Spinal anesthesia for spinal surgery is becoming increasingly popular because this anesthetic technique allows the patient to self-position and avoid neurological injury that may occur with prone positioning under general anesthesia. Spinal anesthesia reduces intraoperative surgical blood loss, improves perioperative hemodynamic stability and reduces pain in the immediate postoperative period. This leads to a reduced need for analgesics and a reduction in the incidence of nausea and vomiting in the postoperative setting. The lumbar vertebrae have the largest bodies and bear the greatest weight.
The centre of gravity of the body is approximately 1 cm behind the sacral promontory. This places the entire weight of the upper body directly on L4–L5 and L5–S1. This is one of the reasons that these two levels are commonly involved with disc herniations. The vertebral bodies are from 2 to 3 cm…
