Vertebral Column: Intervertebral Joints, Sacroiliac Joints, and Pubic Symphysis

Sacroiliac Joints: Anatomy, Stability Mechanisms, and Clinical Significance

The sacroiliac joints (SIJs) are essential components of the pelvis, connecting the sacrum to the iliac bones. They function to distribute weight, absorb shock, and facilitate movement while maintaining stability.

Types and Articular Surfaces

• Synovial joint: The anterior region contains a synovial cavity.
• Fibrous joint: The posterior region consists of strong ligamentous connections.

Ligaments and Stability Mechanisms

Several ligaments reinforce the SIJs, ensuring stability:

• Anterior Sacroiliac Ligament: Strengthens the anterior aspect of the joint.
• Interosseous Sacroiliac Ligament: Provides strong fibrous connections between the sacrum and ilium.
• Posterior Sacroiliac Ligament: Supports posterior stability and restricts excessive movement.
• Sacrospinous & Sacrotuberous Ligaments: Limit pelvic rotation and assist in maintaining proper posture.

Movements of the Sacroiliac Joint

Although the SIJ allows minimal movement, it facilitates:

• Nutation: Anterior rotation of the sacrum relative to the ilium.
• Counter-nutation: Posterior rotation of the sacrum.

Clinical Significance

Understanding SIJ dysfunction is crucial for managing pain and mobility issues. Conditions such as sacroiliitis, instability, and degenerative joint disease can impact its function.

Diagnosis typically involves physical examination, imaging studies, and joint injections. Management includes physical therapy, pain relief measures, and in severe cases, surgical intervention.