Sacroiliac (SI) Joint Pain
The sacroiliac joint (or SI joint for short) is the second most
common area where people experience back pain. Many people
mistakenly refer to it as their “hip”, but the SI joint is part of the
spine. The actual hip joints are located on your sides where your
thighs attach to your pelvis. The SI joint is more to the center and
to the back of your pelvis.

The sacroiliac joints form the connection between the spine and
the pelvis. The sacrum is the foundation of the spine, and if the
Sacroiliac joint is rotated or tilted out of place, the back also
becomes less stable. This can lead to pain higher up in the back
due to compensation.

Now lets look at what the sacroiliac joint does, how it gets out of
place, and how we correct it.
Why do we have SI joints?
There are two purposes of the SI joint: shock absorption and pelvis stabilization. When we walk both SI joints
pivot in the pattern of a figure eight. As our heel strikes the ground, the same side SI joint provides shock
absorption for our pelvis, hip, and back. The other SI joint locks to hold our pelvis together.

What causes it to hurt?
Because there is so much force going into the pelvis when we walk, run, jump, etc there has to be extremely
strong ligaments to hold things together. This is why the SI joint contains the
strongest ligaments in the entire
body. These ligaments firmly connect and stabilize the two pelvic bones, the sacrum and the ilium. These
strong layers of ligaments prevent excessive forward or backward tilting of the sacrum and pelvis. This pelvic
stability provided by the ligaments is known as a “self-locking mechanism”.

Under ideal conditions the sacrum is positioned evenly on both sides, and rests at a 36-42° angle. When the
sacrum and SI joints are aligned well, there is maximum stability. With a swayback posture (hyperlordosis) the
sacrum tilts downward and forward, becoming more horizontal. The ligaments described above are over-
stretched causing the sacroiliac joints to become unstable. This ligament instability impairs the “self-locking
mechanism”. Since the “self-locking mechanism” isn’t working properly, the ligaments then undergo further
stretching, causing the firing of pain receptors. In addition the unstable sacroiliac joints may become locked in
an abnormal alignment, resulting in muscle spasm, trigger points, swelling, and inflammation. This often leads
to radiating pain or numbness down the leg due to irritation of the sciatic nerve.

How do the SI joints get stuck out of place?
The classic way the SI joints are injured is if you are walking on the sidewalk and don’t see the curb, and you
jam the joint.  Or you are walking down the stairs and you don’t notice the last step, and you jam the joint.  Or
maybe you have one foot in front of the other and you are lifting, pushing, pulling, etc.  The bottom line is that
one foot is in front of the other, and some type of a straining or jarring force goes into your pelvis. This locks
the SI joint in a misaligned position. (FYI: When this happens one leg is drawn shorter than the other leg.)

So how does this relate to the ligament instability described earlier? Well, when the ligaments are unstable
and the self-locking mechanism is not working properly, this creates fertile ground for SI joint injury. Then
when you have a jolt into your Sacroiliac joint, due to the lack of stability, it rotates out of place.

To bring the SI joints back into their proper alignment, spinal adjustments are performed to the pelvis.
Because the
lower back muscles and hamstrings connect to the pelvis and provide stabilization, they
should be
stretched and strengthen. Because a forward tilt of the pelvis likely caused the ligament
instability in the first place, spinal adjustments and
postural correction exercises to correct this can be crucial
to healing and prevention of future flare-ups.  
Trigger points in the low back muscles, hamstrings, and
buttocks can cause pain, muscle weakness, muscle fatigue, and muscle tightness.  Because this can lead to
muscle management (The Stick®) also plays an important role in healing and prevention.  In
addition therapies such as
electric muscle stimulation combined with ice, heat, or ultrasound can relieve pain
and speed healing.