Overview of Pericapsular Nerve Group Block
Hip and knee surgeries are quite common, especially among older people. For example, in 2010, about 0.58% of people aged 50 in the U.S. had a total hip replacement, and this number goes up to 5.26% at age 80. A recent study also anticipated a significant surge in these surgeries. It predicted that the total joint arthroplasty, a type of hip and knee surgery, could see a massive increase of about 210% for knee surgeries and 174% for hip surgeries by 2020 compared to 2010 figures.
Moreover, in 2015, it was estimated that over 2.5 million individuals in the U.S. had total hip arthroplasty. Generally, bone diseases like osteoporosis and osteoarthritis are the significant reasons behind these surgeries. But, hip surgery isn’t limited to older adults alone. Even children with congenital hip dysplasia (a condition where the hip joints don’t develop correctly), young adults into sports who might need hip arthroscopy (a type of minimally invasive surgery to diagnose and treat problems in the hip joint), and elderly patients who have multiple health issues and have suffered injuries due to falls may all require this procedure. One thing to bear in mind, however, is that about 7% to 28% of patients might experience chronic pain after hip surgery.
One way to manage pain and assist in recovery during a total hip arthroplasty is with regional anesthesia. Regional anesthesia provides pain relief in a specific part of the body, like the hip. Various types of regional anesthesia techniques are available and frequently used, such as lumbar plexus, femoral nerve, and fascia iliaca blocks. While there are alternative techniques too, newer approaches like the quadratus lumborum block and local infiltration analgesia have also been explored, although more research is needed to fully understand their potential.
Recently, an anatomical study related to hip innervation (the supply of nerves to the hip), found certain landmarks that are targeted by the femoral and accessory obturator nerve. Based on this, a new regional anesthesia technique known as the pericapsular nerve group (PENG) block has emerged. This technique primarily targets the front part of the hip joint and blocks these nerves to mitigate pain after total hip surgeries, all while sparing motor function (preserving the ability to move). The PENG block was first identified by Girón-Arango et al, and it works by placing a local anesthetic in the fascial plane, which is the area between the psoas muscle and superior pubic ramus. These are parts of our body that are located around the hip region. The PENG block is expected to serve as a promising alternative to other regional nerve blocks like the femoral nerve or iliac fascia nerve blocks.
Anatomy and Physiology of Pericapsular Nerve Group Block
The PENG block is a type of anesthesia that targets several nerves in the upper thigh area. It is like a stronger version of the treatment that numbs the nerves in the upper part of the leg known as the femoral nerve, with the additional advantage of numbing two other nerves called the accessory obturator nerve and the obturator nerve. Think of the femoral nerve as a big cable that sends signals from the brain to the leg. This cable begins in the lower back from three sources (spinal nerves L2 to L4 specifically) and goes down the leg, splitting into two branches that control movement in the hip and knee, as well as feelings in the front-middle part of the thigh and the inside part of the leg and foot. Additionally, this nerve controls the contraction of a hip muscle before it runs under a band of body tissue called the inguinal ligament.
The obturator nerve, also formed from the same three sources in the lower back, passes through a muscle in the lower back region (psoas major). It then proceeds in a direction away from the convergence of the body’s two main arteries (common iliac arteries) and along the side of the pelvic wall. When the obturator nerve reaches a channel in the upper thigh (obturator canal), it splits into two branches. One of these branches goes on to provide sensation to the skin in the middle of the inside of the thigh.
With the accessory obturator nerve, it is present in 10% to 30% of people. It begins from the third and fourth nerves in the lower back (from the same L2 to L4 spinal nerve pool) and often controls a muscle in the hip and sensation in the hip joint. In fact, medical studies show that the main nerves that control the feeling in the front part of the hip capsule are these three – the femoral, the obturator, and the accessory obturator nerve.
The hip capsule is divided into front and back parts. The front portion is sensitive to pain and damage, while the back part is sensitive to mechanical changes. The paths these three nerves take, and their relationships with the structures in the hip joint, may indicate possible areas to administer pain relief for hip surgery. This information suggests that injecting local anesthesia in the muscle layer between the psoas muscle and the upper pubic branch can numb these nerves, thus, providing extensive pain relief for hip surgery.
