The most common cause of SI joint pain is hypermobility (excessive movement) of the sacroiliac (SI) joint, leading to instability.
Hypermobility essentially means the SI joint moves too much. This excessive movement can strain the ligaments surrounding the joint, causing pain and inflammation. Several factors can contribute to this hypermobility:
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Pregnancy: Hormonal changes during pregnancy, particularly the increase in relaxin, loosen the ligaments in the pelvic area to prepare for childbirth. This loosening can lead to SI joint instability and pain. The added weight and altered biomechanics of pregnancy also contribute. This explains why SI joint pain is more prevalent in young women.
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Trauma: Injuries, such as falls or car accidents, can directly damage the SI joint ligaments, leading to instability.
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Repetitive Strain: Activities involving repetitive twisting or heavy lifting can gradually wear down the ligaments surrounding the SI joint.
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Leg Length Discrepancy: When one leg is shorter than the other, it can cause uneven weight distribution and strain the SI joint.
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Prior Lumbar Fusion: Fusion surgery in the lower back can place increased stress on the SI joint, potentially leading to hypermobility and pain over time.
While hypermobility is the most common cause, it's important to note that SI joint pain can also arise from hypomobility (too little movement), although this is less frequent. Proper diagnosis by a healthcare professional, including physical examination and imaging if necessary, is crucial to determine the exact cause of SI joint pain and guide appropriate treatment strategies.
