Introduction
The recent hamstring injury sidelined Australia’s star player Bec Allen just before the Paris Olympics 2024[1]. Due to long-term high-intensity training, injuries of muscles, tendons, cartilage, and other parts are often inevitable. Although most athletes make efforts to minimize the impact of injuries during sports events, more and more unpredictable emergencies remind that the Medical Support of Sporting Events should provide a point-of-care diagnosis to ensure athletes can return to peak performance swiftly and safely. In this article, explore further how portable ultrasound scanners are revolutionizing injury evaluation and management in sports medicine, particularly through their applications in musculoskeletal ultrasound (MSKUS).
How Does Portable Ultrasound Help Athletes?
Implementation of portable ultrasound machines at 2020 Tokyo Olympic Games
Tokyo 2020 IOC Venue Ultrasound Program marked a pioneering initiative to integrate diagnostic imaging within Olympic venues through the deployment of portable ultrasound machines. During the Olympic event, two portable laptop ultrasound machines, as shown in the picture below, were strategically distributed to seven Olympic sports events at seven distinct venues. In total, 14 athletes were evaluated using venue ultrasound for injuries. The evaluated injuries included musculoskeletal soft tissue (in 7 cases), osseous (in 5 cases), and non-musculoskeletal (in 2 cases) injuries. 9 athletes were evaluated further by other imaging modalities such as X-ray radiography or magnetic resonance imaging, and all received concordant findings that aligned with the results from the venue ultrasound[2], underscoring the diagnostic precision of the portable ultrasound evaluations.
Physicians evolved all affirmed the utility of ultrasound in refining diagnoses, feeling that ultrasound was helpful in improving the diagnosis, especially for the types of injuries commonly occurring in contact sports, where portable ultrasound can quickly identify whether the injury is a bone injury, muscle injury, or soft tissue injury. Furthermore, the personnel from the National Olympics Committee unanimously endorsed the program, reporting a significant boost in diagnostic confidence and expressing the view that venue ultrasound should be considered for future sports events.
Application of MSKUS in Musculoskeletal System
Sport injuries are associated with high direct and indirect costs, and can lead to early sport retirement for up to 24% of athletes[3]. The application of MSKUS in sports medicine has greatly improved the promptness of care for athletes. MSKUS is effective in diagnosing both short-lived incidents such as fractures, sprains, and strains, ligament injuries, and chronic injuries such as tendonitis, stress fractures, cartilage injuries, and osteoarthritis.
1. Application of MSKUS in muscle lesions
Muscle lesions refer to injuries or abnormalities in the muscle tissue. It can range from minor strains to severe tears and can be caused by various factors, including trauma, overuse, or underlying medical conditions. Athletes are especially prone to muscle lesions due to the high physical demands of their training[4]. Symptoms of muscle lesions often include pain, swelling, bruising, and limited range of motion. In some cases, there may be visible deformities or lumps under the skin.
One common type of muscle lesion in athletes is a muscle hernia. A muscle hernia occurs when a portion of the muscle protrudes through a defect in the surrounding fascia, the connective tissue that encases the muscle. It commonly arises during specific postures and resolves spontaneously or with compression when muscle relaxation occurs. This condition is often caused by trauma or excessive strain on the muscle. Muscle hernia appears as a very painful bump visible on the surface of the skin. The tibialis anterior muscle, located in the lower leg, is the most commonly affected[5].
Diagnosis
Musculoskeletal ultrasound (MSKUS) is particularly effective in diagnosing muscle lesions by performing dynamic assessment where a suspected muscle hernia can be assured to the maximum extent by the real-time imaging of the contraction of the affected muscle.
For radiographic features of muscle hernias, the most characteristic ultrasound finding is the observation of interruption in the continuity of the muscle fascia, with low echogenic spaces appearing in between, alongside visualization of muscle tissue herniating through the disrupted area. The muscle hernias typically present as elliptical formations with well-defined borders, as a mushroom-like protrusion of muscle through the fascial defect, radiating outward from the point of fascial rupture.
- In mild cases, the muscle fascia remains intact but exhibits localized thinning, slight elevation, and minor muscle protrusions.
- In more severe cases, there is a noticeable interruption in the continuity of the fascia with high echogenicity, accompanied by low echogenic spaces[5].
For more comprehensive inspection, CDFI (Color Doppler Flow Imaging) is able to detect arterial blood flow signals at certain sites of muscle hernias, suggesting that the hernia occurs at a weak point in the fascia where vessels or nerves penetrate.
