Overview of Ultrasound-Guided Arthrocentesis
Acute single-joint inflammation is a frequent reason for visiting the Emergency Department (ED). Among these is septic arthritis, an infection in the joints, which impacts around10 out of every 100,000 American patients each year. Septic arthritis is a condition that requires swift diagnosis and treatment. Initially, the doctor will consider a patient’s lab test results and signs like temperature and pulse rate. However, the most reliable test for septic arthritis is analyzing fluid taken from the infected joint through a procedure called arthrocentesis. If this fluid has signs of infection, the patient will be put on antibiotics right away and a joint specialist will be called.
Arthrocentesis is a common procedure often utilized in the ED. This procedure, which is used to remove fluid from a joint, delivers both diagnostic information – helping healthcare professionals identify the problem – and relieves pain and discomfort caused by the build-up of fluid. In the past, professionals would perform this technique blindly, guided only by knowledge of specific anatomical landmarks. However, using a landmark-based approach has its limits, due to variations in individual patient anatomy and fluid accumulation. The success rate varies between 61 to 78% depending on the joint. Today, ultrasound has become a critical tool used alongside the arthrocentesis procedure as it provides certain benefits over a blind approach.
Ultrasound-guided arthrocentesis has several advantages. For one, it allows the doctor to see the fluid build-up directly. This improves accuracy, reduces the number of tries required, and makes it possible to spot small accumulations of fluid that might be missed with a blind approach. Even fluid amounts as little as 4 ml can be detected within the joint space. Additionally, using ultrasound can result in more fluid removal and lower patient discomfort during the procedure. Importantly, adding ultrasound to arthrocentesis speeds up the diagnosis and treatment of septic arthritis.
These advantages become particularly relevant when dealing with younger patients. Children naturally have smaller joints and fluid accumulations, and they might have a harder time dealing with discomfort during the procedure. Research has shown that ultrasound can correctly identify fluid build-up with 80% accuracy, and rule it out with 90% accuracy. The final figures are yet to be determined, but early signs show the potential of ultrasound use in treating arthritis in children. There are also reports that ultrasound-guided arthrocentesis can be conducted safely on a child’s hip or knee.
These ultrasound-guided techniques can be applied in treating arthritis in most major joints in the body. Various techniques have been documented in the literature and practitioners may have their preferences. Finally, while this explanation focuses on the use of ultrasound to support arthrocentesis, many of these same techniques can be applied to inject medication directly into the joint space under the correct clinical circumstances.
Why do People Need Ultrasound-Guided Arthrocentesis
Ultrasound-guided arthrocentesis is a medical procedure used for various purposes. Essentially, it involves using ultrasound images to guide a needle into a joint space. But why would a doctor do this? Well, there are a few reasons:
1. Diagnosing septic arthritis: This is a severe infection in a joint. The bacteria can come from other parts of your body, travelling through your blood to infect a joint.
2. Diagnosing inflammatory diseases: Inflammatory diseases are conditions where your body’s immune system attacks its own tissues, causing significant inflammation. In some cases, these diseases can affect the joints, leading to pain and swelling.
3. Administration of medications into the joint space: Sometimes, medications need to be delivered directly into the joint to be effective. This could be a pain reliever, a steroid to lower inflammation, or other drugs to treat specific conditions.
4. Evaluating for hemarthrosis: Hemarthrosis is a condition where blood fills a joint space. This can occur due to injury, or certain medical conditions that affect the blood.
5. Assessing for synovial stability after penetrating injuries: The synovium is the tissue that surrounds a joint. If there has been an injury that penetrated this tissue, the doctor may want to assess its stability and the potential damage to the joint.
So, if your doctor suggests an ultrasound-guided arthrocentesis, it is likely for one or more of these reasons.
When a Person Should Avoid Ultrasound-Guided Arthrocentesis
There are certain situations where carrying out this procedure is not recommended. The number one case is if the individual has cellulitis, which is a skin infection, right at the spot where the needle would go in. This is because it could lead to bacteria being unintentionally introduced into the joint area. Other times when it might not be a good idea including if the person has bacteremia (bacteria in their blood), has a problem with their blood clotting (this is called coagulopathy), or has a joint prosthesis (an artificially replaced joint).
Equipment used for Ultrasound-Guided Arthrocentesis
The medical team will need the following items while performing a procedure involving the joint and surrounding soft tissue:
* Betadine or Chlorhexidine: These are antiseptic solutions used to clean the skin and prevent infection.
* Sterile gloves: These are used to maintain cleanliness and avoid contamination.
* Sterile drape: This is a clean sheet used to cover the patient and isolate the area where the procedure will be performed.
* Lidocaine or other local anesthetics: These are medications used to numb the area, so the patient doesn’t feel pain during the procedure.
* 27-gauge needle: This small, thin needle is used to inject the local anesthetic.
* 18-20 gauge needle: This is a bigger needle used for withdrawing fluid from the joint for testing.
* Tubes: These are used to collect the fluid for later analysis.
* An ultrasound (US) machine including sterile gel and a sterile cover for the ultrasound probe: Ultrasound uses sound waves to produce images of the joint, guiding the medical team during the procedure. Sterile gel and cover are used to ensure the process is clean.
* A linear high-frequency ultrasound transducer or a lower frequency curvilinear transducer: These are different types of ultrasound tools used to generate the sonic waves needed to create an image of the joint.
Who is needed to perform Ultrasound-Guided Arthrocentesis?
