Our Anesthetic Techniques

What is an adductor canal block?

An adductor canal block is a regional anesthesia nerve block used at HSS to alleviate pain associated with knee surgery, and in some cases, with foot and ankle surgery. The adductor canal block does not usually numb the entire area of pain during surgery, so it is normally administered in conjunction with other peripheral nerve blocks or pain management modalities.

How is an adductor block administered?

After routine monitors have been placed to track your blood pressure, oxygenation, heart rate and respiratory rate, and after intravenous (IV) sedation has been administered, the adductor canal block is initiated. The injection site is prepared with a sterile solution, and then, using ultrasound guidance, a needle is inserted into the medial aspect of the thigh, almost half-way between the groin and the knee. A long-acting local anesthetic is injected in proximity to the target nerve and the needle is withdrawn.

How long do the effects of an adductor canal block last?

The duration of pain relief after an adductor canal block can range from 18 to 24 hours and sometimes longer. 

As with any anesthetic, there are risks and benefits to adductor canal blocks. These can be discussed with your anesthesiologist before your surgery.

The ankle block is a combination of 5 injections around the foot and ankle. Before the performance of the block, you will receive medicine to sedate you. Only after you are adequately sedated will the anesthesiologist proceed with the injections. We do this so that you will not feel any discomfort during the performance of the block. In fact, you probably won’t even remember you had the procedure.

Once sedated, the anesthesiologist will clean your foot and ankle with an iodine solution, identical to the solution used by the surgeons. Then he or she will use very thin needles to inject a local anesthetic, similar to lidocaine, to numb a portion of the foot. Depending on where on the foot the surgery takes place, this may involve 4 to 5 different nerves.

After surgery, you may notice some bruising around the ankle. That is where the anesthetics were injected. Accordingly, you may notice that actual injection points around the ankle. Because we use very thin needles, the marks are not long lasting.

Your foot may be numb for 8 to sometimes 48 hours depending on the medicines used and your sensitivity to local anesthetics. Some may find the sensation of a numb foot discomforting, while others enjoy the long lasting pain relief.

The ankle block provides a numb foot, but the patient can still move the leg and foot. Because any movement precludes precise surgery, the surgeon often requests that either a spinal, epidural, or deep sedation be performed. When those anesthetics wear off, it is the ankle block that will provide the long lasting pain relief.

As with any anesthetic, there are risks and benefits to ankle blocks. These particulars can be discussed with your anesthesiologist before your surgery.

Surgeons often request an axillary block for their patients when the planned operation involves the hand, wrist, forearm, or elbow.

Before the axillary injection is performed, your anesthesiologist will provide some sedation through your intravenous line. Most likely, you won’t even remember the axillary injection.

Next, they will place your hand behind your head, as if you were lounging at the beach. He or she will clean your armpit with an iodine containing solution. They will feel your pulse with one hand and then insert a very thin, 1-inch needle through your pulse. Soon thereafter, they will inject some lidocaine-like medicine to numb your arm. After the injection, they will be squeezing your armpit for about 5 minutes while the surgical team positions your arm. Your arm and hand will get progressively more weak and numb over the next 20 minutes. During that same time, the anesthesiologist will be providing some more sedation to make your experience more comfortable.

The axillary block is a very safe and effective method for providing surgical anesthesia for the upper extremity. The numbness and heaviness lasts from 4 to 18 hours, depending on the medicines used. Most patients will have a bruise in their armpit which is painful to touch for a few days.

As with any anesthetic, there are risks and benefits to axillary blocks. These particulars can be discussed with your anesthesiologist before your surgery.

Spinals and Epidurals are used very often at the Hospital for Special Surgery for any surgery below the waist. All of these blocks are performed once you have received some sedation through your intravenous line. Patients often have no recollection of undergoing a spinal or epidural. Once sedated, your anesthesiologist will either sit you upright or place you on your side for the anesthetic.

