Why Back Pain Is Not Always a Spine Problem: Understanding the True Sources of Chronic Back Pain

"My back hurts, so something must be wrong with my spine." It is a natural assumption, and it is often the starting point for an MRI scan, a diagnosis based on that scan, and sometimes treatment aimed at whatever the scan happens to show.

But the lower back is a crowded region. Within a few centimetres of each other sit the spinal discs, the small facet joints, powerful muscles and their fascia, the sacroiliac joints that connect the spine to the pelvis, the hip joints, nerves travelling to the legs, and organs such as the kidneys. Pain from any of these can be felt as "back pain". Two patients pointing to the same spot may have completely different problems, and need completely different treatment.

This article explains the main sources of chronic back pain, how they can be told apart, and why a careful clinical examination should come before treatment based on imaging alone.

Key takeaways

• "Back pain" describes a location, not a diagnosis. The pain can come from discs, facet joints, muscles, the sacroiliac joint, the hip, nerves or even internal organs.
• Most chronic low back pain has no single structure that can be blamed with certainty. International guidelines call this "non-specific" or "primary" low back pain, and it responds well to active, non-surgical care.
• MRI findings are common in people without pain. A disc bulge on a scan is not automatically the cause of your symptoms.
• History and physical examination are the foundation of diagnosis. They guide which tests, if any, are useful, and which treatment is likely to help.

Why the source of pain matters

Treatment works best when it is directed at the actual pain generator. An injection into a facet joint will not help pain coming from the sacroiliac joint. Spine surgery will not relieve pain that is really coming from an arthritic hip. And months of passive treatment for a "disc problem" will not help someone whose pain is driven mainly by deconditioned muscles, poor sleep and fear of movement.

The reverse is also true. Recognising that back pain is not coming from a serious structural problem can be reassuring, and reassurance plus active rehabilitation is one of the most effective treatments we have for most chronic back pain.

The spine itself: discs and facet joints

Discogenic pain

The intervertebral discs sit between the vertebrae and act as shock absorbers. With age and repeated loading, the disc can develop small tears in its outer ring and lose height and water content. In some people, an irritated or damaged disc becomes a source of pain in its own right. This is called discogenic pain.

Discogenic pain typically:

• Is felt in the centre of the lower back, sometimes spreading into the buttocks
• Is worse with sitting, bending forward and lifting
• May be eased by lying down or changing position

When a disc herniates and presses on a nerve root, the dominant symptom is usually leg pain (sciatica) rather than back pain. This is an important distinction, because leg-dominant nerve pain and back-dominant disc pain are managed differently.

Facet joint pain

Each vertebra connects to the one below through a pair of small joints at the back of the spine, called the facet joints (zygapophyseal joints). Like any joint, they can develop arthritis. Facet joint pain is estimated to account for a meaningful share of chronic low back pain, with published estimates ranging widely depending on the population studied and the diagnostic method used [4].

Facet joint pain often:

• Is felt to one or both sides of the lower spine, sometimes spreading into the buttock or upper thigh
• Is worse with leaning backwards, twisting, or standing for long periods
• Is stiff in the morning and after rest

No single examination finding reliably confirms facet pain. When it is suspected and does not respond to rehabilitation, a diagnostic medial branch block, a small injection of local anaesthetic onto the nerves that supply the joint, can confirm whether the facet joints are the source before longer-lasting treatments such as radiofrequency ablation are considered.

Muscles, fascia and myofascial trigger points

The muscles of the back, buttocks and hips work constantly to keep us upright. They can be strained by sudden loads, overworked by sustained postures, or weakened by inactivity. In chronic back pain, muscles are frequently involved, either as a primary source of pain or as a reaction to pain elsewhere.

Myofascial pain is pain arising from muscle and its surrounding connective tissue (fascia). It is often associated with myofascial trigger points: tender, taut bands within a muscle that can reproduce a patient's familiar pain when pressed, and can refer pain to distant areas [5].

