Vicki Sims, PT, CHT
Gainesville Physical Therapy
1296 Sims Street, Suite A
Gainesville, GA 30501
David Mesnick, PT, cMDT
Atlanta Falcons Physical Therapy Center
550 Peachtree Street, Suite 1760
Atlanta, Georgia 30308
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GENERAL INFORMATION, ANATOMY & TREATMENT
The sacrum (tailbone) connects on each side to the ilia (pelvic bones) to form
the sacroiliac joints.
The pelvic girdle consists of two innominate bones (the iliac bones) and the
sacrum. The innominate bones come together in the front to form the pubis
symphysis (a secondary cartilaginous joint) and with the sacrum in the back
to form the sacroiliac (SI) joints. For more information on Sacroiliac Joint
Dysfunction please click here.
Each innominate bone (ilium) joins the femur (thigh bone) to form the hip
joint. As a person walks or moves the torso and sacroiliac joints also moves.
Muscles and ligaments surround and attach to the SI joint in the front
and back. These can all be the source of pain and inflammation if the
SI joint is dysfunctional. Much of the integrity of the sacroiliac joint
depends on its ligamentous structure. The most commonly disrupted and/or
torn ligaments are the iliolumbar ligament and the posterior sacroiliac
ligament. For a free self-evaluation please click here.
The muscular attachment of the pelvic girdle is very extensive. Many of
the muscles directly influence sacroiliac motion. The primary muscles
The gluteus maximus is a massive structure mainly responsible for extension
of the hip joint. The pull of the gluteus maximus on the sacrotuberous
ligament is thought to produce enough tension to counteract forward
flexion of the sacrum on the ilia (Vleeming et al., 1989). Its direct
attachment to the sacrum may influence the stability of the joint.
The sacroiliac joint (SIJ) and its associated ligaments connect the spine to the
pelvic girdle. The latter articulates with the hip.
The gluteus medius and minimus act to abduct the hip joint. If the femur
is fixed, these muscles are believed to separate the ilia from the sacrum.
Biceps femoris is a hamstring muscle that flexes the knee and extends
the hip. The long head of the muscle originates from the ischial
tuberosity. The muscle may also partly originate from the sacrotuberous
ligament (Vleeming et al., 1989). Like the piriformis and gluteus maximus,
this muscle has an ancillary function of stabilizing the sacroiliac joint
via the sacrotuberous ligament, primarily stabilizing against forward
flexion of the sacrum on the ilia.
The iliopsoas muscle runs across the front of the hip joint immediately in
front of the femoral head. Its action is to flex the hip and contributes to
the stability of the hip during walking and standing. It can also be a
source of groin pain in the presence of a sacroiliac joint dysfunction.
The piriformis muscle, like the gluteus maximus, originates from the
sacrotuberous ligament (Vleeming et al., 1989). It runs from the front
of the sacrum to the femur and its action is to outwardly rotate the femur.
It is a stabilizer of the SI joint via the sacrotuberous ligament. It is
often the source of deep buttock pain associated with a sacroiliac dysfunction.
The quadratus lumborum is a rectangular muscle that runs from the 12th
rib to the top of the ilium. It can often be a source of side pain in
the presence of sacroiliac joint dysfunction.
Occasionally, the joint or its ligaments can become strained and cause pain that
closely mimics sciatica caused by a lumbar herniated disc. The pain starts in the
back and radiates down the leg. It can be felt in the hip region or groin.
It is important to make this distinction because herniated lumbar discs do not
always cause pain. In fact, many peoples have herniated discs that have never
caused pain and are found when a test is done for some other reason! There is no
reason to operate on a disc that is not causing any problem.
Strains of the sacroiliac joint are often due to falls or forceful twisting
motions. The pain can be severe! It is usually worse when getting up from a
chair or climbing stairs and it is often difficult to find a position of
comfort. Urinary frequency may occur in women as well as discomfort with bowel
movement and sexual intercourse. The pain can be felt as an ache in the whole
leg and might involve both legs.
A herniated disc might occur at the same time (often at the L4-5 level because
of a ligament between the vertebra and the SI joint) causing concomitant true
sciatica. The herniated disc is usually recognized and surgically treated but
the pain does not resolve because of the concomitant sacroiliac strain! This
is a scenario that I have encountered many times in clinical practice.
Sacroiliac pain is due to subluxation of the joint. The range of movement is
small and therefore cannot be detected on XRs. Sacroiliac dysfunction must be
diagnosed by clinical exam.
The two sides are compared for symmetry with the painful side considered the
abnormal one. The ilium can be rotated anteriorly or posteriorly. There
can be an upslip (the most frequent) or downslip. Often, the sacrum is also
rotated, placing strain on the facets (the joints of the spine). Those
subluxations can be determined by clinical examination and reduced with various
manipulations and exercises.
Some other tests are meant to mobilize the joint and exacerbate the pain to
confirm the diagnosis but the condition can be so painful that they are not
Numbing the sacroiliac joint with local anesthesia usually confirms the
diagnosis if the pain disappears while the medication is active. Adding
steroids (cortisone derivatives) will decrease the inflammation and help
treatment. However, if the joint remains in an abnormal position, the
pain usually comes back.
Conservative treatment consists in realigning the joint with appropriate
manipulations, then strengthening the tendons and surrounding muscles
with exercises to keep it in position. Sometimes, a sacroiliac belt that
tightens around the hips might be of use.
Some clinicians use sclerotherapy (prolotherapy). This is a technique
where irritant substances are injected in the ligaments and tendons that
surround the joint to produce inflammation and scarring. This thickens
the ligaments and may stabilize the joint. However, this technique is not
presently accepted by the medical community at large and most of the