What is hip-spine syndrome?
Hip-spine syndrome means a hip problem (most often arthritis) and a lower back problem in the same person. It was first described by Offierski and MacNab in 1983.
The two can mimic each other. Finding the main source of pain matters, because treating the wrong one may not help.
The pelvis is the link
Think of the pelvis as a bowl. When you stand, it can tip backward or forward. The lower back curve follows the bowl, and so does the angle of the hip socket.
Each person's pelvis has a fixed shape, measured as the pelvic incidence. It does not change after growth. It sets how much curve the lower back needs to stay balanced. What changes is the tilt: how far the pelvis rotates around the hips.
Side view, facing right. Same pelvis shape in all three; only the tilt and the spinal curves change. Illustrations are simplified and not to an exact scale.
Pattern 1: Pelvic retroversion (posterior pelvic tilt) with lumbar flat back
What it looks like
- Pelvis tucked under, buttocks flat
- Lower back flat instead of gently curved inward
- Upper body and head lean forward
- Hips held straight, knees often slightly bent
Why it happens
The lower back has lost its normal curve. Common reasons are wear of the discs with age, weak back muscles, or a past spinal fusion that left the lower back flat. To stand upright, the body tilts the pelvis back and bends the knees. This is a compensation, and it costs muscle effort all day. When it becomes fixed, it is called flat back syndrome.
What people notice
- Back and buttock ache that builds after standing or walking a short distance
- Leaning on a trolley or bending forward to keep going
- Neck and upper back strain from lifting the head to look ahead
Pattern 2: Pelvic anteversion (anterior pelvic tilt) with lumbar hyperlordosis and thoracolumbar kyphosis
What it looks like
- Pelvis tipped forward, buttocks pushed back, belly forward
- Deep inward curve of the lower back (sway back)
- A rounded section where the mid back meets the lower back
- Hip does not fully straighten when standing
Why it happens
- A stiff, arthritic hip that cannot straighten fully (flexion contracture) pulls the pelvis forward when you stand. The lower back arches to keep you upright.
- A rounded thoracolumbar junction, for example from an old compression fracture, osteoporosis or Scheuermann's disease, tips the body forward. The lower back arches more below it to compensate.
- Tight hip flexors and weak buttock and tummy muscles add to it.
Why standing strains the iliopsoas
The iliopsoas is the main muscle that bends the hip. Its psoas part starts on the sides of the lumbar spine (T12 to L4). Its iliacus part starts on the inside of the pelvis. Both end on a small knob at the top of the thigh bone (the lesser trochanter).
When the hip is stiff or the muscle is tight, standing up straight stretches it. It cannot lengthen enough, so it pulls the lumbar vertebrae forward and tips the pelvis forward. This deepens the lower-back curve and keeps the muscle under strain the whole time you stand. Sitting bends the hip and slackens the muscle, which is why the back often feels better sitting.
What people notice
- Lower back pain on standing and on arching backward, eased by sitting or bending forward
- Leg pain or tingling if a nerve exit becomes narrowed
- Groin pain and a short stride from the stiff hip
X-ray examples. Standing side X-rays of the whole spine, both patients facing right. The dashed line traces the outline of the back. Compare the position of the pelvis and the shape of the curve where the mid and lower back meet.
The two patterns side by side
| Pelvis tilted back (retroversion) | Pelvis tilted forward (anteversion) | |
|---|---|---|
| Lower back | Flat (loss of lordosis) | Over-arched (hyperlordosis) |
| Mid back | Often normal; upper body leans forward | Rounded thoracolumbar junction (kyphosis) |
| Common causes | Disc wear, weak back muscles, flat fusion | Stiff arthritic hip, old fracture at T12–L1, tight hip flexors |
| Typical complaint | Tires quickly standing; leans forward to walk | Back pain on standing and arching; eased by sitting |
| Hip socket | Less front coverage | More front coverage; pinching on deep bending |
Try it: change the sacral slope
(tilted back)NormalHigh slope
(tilted forward)
Balanced: the lower-back curve matches the pelvis, and the head sits over the hips with little effort.
