Knowing the relationship between the SI joint and the lumbar spine will help in understanding why low back pain can actually be a result of SI joint dysfunction.
The sacrum, a triangular shaped bone, is connected by a joint on both sides to two separate iliac bones (pelvis), known commonly as your hip bones.
The pelvis and SI joint are drivers for all of your movement and link your hips and legs to your upper body and core. Together, the pelvis and SI joint are the platforms that enable you to run, walk, sit, lunge or jump.
When doing these common daily activities, it is your SI joint that absorbs the weight loads from the upper body to your hips and legs, which helps relieve the forces received by your spine. The SI joint has very limited motion and is stabilized by several large, very strong ligaments. It is possible that the joint motion is affected by everyday wear and tear and/or injury and allows an unwanted increase in motion to the joint, which may cause some of the following symptoms:
- Low back pain
- Buttock pain, including muscle spasms
- Referred pain to hip and groin
- Pain and/or numbness in lower extremities
- Pain while sitting (or while transferring from sitting to standing)
- Difficulty sleeping on affected side due to pain