What is the SI Joint?
Inside our lower back, there is a joint on both sides, just above the buttocks.
This joint connects the spine (backbone) to the pelvis (hip bones).
This joint is called the Sacroiliac joint, or SI joint.
Many people with lower back pain actually have pain coming from this joint — but it is often missed or wrongly treated.
Why SI Joint Pain Is Often Missed
Most people think back pain always comes from:
- Slip disc
- Nerve problem
- Spine bone problem
But SI joint pain is different.
It is not just a bone problem.
It involves ligaments and muscles.
X-rays and CT scans can be normal, but pain can still be severe.
What Does the SI Joint Do?
The SI joint transfers body weight from the upper body to the legs.
It is made mainly for stability, not movement.
It moves very little.
Why Does SI Joint Pain Happen?
Muscles around the pelvis and back become weak, tight, or imbalanced.
When muscles fail, ligaments take extra load and pain starts.
Where Is the Pain Felt?
- Deep pain in one buttock
- Pain near the groin
- Pain in back of thigh
- Sometimes pain goes down the leg
Why Pain Increases
Pain increases during:
- Long sitting
- Standing up from chair
- Turning in bed
- Walking for long time
Two Types of SI Joint Pain
- Pain from inside the joint – treated with joint injections.
- Pain from ligaments – very common and needs muscle treatment.
Why Injections Alone Are Not Enough
Injections reduce pain but do not fix weak muscles.
If muscles are not treated, pain returns.
How Muscle Treatment Helps
Treating muscles:
- Reduces tightness
- Improves strength
- Reduces load on ligaments
- Gives long-term relief
Correct Way to Treat SI Joint Pain
- Find exact cause
- Reduce pain
- Treat muscles
- Correct posture and exercises
Final Message
SI joint pain is not just a joint problem.
It is a muscle and ligament problem.
With correct treatment, SI joint pain can be controlled and prevented.
