Prevalence and Patterns of Sacral Anomalies in the South Indian Population: A Bone-Based Study

Introduction: Sacrum is a triangular shaped bone present in the posterior aspect of pelvis formed by fusion of five sacral vertebral segments. Sacrum articulates with lumbar vertebrae above, coccygeal vertebrae below and with two hip bones on either side. Sacral vertebra developed from ventromedial sclerotomes of somites. Developmental defect leads to anomalous sacral vertebrae with lumbarisation and Sacralisation. Variations in sacral vertebrae leads to chronic back pain, wrong level of Disc surgery and incorrect needle placement during caudal epidural block. Aim and objective: To study the prevalence and patterns of variations in sacral vertebrae in south Indian population. Materials and Method: The study was conducted in the Department of Anatomy, Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry. The Study designed as a descriptive study includes 105 dry bones of sacrum. The sacrum bones are observed for number of segments, pattern of fusion and other associated anomalies. Results: This study shows sacralisation (21%) is more compared to lumbarisation (7.6 %). This study also includes abnormal curvatures of sacrum, spina bifida and incomplete fusion of adjacent sacral vertebra. Discussion and conclusion: Sacrum is a triangular shaped bone formed by 5 vertebral segments. Vertebrae are intersegmental structures derived from portions of two adjacent somites which is regulated by HOX genes. Sacral variations can impact spinal biomechanics, leading to altered weight transmission and possible low back pain. Thorough anatomical knowledge of Sacral vertebrae is clinically important for procedures like caudal epidural anaesthesia. Keywords: Sacrum, Lumbarisation, Sacralisation, low back pain