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You swing your legs out of the car, shift your weight onto one foot to stand, and a sharp pain catches you low on one side of your back. Or you roll over in bed at night and the same spot grabs again. If that sounds familiar, the problem is not always in your spine itself. Lower back pain getting out of car is one of the classic everyday clues that your sacroiliac (SI) joint, the joint where your spine meets your pelvis, may be involved.
The SI joint is easy to miss because its pain overlaps with disc problems, facet joint pain and sciatica. In this guide, we at Rogers Regenerative Medical Group explain why these everyday movements set it off, the signs that point towards the SI joint, how it differs from sciatica, what triggers flare-ups and how we confirm the diagnosis. This is general information, not a diagnosis, and it is no substitute for an individual assessment.
SI joint pain is pain that comes from the sacroiliac joints, the two joints that link the base of your spine (the sacrum) to your pelvis. It is often felt as one-sided lower back or buttock pain that flares with transitions such as getting out of a car, standing up from sitting or rolling over in bed.
You have one SI joint on each side. They move very little, but they carry the weight of your upper body into your legs every time you stand, walk or climb stairs. Strong ligaments hold them together, and the muscles around them help keep the pelvis steady. When the joint is irritated, or the ligaments and muscles around it are overloaded, even small movements can become painful.
It is frequently overlooked because the pain does not always sit where people expect, and in some people with persistent lower back pain the SI joint turns out to be the main source. Our sacroiliac joint page covers the condition itself in more depth, so here we focus on the everyday movements that set it off.
The SI joint is most sensitive when load is uneven. Getting out of a car, rolling in bed and standing from a chair all involve shifting your weight onto one side, twisting through the pelvis or moving from a long period of stillness into sudden load.
Getting out of a car is an awkward movement. Your hips are bent, your knees are together or twisted to one side, and you then push up through one leg while the pelvis rotates. That combination puts uneven shear and rotation through the SI joint, which is why many people notice a sharp catch low on one side just as they stand.
When you roll over, one leg drags across the other and the pelvis twists relative to the spine. If the joint is irritated or the stabilising muscles are not working well, this twist can feel like a sudden stab in the buttock or lower back. Some people find it wakes them at night, particularly if they sleep on the painful side.
After a long drive or a long spell at a desk, the joint and surrounding muscles stiffen. Standing up then loads the pelvis suddenly. Many people feel buttock pain on standing up from sitting that eases after a few steps, only to return the next time they sit for a while.
No single sign confirms SI joint pain, but a pattern of the following features makes it more likely.
SI joint pain is typically felt on one side, low in the back, just beside the base of the spine. It often spreads into the buttock and hip and can reach the groin or the back of the thigh. Many people can point to the sore spot with one finger. Pain below the belt line on one side is a common description.
Pain tends to flare with getting out of a car, rolling over in bed, climbing stairs, standing on one leg, taking long strides or sitting for a long time on one side. The link to specific movements is one of the most useful clues we listen for.
Some people notice that one leg seems longer or that their hips look uneven. This may reflect a real difference in leg length or a tilt in the pelvis, and either can increase uneven load through one SI joint. It is a clue rather than proof, and it needs to be assessed properly.
A deep, stiff feeling around the pelvis is common, and some people describe a burning or aching sensation in the buttock. If you also have morning lower back stiffness that lasts more than half an hour, especially if you are under 40, mention this to a doctor, because inflammatory conditions of the spine and pelvis can also affect the SI joints.
SI joint pain often settles when you rest or change position, then returns when you load the joint again. That on and off pattern can be reassuring, but it can also lead people to put up with the pain for months without finding the cause.
These conditions can feel similar, which is why they are so often confused. The table below gives general guides, and many people have more than one source of pain.
| Condition | Where you usually feel it | What tends to set it off | Useful clue |
| SI joint pain | One side of the low back and buttock, sometimes the groin or back of the thigh, rarely below the knee | Transitions and uneven loading, such as getting out of a car or rolling over in bed | Usually no marked pain in the middle of the spine |
| Sciatica | Travels down the leg, often below the knee | Coughing, sneezing or prolonged sitting | Tingling, numbness or weakness in the leg |
| Disc-related back pain | Middle of the lower back, sometimes with leg symptoms | Prolonged sitting or bending forwards | Central ache rather than one-sided |
| Facet joint pain | Lower back and buttock, sometimes the thigh | Twisting and arching backwards | Pain that sharpens on extension |
A 2023 analysis published in eClinicalMedicine found that any single SI joint test on its own told clinicians very little. What proved more useful was a cluster of three or more positive provocation tests together with the absence of pain in the midline of the spine. This is why we never rely on one test or one scan to decide where your pain is coming from.
You can read more on our sciatica page, and our guides to disc degeneration options and facet joint pain cover the other two in detail. If your pain sits mostly on one side, our guide to left-sided back pain walks through the other possible causes.
Some changes in the body make the SI joint more vulnerable to irritation:
Beyond physical changes, flare-ups are often linked to habits that load one side of the pelvis more than the other. These include long periods sitting on one side or with your legs crossed, carrying a heavy bag on one shoulder, standing with your weight on one leg, twisting while lifting and sudden increases in running or walking distance.
Small changes often help. When getting out of the car, turn your whole body so that both feet are on the ground and your knees move together, then stand using both legs rather than twisting out. When rolling over in bed, bend your knees and keep them together, or place a pillow between your knees. Break up long periods of sitting every 30 to 45 minutes, spread your weight evenly when you stand and avoid crossing your legs for long periods. If your pain keeps returning despite these changes, it is worth having it properly assessed rather than hoping it will settle.
