Overview of Biceps Tendon Sheath Injection
Ultrasound, also known as US, is a popular tool in healthcare due to its cost-effectiveness, easy transport, and the fact that it doesn’t expose the patient to radiation when capturing images. Its features allow healthcare practitioners from various fields to use it for assessing patients and conducting treatments. Among medical professionals, radiologists are especially well-suited to carry out these assessments and procedures because of their in-depth training, awareness of human anatomy, and ability to interpret different bodily appearances revealed through various imaging methods.
Undergoing training as a radiologist includes learning about medical physics and how medical images are captured. In an ultrasound procedure, a medical professional, such as a sonographer or a physician, uses a device called a transducer to examine the area of the patient’s body in question. The transducer contains something known as piezoelectric crystals which vibrate when they are subjected to an electric current. These vibrations produce sound waves that are sent into the patient’s soft tissues via a layer of ultrasound gel. These sound waves then interact with the tissues and reflect back to the transducer. After returning to the transducer, the sound waves are turned back into an electric current. The machine then uses the time difference between the production of the sound wave and its return to the transducer to figure out the location or depth of the tissue that reflected the wave.
When preparing for a procedure, it’s necessary to pick the type of transducer that will produce the best quality images. There are several types of transducers with different frequencies and shapes. Normally, high-frequency transducers are chosen for examining structures close to the surface of the body due to their superior resolution. However, higher frequency sound waves are more easily reduced and have lower capability to delve into tissues, restricting their application in examining deeper structures. For deeper structures or larger patients, a low-frequency or curved transducer may be preferred. When imaging smaller body parts, like a finger, a smaller transducer (often referred to as a hockey stick) may be beneficial.
Different imaging methods like ultrasound, fluoroscopy, computed tomography (CT), or in some cases, Magnetic Resonance Imaging (MRI) are used to guide procedures. Usually, ultrasound is very useful in guiding procedures involving soft tissues, such as injecting medicine into a tendon sheath, taking a biopsy from soft tissue, or aspirating/drainage of cysts or abscesses. Ultrasound, CT, and fluoroscopy can all be used for both aspirating a joint and administering a therapeutic injection. The method selected may depend upon what’s available, the expertise of the user, the body part that needs treatment, and the patient’s body shape and size. Advantages of ultrasound include no exposure to ionizing radiation and real-time visualization of the needle and surrounding soft tissues during the procedure.
When using fluoroscopic guidance, the needle is continually imaged, and its location is determined relative to the bone structures. The involved soft tissue structures are estimated based on the professional’s knowledge of anatomy. Fluoroscopy often requires a contrast agent to confirm needle placement, unlike ultrasound, which allows direct visualization of the needle position. CT is helpful for biopsy of bone structures or injecting medicine into deep body structures, which might be hard to see with ultrasound or feel during a physical examination.
Anatomy and Physiology of Biceps Tendon Sheath Injection
The long head of the biceps muscle, which is a large muscle in your upper arm, starts deep inside your shoulder in an area called the supraglenoid tubercle and the top part of the glenoid labrum. It moves out of the shoulder joint and runs alongside your upper arm bone (the humerus), entering an area called the bicipital groove.
This part of the muscle is steadied by some special structures – two ligaments (the coracohumeral and transverse humeral ligaments) and fibers of the tendon of another shoulder muscle (the subscapularis tendon).
The long and short heads of the biceps muscle attach to a small bump on the upper part of your radius bone, which is one of the two large bones in your forearm. Depending on which ‘head’ we’re talking about – long or short – they attach at different points on this bone. This means that it’s possible to injure or tear one ‘head’ and not the other.
At the end of the biceps muscle where it attaches to your forearm bones, there’s a tough, flexible tissue called the lacertus fibrosus (also known as the bicipital aponeurosis). This tissue, which starts at the lower end of the biceps tendon, extends over several muscles that help to bend your forearm. Underneath it, you also have important structures such as the median nerve, which provides feeling to your hand, and the brachial artery, which supplies blood to your arm.
The lacertus fibrosus acts like a protective cover and it keeps a torn biceps tendon from retracting, or moving away, too far. If the biceps tendon tears and the lacertus fibrosus is also injured, it could complicate any surgical repair by causing the tendon to retract significantly.
Why do People Need Biceps Tendon Sheath Injection
Ultrasound can be used in many ways to treat problems with muscles, joints, and tendons. For example, it can be used to draw fluid from a joint or bursa (a small fluid-filled sac that reduces friction) to check for infection or diseases caused by the buildup of crystals. Ultrasounds can also guide injections into these areas, which could contain things like medication, steroids, or platelet-rich plasma (a therapy often used for treating joint pain). These injections could help to ease pain or diagnose a patient’s condition based on how they feel after treatment.
