Piriformis Syndrome

How piriformis syndrome happens

The piriformis muscle runs from the lower spine (sacrum) to the top of the thigh bone and helps rotate the hip outward. The sciatic nerve, the largest nerve in the body, passes beneath it, and in some people runs through it. When the piriformis is tight, swollen, in spasm or injured, it can irritate the nerve, producing pain that spreads down the leg.

Piriformis syndrome is now often considered part of a broader deep gluteal syndrome, which includes other muscles and structures in the buttock that can trap the sciatic nerve.

Causes and risk factors

• prolonged sitting, especially on hard surfaces or with a wallet in the back pocket
• running, cycling, rowing and sports with repetitive hip rotation
• climbing stairs or hills
• direct trauma, such as a fall on the buttocks
• muscle imbalances, weak hip abductors and gluteal muscles
• leg length differences or foot overpronation
• anatomical variants where the nerve passes through the muscle
• more common in women

Symptoms

• deep, aching pain in one buttock
• pain, tingling or numbness spreading down the back of the thigh, sometimes below the knee
• pain worse with sitting for more than 15 to 20 minutes
• pain when getting up from sitting, climbing stairs or squatting
• tenderness deep in the buttock
• pain when crossing the affected leg over the other knee
• relief when lying on the back or walking

Back pain is usually minimal or absent, which can help distinguish it from spine problems.

Piriformis syndrome vs sciatica from the spine

See sciatica and herniated disc.

Diagnosis

There is no single definitive test. A doctor or physical therapist will:

• ask about symptoms and activities
• press on the piriformis to check for tenderness
• perform stretch tests (such as FAIR: flexion, adduction, internal rotation of the hip) that reproduce pain
• check strength, sensation and reflexes
• order an MRI of the lower spine if symptoms suggest a disc problem or do not improve
• sometimes use MRI of the pelvis or nerve conduction studies

Other causes considered include sacroiliac joint dysfunction, spinal stenosis, hip joint problems and hamstring tendon injuries.

Treatment

Self-care

• avoid prolonged sitting; stand and walk every 20 to 30 minutes
• remove your wallet from your back pocket
• sit on a cushioned seat
• ice for 15 minutes in the first days, then heat to relax the muscle
• reduce running, stairs and hill training temporarily
• NSAIDs or acetaminophen (paracetamol) for pain, following the label dose

Piriformis stretches

Hold each stretch for 30 seconds, repeat 3 times, 2 to 3 times a day:

1. Supine piriformis stretch: lie on your back, cross the affected ankle over the opposite knee, then pull the uncrossed thigh toward your chest.
2. Knee to opposite shoulder: lie on your back and pull the affected knee toward the opposite shoulder.
3. Seated stretch: sit with the affected ankle on the opposite knee and lean forward with a straight back.

Stretches should cause a gentle pull, not sharp pain.

Physical therapy

• strengthening of hip abductors, external rotators and core
• correcting running technique and muscle imbalances
• soft tissue massage and nerve gliding exercises

Injections and procedures

• corticosteroid or local anesthetic injections into the piriformis, usually guided by ultrasound
• botulinum toxin injections for persistent cases
• surgery (piriformis release) is rarely needed, for severe, persistent cases with confirmed nerve entrapment

Outlook

Most people improve within a few weeks to a few months with stretching, physical therapy and activity changes. Recurrences are common if the triggers continue, so long-term stretching and strengthening help.

Frequently asked questions

What are the symptoms of piriformis syndrome?

The main symptoms are a deep ache in one buttock and pain, tingling or numbness down the back of the thigh. Symptoms worsen with sitting, climbing stairs and running, and ease with lying down or walking. Back pain is usually minimal.

How is piriformis syndrome different from sciatica?

Sciatica is a symptom: pain along the sciatic nerve. It is most often caused by a herniated disc in the spine. Piriformis syndrome is one cause of sciatica, where the nerve is irritated in the buttock rather than at the spine.

What is the best stretch for piriformis syndrome?

A common effective stretch is lying on your back, crossing the affected ankle over the opposite knee and pulling the opposite thigh toward your chest. Hold for 30 seconds and repeat several times daily. A physical therapist can tailor stretches to you.

How long does piriformis syndrome take to heal?

Many people improve within 2 to 6 weeks with stretching, physical therapy and activity changes. Some cases take several months. Persistent symptoms may need injections or further investigation.

Can sitting cause piriformis syndrome?

Prolonged sitting, especially on hard seats or with a wallet in your back pocket, can compress the piriformis and sciatic nerve and trigger or worsen symptoms. Taking frequent breaks and using a cushion help.