Where is the left sacroiliac (SI) joint?

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Last updated: April 28, 2025View editorial policy

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From the Research

The left sacroiliac (SI) joint is located at the junction between the lower spine and the pelvis on the left side of the body, where the sacrum connects with the ilium. This joint is positioned deep in the lower back/buttock area, approximately at the dimple visible on the left side of the lower back in many people 1. The SI joint plays a crucial role in stability when walking and standing, absorbing shock between the upper and lower body. Pain in this area can result from inflammation, hypermobility, or hypomobility of the joint, often manifesting as lower back pain that may radiate to the buttock or thigh. Key characteristics of the SI joint include:

  • A relatively immobile joint that transfers forces between the upper body and lower extremities
  • Located at the base of the spine, connecting the sacrum and ilium
  • Plays a crucial role in stability and shock absorption
  • Pain in this area can be caused by various factors, including inflammation, hypermobility, or hypomobility of the joint, as discussed in the context of sacroiliac joint dysfunction diagnosis and treatment 1. Recent studies have also explored injective treatments for sacroiliac joint pain, including steroid injections and platelet-rich plasma (PRP) injections, with varying degrees of success 2. However, the location and function of the left SI joint remain consistent, regardless of the treatment approach.

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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