Definition

The term coccydynia describes a painful sensation in the area of the tailbone (coccyx).  This is a condition, which is relatively uncommon in men, in the absence of trauma.  The condition is more common in women, possibly due to the relative prominence of the coccyx in women.  The term “coxxydynia”  describes only a symptom (i.e. pain in the coxxyx region), while the underlying cause of the pain (i.e. a definitive diagnosis) is sometimes not discovered.

Pelvis with coccyx (#5), ilial bone (#1,4) sacrum (#2), sacro-iliac joint (#3), superior pubic ramus (#6), inferior pubic ramus (#7), symphysis pubis (#8), head of femur (#9)

The coccyx is located at the bottom end of the human spine and is roughly triangular in shape, consisting of 3-5 segments, the largest of which connects with the lower end of the sacrum.  Like in any segment of the spine, degeneration of the coccygeal vertebrae and discs may arise without a clear-cut traumatic event.

Causes of coccydynia

  1. The most common cause for coccyodynia is thought to be direct, high-impact trauma from falls (about 50% of cases).

    Sacrum and coccyx side view

  2. Prolonged, awkward positioning, especially sitting (i.e. before, during and after childbirth),  a highly sedentary lifestyle, i.e. “television disease, ” and other forms of relatively low-impact repetitive trauma to the sacrum (i.e. rowing machine use, prolonged bicycle riding, etc.) is thought to be the cause for a number of the remaining cases.
  3. In many individuals with coccydynia, no clear cause for the condition can be identified.  In those cases, further investigations (i.e. with X-rays, CT, MRI etc.) should be performed, to rule out other pathology, especially tumors of the pelvis and the pelvic floor, i.e. chordoma, giant cell tumor, schwannoma, intra-osseus lipoma, carcinoma of the rectum or sacral hemangioma, etc..   Occasionally, perineural cysts of the lower sacral nerves may also cause coccygeal pain.

X-ray coccyx fracture, fragment pointing back, click image to enlarge

Other, more controversial causes for coccydynia include:

  1. Spinal disease, including herniated lumbar disks and  arachnoiditis.
  2. Pelvic disease, including peri-rectal abscess or fistula, pilonidal cyst or plevic inflammatory disease.

Treatments

Coccyodynia usually resolves within the first three months with conservative management, consisting of nonsteroidal antiinflammatory drugs as tolerated and lifestyle adjustments, including avoidance of the sitting position, weight loss in obese individuals to lessen the load on the coccyx.  Some patients benefit from a trial of a doughnut pillow, which unloads the coccyx while sitting.

Structures in front of the lower sacrum and coccyx

Structures in front of the lower sacrum and coccyx, with the lower sacrum and coccyx removed, view from the rear

About 20% of patients experience a recurrence of coccyodynia in the first year.

More invasive treatments:

  1. Patients who fail treatment with conservative treatment may benefit from steroid injections to the sacrum.
  2. Manipulations of the sacrum, sometimes done under anesthesia can also help alleviate pain.
  3. Destructive injection techniques to the “ganglion impar” have been described.
  4. Coccygectomy, resection of the coccyx has a success rate of 70-90% in well selected cases and remains the treatment of last resort since most cases respond well to other forms of treatment.

Literature

For a recent review, please refer to:  Nathan ST, Fisher BE, Roberts CS., J Bone Joint Surg Br. 2010 Dec;92(12):1622-7.  Coccydynia: a review of pathoanatomy, aetiology, treatment and outcome.

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