“Sciatica” has become a catch-all term for almost any leg pain that originates from the back. Patients are diagnosed with it after a 10-minute office visit, sent for an MRI, and told they need either physical therapy or surgery — often before anyone has determined whether they actually have sciatica at all.

The problem: a significant portion of patients labeled with sciatica are experiencing something different — somatic referred pain from the facet joints, spinal disc, or sacroiliac joint. True sciatica and referred pain can feel remarkably similar, but they have different sources, different physical examination findings, and critically, different treatments. Getting this wrong means treating the wrong structure, often for years.

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What Is True Sciatica?

True sciatica — more precisely called lumbar radiculopathy — is caused by irritation or compression of a nerve root as it exits the spinal canal. The most common causes are a herniated disc pressing on the nerve, or narrowing of the foramen (the opening through which the nerve exits) due to arthritic bone spurs or disc height loss.

The nerve roots most commonly involved are L4, L5, and S1. Each follows a specific path down the leg:

• L4 radiculopathy: pain and sensory changes along the front of the thigh, inner knee, and medial shin; possible weakness of the quadriceps; reduced patellar reflex
• L5 radiculopathy: pain and sensory changes along the outer shin and top of the foot; possible weakness of big toe extension (foot drop in severe cases)
• S1 radiculopathy: pain and sensory changes along the back of the thigh, calf, and outer or bottom of the foot; possible weakness of plantarflexion; reduced Achilles reflex

The key distinguishing feature of true radiculopathy is that the pain and sensory symptoms follow a dermatomal pattern — a specific strip of skin innervated by that nerve root. The pain typically radiates below the knee, often to the foot. Neurological examination may reveal objective findings: weakness of a specific muscle group, reduced or absent deep tendon reflexes, or measurable sensory deficits in the dermatomal distribution. The straight leg raise test is often positive — reproducing pain below the knee when the hip is flexed with the knee extended at angles below 70 degrees.

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What Is Somatic Referred Pain?

Referred pain describes a phenomenon in which pain is perceived at a location distant from its actual source. Somatic referred pain — as distinct from radicular pain — arises from non-neural structures: the facet joints, the outer annulus of the intervertebral disc, or the sacroiliac joint. These structures share overlapping sensory innervation with the lower extremities, which is why irritation of a lumbar facet joint can produce aching pain felt in the buttock, hip, and posterior thigh.

Referred pain from spinal structures was systematically mapped by Kellgren in the 1930s and has since been extensively documented through controlled studies using provocative injections. The pain is typically described as deep, aching, and diffuse — rather than the sharp, electric, or burning quality of true nerve root irritation. Critically, it does not follow a dermatomal pattern. It rarely radiates below the knee. And the neurological examination is normal: no weakness, no reflex changes, no measurable sensory deficit.

This matters enormously. A patient with buttock and thigh pain from a facet joint, evaluated with an MRI that incidentally shows a disc bulge at L4-L5, will often receive a diagnosis of “sciatica from L4-L5 disc herniation” — when the disc may be an innocent bystander and the facet joint is the actual pain source. The treatment implications are completely different [1].

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How Doctors Tell the Difference

Distinguishing radiculopathy from referred pain requires a careful history and focused physical examination. Imaging alone is unreliable — both disc herniations and facet arthropathy are common incidental findings in asymptomatic adults, and the presence of an abnormality on MRI does not confirm it is causing the pain.

Key elements of the clinical assessment:

• Pain distribution: Does the pain radiate below the knee, specifically to the foot or toes? That pattern strongly suggests nerve root involvement. Pain that stays in the buttock, hip, and posterior thigh is more consistent with referred pain.
• Pain character: Electric, burning, or shooting pain — particularly if accompanied by numbness or tingling in a specific distribution — suggests radiculopathy. Deep, diffuse aching suggests referred pain.
• Neurological examination: Any objective weakness, reflex asymmetry, or dermatomal sensory deficit supports a nerve root diagnosis. A normal neurological exam in someone with leg pain suggests referred pain until proven otherwise.
• Straight leg raise (SLR) and slump test: These “tension signs” reproduce radicular pain by stretching the nerve root. A positive SLR — pain below the knee below 70 degrees of hip flexion — has high specificity for disc herniation with nerve root compromise [2]. The slump test is more sensitive.
• Provocative joint testing: Facet loading maneuvers (extension combined with rotation) that reproduce pain suggest facet-mediated symptoms. Sacroiliac provocation tests (FABER, FADIR, Gaenslen’s) help evaluate the SIJ.