He or she will clean your back with an iodine containing solution. A plastic drape is used to maintain sterility. A small amount of local anesthetic is then injected into the skin to reduce discomfort during the procedure. Your anesthesiologist will insert a needle through the ligaments of your back into the epidural space. Once in the space, he/she will place a smaller needle through the epidural needle into the fluid which normally surrounds the spinal cord. Once in place, a small amount of lidocaine-like medicine is injected. Then, a small plastic tube (catheter) is inserted into the epidural space and all needles are removed.

You will notice at the end of your surgery that you will have some tape along your back, tracing the line of the epidural catheter. However, because there is nothing hard or sharp in your back, you can lie flat on your back without discomfort. The epidural catheter will often stay in place for about 36 hours.

For shorter procedures, a stand-alone spinal is performed. In this procedure, your anesthesiologist will use the same small needle to enter the fluid surrounding the spinal cord but will not leave a catheter in the epidural space.

As with any anesthetic, there are risks and benefits to spinals and epidurals. These particulars can be discussed with your anesthesiologist before your surgery.

At Hospital for Special Surgery, the femoral block has been an effective weapon against pain after surgery on the knee. Patients undergoing total knee replacement or anterior cruciate ligament reconstruction have especially benefited from femoral nerve blocks.

The first step of the femoral nerve block is to provide some sedation to the patient. This is usually the last part of the procedure you will remember. Once you are adequately sedated, the anesthesiologist will clean off your groin on the side of the planned surgery. We use an iodine based antiseptic, which you may notice after surgery. Next, he or she will use a thin, 2-inch needle to locate the femoral nerve. We employ a very low amount of electrical current through the needle to stimulate the nerve. Some patients recall their leg twitching automatically -- this is precisely the response your anesthesiologist is trying to obtain.

Once an adequately low level of current is obtained, your anesthesiologist will inject a long-acting medicine similar to lidocaine to numb the front of the knee. Because the femoral nerve block doesn’t numb the back of the knee, it is inadequate for anesthesia for surgery. Often we will provide the surgical anesthesia with a spinal/epidural and provide pain relief after surgery with a femoral nerve block.

The numbness lasts an average of 16 hours. Studies from HSS show that the pain-relieving properties of a femoral nerve block last much longer - up to 3 days. The block alone is usually not enough pain relief, so patients will have either narcotics or an epidural to help with pain, in addition to the femoral nerve block.

As with any anesthetic, there are risks and benefits to femoral nerve blocks. These particulars can be discussed with your anesthesiologist before your surgery.

Coracoid blocks are often used to provide anesthesia for surgery involving the arm, elbow, wrist, and hand. Sedation is applied as the first step and will likely cause you to have no recollection of the consequent injection. Next, the anesthesiologist will clean the front of your chest near your collarbone with an iodine containing solution. A thin needle is then inserted in front of your shoulder; shortly thereafter, your arm, wrist, or hand will begin twitching involuntarily. Your anesthesiologist may often use ultrasound to guide the needle. You may notice a sticky residue on your chest after surgery, which is the ultrasound gel.

Once the appropriate twitch is elicited, the anesthesiologist will begin injecting a lidocaine-like medicine to make your arm numb. Your arm, down to the fingers, will become progressively heavy and numb until you won’t be able to move it any longer. During this period – which takes about 20 minutes - the surgeons will be positioning and cleaning your arm.

The numbness and immobility lasts anywhere from 4 to approximately 18 hours depending on which local anesthetics are used.

As with any anesthetic, there are risks and benefits to coracoid blocks. These particulars can be discussed with your anesthesiologist before your surgery.

Surgeons almost exclusively request an interscalene block for surgery on the shoulder or upper arm. This block provides excellent surgical anesthesia in a safe and effective manner.

Once you arrive in the operating room, the anesthesiologist may provide a small amount of sedation before the performance of the block. This will help relieve you of most of your anxiety concerning the anesthetic. He or she will place EKG stickers on your chest and neck, a blood pressure will be measured, and a light sensor to measure your oxygen will be placed on an ear or finger. Next, they will clean your neck with an iodine based solution. Your anesthesiologist will begin examining your neck, perhaps asking you to lift your head off the table or sniff with your nose. These maneuvers help the anesthesiologist determine the correct point of injection.

