Anatomy of the Sacroiliac Joint
The sacroiliac joint (SIJ) is one of two joints in your pelvis that connect the tailbone (the sacrum) and the large pelvic bone (the ilium). The SI joints connect your spine to the pelvis, and thus, the entire lower half of the skeleton. Like all joints, there is cartilage that covers the surfaces of the SIJ surfaces. The special thing about the SIJ however is that its cartilage has many ridges and depressions (ridges are bumps and depressions are dips in the surface) so that they fit together like a puzzle and make the joint stable. Therefore the SIJ is not designed for much motion, with movement of only 2-4 millimetres! In fact, it is common for the SIJ to become stiff and actually ‘lock’ as we age.
Function of the SIJ
- Main function appears to be providing shock absorption for the spine through stretching in various directions
- May also provide a self-locking mechanism that enables you to walk. The joint locks on one side as weight is transferred from one leg to the other.
- Transmits all the forces of the upper body to the pelvis (hips) and legs
- Doesn’t have mush movement, so provides a stable base
What is Sacroiliac Dysfunction?
Dysfunction in the sacroiliac joint is abnormal functioning of the joint, which is then thought to cause low back and/or leg pain. The pain can be similar to pain caused by a lumbar disc herniation. This condition is generally more common in young and middle age women, due to hormonal changes and childbirth.
One of the most common causes of problems at the SI joint. The injury can come from a direct fall on the buttocks, a motor vehicle accident, or even a blow to the side of your pelvis. The force from these injuries can strain the ligaments around the joint. Ligaments are the tough bands of connective tissue that hold joints together. Tearing of these ligaments can lead to too much motion in the joint.
Abnormality of Sacrum Bone
The sacrum bone is actually a very specialized set of vertebrae (the bones that make up the spine). Before birth, when your body is undergoing development in the womb, several vertebra fuse together to form the sacrum. However, in some people, the bones that make up the sacrum never fuse together. In these cases, two or more of the vertebra that should fuse together remain separated. This creates an odd situation where a false joint occurs. People who have this seem to have more problems with their SI joints.
Women are at increased risk for developing SI joint problems due to childbirth. During pregnancy, female hormones are released that allow the connective tissues in the body to relax. The relaxation is necessary so that during delivery, the female pelvis can stretch enough to allow birth. This stretching results in changes to the SI joints, making them extra or overly mobile. Overall sacroiliac joint dysfunction arises due to too much movement at the joint, hyper mobility (pregnancy, injury) or too little movement or hypo mobility, (stiffness, age).
Signs and Symptoms
SIJ dysfunctions have numerous signs and symptoms. Following are the most common:
- Back Pain – particularly low back pain
- Buttock Pain
- Thigh Pain
- Sciatic-like Pain – Pain that travels from the sciatic nerve in the lumbar region into your buttocks, back of your thighs, and sometimes calf and foot. The pain is typically caused by irritation of the nerve roots that join outside the spine to make up the sciatic nerve. You might feel numbness, tingling or burning sensations
- Difficulty sitting in one place for too long due to pain
- The symptoms of back pain can be the same or very similar and can often mimic back and pelvic pain. Quite often they can also be related, as sacroiliac dysfunction is very rarely an isolated problem. Also due to its small amount of movement and its very deep position in the body, it is hard to accurately assess, making it very difficult to diagnose and distinguish from other types of low back pain.
As sacroiliac dysfunction is rarely an isolated condition, treatment concentrates on the presenting signs and symptoms given from the assessment with your physiotherapist. Modalities that may be used during your therapy sessions include, heat/ice, iontophoresis, tens, ultrasound, mobilisations and manipulations of the sacrum. Correction of the instability through strengthening and postural correction specifically through a motor program for the TA and back muscles, and even muscle energies techniques.
As part of any rehabilitation program a home exercise program will be specifically designed aimed at improving the stability of your pelvis and back, and correction of posture, through stretches, ROM and strengthening exercises.
Like most back conditions, sacroiliac symptoms should subside with conservative treatment. If however, pain and symptoms don’t diminish, the use of corticosteroid injections into the joint may be used to relieve the inflammation and pain.
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