Common examples in the low back region include:

• Quadratus lumborum, a deep muscle between the lowest rib and the pelvis, which can refer pain to the flank, buttock and hip
• Gluteus medius and minimus, which can refer pain down the side or back of the thigh and mimic sciatica
• Piriformis, a deep buttock muscle close to the sciatic nerve
• Paraspinal muscles running alongside the spine

Myofascial pain is real, common and treatable, but it is easy to miss if diagnosis relies only on scans, because muscles and trigger points do not show up as abnormalities on a routine MRI. It is identified by a careful hands-on examination.

The sacroiliac (SI) joint

The two sacroiliac joints connect the base of the spine (the sacrum) to the pelvis. They are strong, have only a small amount of movement, and transfer load between the upper body and the legs. A review in *Anesthesia & Analgesia* estimated that the SI joint is the primary source of pain in roughly 15–30% of people with chronic mechanical low back pain [3].

SI joint pain:

• Is usually felt below the belt line, over the dimple at the back of the pelvis, on one side
• Can spread into the buttock, groin or back of the thigh, and occasionally below the knee
• Is often worse with standing on one leg, climbing stairs, rolling over in bed, or getting in and out of a car
• Is more common after falls onto the buttocks, during and after pregnancy, after lumbar fusion surgery, and in inflammatory conditions such as ankylosing spondylitis

Because its pain pattern overlaps with disc and facet problems, the SI joint is frequently overlooked. A cluster of specific provocation tests during examination can make SI joint pain more or less likely, and an image-guided diagnostic injection can help confirm it.

The hip: when "back pain" is really a joint problem

Hip osteoarthritis and other hip problems are classic mimics of back pain. The hip joint is supplied by nerves from the same spinal levels as the lower back, so its pain can be felt in the buttock, groin, front of the thigh and sometimes the knee.

Clues that the hip may be involved include:

• Groin pain, or pain in the front of the thigh
• Stiffness putting on socks and shoes, or getting out of a car
• Limping, or pain with walking that is felt deep in the hip
• Reduced and painful rotation of the hip during examination

Hip and spine problems often coexist in older adults. When both are present, deciding which one is driving the symptoms is essential before considering surgery on either. A simple examination of hip movement, which takes less than a minute, can prevent the wrong problem being treated.

Nerves: radicular pain and beyond

When a nerve root is compressed or inflamed, by a disc herniation or spinal stenosis for example, the resulting radicular pain usually travels down the leg in a band-like pattern, often with tingling, numbness or weakness. Patients sometimes describe this as "back pain", but the leg symptoms are usually the more important clue.

Other nerve problems can mimic back or leg pain, including entrapment of nerves around the buttock or groin, and peripheral neuropathy from conditions such as diabetes. Testing reflexes, sensation and strength during examination helps localise the problem.

Referred pain from internal organs

Occasionally, pain felt in the back comes from an organ rather than the musculoskeletal system. This is uncommon in a specialist back pain clinic, but it is important not to miss. Examples include:

• Kidney stones and kidney infection, typically causing flank pain, sometimes with fever or urinary symptoms
• Abdominal aortic aneurysm, a widening of the main artery in the abdomen, particularly in older male smokers
• Pancreatic and other abdominal conditions
• Gynaecological conditions such as endometriosis

Pain that does not change with movement or position, pain with fever, unexplained weight loss, or pain alongside abdominal or urinary symptoms should prompt a broader medical assessment.

The bigger picture: chronic pain is more than a structure

Chronic pain is not simply a signal from a damaged tissue. Over time, the nervous system itself can become more sensitive, so that the same input produces more pain. Sleep, stress, mood, fear of movement and previous pain experiences all influence how much pain we feel and how much it limits us [6].

This does not mean the pain is "in your head". It means effective care addresses both the physical source and the factors that keep pain going. This is why the 2023 WHO guideline on chronic low back pain emphasises comprehensive, person-centred assessment and care that considers physical, psychological and social factors together [1].

Why examination should come before MRI-based treatment

MRI is a powerful tool, but it has a major limitation: many abnormalities it shows are also common in people without any pain. A systematic review of over 3,000 people without back pain found that disc degeneration, disc bulges and facet arthritis become increasingly common with age, and are present in a large proportion of pain-free older adults [7].

