09/12/2025
🐎 Fun Facts About the Horse’s SI Joint!
The sacroiliac (SI) joint doesn’t get nearly enough attention, considering how much work it does. Here are some fun little facts you might not know:
🐴 1. It’s the horse’s power hub.
The SI joint is where the pelvis meets the spine, basically the point where all the propulsion from the hindlimbs transfers forward. If a horse could have a “launch button,” this would be it.
🔒 2. It barely moves… on purpose.
Unlike many joints, the SI joint is designed to be stable, not bendy. Its job is to transfer force, not wiggle around, so it’s packed with strong ligaments rather than relying on big movements.
🎯 3. Tiny issues can look like big problems.
Because the joint moves so little, even small amounts of inflammation or strain can create surprisingly dramatic signs, from poor canter transitions to reluctance to jump or track up.
🧩 4. The SI isn’t just one joint.
It’s actually a combination of two matching joints (left and right), plus an entire complex of supporting ligaments. Think of it as a three-part structure working together to stabilise the back end.
⚡ 5. Weak core = more SI strain.
Just like athletes, horses rely on their core muscles to keep the pelvis steady. Poor posture, weak abdominal muscles, or incorrect work can all increase pressure on the SI region.
🦴 6. It’s closely linked to the lumbar spine and hindlimb mechanics.
If the SI is unhappy, everything connected to it has to compensate, which is why you’ll often see tight hamstrings, uneven stride lengths or tension through the back at the same time.
🙌 7. Massage can really help.
While the joint itself is deep and not something we “manipulate,” releasing the surrounding muscles and improving biomechanics can make a world of difference to SI comfort and function.
Enjoy our beautiful little diagram to help you 🖌️
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