Why do People Need Pericapsular Nerve Group Block
The PENG block is a new type of pain relief method that can help manage pain after hip surgeries or fractures, proving to be more effective compared to other similar methods used for these procedures. This type of pain relief is generally used for injuries or operations related to the hip or thigh. This can include fractures of the acetabulum (part of the hip joint), femoral neck (part of the thigh bone), or the middle of the shaft of the thigh bone. It’s also used for hip replacements, hip arthroscopy (a procedure that allows doctors to see the hip joint), and knee surgeries.
Recent studies showed that PENG block has been used successfully to provide pain relief for a lesion (an area of damaged tissue) located on the inside of the thigh. Additionally, other research has suggested its use in vascular procedures, which are operations related to blood vessels, such as stripping, which targets several skin areas supplied by certain nerves.
However, it’s important to note that a PENG block can’t be used as the only method of pain relief for hip surgeries. This is because a part of the hip joint at the rear and towards the middle gets its supply of nerves from branches of the sacral plexus and the sciatic nerve. That means the PENG block may not cover all the areas needed for adequate pain control in a hip surgery.
When a Person Should Avoid Pericapsular Nerve Group Block
There are certain situations where a PENG block, a type of pain relief for hip surgery, cannot be performed:
– If a patient does not agree to have it.
– If there is an infection where they plan to inject the medicine.
– If the patient is allergic to the medicines used to numb the area (local anesthetics).
– If the patient’s blood is too thin. Doctors measure this with a test called an international normalized ratio. If it’s greater than 1.5, it means the blood is very thin and can make it risky to perform the procedure. Also, if enough time has not passed since the patient stopped taking blood thinners, as per the guidelines by the American Society of Regional Anesthesia and Pain Medicine, the block can’t be performed.
Equipment used for Pericapsular Nerve Group Block
The PENG block is a type of medical procedure that utilizes ultrasound technology to help guide the process. This procedure necessitates specific equipment that includes:
A tool called an ultrasound, along with a particular type of probe – low-frequency curvilinear, that’s covered with a sterile sleeve and uses a special gel. This helps the doctor to view the inner structures of your body on a screen.
A needle, 23 to 25-gauge in size, is used to numb the area on your skin where the procedure will be performed. This makes the procedure more comfortable for you.
20 milliliters of a substance known as local anesthetic. This solution is used to numb a specific part of your body, allowing you to stay awake but not feel any pain during the procedure.
An 80 millimeter B-bevel nerve block needle. This is a type of special needle used to inject the numbing medicine into the right place.
A pack of 4-inch by 4-inch gauze is also required. These small squares of fabric are used to clean and cover the area where the procedure will be performed.
A substance called chlorhexidine gluconate solution is used for skin asepsis to ensure that your skin is properly cleaned before the procedure begins. This helps prevent infection.
Sterile gloves are worn by the medical team to keep everything clean and safe.
A marking pen, which is used to clearly mark the areas on your body where certain steps of the procedure will take place.
Who is needed to perform Pericapsular Nerve Group Block?
The PENG block, a type of local anesthesia, should only be carried out by specially trained doctors. It’s recommended to also give the patient some medicine to help them relax during the procedure. A nurse who has been trained in local anesthesia can also help with this procedure and give the patient the relaxant medicine.
Preparing for Pericapsular Nerve Group Block
Before a regional nerve block procedure, which is a type of treatment to reduce pain, the doctor must do a thorough check-up of the patient following the guidelines set by the World Health Organization. This check-up includes understanding the patient’s medical history, doing a physical exam, assessing the patient’s airway, and reviewing any tests done before the procedure. It is also essential for the doctor to be aware of any current treatment the patient is receiving, such as painkillers and blood-thinning medications, as this could affect the procedure, particularly in reducing the risk of excessive bleeding.
Patients must be made fully aware of the pros and cons of receiving the PENG block, a type of regional nerve block. The doctor will explain the procedure in detail so that patients can make an informed decision about their treatment. This process is called obtaining informed consent, which means patients agree to the treatment after understanding what it involves.
Last but not least, this procedure has to take place in a well-equipped clinical center, where appropriate monitoring equipment is available to ensure patient safety and the success of the procedure.
