Pain below the kneecap can be caused by many things, such as patellofemoral pain, knee arthritis, and tendonitis. A less common cause of knee pain is saphenous entrapment close to the knee, which can cause significant knee discomfort and reduced mobility. What causes saphenous nerve pain, and how can we treat it?

What is the saphenous nerve?

The saphenous nerve is a branch arising from the femoral nerve in the front of the thigh. It starts above the inside of the knee and courses down to the inner part of the shin and foot. It provides sensation to the inner side of the knee, leg, and foot.

saphenous nerve anatomy lower leg

Causes of saphenous nerve entrapment 

There are many potential causes of saphenous nerve entrapment, including the following:

  • Trauma or Injury: Direct trauma to the knee, thigh, or shin, such as from sports injuries or accidents, can bruise the nerve. Ankle sprains or prolonged kneeling can also stretch or irritate the nerve.
  • Surgical Procedures: Surgeries can inadvertently damage the saphenous nerve. Knee arthroscopy, total knee replacement, or vein harvesting for coronary artery bypass grafting are examples of surgeries that can lead to saphenous nerve pain.
  • Compression or Entrapment: Scar tissue or adhesions at specific sites, such as the adductor canal (Hunter’s canal) in the lower thigh, can cause nerve trapping.
  • Inflammation: Inflammatory conditions like knee arthritis or tendinitis may irritate the nerve indirectly.
  • Neuritis: Conditions like diabetes or peripheral neuropathy can increase susceptibility to nerve pain.

Saphenous nerve pain symptoms

In general, saphenous nerve pain manifests with sensory changes, which may include a few of the following:

  • Patients describe pain as burning, sharp, or aching along the inner thigh, knee, or shin. It is often exacerbated by movements such as bending the knee, walking, or kneeling.
  • Pins and needles sensation or numbness is common on the inside of the knee, shin or foot.
  • Sometimes, there is increased sensitivity to light touch or pressure.

Saphenous nerve pain location 

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

anteromedial knee pain in women secondary to saphenous nerve pain

How to diagnose saphenous nerve entrapment 

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

Your doctor will take a comprehensive history, including a history of trauma or recent surgery. Examination of saphenous nerve pain reveals focal tenderness at the inner thigh, knee or shin. Tapping the nerve (also called percussion tenderness) reproduces the pain sensation.

Investigations help confirm nerve entrapment and exclude other pain causes. Your doctor may consider the following investigations:

  • Ultrasound can visualise the nerve and identify compression, swelling, or injury to the nerve. It can also identify possible causes of nerve trapping, such as arthritis, tendinitis, and scar tissue.
  • MRI helps to rule out other soft tissue and joint causes of knee or shin pain.
  • Nerve studies can confirm a saphenous nerve injury or other causes of nerve pain (such as peripheral neuritis).

Sometimes, we use a local anaesthetic nerve block with ultrasound-guidance. A positive block helps confirm the diagnosis of a trapped nerve.

Saphenous nerve pain treatment 

If saphenous neuritis is suspected, we often use simple treatments first. Generally, most patients will respond to simple treatments within weeks to a few months. Modifying provocative activities such as repeated kneeling with help. Phyiostherpay incorporating specific nerve stretches and fascia release to reduce nerve tension can be very effective. A trial of topical medication such as capsaicin cream or lidocaine patches plays a role in desensitising the nerve.

Medication 

Sometimes, we use specific medications to reduce nerve pain. Examples include amitriptyline and duloxetine. These medications have side effects, so you should ask your doctor whether you would be a good candidate for a medication trial.

Injections 

Generally, we use injections if simple treatments fail to work. Some doctors perform a localised cortisone injection to reduce swelling at the site of nerve trapping. Sometimes, we use a more advanced procedure called a nerve hydrodissection. This procedure is a minimally invasive technique where fluid (saline, dextrose, or anaesthetic) is injected around the saphenous nerve under ultrasound guidance to release adhesions, reduce compression, and restore nerve mobility. Recently, platelet-rich plasma or PRP has had some success.

If injections are effective but the pain returns, a more aggressive nerve ablation procedure can provide longer-term relief.

Surgery

We consider surgery in rare cases where conservative and minimally invasive treatments fail. Procedures include:

  • Nerve Decompression: Releasing the nerve from surrounding tissues.
  • Neurolysis: Removal of scar tissue or adhesions compressing the nerve.

Generally, we should use surgery cautiously and only when the diagnosis is confirmed and other treatments have failed.

Other frequently asked questions about saphenous nerve entrapment

Should injections for saphenous neuritis be performed using ultrasound?

Yes, Ultrasound-guided injections are more accurate and effective than landmark-guided injections.

Final word from Sportdoctorlondon about Saphenous Nerve Pain

Saphenous nerve pain, though uncommon, can significantly pain and impact quality of life. Early recognition of symptoms and accurate diagnosis are essential for effective management. Treatment options, from physiotherapy and topical and oral medications to advanced interventions like nerve hydrodissection, offer relief for most patients. You should see an experienced sports doctor who can diagnose and treat this condition.

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