Saphenous neuritis: a poorly understood cause of medial knee pain.

Saphenous neuritis is a painful condition caused by either irritation or compression at the adductor canal or elsewhere along the course of the saphenous nerve. The condition also may be associated with surgical or nonsurgical trauma to the nerve, especially at the medial or anterior aspect of the knee. Saphenous neuritis can imitate other pathology around the knee, particularly a medial meniscal tear or osteoarthritis. Unrecognized saphenous neuritis can confuse the patient's clinical picture, complicate treatment, and compromise results. As an isolated entity, saphenous neuritis may appear in conjunction with other common problems, such as osteoarthritis and patellofemoral pain syndrome, and it can have an indolent and protracted course. Its clinical appearance is characterized by allodynia along the course of the saphenous nerve. The diagnosis is confirmed by relief of symptoms after injection of the affected area with local anesthetic. Initial treatment can include non-surgical symptomatic care, treatment of associated pathology, and diagnostic or therapeutic injections of local anesthetic. In recalcitrant cases, surgical decompression and neurectomy are potential options. The key to treatment is prompt recognition; palpation of the saphenous nerve should be part of every routine examination of the knee.