High incidence of persistence of sacral and coccygeal intervertebral discs in South Indians - a cadaveric study.

The sacrum, by virtue of its anatomic location plays a key role in providing stability and strength to the pelvis. Presence of intervertebral discs in sacrum and coccyx is rare. Knowledge of its variations is of utmost importance to surgeons and radiologists. The current study focused on the presence of intervertebral discs between the sacral and coccygeal vertebrae in south Indian cadaveric pelvises. We observed 56 adult pelvises of which, 34 (61%) pelvises showed the presence of intervertebral discs between the sacral vertebrae and between the coccygeal vertebrae, while 22 (39%) pelvises did not have the intervertebral discs either in the sacrum or the coccyx. We also found that most of the specimens had discs between S1 and S2 vertebrae (39%), followed by, between S4 and S5 (18%), between S2-S3 (14%) and least being between S3-S4 (13%). In the coccyx it was found that 7% of pelvises had disc between Co1-Co2, 4% of them had between Co2-Co3 and 4% had between Co3-Co4. Knowledge regarding such anatomic variations in the sacro-coccygeal region is important to note because they require alterations in various instrumentation procedures involving the sacrum.