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It is a very unpleasant condition although it is quite rare and it represents less than 1% of all back pain conditions reported to physicians.
Although the pain is very strong, the reasons behind coccygodynia are not completely understood. There are many possible theories as to what causes this painful state
and they include:
1. Pain from the soft tissues around the tail bone
2. Spasm of the muscles of the pelvic floor,
3. Referred pain from lumbar pathology,
4. Inflammation of the lower sacral nerve roots,
5. Local posttraumatic lesions,
Although almost any of these could be the cause of the pain, patients often mention a fall on the buttocks or a delivery before the pain started so the reasons are probably mechanical such as fracture of the coccyx or fracture dislocation of the coccygeal vertebra.
In most cases, the patients feel the pain while in the sitting position. It is 5 times more common in women than in men, probably due to the fact that it is more prominent in women. Almost one third of all cases of coccygodynia are idiopathic in nature, which means that the real cause is unknown.
Anatomy of the sacrococcygeal structure
Tailbone is the last bone of the vertebral column. It is a tiny triangular bone, which is usually made of 3 to 5 vertebrae that are fused together. There is a joint where this part is connected to the sacrum, a part of pelvis,. The movements of the coccyx are restricted to flexion and extension. Range of motion of the coccyx is measured in degrees.
Flexion larger than 25-30 degrees represents hypermobility and slipping larger than 25% represents luxation.
The levator ani muscle, the anococcygeal and sacrotuberal ligaments, the sacrospinal ligament, and the gluteus maximus muscle of the buttock all play a very important role in the movement of the coccyx.