Sacrum/Coccyx and SI Jnts.
Routine Views:
Sacrum/Coccyx
 AP axial
 Lateral

AP Axial Sacrum
Structures Shown
 The
entire sacrum free of superimposition
Good film:
The pubic bones should not overlap the
sacrum
 No foreshortening (angle 15 degrees up)
 Good even contrast
 No rotation
 Sacrum centered to film
 Good collimation
 Fecal material should not overlap the sacrum

AP Axial coccyx
Here is a list of some of physical traumas that
tailbone sufferers have experienced and reported
from Tailbone.com:
Auto Accident, rear-end collision
Auto Accident, vertical fall from a cliff
Child birth (vaginal) delivery
Dead-lifting of heavy weights or barbells
Fall on the buttocks down the stairs or ladders
Fall on the buttocks during Cheerleading Stunts (Throw & catch or Pyramids)
Fall on the buttocks during gymnastics on a balance beam
Fall on the buttocks during ice skating
Fall on the buttocks during roller blading or in-line skating
Fall on the buttocks during roller skating
Fall on the buttocks during skiing
Fall on the buttocks during snow boarding
Fall on the buttocks from a swing
Fall on the buttocks in a bath tub
Fall on the buttocks in a bathroom
Fall on the buttocks on a frozen sidewalk
Fall on the buttocks on a oily or greased floor
Fall on the buttocks while skate boarding
Horseback riding or falling from a horse
Martial Art accidental contact with buttocks
Prolonged sitting
Sexual intercourse
Sitting during Pregnancy
Sitting on a bicycle seat with gel padding
Sitting on a broken car seat or office chair
Sitting on a thinly padded bicycle seat
Sitting on hard surfaces such as stadium bleachers
Slip and fall on a hard slippery/wet tile floor
Sports injury, accidental kick in the buttocks
Straddle injury on a fence top or tree limb
Water slide drops and jumps
Structures Shown

The whole coccyx and distal sacrum free of
superimposition
Good Film
The coccygeal segments should not be
superimposed by pubic bones (angle)
 Good even contrast
 Coccyx should be centered to film and seen
in its entirety
 No rotation
 Good collimation
 Do they need to use the
restroom?

Lat. Sacrum/coccyx
Structures Shown

The lateral aspect of the entire sacrum and
entire coccyx (**for L-S spine it is okay to clip
coccyx)
Good Film:
The sacrum and coccyx should be seen
clearly with even contrast
 Good collimation
 Superimposed iliac crest

SI joints
AP Axial ( same as up shot on L-S spine)
 RPO/LPO

AP Axial SI joints
Same as AP axial for L-S spine Junction
RPO/LPO SI joints
R
L
LPO
RPO
Structures shown:
 Shows
the sacroiliac joint farthest from the IR
and an oblique projection of the adjacent
structures
**Always do both obliques for comparison
Good Film:
Open SI joint space with minimal overlapping
of the ilium and sacrum
 Joint centered on the film