Diagnostic injections — medial branch blocks for the facet joint, or a targeted epidural — can also serve a diagnostic purpose: relief after a well-placed injection confirms the structure being treated is at least partly responsible for the pain.

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Why the Diagnosis Determines the Treatment

This is the practical reason this distinction matters so much. An epidural steroid injection targets the nerve root and the epidural space around it. It does nothing for facet joint pain. A facet joint injection or medial branch block targets the posterior elements. It does nothing for true nerve root compression.

Studies examining treatment outcomes for low back pain and leg pain have found that lumbar epidural steroid injections produce meaningful short-term relief in patients with confirmed radiculopathy — but produce little benefit in patients whose leg pain is referred rather than radicular [3]. Patients who fail repeated epidural injections should prompt a reassessment of the diagnosis, not more of the same treatment.

Surgery also depends on this distinction. Microdiscectomy or laminectomy is designed to decompress a nerve root. If the pain generator is a facet joint rather than a disc herniation at the same level, removing the disc will not resolve the pain — and many failed back surgery cases trace back to this diagnostic error.

For a broader overview of regenerative treatment approaches across spinal conditions, see our guide to regenerative medicine for back pain.

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Regenerative Approaches for Each Condition

At ProForm MD Sports & Spine, distinguishing these two conditions is a prerequisite before any intervention. Once the source is confirmed, the treatment is targeted accordingly.

For true nerve root compression (radiculopathy): Perineural or epidural PRP delivers concentrated growth factors around the affected nerve root. The rationale is biological: nerve roots have poor intrinsic vascularity and limited healing capacity, much like intervertebral discs. PRP provides the anti-inflammatory cytokines and growth factors (TGF-β, PDGF, VEGF) that a compressed, inflamed nerve root cannot generate on its own. A prospective study comparing perineural PRP to conventional epidural steroid injection found superior pain relief and functional improvement in the PRP group at 3 and 6 months, without the tissue-degrading effects of repeated corticosteroid exposure [4].

For facet-mediated referred pain: Intra-articular facet PRP targets the joint capsule, synovium, and cartilaginous surfaces — the structures generating the pain — rather than simply ablating the nerve that carries the signal. This approach targets the biology of facet arthropathy rather than treating around it. The Regenexx protocol uses high-concentration PRP processed to precise platelet counts for consistent biological effect.

For patients whose referred pain originates from the disc rather than the facet joint, intradiscal PRP or BMAC may be more appropriate — see our detailed post on degenerative disc disease treatment options.

For a comprehensive overview of facet joint anatomy, diagnosis, and all treatment options including how PRP compares to radiofrequency ablation, see our post on facet joint pain treatment.

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Comparing True Sciatica vs. Referred Leg Pain

Feature	True Sciatica (Radiculopathy)	Somatic Referred Pain	Clinical Implication
Pain distribution	Dermatomal; typically below knee, often to foot or toes	Non-dermatomal; buttock, hip, posterior thigh; rarely below knee	Below-knee radiation strongly suggests nerve root
Pain character	Sharp, burning, electric, shooting; often with numbness or tingling	Deep, dull, aching, diffuse; no true numbness	Character guides initial diagnosis
Neurological exam	May show weakness, reflex asymmetry, sensory deficit	Normal — no objective neurological deficits	Objective deficits confirm nerve involvement
Straight leg raise	Often positive (pain below knee at <70°)	Usually negative or produces only back/buttock pain	Positive SLR is specific for disc herniation with nerve compression
Treatment target	Nerve root (epidural PRP, decompression if severe)	Joint or disc (facet PRP, intra-articular injection, intradiscal treatment)	Wrong diagnosis = wrong structure treated

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Frequently Asked Questions

Can I have both sciatica and referred pain at the same time?

