Diagnostic and Interventional Musculoskeletal Ultrasound
Doctors order various imaging studies to help diagnose an injury or underlying problem, including x-rays, Magnetic Resonance Imaging (MRI), and Computerized Tomography (CT) scans. Over the last 15 or so years ultrasound has become a widely utilized imaging modality in sports medicine for musculoskeletal complaints given its practicality and rapidly improving imaging technology.
While MRI and CT scan provide great 3-dimensional views of the body, these modalities are not only expensive, but also time-consuming and, in the case of CT, expose the patient to high amounts of ionizing radiation. In the setting of a musculoskeletal injury, MRI utilizes powerful magnets to provide images, which identify bone stress (such as fracture or contusion), ligament tears, joint fluid (also called effusion), cartilage injury, and soft tissue inflammation. CT, on the other hand, uses x-ray radiation to provide high-resolution images of bones to identify specific fracture details and bony deformities. Generally, these imaging methods require static setting, that is, the patient must sit completely still.
Ultrasound (that’s right, good ole fashioned ultrasound) uses sound waves (no ionizing radiation) to create 2-dimensional images of soft tissues. Because of the live capture of images, dynamic movement of the body (joint, muscle, or tendon) can be performed to help identify an injury or problem. The “echo” of sound waves allow clinicians to visualize the surface of the bone, and differentiate the overlying soft tissues, such as muscle, tendons, blood vessels and fluid. With ultrasound it is possible to identify a fractured bone, swelling within a joint or muscle, collection of fluid (such as ganglion cyst), a torn ligament (such as ankle sprain), cartilage injuries (some meniscus tears), complete or partial tendon tears, chronic tendinitis, and even nerve entrapment (carpal tunnel syndrome, for example). The use of Doppler can also help identify tissues that are inflamed or were recently injured, such as the case with a medial collateral ligament sprain, or ankle sprain. Neo-vascularity can also be assessed, which is commonly seen in chronic tendinosis when regenerative injections may be indicated to help with the recovery process.
With real-time ultrasound, dynamic testing can be performed when static images (such as MRI or CT) are not sufficient to make the diagnosis. Although many structural lesions can be seen on static images, most functional abnormalities require real-time dynamic images to confirm the diagnosis. With ultrasound, dynamic testing can be performed by obtaining high-resolution images while loading, stressing, or moving a joint. This is particularly useful in assessing ligament and tendon integrity under stress or load. Dynamic functional ultrasound testing is also critical for impingement or entrapment syndromes, which generally occur only in certain end ranges of motion.
In addition to diagnostics, ultrasound can aid in the guidance of a needle through the tissue for delivering local anti-inflammatories or other regenerative biologic substances (platelet-rich plasma, or prolotherapy) into the inflamed or injured area of tissue. Diagnostic injections can also be performed with ultrasound to confirm the origin of pain. For example, an intra-articular hip injection can confirm a symptomatic labrum tear or a shoulder subacromial bursa injection can confirm bursitis. During these “diagnostic” injections, cortisone is often used to provide long-term relief through its anti-inflammatory effects and promote optimal physical therapy and rehabilitation gains.
Benefits of Real-Time Dynamic Ultrasound:
- Reduce the need for X-rays, scans, and radiation
- Advanced imaging algorithms with fine-tuning of depth, gain, and color
- Dynamic studies capturing muscle, tendon, ligament, and soft tissues during motion
- Doppler and functional studies to evaluate for vascular and nerve entrapment
- Pediatric-focused studies evaluating growth plates without the use of X-ray radiation
Case (Static Ultrasound Evaluation)
19 year old runner with fibular stress fracture (X-rays and radiation differed)
Case (Dynamic Ultrasound Evaluation)
27 year old with medial meniscus radial cleft tear noted with dynamic flexion/extension views.
Case (Interventional Ultrasound)
17 year old basketball player with a partial tear of the proximal patellar tendon, and chronic tendinitis (tendinosis).
By Jon Minor, MD & Mo Mortazavi, MD
Ultrasound images were taken by Jon Minor, MD.
All other images: