Known as coccydynia.
Most cases are idiopathic without known cause, but may be secondary to trauma or malignancy.
Frequently severe and persistent.
Often minimalized or dismissed by physicians.
Many patients sit leaning forward with flexion at the lumbosacral and hip regions shifting more weight to the bilateral ischium rather than the coccyx, although some sit leaning towards one side with body weight on one ischial tuberosity.
The coccyx, also known as the tailbone, is the terminal end of the spine and is inferior to the sacrum.
The coccyx is composed of 3-5 coccygeal vertebra, with 80% of individuals having 4 such vertebrae.
There is variation in the number of spinal segments, degree of fusion and angulation of the coccyx among individuals.
The coccyx is considered a vestigial remnant of a tail.
The coccyx is concave anteriorly and convex posteriorly.
Muscles including the levator ani insert on the anterior coccyx.
The levator ani that inserts into the coccyx may be made up of separate muscles-the coccygeus, iliococcygeus and pubococcygeus muscles.
The muscle groups noted above support the pelvic floor and help maintain fecal continence.
The anococcygeal raphe supports the position of the anus.
The gluteus maximus muscle originates from the posterior coccyx.
The anterior and posterior sacrococcygeal ligaments attach the sacrum to the coccyx.
Laterally, the transverse process of the coccyx attaches to the lateral sacrococcygeal ligaments and the fibers from the sacrospinous ligament and the sacrotuberous ligament.
The coccyx helps in weight-bearing in the seated position along with the ischial tuberosities and the inferior rami of the ischium.
When seated and leaning backwards the coccyx bears more weight.
Plain x-rays the usual initial imaging study for this complaint especially in cases of sacrococcygeal trauma.
X-rays include anterior-posterior and lateral lumbosacral x-rays.
X-rays include visualization of the entire sacrum, coccyx, lower lumbar spine and frequently the ilia and hip joints.
Focused coned-down x-rays of the coccyx may be necessary to identify pathology.
X-ray examination may reveal fractures, osteophytes, abnormal curvature and dislocations of the sacrococcygeal junction or intracoccygeal segments.
Because there is great variability of the coccyx in terms of angulation and degree of fusion between coccygeal vertebrae pretrauma, the significance of posttraumatic x-rays studies may be problematic.
Coned down films in the seated position and compared t the non weight bearing position of lying on one’s side allows assessment for dynamic instability.
The first coccygeal vertebra on anterior-posterior x-rays reveal bilateral coccygeal cornu posteriorly and the bilateral transverse processes laterally which are larger than other transverse processes of the inferior coccygeal segments.
The apex of the coccyx is round but may be bifid and midline.