Dislocation of the coccyx
The coccyx is the "tailbone"; the lower bone in the spine.
It is located under the sacrum.
Side view of the spine
It is what in other animals becomes a tail, and it is joined to
the sacrum by several ligaments which contain many nerve fibers.
The dislocation of the coccyx occurs when there is a separation
of the coccyx from the sacrum. Usually, if the coccyx is displaced
backwards, it does not completely separate from the sacrum, but
pivots backwards, so that the fibers at the front of the
ligaments are torn or strained. Conversely, if the coccyx
pivots forward, it is the fibers in the back of the ligaments which
are torn or strained.
Consequently, this is not really considered to be common
back pain, since this is really due to trauma and displacement
of the bone.
How it happens
In order for the coccyx to be displaced, it must be subjected
to a significant force. The two most frequent causes are:
- Falling on the tailbone, where the intensity of the fall
displaces the coccyx.
- Labor, in which the fetus displaces the coccyx, usually
backwards, during its passage through the birth canal. This can
occur when the size of the baby and the size of the mother's pelvis
are slightly out of proportion.
Given that the ligaments which join the coccyx to the sacrum house
many nerve fibers, the strain or tearing of such fibers may be very
painful. Once the pain
nerves are activated, inflammation
may ensue in the area.
The dislocation of the coccyx causes highly localized pain
in the tailbone area, usually lacking referred
pain in the leg.
Pain usually appears when in a seated position, particularly
if you are sitting on a hard surface, as this increases the strain
on the ligaments or the pressure upon torn ligaments. Immediately
after dislocation, pain is usually constant and increases when sitting
The dislocation in itself does not involve any risks.
The main risk is that the injury takes a long time to heal
completely. This is because, under normal conditions, the joint
between the coccyx and the sacrum does not move and, contrary to
what happens with other joints which are stabilized by powerful
muscles, the ligaments are practically the only structure which
keeps both bones together. Therefore, if the tear is important,
spontaneous healing may take a long time.
Normally, the medical
history and the physical
examination are sufficient. If the dislocation is significant,
it may be observed by radiography.
Among healthy individuals a range of variations within the norm
exists with regard to the position of the coccyx, and one can come
across some individuals with a coccyx in a more horizontal position
(or pivoted backwards) than others. For this reason, the observation
of a coccyx in a position which is pivoted backward or forward is
not enough for the diagnosis of dislocation. There must be some
previous history justifying dislocation, or a previous radiography
which helps to compare the position of the bone and, above all,
both the symptoms and physical examination must point toward dislocation.
In most cases, dislocation is not important and is due to the
strain of the ligaments which heal over time. In these cases, analgesics
medication should suffice during the acute phase, until the pain
is easily tolerated.
A cushion with a hole in the middle, a rubber ring, or
any other system which prevents direct pressure on the coccyx when
seated may also be used.
In some cases, the manual reduction of the dislocation
is attempted, where the physician tries to restore it to its correct
position. In extraordinary cases, when the dislocation is very significant
and the patient suffers significant pain and restriction of activity
with no signs of healing, surgery may be considered in order
to restore the coccyx to its correct position or even to remove