Is my pain from the hip or the spine?
These clues help, but many people have both. Examination and imaging sort it out.
| More likely the hip | More likely the spine |
|---|---|
| Groin pain, sometimes to the front of the knee | Lower back and buttock pain |
| Pain putting on socks or shoes, getting out of a car | Pain, numbness or tingling below the knee |
| Pain when the hip is rotated | Worse standing or walking, eased by sitting or leaning forward |
| Limp and stiffness after rest | Weakness in the leg or foot |
How it is assessed
- Examination of hip movement, a tight hip front (Thomas test), nerve function and standing posture.
- Standing X-ray of the whole spine and hips to measure pelvic tilt and the spinal curves.
- Sitting and standing side X-rays to see how much the pelvis moves between positions. This matters before a hip replacement.
- MRI of the spine if there are nerve symptoms.
- Hip joint injection with local anaesthetic. If the pain goes away for a few hours, the hip is likely the main source.
Treatment
- Exercise and physiotherapy matched to your pattern. A flat back benefits from strengthening the back and buttock muscles. A forward-tilted pelvis benefits from stretching the hip flexors and strengthening the buttocks and core.
- Pain relief, weight management and activity changes while the muscles build up.
- Injections to confirm the source and ease pain.
- Surgery when needed. If both the hip and spine need surgery, the order is decided case by case. Nerve compression with leg weakness may need the spine treated first.
When to see a doctor
See a doctor if hip or back pain lasts more than a few weeks or stops you walking. Seek care urgently for:
- New bladder or bowel problems
- Numbness around the groin or buttocks
- Leg weakness that is getting worse
- Fever, unexplained weight loss or night pain
Frequently Asked Questions (FAQ)
1. Can a hip problem cause back pain?
Yes. A stiff hip changes how the pelvis sits, which changes the lower back curve. This can load the back joints and cause pain.
2. Will fixing my hip help my back?
Sometimes. Back pain often eases after hip replacement in people with both problems, but not always. It depends on how much of the pain comes from the spine itself.
3. Is posture training enough?
For mild cases, a targeted exercise programme can help a lot. Fixed changes, such as advanced arthritis or a rigid spinal curve, may need further treatment.
4. Why do I need X-rays standing up?
Pelvic tilt and spinal balance only show when you bear weight. Lying-down scans do not show them.
5. What is hip-spine syndrome?
Hip-spine syndrome is a hip problem, most often arthritis, and a lower back problem in the same person. The pelvis links them, so each changes how the other works, and their pain can feel alike.
6. Can anterior pelvic tilt cause lower back pain?
It can. When the pelvis tips forward, the lower back arches more. The deeper arch loads the small facet joints at the back of the spine and can narrow the nerve exits. A tight iliopsoas muscle often adds to it.
7. What is flat back syndrome?
Flat back means the lower back has lost its normal inward curve. To stay upright, the pelvis tilts back and the knees bend. People tire quickly when standing and tend to lean forward.
8. What is sacral slope?
Sacral slope is the angle between the top of the sacrum (the base of the spine) and a horizontal line, measured on a standing side X-ray. A low slope means the pelvis is tilted back; a high slope means it is tilted forward.
Related reading
References
- Offierski CM, MacNab I. Hip-spine syndrome. Spine. 1983;8(3):316–321.
- Legaye J, Duval-Beaupère G, Hecquet J, Marty C. Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves. Eur Spine J. 1998;7(2):99–103.
- Lazennec JY, Brusson A, Rousseau MA. Hip-spine relations and sagittal balance clinical consequences. Eur Spine J. 2011;20(Suppl 5):686–698.
Need help with hip or back pain?
If hip or lower back pain lasts more than a few weeks, an assessment with standing X-rays can show where it is coming from and what can be done.
Disclaimer: This article provides general medical information and is not a substitute for personalised assessment. Individual conditions vary. Please seek professional medical advice for diagnosis and treatment.