Fractures of the coccyx are thought to be trivial injuries, however, they can take a long while to heal. (Chronic coccyx pain is termed coccydynia). The coccyx is broken by a direct blow, such as a fall on the buttocks. Another less common mechanism is by pressure from the passage of the fetus down the birth canal during delivery.
The coccyx (aka the "tailbone") is the most caudal segment of the spine. It comprises three to five coccygeal vertebrae). It is attached rostrally to the sacrum and is unattached distally. This lower end is susceptible to injury.
The original classification system of coccyx fractures was given by Tuchis in 1848. A Tuchis type I fracture involved the olecranon, a type II involved the radial head. (He did not know his ass from his elbow.)
The typical patient is one who recalls a recent fall on the tailbone and now complains of focal pain with sitting and defecation. On physical examination (digital rectal exam), there is point tenderness at the coccyx.
X rays are probably not required as there is a reasonably high false negative and false positive rate: small fractures may be missed and congenital anomalies can look like fractures. Moreover, the treatment offered is palliative only, hence empiric therapy is reasonable.
If the diagnosis remains in doubt, a local anesthetic may be injected in vicinity of the coccyx to determine whether the origin of the pain is from the bone
A doughnut cushion for sitting may alleviate direct pressure. Mild analgesics and stool softeners may provide additional symptomatic relief. Excision of a non-united fragment may be needed in rare cases.
fractures may fail to unite, in which case surgical excision can be offered
Red Flags and Controversies
do not assume all buttock pain is coccydinia