The SI joint itself does not need to be strengthened, but the muscles that support the pelvis do. Stronger gluteal muscles and a steady deep core help the pelvis share load evenly, which may reduce the strain on the joint. These exercises are general suggestions. If you are in significant pain, or you have not yet had a diagnosis, speak to a clinician or physiotherapist before starting.
Move slowly, stay within a comfortable range and stop if an exercise sharply increases your pain. Avoid forcing deep stretches into the hip or buttock during a flare-up, because overstretching an already irritated joint can make symptoms worse.
See your GP or a private back pain specialist if your pain has lasted more than a few weeks, keeps returning, limits driving, sleep, work or exercise, or has not improved with sensible self-care. A specialist assessment is especially useful when the diagnosis is unclear, for example when you have been told it is a disc or sciatica but the pattern does not quite fit.
Some symptoms need urgent attention. Contact NHS 111, your GP urgently or go to A&E if you have:
We begin with a detailed history and examination. We ask which movements provoke the pain, where exactly you feel it, whether it travels below the knee and how it behaves with rest. We also look at how your pelvis, hips and lower spine work together, including how you move and walk, and we use several SI joint provocation tests, because the pattern across them is more informative than any single one. Our full assessment process is set out on our SI joint page.
Imaging has a role but it is not the whole answer. An X-ray or MRI can rule out other problems and show inflammatory or degenerative change, but changes in the SI joint are also common in people who have no pain at all. A scan alone cannot tell us whether the joint is the source of your symptoms.
When the examination points to the SI joint but we want to be sure, a diagnostic injection of local anaesthetic into the joint, guided by imaging, can help. If your pain drops noticeably in the hours afterwards, it supports the SI joint as the pain source. If it does not, we know to look elsewhere, which saves you from treatment aimed at the wrong target.
It is important to be clear about the purpose here. National guidance from NICE (NG59) advises against spinal injections as a way of managing non-specific low back pain. A diagnostic SI joint injection is a different thing. It is used to answer a specific question, whether this joint is the source, when there is a clinical reason to suspect it, and the result guides what happens next. It is not a routine treatment for everyone with back pain, and whether it is appropriate for you will depend on your assessment.
Treatment depends on what we find and on your goals. For many people the first steps are targeted physiotherapy, rehabilitation to build pelvic and hip stability, activity modification and practical changes such as those above. If the joint is confirmed as the source and pain continues despite this, we can discuss further image-guided options with you, along with their benefits and limitations. We do not promise a particular result, and not every treatment is suitable for every patient. Your plan will reflect your diagnosis, medical history and what you want to get back to doing.
We are a private regenerative orthopaedics and sports medicine clinic on Blythe Road in London, founded by Dr Ralph Rogers. We work with a wide range of insurance providers, as well as self-funding patients, so getting a clear answer on where your pain is coming from does not have to wait.
If lower back pain getting out of car, rolling over in bed or standing up from sitting keeps interrupting your week, your assessment gives you a detailed look at which movements set your pain off, an examination of your pelvis, hips and lower spine, image-guided testing where it is clinically appropriate rather than a guess from a scan alone, a plan built around your diagnosis with no pressure to go ahead with any procedure, and the reassurance of Dr Ralph Rogers’s personal involvement in your care. Dr Rogers brings years of image-guided musculoskeletal experience to every assessment, which is why we confirm the source of your pain before recommending treatment.
Putting up with the same sharp catch every time you stand can go on for months without anyone finding the cause, so an earlier answer saves a lot of guesswork.
Booking is simple: fill out our request an appointment form with a short description of your symptoms, and our team will get back to you to arrange a time.
| Service | Indicative Price |
| Initial consultation | From £300 |
| Follow-up consultation | From £215 |
| Sacroiliac joint injection (bilateral) | From £1,850 |
Visit our current fees page for exact, up to date pricing, since costs can vary by hospital location.
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Why does my lower back hurt when I get out of the car?
It is often caused by uneven load and twisting through the pelvis as you stand. This can irritate the SI joint, but disc, facet joint and muscle problems can cause similar pain. If it keeps happening, an assessment can identify the source.
How do I know if my back pain is SI joint or disc?
SI joint pain is usually one-sided, felt low and beside the spine, and triggered by transitions such as getting out of a car or rolling over. Disc pain is more often central and linked to bending or prolonged sitting. No single feature is conclusive, so a clinical examination is needed.
Can SI joint pain feel like sciatica?
Yes, it can refer pain into the buttock, groin and back of the thigh. However, pain that travels below the knee, or comes with numbness, tingling or weakness, points more towards a nerve problem such as sciatica.
Why does my back hurt rolling over in bed?
Rolling twists the pelvis against the spine and loads the SI joint and its ligaments. Keeping your knees together, bending them slightly and placing a pillow between them may reduce the strain.
Dr Rogers has had a rich and illustrious career so far, which is continuing to grow and develop. Everything Ralph has been involved in since qualifying has added value to his knowledge and experience, but there have been some impressive highlights to note:
2018 – Present Founder Medical Director: Rogers Regenerative Medical Group (RRMG)
2012 – 2024 Medical Advisor – National Basketball Association
2008 – 2018 Medical Director: The London Sports Injury Clinic London
2010-2011 First Team Doctor, Chelsea Football Club
2007- 2010 The Football Association (Team Physician for England under 19 and development squads)
2005-2006 Medical Advisor: Trinidad & Tobago World Cup Football Team
2002 – 2008 Club Doctor: Walsall Football Club, West Midlands England
1998 – 2009 Medical Director: Medical & Orthopaedic Sports Therapy,
2000 – 2005 Sports Physician: Warwickshire County Cricket Club, Birmingham