Next, he or she will slowly insert a very thin, 1-inch needle into the side of your neck. (This is almost always less uncomfortable than it sounds.) Shortly thereafter, you will feel a “funny bone” sensation at a location different than the needle. It may feel like a sensation of electricity or an involuntary twitch. Without moving, you will let your anesthesiologist know where you felt that sensation. Your anesthesiologist will determine if the response is optimal and then begin injecting lidocaine-like medicine to numb your shoulder and arm. An alternative method is to use small amounts of electricity to determine the location of nerves for the shoulder. It is the attending anesthesiologist who will determine which method is optimal for you.

Over the next 15 to 20 minutes, you will be positioned in a semi-sitting/reclining pose. This offers excellent exposure to your shoulder for the surgeon. Most anesthesiologists provide relatively deep levels of sedation. It allows better blood pressure control, less bleeding, and ultimately more patient comfort, while reducing the incidence of episodes of dangerously slow heart rates. Ultimately, your level of sedation is the decision of your attending anesthesiologist.

At the end of surgery, when the sedation wears off, you will notice a few things. First, you won’t be able to move or feel your shoulder, arm, and sometimes your hand. Your voice can be very horse and you may feel that you weren’t taking as deep a breath as you did before surgery. These are normal experiences, and they will disappear as the block wears off.

The block can last anywhere from 4 to 18 hours, depending on which medicines are used.

As with any anesthetic, there are risks and benefits to interscalene blocks. These particulars can be discussed with your anesthesiologist before your surgery.

Interspace between the popliteal artery and capsule of the posterior knee (IPACK) blocks are used at HSS to reduce pain after knee surgery. Patients who have an IPACK block will have the posterior part of their knee numbed. This will help minimize the opioids you need to take in the immediate recovery phase. Because it does not cover the entire knee, the IPACK block is often used in combination with an anterior knee block and a spinal or epidural for surgical anesthesia.

Once you have arrived in the operating room, your anesthesiologist will provide sedation intravenously to make you comfortable and relaxed for the nerve blocks. The IPACK block is performed using the latest ultrasound equipment to pinpoint the exact location to infiltrate nerves going to your knee joint. They will inject this area with a long-acting local anesthetic like novocaine used by your dentist. A long thin needle will be inserted on the side of your thigh to inject behind your knee.  

Immediately after surgery, both your legs may be numb and immobile because of your spinal anesthesia. After the spinal wears off, behind your knee will feel number. Since there are nerves in the posterior thigh that not only go to your knee but also to your foot, your foot may feel numb as well. The numbness caused by an IPACK block may last as long as 24 hours. 

As with any anesthetic, there are risks and benefits to nerve blocks. These particulars can be discussed with your anesthesiologist before surgery.

Lumbar plexus block is sometimes performed at Hospital for Special Surgery to help alleviate hip pain. It can be used alone or in combination with epidural anesthesia for postoperative pain control in patients after hip replacement surgery.

Once you arrive in the operating room, the anesthesiologist will provide some sedatives to make you feel drowsy. Your vital signs will be taken and you will receive oxygen via a small nasal tube. You will be asked to turn on your side. After you are properly positioned, the anesthesiologist will thoroughly clean your back in preparation for the block. The lumbar plexus, which is a set of nerves that go to the front part of the hip and thigh, is identified with a long thin needle along with a small electric current. Sometimes patients may recall feeling involuntary leg twitching - that is the response that your anesthesiologist seeks.

The Novocain-like medication that your anesthesiologist injects will gradually make your hip and thigh numb. Your thigh and leg will also feel heavy or be difficult to move. The pain relief, along with the numbness and heaviness, typically lasts for 12 to 24 hours, depending on the medications used.

The nerves of the lumbar plexus do not cover the posterior portion of the hip, so blocking these nerves alone will not provide adequate anesthesia for hip surgery. Your anesthesiologist will often combine this block with a spinal or epidural anesthesia to provide complete coverage for your surgery.

