Evaluation of Coccyx Variability using Multislice Computed Tomography- A Cross-sectional Study

Introduction: Coccyx is the terminal vestigial segment of human spine. There is a lack of data on the structure of coccyx causing hindrance in the treatment aspect of coccydynia. Aim: To determine type of coccyx, number of coccygeal segments, prevalence of sacrococcygeal, intercoccygeal fusion and coccygeal spicule of human adult coccyx using pelvic Computed Tomography (CT) scans. Materials and Methods: A cross-sectional study of 49 adult patients was done who underwent CT scans for benign clinical conditions like ureteric colic, abdominal pain evaluation in Hassan Institute of Medical Sciences, Hassan, Karnataka, India. The coccyx bone was evaluated for number of segments, sacrococcygeal and intercoccygeal fusion and prevalence of spicules and configured as types I-IV according to Postacchini F and Massobrio M classification. Chi-square test was used to find association of the type of coccyx with age and gender. Results: Type I coccyx (32, 65.3%) was the most common type followed by type II (9, 18.3%). Majority had four coccygeal segments (39, 79.6%). The sacrococcygeal fusion was seen in 13 (26.5%) and intercoccygeal fusion was observed in 41 (83.7%) patients. Coccygeal spicule was seen in 21 (42.9%) subjects. The tip of coccyx was retroverted in only 3 (6.1%) patients. The terminal coccygeal segment showed ventral angulation in 8 (16.3%) cases. Conclusion: In present study, Type I coccyx was most common with four coccygeal segments. Intercoccygeal fusion was more commonly seen than sacrococcygeal fusion. Comprehension of in vivo structure of coccyx through CT scans will help in care of patients with coccydynia.