Some low back pain does not behave like the rest. It sits low and to one side, right around the dimple above the buttock. It can make getting out of a car awkward, hurt when you roll over in bed, and ache after standing on one leg to put on pants. Patients often tell us they have been treating a "bad back" for months without much change. In some of these cases, the sacroiliac joint, usually called the SI joint, is part of the picture.
What the SI joint does
You have two SI joints, one on each side where the base of the spine (the sacrum) meets the pelvis. They do not move much, and they are not supposed to. Their job is to transfer load between your upper body and your legs. Strong ligaments hold them in place, and they work best when the hips, pelvis, and low back share the work evenly.
When one side is irritated or moves poorly, the area can become sore with everyday activity. Common contributors include uneven weight bearing, long stretches of sitting with one leg crossed, a fall onto the tailbone, repetitive twisting, and changes in the pelvis during and after pregnancy. Sometimes there is no obvious trigger at all.
What it often feels like
SI joint trouble varies, but patients commonly report:
- A localized ache on one side of the low back, low enough to cover with one hand
- Pain that is worse climbing stairs, standing up from a chair, or standing on one leg
- Stiffness after sitting for a long time
- Discomfort that can reach into the buttock or upper thigh
- A feeling that one side of the pelvis is "off"
Because these patterns overlap with disc problems and sciatica, it is easy to guess wrong. We compare those conditions in our article on sciatica versus piriformis syndrome, and our lower back pain and hip pain pages explain how we sort these out at the exam.
Why guessing does not work
Stretching harder is the usual first response, and it is not always the right one. If a joint is irritated, aggressive stretching of the surrounding muscles can aggravate it. If the real problem is a nerve or disc, working the hip will miss the source. That is why we start with testing instead of assumptions.
A testing-first visit looks at how you stand, walk, and move. We check hip and spine range of motion, compare one side to the other, and perform orthopedic and palpation tests that help show whether the SI joint, the lumbar spine, the hip, or a combination is involved. If your history or findings point to something outside our scope, we tell you and refer you appropriately.
How care is approached
When an SI joint problem is identified, care typically focuses on restoring comfortable motion at the pelvis and low back and addressing what keeps loading the area unevenly. That can include gentle chiropractic adjustments, movement guidance, and a short list of exercises for the hips and core. Our rehab and exercise therapy service supports that work. Results vary from person to person, and we do not promise a particular outcome or timeline.
Everyday adjustments worth making
- Avoid sitting for long periods with one leg crossed or all your weight on one hip.
- Keep a wallet out of your back pocket while you drive or work.
- Take short walks during long sitting stretches.
- When you stand, spread weight evenly through both feet.
- Sleep on your side with a pillow between your knees if lying flat is uncomfortable.
Frequently asked questions
How do I know if my back pain is from the SI joint?
You cannot reliably tell on your own. A pattern of one-sided pain near the belt line that flares with stairs or standing on one leg is a clue, but a hands-on exam is the way to separate it from disc, hip, or nerve problems.
Can pregnancy affect the SI joints?
Yes. Hormonal changes and shifts in posture and weight distribution can affect the pelvis. If you are pregnant or postpartum with low back or pelvic pain, we can talk through gentle options. See our page on prenatal chiropractic for more.
Should I rest or keep moving?
For most everyday aches, gentle walking tends to be more helpful than prolonged bed rest. If pain is severe, follows a fall or accident, or comes with leg weakness, numbness, or changes in bowel or bladder control, seek medical care promptly.
What to do next
If a one-sided low back ache keeps interrupting your day, get a clear answer instead of guessing. New patients start with a $59 New Patient Special, including a full consultation and exam. Call (425) 276-8044 or book your first visit online with Dr. Andrew Winger at Lakeside Spine and Wellness in Renton.
References
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, Back Pain
- Cleveland Clinic Health Library, Sacroiliac Joint Pain
