You may not give much thought to your coccyx, the triangle-shaped bony structure at the base of the spine, whose name comes from the Greek word for cuckoo (“kokkux”) because it resembles the curved beak of the bird. But sometimes the coccyx—also referred to as the tailbone—rears its ugly head, so to speak, and causes problems.
There’s actually a medical name for pain in the coccyx: coccygodynia, which was coined in 1859 but is now more commonly called coccydynia. And there’s even a Coccyx Pain Center at Rutgers New Jersey Medical School, which sees several hundred patients a year.
Here are answers to questions you may not have even thought to ask about your tailbone.
Does the coccyx serve any purpose?
As a vestigial remnant of a lost tail (which helped our lower primate ancestors with balance and mobility), the coccyx was once widely thought to have no function in humans. But it’s now understood that the coccyx provides a base of support for sitting and a place of attachment for various muscles, tendons, and ligaments, including the large gluteus maximus (buttock) muscle and muscles that support the pelvic floor and anus (which play a role in defecation).
What causes coccygeal pain?
Coccydynia is often due to an acute trauma like falling backwards or otherwise landing derrière-down on a hard surface, which can bruise or even dislocate or break the coccyx.
It can also occur from repetitive trauma, such as from prolonged sitting on hard or narrow seats (like bicycle seats); abnormal or excessive mobility of the coccyx (which leads to inflammation and possible degenerative changes in the bone); subluxation (misalignment) of its joints; spasms of the pelvic floor muscles (which pull on the coccyx); and, rarely, infections or tumors.
Sometimes coccyx pain is referred from a herniated disc in the spine. But often there’s no identifiable cause. The pain can be debilitating and interfere with daily activities, since it typically occurs when sitting (especially for long periods and in a reclined position), when getting up, and sometimes even during sexual intercourse or while having bowel movements.
Are all tailbones alike?
The structure of the coccyx varies in many ways, including the number of vertebral segments (typically three to five), its length, the angle of the curve (including sometimes a side curve), and the degree of mobility. A study in the European Spine Journal found that the coccyx tends to be shorter and straighter in women, that fusion between the segments and between the coccyx and sacrum is common, and that about 25 percent of people have a bony spur (spicule) on it. But the research on the anatomical structure of the coccyx is relatively sparse, and studies have had inconsistent findings.
Why do women have more coccyx pain than men?
Coccydynia occurs more often—four or five times more often, some papers note—in women, possibly because they have a broader pelvis so the coccyx is more exposed, or possibly due to anatomical differences in terms of the size and angle of curvature of the coccyx. A major cause of coccydynia in women is childbirth, especially if there is prolonged labor. According to some sources, including the National Health Service of the U.K., wearing tight jeans may worsen coccydynia.
Does being overweight or obese protect the coccyx?
No. It’s actually the opposite. You might think that having extra fat would pad the tailbone area and that thin people would be at greater risk for tailbone injuries. But as body weight increases, there may be an increased risk of misalignment or subluxation of the coccyx. As one paper put it, “the coccyx of an obese patient will jut out more posteriorly when he or she is sitting down” and obese people “tend to let themselves drop onto a seat with insufficient pelvic rotation,” while in lean people the coccyx tucks under during sitting, “where it will be reasonably well protected.”
Or as another paper noted, in normal-weight and thin people the coccyx rotates “in a more optimal fashion to lessen the forces from falls and sitting.”
How is coccyx pain treated?
If you have coccyx pain, applying ice or heat may help. You can also try over-the-counter pain relievers. To keep pressure off your coccyx, avoid leaning back in a chair, as well as activities like cycling, rowing, and horseback riding. Leaning forward may be most comfortable.
Special wedge-shaped cushions (“coccygeal cushions”) may relieve pressure if positioned right—or you can simply try sitting on a pillow folded lengthwise, with your tailbone area hanging off at the back.
On the other hand, circular (donut) pillows, though commonly recommended, can actually put more pressure on the coccyx, according to a review paper published in 2014. Stool softeners may be useful if you have pain when defecating.
If the problem persists, see your health care provider. Imaging scans, including X-rays, can be done to help pinpoint the cause. You might be referred to a physical therapist (ideally one skilled in pelvic floor problems), who can do massage or mobilization, give you strengthening and stretching exercises to correct any muscle weakness or tightness that may be contributing to your pain, and suggest ergonomic adaptations suitable to your posture and sitting position. Self-massage techniques—such as sitting atop a tennis ball placed adjacent to (not directly on) the coccyx—may be recommended.
Some therapists also perform internal manipulation, which involves inserting a gloved finger into the anus—though this may not be everyone’s cup of tea, and how well it works may depend on the structure of the coccyx and the specific technique used. Injections of steroids or anesthetics are also sometimes given, with variable results.
The last resort is coccygectomy (surgical removal of the coccyx), which is done on only about 1,300 people a year in the United States.