Muscle Hernia and Its Ultrasonogram
2. Application of MSKUS in tendinopathy
Tendinopathy is commonly seen in conditions like tennis elbow, golfer’s elbow, jumper’s knee, and swimmer’s shoulder[6]. Common symptoms of tendinopathy include pain, swelling, stiffness, and reduced mobility in the affected area. Achilles tendinopathy is one of the most common types of tendinopathy among athletes, accounting for over 55.9% of all tendon-related cases[7], with an estimated lifetime incidence of up to 24% in athletes[8]. Achilles tendinopathy is often caused by repetitive stress and overuse, particularly in sports involving running and jumping. It is characterized by localized tendon enlargement, which may be accompanied by neovascularity and partial tears[8].
Diagnosis
Sonographic manifestations of tendinopathy include tendon thickening, contour change, echotexture change at an early stage, and further tendon thickening, loss of normal fibrillar pattern with hypoechoic heterogeneity in progressive changes[9].
Achilles Tendon Rupture and Its Ultrasonogram
A dynamic ultrasound examination during ankle dorsiflexion and plantarflexion is beneficial in distinguishing between complete and partial ruptures of the Achilles tendon.
- Partial tears are characterized by clearly defined low echogenic or anechoic gaps along the tendon’s internal borders, with the thickening of the tendon exceeding 1 cm, accompanied by significant internal echogenic abnormalities.
- Complete ruptures exhibit total disruption of the tendon fibers with retraction of the tendon ends. The ruptured ends appear conical, and posterior to the retracted tendon. Refractive shadowing may be observed at tendon stumps[10].
Following an Achilles tendon rupture, the retracted ends often curve toward the anterior aspect of the Kager fat pad. Physicians can further adopt Color Doppler Imaging with increased sensitivity for hyperemia detection, figuring out if the space between the two ends is filled with mixed echogenic fluid or hematoma. High echogenicity fat pads may be partially visible.
Apart from determining the extent of the tendon damage, MSKUS also helps in treatment planning and surgical intervention. A study by Université de Montréal scanned 41 participants with unilateral midportion chronic AT, and the tendon images were analyzed bilaterally in both longitudinal and transverse planes and measured pain, ankle flexibility, strength, and function. The research result proved MSKUS’s clinical utility in visualizing in vivo tendon integrity and diagnosing AT. Also, the study suggested that MSKUS should be considered an integral component of a comprehensive neuro-musculoskeletal assessment, as it complements evaluations of pain, flexibility, strength, and function. Together, these assessments can guide the creation and monitoring of a personalized rehabilitation treatment plan[11].
3. Application of MSKUS in ligament lesions
Ligaments are strong, flexible tissues that connect bones and stabilize joints, found around the knees, ankles, elbows, shoulders, and other joints. They allow for movement but have limited flexibility. Ligament damage occurs when a ligament is twisted, stretched beyond its normal range, or impacted. Common ligament injuries include sprains, strains, and tears.
For example, the superficial medial collateral ligament (sMCL) is the largest and most important structure of the medial knee and is also the most commonly injured ligamentous structure in the knee. MCL injuries often result from contact, such as a lateral knee blow in rugby and football, or non-contact mechanisms, especially in skiers. Another pattern involves a valgus force with tibial external rotation, common in soccer, basketball, and skiing. Symptoms include medial knee pain, swelling, limited motion, pain with weight-bearing, and potential side-to-side instability.
Diagnosis
Acute ligament injuries on MSKUS can show ligament thickening, decreased echogenicity, heterogeneity, and the presence of surrounding edema or hematoma. Additionally, MSKUS can detect smaller avulsion fractures at the ligament-bone junction, even when X-rays show no abnormalities.
- In cases of acute partial tear, there is swelling and thickening of the collateral ligament, accompanied by reduced echogenicity and indistinct, poorly defined borders.
- In acute complete tears, the echogenicity of the ligament is interrupted, and when associated with a hematoma, a localized hypoechoic area with swelling can be observed.
- Chronic partial tears exhibit a loss of the fibrous structure of the ligament, with no interruption in echogenicity, and may show localized or diffuse areas of increased echogenicity or calcification within the ligament. For instance, chronic medial collateral ligament (MCL) injury with a thickened inhomogeneous ligament intratendinous fissure and neovascularity[12].
Apart from knee ligament injuries, scapholunate and other perilunate injuries are often underestimated and frequently dismissed as simple “sprains,” particularly in athletes[13]. In evaluating the wrist and proximal hand, ultrasound enables static and dynamic imaging of small joints and joints as well as adjacent structures (i.e. imaging while fiddling with the joint) with a resolution comparable to or better than MRI[14]. The ultrasound feature of a ruptured scapholunate ligament appears as an increased distance between the scaphoid and lunate bone and thickened hypervascularized soft tissues[15]. Delays in proper treatment can greatly impact outcomes, as acute scapholunate and perilunate injuries respond better to treatment than chronic ones.