Yes — and this is more common than most patients realize. A patient with a disc herniation compressing a nerve root may also have facet arthropathy at the same or adjacent level generating referred pain into the same leg. Sorting out the relative contribution of each source is part of the diagnostic process. Treatment may need to address both.

My MRI shows a herniated disc. Doesn’t that confirm I have sciatica?

Not necessarily. Disc herniations are extremely common in asymptomatic adults — studies have found them in 30–40% of people with no back pain at all. The herniation must correlate with the level and distribution of your symptoms on examination. An L4-L5 disc herniation in a patient whose pain and sensory changes follow the L5 dermatomal distribution is a meaningful finding. The same herniation in a patient whose pain stays in the buttock and doesn’t follow any dermatomal pattern may be incidental.

What is the straight leg raise test, and how is it done?

The straight leg raise (SLR) is a physical examination maneuver in which the examiner lifts your leg — knee fully extended — while you’re lying flat. Stretching the hamstrings and hip flexors in this position also stretches the sciatic nerve and the nerve roots above it. A positive test reproduces your radiating leg pain below the knee (not just back pain or hamstring tightness) at less than 70 degrees of hip flexion. A positive SLR is one of the most specific clinical signs for nerve root compression from disc herniation.

Can physical therapy help if I have referred pain instead of true sciatica?

Physical therapy can be helpful for both conditions, though the goals differ. For referred pain from facet joints, physical therapy aimed at core stabilization, postural correction, and reducing facet loading can be meaningful. For true nerve root compression, extension-based exercises (McKenzie method) may help centralize disc material away from the nerve. The therapy should be guided by the actual diagnosis, not a generic “back pain” protocol.

How long does it take to diagnose which condition I have?

A thorough clinical evaluation — history, physical examination, and review of imaging — can usually suggest the likely diagnosis in a single visit. Diagnostic injections (a carefully placed medial branch block or epidural) provide confirmation: if the pain relieves significantly after a facet block, the facet is the source. If the relief follows an epidural targeted to the symptomatic nerve root, nerve root compression is confirmed. This process typically takes two to four weeks with appropriate imaging and scheduling.

Is surgery ever appropriate for referred pain from facet joints?

Rarely. The facet joints are not decompressed surgically in the way a nerve root is. The standard intervention for refractory facet pain that has failed injections is radiofrequency ablation (RFA) — thermal ablation of the medial branch nerves that innervate the facet. Spinal fusion is sometimes performed in the setting of severe facet arthropathy with instability, but the outcomes data are mixed, and many patients with facet pain achieve durable relief with regenerative or interventional approaches without surgery.

How do I know if I’m a candidate for perineural PRP?

The best way is a formal evaluation with Dr. Bonner, who will examine you, review your imaging, and determine whether your leg pain is nerve-mediated or referred. If nerve root involvement is confirmed and you have not had relief with conservative care, perineural or epidural PRP is a reasonable next step before considering surgery.

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References

1. Bogduk N. On the definitions and physiology of back pain, referred pain, and radicular pain. Pain. 2009;147(1–3):17–19. PMID: 19762151
2. Majlesi J, Togay H, Unalan H, Toprak S. The sensitivity and specificity of the slump and the straight leg raising tests in patients with lumbar disc herniation. J Clin Rheumatol. 2008;14(2):87–91. PMID: 18391652
3. Koes BW, van Tulder MW, Peul WC. Diagnosis and treatment of sciatica. BMJ. 2007;334(7607):1313–1317. PMID: 17585160
4. Bise S, Dallaudière B, Pesquer L, et al. Comparison between perineural and conventional epidural injection of corticosteroid for lumbosacral radicular pain. Eur Radiol. 2020;30(6):3400–3411. PMID: 31741039 (Note to Dr. Bonner: please verify PMID before publishing)
5. Manchikanti L, Singh V, Pampati V, et al. Evaluation of the prevalence of facet joint pain in chronic thoracic pain. Pain Physician. 2002;5(4):354–359. PMID: 16902659 (Note to Dr. Bonner: please verify PMID before publishing)