Can the SI joint cause Tailbone and Pelvic Pain

By Kim Vopni, The Vagina Coach — Certified Pelvic Floor Fitness Specialist · Published September 7, 2022

Direct Answer

Yes — SI joint dysfunction and tailbone (coccyx) injury are common, often related causes of low back and pelvic pain, especially after childbirth, a fall, or prolonged sitting. Restoring proper pelvic stability and joint mobility, rather than just resting, is usually the most effective way to reduce pain and prevent it from becoming chronic.

Key Takeaways

• The SI joint connects the spine to the pelvis and can become inflamed or shift due to injury, pregnancy, or repetitive strain.
• The coccyx (tailbone) can become painful from falls, prolonged sitting, or childbirth-related pressure.
• Pregnancy hormones like relaxin loosen pelvic ligaments, making the SI joints more prone to shifting during and after birth.
• Restoring pelvic stability and movement, not just resting, is the primary way to resolve pelvic, SI joint, and tailbone pain.

The SI joint is a true diarthrodial joint, the most common and moveable joint in the body. The SI joints and coccyx are often the cause of intense low back and pelvic pain.

The Sacroiliac (SI) joint is part of the pelvis and is located where the ilium joins the sacrum. The SI joint is the connection between the spine and the pelvis and acts as a shock absorber and, by design, is prone to dysfunction. It can become inflamed, causing great pain or discomfort.

The coccyx is the tailbone and will become inflamed in the same way as the SI joint, causing coccygeal pain. You can experience pain in the coccyx if an injury or some type of excess pressure on the area causes the bones to move beyond their normal limited range of motion, resulting in inflammation and localized pain.

Strain and injury to the SI joint are produced by a combination of vertical compression and rapid rotation, such as carrying a heavy object and twisting or by falling on your bottom. While a slip and fall can injure any part of the body, landing right on your bottom can result in shifting of the SI joints or the coccyx.

Causes for pain

Skiers and other athletes often experience the pain of a shifted or locked SI joint from multiple falls.

Many people tend to slouch when they are sitting. Instead of sitting up with their weight on their “sit bones,” people will round their lower back, putting strain on the ligaments of the pelvis. Repeated strain on the ligaments can cause the SI joints or coccyx to shift, resulting in a sharp stabbing pain. If you get back pain when sitting in a reclining chair/couch, you’ve probably irritated your SI Joint.

When a woman is pregnant, hormones, such as relaxin, are released that cause the ligaments of the pelvis to relax. This makes the birthing process easier however, it also makes the SI joints and joints of the coccyx more susceptible to shifting. During the birthing process, the joints of the pelvis are placed under tremendous strain. Women often report feeling SI pain for weeks or months after delivery.

Are you tired of suffering from Pelvic, SI Joint, and Tail Bone pain?

The primary focus when treating pelvic pain is to restore the proper movement and stability to the joints of the pelvis. 

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• The role of diet and exercise

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Frequently Asked Questions

What does SI joint pain feel like? SI joint pain often presents as sharp or aching pain in the low back, hip, or buttock, sometimes radiating down the leg, and can worsen with standing, twisting, or climbing stairs.

Can pregnancy cause SI joint or tailbone pain? Yes. The hormone relaxin loosens pelvic ligaments during pregnancy, making the SI joints and coccyx more prone to shifting, and many women continue to feel this pain for weeks or months after delivery.

What's the difference between SI joint pain and tailbone pain? SI joint pain originates where the pelvis meets the spine and often affects the low back and hip, while tailbone (coccyx) pain is localized at the very base of the spine, often from a fall or prolonged sitting.

How is SI joint and tailbone pain treated? Treatment focuses on restoring proper pelvic movement and stability through targeted pelvic floor and core exercise, rather than prolonged rest, along with posture and movement adjustments.

When should I see a professional about pelvic or tailbone pain? If pain persists beyond a few weeks, worsens, or limits daily activities, working with a pelvic floor physiotherapist or coach can help identify the cause and guide safe, effective treatment.

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