Pain in the shoulder can be tough to figure out because it can be caused by many different things. Doctors use a mix of physical examinations, patient history, and scans (like an MRI) to find out what might be the issue. Sometimes, an MRI might show several possible issues, and injections can help the doctor figure out what’s actually causing the pain. For example, an MRI might show a tear in the shoulder’s labrum (the ring of cartilage that surrounds the shoulder socket), tendinosis in the biceps (where the tendons are damaged but not inflamed), and a tear in the rotator cuff (the muscles and tendons that keep the shoulder in its socket). But if the physical exam mostly points to a problem with the rotator cuff, the doctor might inject medication into the biceps tendon. How the patient reacts to this can help the doctor decide if they should also treat the biceps when they do surgery to repair the rotator cuff.
When a Person Should Avoid Biceps Tendon Sheath Injection
There are a few reasons why a doctor might avoid giving a corticosteroid injection. One is if there is an infection in the area where the shot would be needed, another is if the patient has bacteria in their bloodstream, known as bacteremia. The shot should also be avoided if the patient has septic arthritis, an infection in a joint, or a broken bone within a joint.
When a shot is directed into the cover of the biceps tendon, it’s important to remember that the medication will also enter the shoulder joint because these two areas are connected. If the doctor wants to examine the joint or tendon sheath for signs of infection, they need to carefully check the surrounding soft tissues for signs of skin infection, also known as cellulitis. It’s very important to prevent any contamination or infection from entering the joint or tendon sheath with the needle.
Furthermore, doctors might consider other factors before deciding if a corticosteroid injection is safe. These factors include if the patient has bone weakness near the joint known as osteoporosis, bleeding disorders known as coagulopathy, or if they’ve recently had an injection or multiple injections in the last year or the last six weeks. The doctors are cautious to not overuse the injections which can lead to harmful effects.
Equipment used for Biceps Tendon Sheath Injection
There are different types of steroids available, including methylprednisolone acetate, triamcinolone, betamethasone acetate with betamethasone sodium phosphate, and dexamethasone sodium phosphate. Each of these steroids has its own pros and cons. In America, the most commonly used steroids are methylprednisolone, triamcinolone hexacetonide, triamcinolone acetonide, and betamethasone.
Different steroids have different strengths. For example, betamethasone and dexamethasone sodium phosphate are nearly five times as potent as the others. How well they dissolve in the body also varies. For instance, the acetate part of betamethasone doesn’t dissolve well, while the sodium phosphate part of betamethasone and dexamethasone sodium phosphate dissolves very easily in water. The size of steroid particles also differs, ranging from 0.5 micrometers for dexamethasone to over 500 micrometers for methylprednisolone acetate. Triamcinolone particles tend to clump together, which requires thorough mixing before being injected.
The amount of steroid given depends on the chosen steroid and the area being treated. Smaller joints like the finger joint, small spinal joints, or collar bone joint needs less steroid compared to medium-sized joints like the elbow or wrist. Larger joints like the knee, shoulder, hip, or ankle would need even more steroid. For instance, a large joint might need 40 to 80mg of methylprednisolone acetate, but if you’re using dexamethasone sodium phosphate, you’d only need 8 to 15 mg for the same joint. And a small joint might require 4 to 10 mg of methylprednisolone acetate, while the same joint would only require 0.8 to 2 mg of dexamethasone sodium phosphate. The clinic I work at often uses a mixture of 3.75 mg dexamethasone with 2 ml 1% lidocaine or 1ml betamethasone (6 mg/ml) with 2 ml 1% lidocaine for injection to the tendon in the upper arm.
Before we inject the steroids, a local anesthetic (which numbs an area of your body) is given to numb the skin and shallow tissues. This is typically 1% lidocaine. While around 5 to 7 mL is often used for local anesthesia, the maximum safe dosage for lidocaine in the United States is 300 mg, which equals 30 mL of 1% lidocaine. There’s another numbing medicine called bupivacaine that can be useful because it works for a long period of time. However, it’s been shown to be very toxic to chondrocytes, cells found in cartilage. Because of this, it should never be used for injecting directly into a joint.
Preparing for Biceps Tendon Sheath Injection
Before any procedure guided by imaging technology like X-rays, ultrasounds, or MRI, doctors need to check the patient’s medical history, previous scans, and the reasons why the procedure is necessary. The doctor will then decide if the requested procedure is indeed the right one to address the patient’s health issue. Doctors also need to review all the medicines a patient is taking, especially those that can thin the blood like aspirin, certain vitamins, or fish oil.
Each case is unique, so the doctor might need to talk with the health provider that recommended these medicines to decide if the patient should continue or stop taking them for a while. Additionally, the doctor will verify if the patient is allergic to any of the medications, cleansing agents, or adhesives that will be used during the procedure.
