Pain below the kneecap has many causes — patellofemoral pain, knee arthritis, and tendonitis among them. A less common cause is saphenous nerve entrapment close to the knee, which can cause significant discomfort and reduced mobility. So what causes saphenous nerve pain, and how is it treated?

What is the saphenous nerve?

saphenous nerve anatomy lower leg

The saphenous nerve is a branch of the femoral nerve at the front of the thigh. It starts above the inside of the knee and runs down to the inner shin and foot, providing sensation to the inner side of the knee, leg, and foot. It’s a purely sensory nerve, so entrapment causes pain and altered sensation rather than weakness.

Causes of saphenous nerve entrapment

There are several potential causes:

  • Trauma or injury — direct trauma to the knee, thigh, or shin (from sport or accidents) can bruise the nerve, and ankle sprains or prolonged kneeling can stretch or irritate it.
  • Surgery — knee arthroscopy, total knee replacement, and vein harvesting for coronary bypass grafting can all inadvertently injure the saphenous nerve.
  • Compression or entrapment—scar tissue or adhesions at specific sites, particularly the adductor canal of the lower thigh (Hunter’s canal) —can trap the nerve.
  • Inflammation — nearby conditions such as knee arthritis or tendinitis may irritate the nerve.
  • Neuritis — conditions such as diabetes or peripheral neuropathy increase susceptibility to nerve pain.

Saphenous nerve pain symptoms

Saphenous nerve pain shows up as sensory changes, which may include:

  • Burning, sharp, or aching pain along the inner thigh, knee, or shin — often worse with bending the knee, walking, or kneeling
  • Pins-and-needles or numbness on the inside of the knee, shin, or foot
  • Sometimes, there is increased sensitivity to light touch or pressure

Saphenous nerve pain location

People often point to the inner aspect of the knee, just below the kneecap. Sometimes the pain spreads to the inner shin or foot.

How to diagnose saphenous nerve entrapment

Saphenous nerve entrapment is often hard to distinguish from other causes of inner knee pain, such as knee arthritis, pes anserine bursitis, or patellar tendonitis.

Your doctor takes a thorough history, including any trauma or recent surgery. Examination reveals focal tenderness over the inner thigh, knee, or shin, and tapping the nerve (percussion tenderness, a Tinel’s sign) reproduces the pain.

Investigations confirm entrapment and exclude other causes:

  • Ultrasound can visualise the nerve and identify compression, swelling, or injury, as well as possible causes such as arthritis, tendinitis, or scar tissue.
  • MRI helps rule out other soft-tissue and joint causes of knee or shin pain.
  • A diagnostic ultrasound-guided local anaesthetic block — a positive block helps confirm a trapped nerve.

Saphenous nerve pain treatment

Where saphenous neuritis is suspected, we use simple treatments first, and most people respond within weeks to a few months.

Modifying provocative activities, such as repeated kneeling, can be very effective. Physiotherapy — specific nerve glides and fascia release to reduce nerve tension — often helps, and a trial of topical treatment such as capsaicin cream or lidocaine patches can desensitise the nerve.

Medication

Sometimes we use specific medications to reduce nerve pain, such as amitriptyline and duloxetine. These have side effects, so ask your doctor whether a trial is right for you.

Injections

We use injections when simple treatments don’t settle the pain. Some physicians use a localised corticosteroid injection to reduce swelling at the entrapment site. More often, we use nerve hydrodissection — a minimally invasive technique in which fluid (saline, dextrose, or anaesthetic) is injected around the saphenous nerve under ultrasound guidance to release adhesions, reduce compression, and restore nerve mobility. PRP has recently shown some success. If injections help but the pain recurs, a nerve ablation procedure may give longer-term relief.

Surgery

Surgery is reserved for rare cases where conservative and minimally invasive treatments have failed:

  • Nerve decompression — releasing the nerve from the surrounding tissues
  • Neurolysis — removing scar tissue or adhesions, compressing the nerve

Surgery is used cautiously, only when the diagnosis is confirmed, and other treatments have failed.

Frequently asked questions about saphenous nerve pain

How is saphenous nerve pain told apart from knee arthritis or pes anserine bursitis?

All three can cause inner knee pain, so they’re easy to confuse. The clue with saphenous nerve pain is its nerve character — burning, tingling, or numbness, with a positive tap (Tinel’s) sign over the nerve — rather than the deeper, mechanical pain of arthritis or the localised tenderness of pes anserine bursitis. A diagnostic ultrasound-guided nerve block often settles the question.

Can saphenous nerve pain occur after knee surgery?

Yes. It’s a recognised complication of knee arthroscopy, total knee replacement, and vein harvesting for cardiac bypass, because the nerve or its branches can be injured or caught in scar tissue. New burning pain in the inner knee or inner shin after these procedures should raise the possibility.

What is the adductor (Hunter’s) canal, and why does it matter?

It’s a tunnel in the lower thigh through which the saphenous nerve passes. Scar tissue or compression here is a common site of entrapment — and it’s also where a targeted injection or hydrodissection is often directed.

Does saphenous nerve pain go away?

Most cases improve within weeks to a few months with activity modification, physiotherapy, and topical or oral medication. More stubborn cases respond to a nerve hydrodissection, and only a few need surgery.

What is a nerve hydrodissection for the saphenous nerve?

An ultrasound-guided injection of fluid around the nerve to free it from surrounding adhesions and reduce compression. Because a good response also confirms the nerve as the source of pain, it helps with both treatment and diagnosis.

Should injections for saphenous neuritis be performed under ultrasound?

Yes — ultrasound-guided injections are more accurate and effective than landmark-guided ones, and they help avoid nearby vessels in this region.

Final word from Sport Doctor London about saphenous nerve pain

Saphenous nerve pain, although uncommon, can significantly affect quality of life. Early recognition and an accurate diagnosis are essential, and treatments — from physiotherapy and topical or oral medication to advanced options such as nerve hydrodissection — relieve most patients. See an experienced sports doctor who can diagnose and treat this condition.

If you have persistent inner-knee or inner-shin pain, Dr Masci can assess you in London, including an ultrasound in the clinic. Contact the team here or call +44 (0) 203 488 0350.

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