If treatment is chosen on the basis of the scan alone, there is a real risk of treating a finding that is not causing the symptoms, while the true source, perhaps the SI joint, the hip or a muscle, is missed.

A careful clinical assessment includes:

1. A detailed history: where the pain is, how it started, what makes it better or worse, whether it travels into the leg, and how it affects sleep, work and mood
2. Screening for warning signs that need urgent investigation
3. Observation of posture and movement, including how you bend, walk and stand on one leg
4. Examination of the spine, SI joints and hips, including specific provocation tests
5. A neurological examination of strength, reflexes and sensation
6. Palpation of muscles for tenderness and trigger points

Only then can imaging be requested appropriately, and interpreted in the context of the patient in front of us. In many cases of chronic back pain without warning signs, the examination itself provides the information needed to start effective treatment. The American College of Physicians advises against routine imaging for non-specific low back pain [8].

Red flags that need prompt medical attention

Seek urgent medical care if back pain comes with loss of bladder or bowel control, numbness around the groin, progressive leg weakness, fever, unexplained weight loss, a history of cancer, or follows a significant injury.

How treatment differs by source

Once the likely sources have been identified, treatment can be targeted:

• Non-specific or primary chronic low back pain: education, a structured exercise programme, and addressing sleep, activity and fear of movement form the core of care [1][2]
• Myofascial pain: targeted physiotherapy, stretching and strengthening, and in selected cases trigger point injections or dry needling as part of a broader plan
• Facet joint pain: rehabilitation first; diagnostic medial branch blocks and radiofrequency ablation in carefully selected patients
• SI joint pain: pelvic and hip stabilisation exercises; image-guided SI joint injection in selected cases
• Hip-related pain: management directed at the hip, from exercise to injection or joint replacement where appropriate
• Nerve root (radicular) pain: activity modification, medication for nerve pain, physiotherapy, epidural injections and, where needed, surgery

Frequently asked questions

My MRI shows a disc bulge. Isn't that the cause of my pain?

It may be, but not necessarily. Disc bulges are very common in people with no pain at all. Whether a bulge is relevant depends on whether it matches your symptoms and examination findings.

Can a muscle problem really cause months of pain?

Yes. Myofascial pain and deconditioned, overloaded muscles are common contributors to chronic back pain. They often improve well with a structured rehabilitation programme.

How can I tell if my pain is from the hip rather than the back?

Groin pain, pain in the front of the thigh, and stiffness putting on shoes or socks point towards the hip. A simple examination of hip movement can usually clarify this.

Do I need an injection to find out where my pain comes from?

Not usually. Most patients can be diagnosed and treated with history, examination and, where needed, imaging. Diagnostic injections are reserved for selected patients when it would change treatment, for example before radiofrequency ablation.

The bottom line

Back pain is a symptom with many possible sources: the discs, facet joints, muscles and fascia, the sacroiliac joints, the hips, the nerves, and occasionally internal organs. Effective treatment starts with understanding which of these is responsible, and that begins with listening to the patient and examining them carefully, not with the scan alone.

If you have back pain that has lasted more than a few weeks, keeps returning, or has not improved with treatment directed at your "spine", a thorough specialist assessment may reveal a different, and more treatable, source.

References

1. World Health Organization. WHO guideline for non-surgical management of chronic primary low back pain in adults in primary and community care settings. 2023.
2. Foster NE, et al. Prevention and treatment of low back pain: evidence, challenges, and promising directions. Lancet. 2018.
3. Cohen SP. Sacroiliac joint pain: a comprehensive review of anatomy, diagnosis, and treatment. Anesth Analg. 2005.
4. Cohen SP, Raja SN. Pathogenesis, diagnosis, and treatment of lumbar zygapophysial (facet) joint pain. Anesthesiology. 2007.
5. Shah JP, et al. Myofascial trigger points then and now: a historical and scientific perspective. PM R. 2015.
6. Vlaeyen JWS, Linton SJ. Fear-avoidance model of chronic musculoskeletal pain: 12 years on. Pain. 2012.
7. Brinjikji W, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015.
8. Chou R, et al. Diagnostic imaging for low back pain: advice for high-value health care from the American College of Physicians. Ann Intern Med. 2011.