This procedure can be done by just one doctor, but having an extra member on the team can be really helpful. This additional person can assist in caring for the patient, dealing with any potential issues with the medical equipment, handling the ultrasound device before it’s sterilized, and taking notes about the procedure.
Preparing for Ultrasound-Guided Arthrocentesis
Before getting started with a procedure called arthrocentesis (which is used to take out fluid from a joint), it’s crucial to have all the necessary tools within reach. One of the important tools is the ultrasound machine, which comes with a special part called a probe. This probe can come in different shapes and sizes, depending on the specific needs of the procedure. For example, a high-frequency linear probe is often used because it gives a clear, detailed picture of the surrounding tissues. However, if the doctor needs to reach deeper into the body or use a wider needle, a low-frequency curvilinear probe might be the better choice.
Patient comfort is a top priority, so the position they’re placed in will vary depending on which joint is being worked on. To ensure the patient’s comfort and relaxation throughout the procedure, painkillers or sedatives may be given beforehand.
When all the equipment is ready, the doctor will clean the area around the joint with an antiseptic solution like betadine or chlorhexidine. This helps to remove any germs and prevent infection. Once the skin is clean, they’ll use a sterile cover and gel on the probe to keep everything germ-free. This way, the procedure can happen in a clean and safe way.
How is Ultrasound-Guided Arthrocentesis performed
There are many ways a doctor can perform an arthrocentesis (a procedure to remove fluid from a joint) using ultrasound guidance. Two common approaches are the in-plane and out-of-plane techniques. The in-plane method involves placing the needle directly under the ultrasound tool so that the full length of the needle can be seen on the ultrasound screen. On the other hand, in the out-of-plane method, only part of the needle, ideally the tip, can be seen on the ultrasound screen. The needle is inserted at a steep angle and the depth of the fluid buildup is calculated. With both techniques, adjustments need to be made to properly identify the needle and the fluid.
The following recommendations are for ultrasound-guided arthrocentesis of different joints, although there may be some variations.
Ankle Arthrocentesis
To perform this procedure, your doctor will identify two landmarks on your ankle: the tibialis anterior tendon and the medial malleolus. They will slide the ultrasound device down from the tibia until they find the space between it and another bone called the talus. The needle, using an out-of-plane technique, will then be inserted and start draining the fluid once it is seen within the fluid buildup.
Elbow Arthrocentesis
Your elbow will be bent at a 90-degree angle and rested on a table. Your doctor will place the ultrasound device along your arm bone (humerus) to identify the fluid buildup. The needle will be inserted laterally (from the side) using the in-plane technique and the fluid will be drained.
Hip Arthrocentesis
The ultrasound device may be placed on your groin to find the femoral nerve, artery, vein, and the head and neck of your femur (thigh bone). A needle will then be inserted under the ultrasound device in an in-plane approach so it can be seen at all times. The needle will be advanced to the anterior synovial recess (a small cavity in the joint) where the fluid will be aspirated.
Knee Arthrocentesis
Your doctor will place the ultrasound device above your kneecap (patella) to locate the fluid buildup. The needle will be inserted laterally using an in-plane technique and advanced into the space above the femur (thighbone) and below the quadriceps tendon. The fluid will then be removed.
Shoulder Arthrocentesis
In this procedure, your doctor will use the ultrasound device to view the joint between the glenoid fossa (the socket part of your shoulder joint) and humeral head (top part of your upper arm bone) from a posterior (back) view. They will then use an out-of-plane approach to take out the fluid.
Possible Complications of Ultrasound-Guided Arthrocentesis
While it’s not common, certain complications can come up with joint fluid testing guided by ultrasound. Here are a couple of things that can happen and how doctors work to prevent these issues:
1. Infection. Doctors have to carry out this procedure very carefully and cleanly to make sure they don’t allow bacteria into the clean joint space. To lower this risk, they cover the patient and prepare them in typically sterile ways. They make sure not to go through infected skin with the needle. Also, they use a clean cover for the ultrasound and a bacteria-free gel during the procedure.
2. Bleeding. This is rare during the procedure, but it can happen in patients with blood clotting disorders, such as those taking blood-thinning medications. Doctors are very careful when inserting the needle, avoiding any side-to-side movements to prevent injuring the structures around the joint space and blood vessels. In other words, they take extra care not to cut these areas when doing the procedure.
What Else Should I Know About Ultrasound-Guided Arthrocentesis?
Arthrocentesis is a procedure that can be used both for diagnosis and treatment. It involves using an ultrasound for guidance and visualisation of the important parts of the body, such as bones, diseases, and the needle used during the procedure. This ultrasound-guided method has several advantages compared to traditional techniques.
Firstly, it allows the doctor to remove small amounts of fluid for further testing. It also makes it easier to remove more fluid from the joint if it’s needed. With this approach, the doctor is able to determine the diagnosis faster, cause less pain for the patient during the operation, and increase overall safety by avoiding important body components like nerves, cartilage, and ligaments.
Aside from these, another benefit of ultrasound-guided arthrocentesis is that it allows for real-time documentation of the procedure. If the ultrasound video is kept within the patient’s medical records, it can provide valuable documentation of what actually happened during the operation. All these advantages make ultrasound-guided arthrocentesis the preferred technique when an ultrasound machine is available. Moreover, using an ultrasound could also boost the doctor’s confidence and encourage them to perform arthrocentesis when it’s necessary for the patient’s situation.
