Sciatica: What It Really Is
and Why Treatment Often Fails

"Sciatica" is one of the most over-used and misunderstood terms in musculoskeletal medicine. In clinical practice, I regularly see patients who have been told they have sciatica, have been living with the diagnosis for months or years, and have received treatments that haven't worked — because the diagnosis, while technically not wrong, was never complete enough to guide effective treatment.

This article explains what sciatica actually is, why it's so frequently under-treated, and what an assessment and treatment approach that actually addresses the cause looks like.

What sciatica actually is

"Sciatica" is a symptom description, not a diagnosis. It describes pain, tingling, numbness, or weakness that travels along the course of the sciatic nerve — typically from the lower back, through the buttock, and down the back of the leg, sometimes reaching the foot. The sciatic nerve is the longest and widest nerve in the body, and when it's compressed or irritated anywhere along its path, it produces these characteristic symptoms.

What causes the compression or irritation is a different question entirely — and this is where most treatment fails. The most common causes include:

• Lumbar disc herniation — a bulging or herniated disc pressing on a nerve root in the lumbar spine (L4, L5, or S1 most commonly)
• Piriformis syndrome — the sciatic nerve runs directly beneath (or in some people, through) the piriformis muscle in the buttock; when this muscle is tight or in spasm, it can compress the nerve
• Facet joint restriction — stiff or inflamed facet joints in the lumbar spine can irritate nearby nerve roots
• Stenosis — narrowing of the spinal canal, more common in older patients
• Sacroiliac joint dysfunction — the SI joint sits immediately adjacent to the sciatic nerve root, and dysfunction here can produce symptoms that closely mimic disc-related sciatica

Why the disc often gets blamed (whether it's the cause or not)

MRI scans are the standard investigation for back pain with leg symptoms. The problem is that disc bulges and herniations are extraordinarily common in the general population — studies show that 30–40% of people with no back pain whatsoever have disc herniations visible on MRI. This means that if you scan a patient with sciatica and find a disc bulge, it's tempting to conclude that the bulge is causing the symptoms. But in many cases, the bulge was there before the symptoms started and isn't the primary driver of the pain.

When a disc bulge receives the diagnosis, treatment is directed at the disc — rest, anti-inflammatory medication, possibly steroid injections, and sometimes surgery. If the disc wasn't actually the main cause of the symptoms, none of these will work particularly well, and the patient is left confused about why they're not improving.

Piriformis syndrome — the most commonly missed cause

The piriformis is a small, deep muscle in the buttock that externally rotates the hip. The sciatic nerve passes directly beneath it in approximately 85% of people, and actually through it in the remaining 15%. When the piriformis becomes tight — which it does readily in people who sit for long periods, run significant mileage, or have a leg length discrepancy — it can compress the sciatic nerve directly.

Piriformis syndrome produces symptoms that are almost identical to disc-related sciatica: pain in the buttock and down the back of the leg, sometimes reaching the foot. What distinguishes it is that the pain tends to be worse with prolonged sitting (especially on hard surfaces), with activities that internally rotate the hip, and is often reproduced by direct pressure on the piriformis in the buttock.

Critically, piriformis syndrome doesn't show up on MRI — MRI images soft tissue and bony structures, not dynamic muscle tension. This is why it gets missed. An experienced clinician can identify it in a thorough physical examination in minutes.

Osteopathic treatment for piriformis syndrome involves direct myofascial release of the piriformis, mobilisation of the sacroiliac joint and hip, and addressing the postural and movement patterns that caused the piriformis to tighten in the first place. Results are typically good and often rapid — many patients with piriformis-driven sciatica see significant improvement within 2–4 sessions.

What a proper assessment looks like

A thorough assessment for sciatica involves more than a review of your MRI. It should include:

• A detailed history — when did it start, what makes it better or worse, is there any bladder or bowel involvement (important red flag), is there a history of trauma
• Neurological assessment — testing sensation, reflexes, and muscle strength in the lower limb to identify if and where nerve compression is occurring
• Movement assessment — lumbar flexion and extension, hip range of motion, provocation tests for SIJ and piriformis
• Palpation — identifying restrictions and tender areas in the lumbar spine, SIJ, piriformis, and surrounding structures
• Review of any imaging — with the understanding that imaging findings are a piece of the puzzle, not the answer in isolation

Can osteopathy help disc herniation?

Yes — with some important caveats. Osteopathic treatment for disc-related sciatica is gentle and targeted; high-velocity manipulation directly at the level of the herniation is generally avoided. Instead, treatment focuses on reducing the mechanical compression and inflammation around the affected disc level, restoring mobility to the levels above and below, releasing the muscular protective spasm that typically develops, and addressing the whole-body postural patterns that contributed to the herniation.

The majority of disc herniations, including those causing significant leg symptoms, resolve without surgery given sufficient time and appropriate conservative management. The evidence for osteopathic and manual therapy approaches in this context is good, and most patients improve meaningfully within 6–12 weeks of consistent treatment.