As with any anesthetic, there are risks and benefits to lumbar plexus blocks. These particulars can be discussed with your anesthesiologist before the procedure.

Popliteal Blocks are used at HSS to help alleviate pain after foot and ankle surgery. Patients who have a popliteal block will have the outside 75% of their foot numbed. Because it does not cover the entire foot, this block is often used in combination with a spinal or epidural for surgical anesthesia.

Once you have arrived in the operating room, the anesthesiologist may ask you to turn onto your stomach. The injection may be placed either in the back of knee or on the side of the leg. Once you are in position, your anesthesiologist will provide some sedation intravenously. This will reduce any pain or anxiety you may be having.

When you have achieved a desired depth of sedation, a long thin needle is inserted and directed toward your nerves. You may feel your foot twitch involuntarily – that is exactly the desired response from the anesthesiologist. When the appropriate response is elicited, a long-acting, lidocaine-like medicine is injected through the needle.

After surgery, your spinal and sedation will be wearing off. At that point, the outside of your foot will be numb. That numbness may last for 4 to approximately 18 hours.

As with any anesthetic, there are risks and benefits to popliteal blocks. These particulars can be discussed with your anesthesiologist before your surgery.

At Hospital for Special Surgery, a saphenous nerve block may be used for pain control after surgery of the knee and foot. The saphenous nerve is a branch of the femoral nerve. It is purely a sensory nerve, that is, it conveys only sensory information and does not control any muscle in the leg. It transmits pain, temperature, and touch sensation from parts of the knee and along the inner aspect of the lower leg and foot.

Blocking the function of the saphenous nerve (a technique known as a saphenous nerve block) is one the methods used for controlling pain after knee and foot surgery. Another closely related method is the femoral nerve block. However, the femoral nerve innervates several muscles in the thigh, and blocking this nerve may result in temporary weakness of those muscles. In contrast, the saphenous nerve block would result in less muscle weakness, while providing similar degree of pain control. Some patients may benefit from a saphenous nerve block compared to a femoral nerve block, and the choice will be made between you and your anesthesiologist.

Prior to the placement of the block, you will be given sedation with intravenous medication. Your anesthesiologist will clean the skin with an antiseptic solution and, depending on the site of the injection, an ultrasound machine may be used to identify the saphenous nerve.

Local anesthetic is deposited around the nerve via a small needle. Pain relief is expected to last between 6 to 18 hours, depending on the mixture of local anesthetics used. As with any anesthesia procedure, there are risks and benefits associated with the saphenous block. Details will likely be included in the discussion of the anesthesia plan for you.

When one discusses the experience of surgery under regional anesthesia, an explanation of sedation is required. Patients are often very concerned about what they will feel during surgery.

At HSS, sedation is a significant part of an enjoyable surgical experience. We provide medicines that relieve anxiety and pain before the performance of most blocks so that patients are usually unaware that they have experienced an anesthetic procedure. In other words, they don’t even remember “the needle.” Once patients understand that they will feel no discomfort during this part of surgery, most of the anxiety is eliminated.

The level of sedation experienced during surgery varies from patient to patient. They may remember every detail of the surgery, or they may not remember anything until they wake up in the recovery room. There are many factors that determine how awake or asleep the patient is during the surgery, including the type of surgery, the patient’s position, any heart, lung, or airway anomalies, and the comfort level of the surgeon and anesthesiologist. In the end, it is the decision of the attending anesthesiologist as to how to manage the patient’s awareness during regional anesthesia in order to provide the safest, most enjoyable experience possible.

Supraclavicular Blocks are often used to provide anesthesia for surgery on the shoulder or arm. This block is commonly performed at HSS with ultrasound guidance. This is a newer technique that has been shown to be safe and effective and is rapidly gaining popularity.

Once you arrive in the operating room the anesthesiologist will apply sedation before performance of the block. This will help relieve you of anxiety and will likely cause you to have no recollection of the effects of the block. Next, monitors such as electrocardiogram (EKG) “stickers” will be applied to your chest. A blood pressure cuff will be placed and a measurement taken. Oxygen will be supplied to your nose, and a light sensor will be placed on a finger to measure your oxygen level.

