Piriformis Syndrome

The piriformis is a small muscle located deep in the buttock that runs from the sacrum to the greater trochanter of the femur. It plays an important role in external rotation and stabilisation of the hip. The sciatic nerve runs immediately beneath (and in some individuals, through) the piriformis muscle on its way from the pelvis into the back of the thigh.

Piriformis syndrome occurs when the piriformis muscle becomes tight, inflamed or spasms, and irritates or compresses the sciatic nerve. This causes pain in the buttock that may radiate down the back of the leg, mimicking the symptoms of sciatica from a lumbar spine problem. It is more common in women than men and is often seen in runners, cyclists, and people whose occupation involves prolonged sitting.

Common causes and predisposing factors include:

• Prolonged sitting, particularly on hard surfaces or with a wallet in the back pocket

• Direct trauma to the buttock or a fall onto the buttock

• Overuse from running, cycling or repetitive lower limb activity

• Muscle imbalance or weakness of the hip abductors and external rotators

• Anatomical variants in which the sciatic nerve passes through or around the piriformis muscle

• Leg length discrepancy or abnormal lower limb biomechanics

• Following hip or pelvic surgery

Symptoms may include:

You should consider seeing a knee specialist if:

Early assessment can help identify the cause of your symptoms and determine whether treatment can prevent further joint damage.

Treatment might include surgical and nonsurgical treatments:

Non-surgical treatment: the vast majority of patients improve with a structured non-operative program. This includes activity and posture modification, avoiding prolonged sitting and aggravating activities, and a tailored physiotherapy program focused on stretching the piriformis muscle, strengthening the hip abductors and external rotators, and correcting lower limb biomechanics. Anti-inflammatory medications, muscle relaxants and neuropathic pain medications may be prescribed. Image-guided injections of corticosteroid, local anaesthetic or botulinum toxin into the piriformis muscle can provide significant relief when conservative measures are not enough.

Surgery: is rarely required and is reserved for the small group of patients with persistent, disabling symptoms despite prolonged and comprehensive non-operative treatment, and where other causes of sciatic pain have been confidently excluded. Surgical options include open or endoscopic release of the piriformis muscle and decompression of the sciatic nerve.