4. Application of MSKUS in joint diseases
As one of the most common joint diseases, rheumatoid arthritis (RA) is a chronic systemic inflammatory disease characterized by inflammation in the small joints with symmetrical involvement of the upper and lower extremities, causing structural damage and disability. After tennis champ Caroline Wozniacki was diagnosed in 2018, she dropped from the top rankings and retired in 2020. The same year, RA forced top cyclist Ian Stannard into retirement. The destruction caused by RA occurs early in the disease outcome leading to the concept of a window of opportunity. Thus, rheumatologists need sensitive tools to detect RA at an early stage and evaluate disease activity[16].
Diagnosis
For an accurate diagnosis, studies have established musculoskeletal ultrasound (MSKUS) when compared to clinical examination to be more sensitive in identifying synovitis[17], characterized on grayscale ultrasound by intra-articular tissue that is abnormally thickened, hypoechoic, or anechoic (relative to subdermal fat), nondisplaceable, and poorly compressible[18]. Further, ultrasound can visualize pathophysiological changes such as synovitis, tenosynovitis, enthesitis, bone erosions, and crystal deposits at a subclinical level, which makes it an effective technique to identify and differentiate most common types of inflammatory arthritis[18].
(Left: B-mode; Right: Power Doppler Image)
For practical examples, Figure A shows the longitudinal scan of the dorsal aspect of the second metacarpophalangeal joint. One black cave above the metacarpal head (at the star mark) is visible indicating a fluid accumulation. Figure B shows the longitudinal ultrasound examination of the dorsal tibiotalar joint in dorsiflexion. A darker shadow is found (at the star mark), indicating an intra-articular effusion.
Figure A (P2: second proximal phalanx; MC: metacarpal head)
Wrapping Up
The comprehensive applications of ultrasound machines in sports events highlight their versatility and indispensability in modern sports medicine. From diagnosing acute injuries to sports rehabilitation, portable ultrasound scanners have become the first choice because they are easy to carry anywhere, anytime, which is crucial for the immediate and effective treatment of athletes.
But how do these ultrasound techniques compare to other diagnostic imaging methods? What are the strengths and weaknesses of CT, MRI, and X-ray in sports medicine? And can portable ultrasound devices revolutionize on-spot diagnosis in sports events? Find answers in the newly released article, and explore the broader applications of musculoskeletal ultrasound in sports medicine.
References:
[1] Australia loses Bec Allen for Paris Olympics with hamstring injury in final warmup game (2024)
https://apnews.com/article/olympics-2024-basketball-bec-allen-c2b1fb31a05cdf558bcc47512651d36d
[2] The International Olympic Committee Venue Ultrasound Program: A Pilot Study From Tokyo 2020 Olympic Games (2023)
https://journals.lww.com/ajpmr/fulltext/2023/05000/the_international_olympic_committee_venue.10.aspx
[3] Analyzing injuries among university-level athletes: prevalence, patterns and risk factors (2017)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5596969
[4] Muscle Injuries: A Brief Guide to Classification and Management (2014)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4592039
[5] Muscle hernia – Radiopaedia (2023)
https://radiopaedia.org/articles/muscle-hernia?lang=us
[6] Golfer’s elbow – Symptoms and causes – Mayo Clinic (2022)
https://www.mayoclinic.org/diseases-conditions/tendinitis/symptoms-causes/syc-20378243
[7] Poster 383: Incidence of Sports Related Tendon Ruptures in the United States (2023)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10392213
[8] Treatment of Achilles tendinopathy (2023)
[9] Tendinopathy – Radiopaedia (2024)
https://radiopaedia.org/articles/tendinopathy-1?lang=us
[10] Case Review: Ultrasound of Achilles Tendinosis and Tear (2022)
[11] To What Extent Do Musculoskeletal Ultrasound Biomarkers Relate to Pain, Flexibility, Strength, and Function in Individuals With Chronic Symptomatic Achilles Tendinopathy? (2021)
https://www.frontiersin.org/journals/rehabilitation-sciences/articles/10.3389/fresc.2021.726313/full
[12] Medial collateral ligament – Ultrasound Cases (2020)
https://www.ultrasoundcases.info/medial-collateral-ligament-2747
[13] Scapholunate and perilunate injuries in the athlete (2017)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344854
[14] Musculoskeletal ultrasound of the wrist (2024)
https://www.uptodate.com/contents/musculoskeletal-ultrasound-of-the-wrist
[15] Ligament trauma – Ultrasound Cases (2020)
https://www.ultrasoundcases.info/ligament-trauma-1500
[16] Ultrasound and follow-up of rheumatoid arthritis (2017)
https://www.sciencedirect.com/science/article/abs/pii/S1297319X16301555
[17] The role of ultrasound in diagnosing rheumatoid arthritis, what do we know? An updated review (2017)
[18] The importance of ultrasound in identifying and differentiating patients with early inflammatory arthritis: a narrative review (2020)
