Saphenous Neuritis

Saphenous neuritis is a relatively uncommon cause of pain in the front inside part of the ankle that may radiate into the arch of the foot (Figure 1). The pain often has a burning sensation. There may be a history of localized injury or irritation that causes the saphenous nerve to become inflamed or scarred. The saphenous nerve is a branch of the femoral nerve which originates from the lumbar spine. The saphenous nerve has a number of branches, including one that can cause pain and irritation to the inside part of the knee. However, saphenous neuritis that affects the foot usually results from irritation, injury, or damage to the lower part of the saphenous at or near the level of the ankle. 

Findings Seen in Saphenous Neuritis of the Foot

Saphenous neuritis affecting the foot creates a burning pain that often radiates across the front inside part of the ankle into the arch of the foot. The saphenous nerve at this level does not supply any muscle, so there is no associated muscle weakness. There may be localized discomfort associated with the area of the nerve that has been irritated or damaged. This can often be determined by tapping over the course of the nerve with pain being exacerbated where the nerve is scarred. Patients with saphenous neuritis may have some decreased sensation over the inner aspect of the foot. Anything that stretches the nerve such as rotating the foot to the outside (eversion) may exacerbate the symptoms. Similarly, direct pressure from shoes or tight socks may also aggravate symptoms.

Imaging studies

X-rays of the foot and ankle are usually negative. An MRI will also often be normal, unless there is a pronounced local injury around the nerve. 

Non-Operative Treatment of Saphenous Neuritis 

Fortunately, a painful saphenous neuritis affecting the foot is a relatively uncommon problem. Symptoms can often be improved by avoiding local pressure over the nerve. Physical therapy focusing on desensitization of the nerve and mobilization of any soft tissue scarring is often helpful. This soft-tissue mobilization and nerve desensitization may need to be performed over a number of weeks.

Surgery for Saphenous Neuritis

In rare instances symptoms will remain considerable. In this situation surgery may need to be considered. If there has been extensive localized damage to the saphenous nerve cutting the nerve just before the damaged area can be helpful. The end of the cut nerve then needs to be implanted into a muscle belly or bone to minimize the risk of a painful neuroma forming. If there is considerable scar tissue around the nerve, but the nerve is otherwise in good condition removing the scar tissue in a procedure called a neurolysis can be performed. Once the scar tissue has been cleared, the nerve is often wrapped to protect it from future scarring.

October 16th, 2024