How is Pericapsular Nerve Group Block performed
The PENG block is a type of medical procedure done to help manage pain. This procedure is carried out using a device called an ultrasound with a special low-frequency probe. There are two main ways it can be performed: the “Out-of-Plane Technique” and the “In-Plane Technique.”
For the Out-of-Plane Technique:
Before you start the procedure, you’ll be given medicine to help you relax. You’ll be asked to lie flat on your back with your hip stretched out. The doctor will then clean the area and inject a local anesthetic, which is a medicine that numbs the area so you will not feel any pain. With the ultrasound, they’ll carefully look at the area on your hip where the bones meet. Using the information from the ultrasound, a specialist will insert a specialized needle and infuse a numbing medication into a pinpointed area.
For the In-Plane Technique:
Again, you’ll have to lie flat on your back. Using the ultrasound, the doctor will identify some specific landmarks on your hip. These landmarks will guide how they angle and insert their needle. The needle is inserted at a particular angle, and the medication is placed in a precise area between certain structures in your hip. The procedure aims to avoid damaging any tendons, which are bands of tissue that connect muscle to bone.
Each procedure is designed to deliver medication exactly where it’s needed, and the choice of technique will depend on your particular situation. The ultimate goal here is to help manage and lessen your pain.
Possible Complications of Pericapsular Nerve Group Block
Getting regional anesthesia involves a detailed understanding of the possible complications that can come with it. Complications from peripheral nerve blocks, which is a type of regional anesthesia where specific nerves are numbed, might range from infections, bleeding, and nerve damage to toxicity caused by the local anesthetic. Sometimes, this kind of toxicity can happen if the anesthetic is accidentally injected into a blood vessel or if the dose is too high. If this situation arises, the immediate steps would be to give the patient an intravenous fat-based solution (intralipid) and offer the required supportive measures to stabilize the body’s vital functions.
The Second American Society of Regional Anesthesia and Pain Medicine Practice Advisory has shed more light on the complications related to nerve damage due to mechanical stress, decreased blood supply (ischemia), or damage due to toxic substances (neurotoxic lesions) in the peripheral nervous system.
The PENG block is a new nerve-numbing technique and there isn’t a lot of data about specific complications yet. However, using ultrasound guidance helps to keep the risks like damage to the femoral nerve (main nerve in the thigh) or nearby blood vessels to a minimum. The chance of permanent damage to peripheral nerves from these blocks is fairly low, occurring in about 2 to 4 out of 10,000 nerve blocks.
What Else Should I Know About Pericapsular Nerve Group Block?
The PENG block is a new type of regional pain relief method used particularly for hip surgeries. It works by blocking specific nerve branches around the hip area, which can help reduce pain without causing weakness in your thigh muscles. This makes it easier to start moving again after surgery.
Using the PENG block can be combined with other methods of regional pain relief to effectively numb the front part of the hip joint. It offers an alternative to femoral nerve or lumbar plexus block, methods traditionally used to prevent leg muscle weakness and aid quicker recovery after the operation.
Further, when the PENG block is used in combination with other forms of pain relief methods, including other nerve blocks and joint infiltration techniques, it can minimize the need for opioid pain medications after surgery. This approach, known as multimodal analgesia, can enhance recovery by reducing complications related to opioids and shortening hospital stays.
A comprehensive review followed, to evaluate how effective the PENG block is for hip surgery. This review looked at both adult and children studies and found 345 related articles. However, the author found that the evidence on the PENG block’s effectiveness for hip surgery or hip pain has so far been limited to case studies. More robust studies, such as randomized controlled trials, are needed to gain a clearer understanding of the pain relief efficiency and potential side effects of the PENG block.
Another study retrospectively examined the pain-relieving benefits of adding the PENG block to a local anesthetic after complete hip replacement surgery. This study included 123 patients, some of whom received the PENG block and some did not. The study concluded that the PENG block was associated with lesser opioid consumption in the first 24 hours after the operation.
Following the first discoverer of the PENG block, articles by other authors documented their clinical experience of using the PENG block in patients undergoing hip dislocation repair or hip replacement surgery. They reported that the PENG block effectively numbed both the femoral and obturator nerves, thus making it a beneficial pain relief option for such types of hip surgeries.