An antiseptic solution will then be applied to the area above your collarbone on the side of the surgery. You will be asked to turn your head to the other side as ultrasound gel and an ultrasound probe are placed in the area. This is to help the anesthesiologist see the nerves they will inject local anesthetic around. You will be warned and may feel a slight pinch as a very thin needle is inserted into the area above your collarbone. Shortly thereafter, your shoulder or arm will begin twitching involuntarily. This is not painful, and as mentioned before, you will most likely not remember this process at all.

The anesthesiologist will then inject a novocaine-like medicine, or local anesthetic, to make your shoulder and arm numb for the surgery. The needle is removed at the completion of the injection and the ultrasound gel is wiped off the area. As your arm is getting numb, a process that takes several minutes, the surgeons will be positioning and cleaning your arm. You will likely not be able to move your arm at this time. You will be given additional sedation prior to the start of surgery.

After the surgery the numbness and immobility lasts anywhere from 4 to approximately 18 hours, depending on which local anesthetics are used. Your voice may be a little hoarse and you may not be able to breathe as deeply on the side of the surgery. These are normal experiences, and they will disappear as the block wears off.

As with any anesthetic, there are risks and benefits to supraclavicular blocks. These particulars can be discussed with your anesthesiologist before your surgery.

George A. Anastasian, MD
Regional Anesthesia Fellow 2006-2007

A safe and successful practice of regional anesthesia relies on anesthetizing nerves that carry sensations from the surgical site without damaging their structure. A local anesthetic, such as mepivacaine or bupivacaine, is injected around the desired nerves using a nerve block needle. Disruption of the nerve structure with the needle can cause undesirable neurological consequences and must be avoided. Anesthesiologists trained in regional anesthesia achieve this goal by relying on anatomical landmarks, the patient’s own feedback, and the use of nerve stimulators to locate the targeted nerves. A nerve stimulator is a device that discharges a small electrical current that is delivered through a needle. When the needle tip approaches the nerve, the electrical current causes a twitch of the muscle that is supplied by that nerve, providing information to the anesthesiologist. Using this technique, the anesthesiologist can target specific nerves and deliver a dose of local anesthetic to anesthetize the surgical site. Nerve stimulation has been used to locate nerves for many years and is currently the most common technique. However, there are also drawbacks to this technique, one of which is the inability to directly visualize the path of the needle as it passes through tissue.

In the last decade, a new technique has emerged: the ultrasound-guided peripheral nerve block. The use of ultrasonography in the field of regional anesthesia helps visualize the targeted nerves, the needle as it moves through tissues, any vital structures in the vicinity, and adequate spread of the local anesthetics around the nerves. As previously mentioned, accurate delivery of local anesthetics around nerve structures ensures the right amount of anesthesia. Technological improvements and lower costs have made it possible for the anesthesiologist to utilize this technique in his/her practice of regional anesthesia.

The concept of ultrasound imaging relies on the ability of human tissue to reflect sound waves. Sound waves are emitted from the ultrasound probe into the tissue over which it is applied. These sound waves are then reflected back towards the probe as they cross different areas of the body. The probe receives the reflected waves and an image is created on the screen of the ultrasound machine. When using this technique, the anesthesiologist can visualize, in real time, the structures that he/she is looking for, pass the needle toward the targeted nerves, and avoid any vital structures on the way. This ensures success of the block by confirming an adequate spread of the local anesthetic solution around the nerve.

Because this technique is relatively new, many anesthesiologists are not familiar with it. However, the majority of our anesthesiologists at Hospital for Special Surgery do perform ultrasound-guided nerve blocks. Many of our staff members are also involved in clinical research to establish the safety and success of this technique. Some of our surgeons also participate in our research, and they recommend this technique to their patients.

Daniel B. Maalouf, MD, MPH
Assistant Attending Anesthesiologist, Hospital for Special Surgery
Clinical Instructor in Anesthesiology, Weill Medical College of Cornell University