Sacroiliac (SI) joint pain refers to discomfort arising from one or both of the sacroiliac joints. These two joints are located on either side of the sacrum, the triangular bone at the base of your spine, where it connects to the ilium, the large bones of your pelvis. The SI joints act as shock absorbers, transferring weight and forces between your upper body and legs, while also providing stability to the pelvis. Understanding the factors that can worsen or trigger this pain is an important step toward finding relief.
Specific Movements and Activities
Certain physical actions can place undue stress on the sacroiliac joints, leading to increased pain. Bending and twisting simultaneously, such as when reaching for an object on the floor while rotating your torso, can create shearing forces across the joint surfaces. This combined movement can disrupt the normal, limited motion of the SI joint.
Lifting heavy objects, especially without proper technique, can also aggravate the SI joint. Incorrect lifting often involves rounding the back and relying on spinal muscles instead of leg muscles, which can strain the lower back and place asymmetrical loads on the pelvis. High-impact activities like running, jumping, or contact sports generate repetitive jarring forces that transmit through the legs to the pelvis and spine. These forces can repeatedly compress or shear the SI joints, potentially leading to inflammation or microtrauma.
Movements such as climbing stairs or navigating uneven surfaces can cause asymmetrical loading on the pelvis, where one leg bears more weight or moves differently than the other, creating imbalance at the SI joints. Sudden movements, including quick turns, unexpected jolts, or rapid reaching, can also destabilize the joint, particularly if the surrounding muscles are not prepared to support the movement. Repetitive motions, common in certain occupations or hobbies that involve consistent one-sided stress, can cumulatively strain the ligaments and muscles supporting the SI joint, reducing its ability to maintain stability over time.
Prolonged Positions and Posture
Maintaining static body positions for extended periods can also contribute to or worsen sacroiliac joint discomfort. Prolonged sitting, especially with poor posture like slouching or leaning heavily to one side, can apply sustained, uneven pressure on the SI joints. This can lead to stiffness and reduced joint mobility over time.
Extended periods of standing, particularly if one tends to stand unevenly or with one hip hiked, can create ongoing strain on the joint ligaments and surrounding muscles. This uneven weight distribution can pull the pelvis out of alignment, increasing stress on the SI joint. Sleeping positions also play a role; sleeping on one side with the legs unaligned, or on a mattress that is either too soft or too firm to adequately support spinal alignment, can lead to muscle imbalances and sustained pressure on the SI joint throughout the night.
Overall poor posture, including a slouching posture or an exaggerated anterior pelvic tilt, can alter the natural alignment of the pelvis and spine. Such postural imbalances can place increased tension on the ligaments that stabilize the SI joint, leading to muscle fatigue and discomfort. Over time, these sustained positions and poor alignment can result in muscle imbalances, joint stiffness, or increased stress on the SI ligaments.
Lifestyle and Environmental Factors
Broader lifestyle elements and external factors can indirectly influence sacroiliac joint pain. Excess body weight increases the overall load on weight-bearing joints, including the SI joint. This added mechanical stress can accelerate wear and tear on joint cartilage and ligaments.
Inappropriate footwear, such as high heels or unsupportive shoes, can alter gait mechanics and pelvic alignment, leading to uneven weight distribution and increased strain on the SI joints. Worn-out shoes that lack proper cushioning or support can also contribute to these biomechanical imbalances. Psychological stress can lead to increased muscle tension throughout the body, including the muscles surrounding the pelvis and lower back, which can exacerbate pain perception and reduce the body’s ability to cope with physical stress on the SI joint.
While not a direct aggravator, a diet high in inflammatory foods can contribute to systemic inflammation, potentially worsening joint pain, including in the SI joints. Dehydration can affect the lubrication of joints and the flexibility of connective tissues, potentially making the SI joint more susceptible to stiffness and pain.
Underlying Health Conditions
Pre-existing medical conditions or past events can make the sacroiliac joint more vulnerable to aggravation. Various forms of arthritis, such as osteoarthritis, ankylosing spondylitis, or psoriatic arthritis, can directly affect the SI joint, causing inflammation and degeneration that predispose it to pain with movement or pressure. These conditions can reduce the joint’s natural shock-absorbing capacity.
Traumatic events, including falls, car accidents, or direct impact to the pelvis, can damage the ligaments and joint surfaces of the SI joint, leading to instability or inflammation that makes it more sensitive to aggravating factors. Pregnancy and childbirth also place significant stress on the pelvis; hormonal changes, particularly the release of relaxin, can loosen ligaments, while the mechanical stress of delivery can strain the SI joints, leaving them susceptible to ongoing pain.
A leg length discrepancy, where one leg is measurably shorter than the other, can lead to uneven weight bearing and chronic strain on the SI joint on the longer side, or compensatory strain on the shorter side. Muscle imbalances, such as weak core muscles, tight hip flexors, or weak gluteal muscles, can compromise pelvic stability and alter the biomechanics of the SI joint, increasing its susceptibility to aggravation. Previous spinal surgery, especially lumbar fusion, can alter the biomechanics of the lower back and pelvis, potentially increasing the load and stress on the adjacent SI joints.