What is saphenous nerve block?
Saphenous nerve block is performed by injecting local anesthetic (usually lidocaine or bupivacaine) with a small needle near the knee or ankle. Sometimes an ultrasound machine is used to locate the nerve that runs behind the leg and near the knee. Injecting an anesthetic in the area of the nerve near the knee or ankle will numb all the structures served by that nerve, which includes the shin, fibula, ankle, and foot.
What is a saphenous nerve block used for?
Saphenous nerve block is used:
- For wound repair or exploration of the ankle or lower leg
- As part of an ankle block required to manipulate a fractured or dislocated ankle
- For incision and drainage of an abscess in the ankle or lower leg
- For foreign body removal in the ankle or lower leg
- To control pain after surgical repair of the meniscus (partial meniscectomy)
How do you treat saphenous nerve pain?
- Nonsteroidal anti-inflammatory pain medications (NSAIDs) such as
- Physical therapy
- Leg braces
- Medications that modify nerve pain such as
- Opioid pain medications
- (not recommended for long-term use)
- Lidocaine patches
- Capsaicin cream
- Transcutaneous electrical nerve stimulation (TENS)
How is the saphenous nerve block procedure performed?
The block may be performed at the knee or ankle. The following are the usual steps for performing a saphenous nerve block:
- The patient is positioned laying down.
- An ultrasound machine is sometimes used to find the location of the nerve at the knee or ankle.
- The area to be anesthetized at the knee or ankle is draped with sterile drapes and prepped with a cleaning solution, usually betadine or chlorhexidine.
- The anesthetic (usually lidocaine or bupivacaine) is slowly injected into the area around the nerve, being careful not to inject directly into the nerve or the vascular structures nearby.
- After a few minutes, the patients will notice numbness in the area of the lower leg, ankle, or foot.
- The area where the anesthetic was injected is cleaned again, and a sterile bandage is placed over the area.
- The anesthesia (numbness) from the nerve block can last from 1 to 36 hours, depending on the anesthetic used.
What are the risks and complications of a saphenous nerve block?
Complications of a saphenous nerve block procedure include:
- Infection: Any procedure that involves injecting medications into the skin has the potential to cause infection. This can occur if the injection site is not properly cleaned prior to the procedure.
- Nerve injury: If the anesthetic medication is injected into the nerve itself, it may result in temporary or permanent damage to the nerve. The patient may have numbness, tingling, or pain, at the site of the injection if this occurs.
- Allergic reaction: Most anesthetic blocks are safe and rarely cause allergic reactions. When allergic reactions occur, they can range from delayed hypersensitivity (mild itching and swelling) to full anaphylactic shock. If you have a known allergy to injectable anesthetic medications such as lidocaine or bupivacaine, discuss this with your doctor prior to receiving a saphenous nerve block.
- Bleeding: Because a saphenous nerve block is performed with injectable medication, bleeding under the skin (bruise or hematoma) may occur.