Coccyx Debate

Two medical papers (Postacchini and Massobrio1 and Kim and Suk2) found that test subjects with fused coccyxes that didnt flex upon sitting were more likely to experience tailbone pain than those with a normal coccyx. Postacchini and Massobrio performed radiographic studies of 171 coccyxes, and found less than 10 percent were fused into one piecenearly all had two or three, and a few had four segments. The primary conditions they found to be associated with coccyx pain were: coccyx angled sharply forward; coccyx side-bending more to one side than the other; and coccyx completely rigid (all segments fused together and fused to the sacrum).
Even though none of the abnormalities listed above always cause pain, clients seem more likely to experience coccyx problems when one or more of these conditions exist. Over the years, I have noticed clients with particularly long coccyxes also seem more likely to report local tenderness and pain. Although not reported in the literature, it seems understandable that a long coccyx would be more likely to suffer damage than a shorter one.
Why some hurt and others dont is vague. In the case of a misaligned coccyx, it might be that the pain is brought about by the coccyx pulling on muscles, ligaments or overstretching the filamen terminale (end of the dural tube). Connective tissues named the filum durae spinalis enclose the end of the spinal cord and attach it to the deep dorsal sacrococcygeal ligament.
Idiopathic head and low back pain syndromes often manifest when a distorted coccyx tugs on the dural tube, causing reverberating tensional forces to travel all the A major source of hip and back pain occurs as fibrotic sacrococcygeal ligaments anteriorly flex (hook) the coccyx and compress/overstretch the sensitive filum terminale (Fig.1). In the case of a rigid coccyx, it might be that the tissues under the inferior segments might form a pad of irritated tissue (like a bunion) that can rub the dura raw. But the most widespread pain-generator helped by manual therapists is neuroreceptor pain from a misaligned sacrococcygeal joint way up to the occiput.
Coccydynia (Coccyx Pain)
When one is sitting, the coccyx shifts forward and acts as a shock absorber. Though, falling on the tailbone or events such as childbirth can lead to coccygeal pain, known as coccydynia. In most cases, the pain is brought about by an unstable coccyx, resulting in chronic inflammation of the sacrococcygeal joint. Coccydynia also can be accredited to a malformed or dislocated coccyx and the growth of bony spurs on the coccyx. Resulting pain frequently is resolved by performing specific soft tissue techniques to release the levator ani muscle, anococcygeal, sacrotuberal and sacrospinal ligaments, as well as the gluteus maximus muscles.
Another familiar etiology is childbirth. The coccyx is considered by some to be in the way through childbirth. At the end of the third trimester, particular hormonal changes enable the synchondrosis between the sacrum and the coccyx to soften and become more mobile. This increased mobility of three to five coccygeal segments allows for more flexion and extension, which might permanently alter the resting tension of the surrounding ligaments and muscles. Unlike fractures, which can remodel, injuries to the sacrococcygeal junction often become inflamed as the joint is repeatedly forced out of its normal position. Physical examination should include direct palpation of the coccyx for tenderness. In true coccydynia, the coccygeal region frequently is markedly tender. If the client reports coccygeal pain although is not tender upon palpation, the therapist should refer out for an orthopedic workup to rule out lumbar disk disease.
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