The Benefits of Ultrasound Guided Injections

By Lauren Porras, MD and David Berkoff, MD

Ultrasound, also known as sonography, is an imaging method that uses high-frequency sound waves to produce real-time and dynamic images of the body. Ultrasound is increasingly being used to assist Sports Medicine Physicians, Rheumatologists, Orthopedists, and Primary Care Physicians in performing evaluations and injections of different muscles, tendons, ligaments and joints. With the advancement of this technology, ultrasound machines have become smaller and more portable. This has allowed treating clinicians to be able to use real time, point of care ultrasound, to assist in the diagnosis and treatment of their patients. Although ultrasound is frequently used to identify injuries or abnormalities; it is also used when performing injections into the knee, shoulder and hip.

Injections can be beneficial for both the diagnostic and therapeutic treatment of a variety of problems involving the hip, shoulder, and knee. Typical problems include osteoarthritis, rheumatoid arthritis, labral tears, muscle tears, ligament tears and tendonopathies. Injections have been used in the management of inflammatory and degenerative conditions when rest, ice and anti-inflammatory medications fail to provide adequate relief. The use of ultrasound improves the accuracy of the injection of corticosteroids, hyaluronic acid or other therapies such as Platelet Rich Plasma, Prolotherapy or Stem Cells. Ultrasound can also be used for joint aspirations to rule out joint infection or gout. Lastly, guided injections can be used diagnostically to help determine which structures are generating the patient’s pain.

Ultrasound-guided injections allow the practitioner to visualize the needle in real time as it enters the body and traverses to the desired location. This assures that the medication is accurately injected at the intended site. Despite good intentions, even in the most experienced hands, blind (injections performed without imaging) injections are not 100% accurate and in some joints accuracy is as low as 30%-40%. With ultrasound guidance the accuracy of nearly every joint injection exceeds 90% and approaches 100% in many. Additionally, ultrasound guided injections have been shown to be less painful than blind injections. Ultrasound injections also have the advantage of giving “real time” and “dynamic” feedback that the patient and the doctor can see and use immediately. The doctor is able to watch the desired treatment being delivered to the intended target and even visualize surrounding structures both before during and even after the procedure.

Although there are many different types of imaging that can be used to assist with injections, ultrasound has a few distinct advantages.

1) Ultrasound has no radiation. Flouoroscopy (a type of real time X-ray) allows the provider to easily visualize the joint making injections easier, however, fluoroscopy is associated with repeated doses of radiation. Additionally with fluoroscopy the providers are unable to visualize surrounding soft tissue structures including tendon, blood vessels or nerves that may be in the path of the needle. This could lead to increased pain or other complications from the injection.

2) Ultrasound allows us to visualize the bony joint as well as all of the surrounding structures. Moving the ultrasound probe the practitioner can visualize what may be in the path of the needle and avoid any unwanted complications before they happen.

3) Ultrasound is able to identify fluid better than conventional radiographs and can see fluid that may have accumulated in and around joints, tendons, muscles, nerves and other soft-tissue structures. CT-guided (or CAT Scan) injections are also frequently used to assist in delivering treatments. With the CT we are able to get a 3-D view of the joint to be injected and can accurately deliver the intended medication, however, these tests come with an increasingly large dose of radiation, they are expensive and time-consuming. Ultrasound injections have been shown to be as accurate as these other imaging-modalities with less cost, improved soft tissue visualization and without the associated radiation.

Ultrasound-guided injections have been extensively studied and have been found to have very few complications.

The risks associated with these procedures are the same as any type of injection: incomplete reduction of pain, bleeding, damage to surrounding structures and infection. The overall risks for injections are very low and the use of ultrasound guidance may further reduce some of these risks.

Ultrasound is beneficial when performing injections in the knee, shoulder and hip; as well as many other structures throughout the body.

Knee: Ultrasound can help evaluate a variety of structures within the knee including the quadriceps and patellar tendons, the extra-articular (outside the joint) ligaments, and some meniscus injuries. It can also be used to see if there is fluid within the knee joint. Although knee injections are typically performed without imaging, imaging can be particularly helpful in patients with difficult anatomy or in overweight patients.

Hip: Hip joint injections may be performed for osteoarthritis of the hip and the diagnosis and management of labral tears. Imaging is nearly always used when performing injections into the hip joint due to the deep location of the joint and the proximity of blood vessels and nerves. It is estimated that blind injections are accurate 50% to 80% of the time. Ultrasound allows us to visualize the hip joint, bursa, muscles and tendons surrounding the hip. The use of ultrasound when performing a hip injection increases the accuracy to up to 96%. Whereas in the past, hip injections were mainly performed using Fluoroscopy, ultrasound- guided injections have become more popular due to its ease of use, lower cost and ease of perform in the office setting.

Shoulder: Studies have shown that Ultrasound of the shoulder is just as sensitive and specific as MRI in the diagnosis of rotator cuff injury. Ultrasound can facilitate the more accurate injection of multiple different structures in the shoulder including the Acromioclavicular (AC) joint, the Glenohumeral joint (the true shoulder joint), the biceps tendon, and the subacromial bursa. All of these can be injected with or without guidance, however, as noted above the accuracy of these injections is significantly improved with the use of ultrasound guidance.

AMSSM Member Authors
Lauren Porras, MD and David Berkoff, MD