Ultrasound-Guided Ankle Nerve Block

Introduction:

Foot surgery can cause much pain, especially for patients going home the same day. Good pain management is vital for their comfort and early discharge. Regional anesthesia targets specific areas to relieve pain. Methods like spinal anesthesia, leg nerve, or ankle blocks are used. Ankle blocks are beneficial for extended pain relief and quicker mobility. During an ankle block, doctors choose between anatomical landmarks or ultrasound guidance. Ultrasound is better, especially for less experienced doctors. It helps visualize nerves clearly and accurately locate the right spot for numbing medication. Using ultrasound to guide an ankle block during foot surgery improves pain relief precision, similar to using a map to find the perfect spot. This ensures better comfort and quicker recovery for patients.

What Are the Benefits of Ultrasound-Guided Ankle Nerve Block?

An ankle block is a type of anesthesia used for foot surgeries. It is a simple and safe technique where numbing medicine is injected near the ankle so you do not feel pain during the surgery.

There are many benefits to using this technique:

• It is easy for doctors to do.

• It is very safe with few side effects.

• It almost always works well.

• Usually, only one injection is needed.

• Even doctors who are not very experienced can learn to do it.

• A combination of mild sedative and pain-relieving medication is given to make patients more comfortable and less anxious during the procedure.

• Even if someone has a condition like diabetes with nerve problems, the ankle block can still be used effectively. It might work even better because of the existing reduced sensation in the foot.

• Ankle blocks are a good choice for people with various health issues. They do not have the significant effects on the body that other types of anesthesia might have.

• Although it is often called a "volume" block because a lot of numbing medicine is used, a lower concentration can be used since the goal is to stop pain rather than block movement.

Which Nerves Are Involved in the Ankle Block?

Using ultrasound to guide an ankle block can help reduce the amount of numbing medicine needed. An ankle block can numb the foot for surgery or pain relief. This technique is technically simple because the nerves are near the skin's surface. However, knowing the ankle's anatomy is essential to ensure it works well.

The ankle block involves numbing five different nerves:

• Two deep nerves - the tibial nerve and the deep peroneal nerve.

• Three superficial nerves - the superficial peroneal nerve, the sural nerve, and the saphenous nerve.

Most of these nerves come from a more prominent sciatic nerve, except the saphenous nerve, which comes from the femoral nerve.

• The Posterior Tibial Nerve: It helps to feel the bottom of the foot and the toes. It has three parts: one for the middle part of the foot, one for the side of the foot, and one for the back of the heel.

• The Deep Peroneal Nerve: It helps to feel the top of the foot between the big and second toes.

• The Superficial Peroneal Nerve: It helps to feel the top of the foot and the toes, except for the space between the big toe, the second toe, and the foot's outer side.

• The Sural Nerve: It helps to feel the outer side of the foot and the heel.

• The Saphenous Nerve: It is responsible for feeling the skin on the ankle's inner part, the foot's middle part, and the big toe's inner side.

What Is the Procedure for Ultrasound-Guided Ankle Nerve Block?

Before the Block:

• Prepare monitoring equipment (ECG, blood pressure, and oxygen levels) and insert an intravenous (i.v.) line.

• Ensure all the necessary tools are available: ultrasound machine with a probe, sterile probe cover, needles, syringes, and local anesthetic.

Items Needed for Administering the Block:

• Medical equipment for resuscitation and medications in case of emergencies.

• Supplies for surgery preparation like sterile towels, gauze packs, gloves, and a mask.

• A marking pen.

• Three 10-mL syringes (preferably controlled or ring syringes).

• A 25-gauge, 3.8 cm needle.

• An 18-gauge needle.

• Local numbing medicine.

General Technique to Follow:

• Position the patient properly for the block.

• Keep the ultrasound screen and needle in line to view what is being done.

• The patient can lie on their back with the leg supported, or the leg can be positioned differently.

• The foot is cleaned in an immaculate way to prevent infections.

• A special syringe is used to help put the foot in the best position.

• The ultrasound helps guide where to put the numbing medicine.

How the Block Is Given:

Tibial Nerve:

• Scan above the medial ankle bone to find the critical structures.

• Insert the needle just behind the artery.

• Inject a small amount of numbing medicine around the nerve.

Deep Peroneal Nerve:

• Place the ultrasound probe over the ankle joint.

• Find the anterior tibial artery and trace it to locate the nerve.

• Carefully inject numbing medicine near the nerve.

Superficial Peroneal Nerve:

• Place the probe on the front part of the leg.

• Identify the structures and inject numbing medicine where the nerve is found.

Sural Nerve:

• Put the probe over the back of the leg, near the outer ankle.

• Locate the nerve near a vein and inject numbing medicine.

Saphenous Nerve:

• Gently position the probe on the inner side of the ankle.

• Try to find the nerve close to a vein and inject numbing medicine.

After the Block:

• Manage the patient's pain and provide necessary analgesia.

• Instruct the patient on using crutches and taking postoperative pain relief.

Things to Consider:

• Ultrasound helps see where to put the numbing medicine.

• Different nerves are numbed to help with surgery or pain relief.

• Patient positioning and ultrasound alignment are essential.

• Use tiny needles and syringes for injection.

• Choose the right numbing medicine based on the surgery and pain relief needs.

• This technique helps patients avoid general anesthesia.

• It is effective for foot surgery, providing rapid and reliable anesthesia.

• Depending on the numbing medicine used, the block can last from a few hours to a full day.

• Patients are taught how to use crutches and given pain relief instructions.

• The patient is positioned lying on their back.

How Ankle Blocks Are Combined With Another Type of Anesthesia?

• Foot surgery often involves using anesthesia techniques, including ankle blocks.

• These anesthesia methods can be used alone or with general anesthesia (GA) or spinal anesthesia (SA).

• Peripheral nerve blocks (PNBs) are the most effective for pain relief during foot surgery.

• However, implementing PNBs can be challenging due to organizational, technical, and expertise limitations.

• GA or SA can be used alongside PNBs to ensure adequate pain control in such cases.

• Ankle blocks are performed before surgery to decrease the depth of GA and minimize intense pain upon awakening from anesthesia.

• If the anesthesia team lacks expertise in ankle blocks, an alternative approach involves using a sciatic nerve block with a rapid-acting numbing medication for pain relief during surgery.

• Additionally, a combination of deep peroneal and tibial nerve blocks with a longer-acting numbing medication can be used for extended pain relief after the surgery.

• This combination approach allows for quicker recovery of movement and sustained pain relief following the operation.

Conclusion:

Using ultrasound to guide an ankle block improves its accuracy, safety, and how well it works. This technique reduces the amount of numbing medicine needed, making it possible to numb both ankles. It is suitable for many patients and specific surgeries, allowing them to start moving soon after the procedure and reducing pain. This modern approach speeds up recovery and shortens hospital stays. Ankle blocks effectively numb during surgery and provide long-lasting pain relief afterward. Dexamethasone, given locally or systemically, reduces opioid use and offers similar post-surgery pain relief.