and S3 foramen was 14.9 ± 3.5mm and between S3 and S4 foramen was 13.4 ± 2.2 mm. The distance PSIS – S2 on the right was 28.8 ± 5 mm and the PSIS – S2 on the left was 28.5± 5 mm. The PSIS – S2 angle on the right was 51.9º ± 4.5 and PSIS – S2 angle on the left was 51º ± 4.2.

Item Type: Thesis (Masters)
Additional Information: 201733201
Uncontrolled Keywords: sacrum, sacral hiatus, caudal epidural block, posterior sacral foramina.
Subjects: MEDICAL > Anatomy
Depositing User: Subramani R
Date Deposited: 06 Feb 2021 03:50
Last Modified: 06 Feb 2021 03:50
URI: http://repository-tnmgrmu.ac.in/id/eprint/13916

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