Before going ahead with the procedure, doctors will inform the patient about what it entails, its benefits, risks, and other possible alternatives. Most injections guided by ultrasound in the muscles and bones are deemed low risk. However, there can be possible side effects such as pain, infection, bleeding, damage to nearby structures, allergic reactions, discoloration of skin, or failure to relieve pain. In certain rare cases, pain relief injections containing steroids can cause weakness in tendons, increasing the chances of them rupturing.
Once the patient understands all these details and clears all their concerns, they’ll be asked to give their consent in writing. Additionally, if the procedure is meant to relieve pain, the patient’s pain levels will be noted before and after it to track the changes.
Following the procedure, patients are told when they should return for check-ups. They are also informed about any abnormal signs like increased pain, redness, swelling, or fever, which might point towards an infection from the procedure. Though infections within a joint are very rare, they need urgent medical attention. Hence, patients are cautioned to go for immediate medical care if such symptoms appear when the clinic is closed.
How is Biceps Tendon Sheath Injection performed
The best position for this procedure can depend on the patient, but usually, the patient will be lying flat on their back with their arm turned outward. The ultrasound device, which is like a small paddle, is placed on the skin, lined up with the length of the biceps tendon (a tendon is a thick cord that attaches muscle to bone). The ultrasound image will show the bicipital groove (a kind of groove in the bone where the tendon sits) as a half-moon shape, and the tendon looking like a circle or an oval.
The doctor will move from the outside of your arm towards the center using a technique called “in-plane”. This guides the needle to be parallel, or in line, with the ultrasound device, for better viewing. After marking the spot for injection, the skin is cleaned and covered in a sterile way. A sterile cover is placed onto the ultrasound device. The skin and tissues beneath are then slightly numbed with a local anesthetic as the needle is guided towards the biceps tendon using ultrasound for accuracy. Ideally, the needle should enter the tendon sheath, or the protective layer around the tendon, where the groove in the bone is shallow, so the needle can be placed somewhat parallel to the ultrasound device. This parallel placement allows the needle to be clearly seen on ultrasound. An approach that is too steep can result in poorer visibility due to less sound waves bouncing back to the ultrasound device.
If the needle is positioned too close to the skin, fluid can accumulate under the deltoid muscle (the muscle that covers the shoulder), making it look like the tendon sheath, so the ideal positioning is below the tendon to avoid this mistake.
A technique called “in-plane”, where the needle is parallel to the ultrasound device, provides a better view of the entire needle and reduces the risk of potential harm to nearby structures. Alternatively, an “out-of-plane” technique only allows viewing of a small portion of the needle, which makes it hard to accurately locate the position of the needle tip. There are different ways to enhance needle visibility, like adjusting the beam direction, using special maneuvers, using a larger needle, or starting the insertion further from the target area, which allows a more parallel approach but a longer needle path.
As the biceps tendon is just beneath the skin surface, a high-frequency ultrasound device (10 to 15 MHz) is used for better imaging of the near surface area. Keeping the device perpendicular, or at a right angle to the tendon, ensures maximum reflection of sound beams for an optimal image and prevents anisotropy, a phenomenon that can result in poor visibility of the tendon.
Possible Complications of Biceps Tendon Sheath Injection
After receiving a steroid injection, which is a common treatment method for various conditions, there might be some side effects or complications to be aware of. These could include general complications like pain, infection, bleeding, allergic reactions, and ineffective results. There can also be additional complications specifically related to the steroids used.
These problems might include arthritis cause by bacteria, increased pain after the injection, local tissue shrinkage, skin color changes, a broken tendon, damage to cartilage (the soft material that cushions your bones), the death of bone tissue due to lack of blood flow, redness or warmth of your skin (known as flushing), and elevated blood sugar levels.
In some rare cases, if the injection is accidentally administered into a blood vessel, harsh effects on the brain and heart could occur. This is typically found with specific types of steroid injections that do not dissolve in water, like triamcinolone. These can travel through your blood vessels and, in rare cases, lead to a stroke.
As another caution, in the U.S., there is a certain safe limit for using lidocaine – a kind of local anesthetic, which is 300 mg or 30 ml of 1% lidocaine. If the dosage goes beyond this safe limit, it could lead to side effects involving the brain, heart, and skeletal muscles.
There are other kinds of local anesthetics, such as bupivacaine and ropivacaine. Bupivacaine is known to be most damaging to the cartilage cells whereas ropivacaine is least damaging. Lidocaine is most commonly because of its cost-effectiveness and easy availability. However, it is important to note that all of these have been found harmful to cartilage cells according to both animal and in-vitro human studies.
