Picture of the coccyx
The coccyx refers to the last few vertebrae at the base of the spine. The name “coccyx” comes from the Greek word meaning “cuckoo” referring to the beak-like curved shape of the coccyx, which points towards the front of the body.
The coccyx is made up of three small, loosely fused bones that are attached to the sacrum and located just above the cleft of the buttocks. It is sometimes called the 'tailbone' because it’s considered the remnant of the full tail of our ape-like ancestors. However, it does have useful functions, including:
- Weight-bearing when sitting down
- Serving as an important attachment site for various muscles, tendons and ligaments
Coccydynia refers to pain and discomfort caused by damage to the coccyx.
This is an uncommon condition. It’s estimated around 1 in 100 cases of lower back pain are the result of coccydynia. Pain can range from mild to severe and usually worsens when sitting down. Injuries may consist of:
Women are five times more likely to develop coccydynia than men. This is because a woman’s pelvis is wider and the coccyx is more exposed and vulnerable to injury. Giving birth is believed to be the most common cause of coccydynia. During pregnancy, the coccyx becomes more flexible to allow more room for birth. However, in some cases, the muscles are overstretched and permanently alter, so that the coccyx is no longer supported, triggering coccydynia.
Other causes include:
- A fall against a hard surface in the seated position, such as a fall from a horse
- A direct blow to the coccyx, such as in contact sports
- Straining or dislocating the coccyx. This can happen due to poor posture while driving, or repetitive injury from sports such as rowing or cycling
- Being overweight or obese may put excess pressure on the coccyx
- Being underweight may create less cushioning for the coccyx
- Ageing causes the cartilage that holds the coccyx to wear down or the bones can become fused
- Cancer can occasionally spread to and affect the coccyx
Other less common injuries include bone spurs, nerve compression, infection, tumours or injury during anal sex. No clear cause can be found in about a third of cases.
Symptoms of coccydynia
Symptoms of coccydynia include:
- Backache or severe pain in the tailbone area
- Shooting pains down the legs
- A visible bruise
- Pain during sitting or direct pressure on the area
- Pain going to the toilet
- Pain during sex
- Increased pain during menstruation
- Difficulty sleeping
Coccydynia is not usually serious, but seek medical advice if you have signs and symptoms of a coccyx injury or unexplained discomfort in the tailbone area.
Other complications of coccydynia
If you injure your tailbone look out for these symptoms, which may indicate a spinal cord injury: