Coccygodynia 

Coccygodynia (ie, coccydynia) has been defined as pain in and around the region of the coccyx.^[1] It was described as early as the 1600s, but the term actually was first used by Simpson in 1859. The word coccyx comes from the Greek term kokkoux for cuckoo, as it resembles the shape of a cuckoo's beak. This condition is quite rare and accounts for less than 1% of all back pain conditions reported to physicians. It is 5 times more common in women, supposedly because the coccyx is more exposed and prominent in women than in men. Various authors have described the typical patient with coccydynia as a female with a thin body who has either sustained direct trauma to the coccyx or injured the coccyx during childbirth.

Recent studies

Bilgic et al compared the clinical outcomes and wound complications in patients who underwent coccygectomy with or without subperiosteal resection. In 11 patients, all mobile coccygeal segments were resected, including the periosteum; in the other 14 patients, the periosteum was spared. Overall, 84% of patients who underwent coccygectomy benefited from surgery, and results were statistically similar in the 2 groups; however, the patients in whom the periosteum was preserved had a lower rate of infection.^[2]

In a study by Wu et al, infrared thermography was shown to be useful as a quantifiable tool for monitoring the dynamics of disease activity in coccygodynia. A total of 53 patients 18-71 years of age and clinically diagnosed with coccygodynia received therapeutic modalities consisting of 6-8 sessions of massage of the levators, followed by Maigne's manipulative technique, and short-wave diathermy 3 times a week for 8 weeks. There were significant differences in both numeric pain rating scale measurements and surface temperatures obtained by infrared thermography in the 12-week follow-up. Correlation between numeric pain rating scale improvement and temperature decrease was shown to be significantly high.^[3]

For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center. Also, see eMedicine's patient education articles Tailbone (Coccyx) Injury and Back Pain.

Surgical treatment for coccygodynia has traditionally involved a coccygectomy. This surgery is rarely performed anymore. Recently, a limited coccygectomy has been proposed that involves only the resection of the mobile or hypermobile segment of the coccyx.

Coccygodynia is a cause of lower back pain.

Frequency

Coccygodynia accounts for less than 1% of all reported causes of lower back pain. It is 5 times more common in women than men.

Various etiologies have been described for this coccygodynia. The most common are falls resulting in direct injury to the sacrococcygeal synchondrosis. These can occur either from a kick, an injury on a trampoline when one hits the bar or springs that surround the trampoline jumping pad, or falling from a horse or skis. The result is an injury or partial dislocation of the sacrococcygeal junction that causes abnormal movement of the coccyx, especially when sitting pressure is applied to this region. Resulting pain can involve the levator ani muscle and the anococcygeal, sacrotuberal, and sacrospinal ligaments, as well as the gluteus maximus muscles.^[4]

Another common etiology is childbirth. The coccyx (tailbone) is considered by some authors to be in the way during childbirth. At the end of the third trimester, certain hormonal changes enable the synchondrosis between the sacrum and the coccyx to soften and become more mobile. This increased mobility of the 3-5 segment fused or unfused coccyx allows for more flexion and extension, which may result in stretching and a permanent change in the resting tension of the ligaments and muscles that surround and attach to the coccyx. Unlike fractures, which can remodel, injuries to this region can result in this synchondrosis being repeatedly forced out of its normal position, causing inflammation of the tissues surrounding the coccyx.^[5]

Up to one third of all cases of coccygodynia are idiopathic in nature.^{[6, 7, 8]} Other less common causes of this condition include piriformis pain, pudendal nerve injury or neuropathic pain secondary to repeated damage to nerves (eg, in bike riders), pilonidal cyst formation, so called Tarlov cysts or meningeal cysts, obesity (due to excess pressure on the coccyx when sitting), and a bursitislike condition that can arise in slim patients who have little buttocks fat padding, allowing the tip of the coccyx to rub against the subcutaneous tissues, causing friction.

Common pathophysiologic pathways for this condition may include the following:

• Fall
• Childbirth
• Partial dislocation of sacrococcygeal synchondrosis that results in abnormal movement of the coccyx when sitting and riding in car
• Joint being repeatedly forced out of its normal position, causing repetitive trauma (stretching) of the surrounding ligaments and muscles attached to the coccyx and resulting in inflammation of these tissues with pain and soreness when sitting or with straining
• Healing of this condition prevented by continued movement, resulting in further damage and perpetuation of the cycle

History may consist of either a direct fall or contusion to the sacrococcygeal region. This can result in a fracture of the coccyx or fracture dislocation of the coccygeal vertebrae. The other most common cause revealed by history is childbirth.

Coccygodynia can be due to repetitive strain, such as in cycling and rowing. Prolonged sitting in a soft seat with direct pressure on the coccyx (as in computer users) is also noted on history. Anal intercourse has been mentioned as a cause of coccydynia.

Physical examination should include direct palpation of the coccyx for tenderness. In true coccydynia, the coccygeal region usually is markedly tender. If the coccygeal region is not tender, the examiner should consider other diagnoses, such as lumbar disk disease or herniated disk. A rectal and pelvic examination also should be performed to check for any masses (tumors).

Failure to respond to reasonable conservative management, failure to have pain and symptoms adequately controlled with this management, or worsening symptoms in a well-screened patient are indications for surgical intervention.

The anatomy of the sacrococcygeal region is well known to most orthopedists, as seen in the image below. Of importance is the motion of the sacrococcygeal segment with the iliac wings, as well as the action of the levator ani muscle, the anococcygeal and sacrotuberal ligaments, the sacrospinal ligament, and the gluteus maximus muscle of the buttock. All can be involved in sacrococcygeal dysfunction.

Criteria for surgery are, at best, vague at present; therefore, the surgical contraindications are also not well defined. The presence of an active infection would be a contraindication. Patients who demonstrate a neurotic-type behavior and patients who have pending litigation due to an accident or an on-the-job injury (worker's compensation) should be evaluated carefully.