Imaging of Muscle Injuries in Sports Medicine: Sports Imaging Series

Myositis and Its Mimics: Guideline Updates, MRI Characteristics, and New Horizons

Myositis is defined as inflammation within skeletal muscle and is a subcategory of myopathy, which is more broadly defined as any disorder affecting skeletal muscle. Myositis may be encountered as a component of autoimmune and connective tissue diseases, where it is described as idiopathic inflammatory myopathy (IIM). Myositis can also be caused by infections as well as toxins and drugs, including newer classes of medications. MRI plays an important role in the diagnosis and evaluation of patients with suspected myositis, but many entities may have imaging features similar to those of myositis and can be considered myositis mimics. These include muscular dystrophies, denervation, deep venous thrombosis, diabetic myonecrosis, muscle injury, heterotopic ossification, and even neoplasms. In patients with suspected myositis, definitive diagnosis may require integrated analysis of imaging findings with clinical, laboratory, and pathology data. The objectives of this article are to review the fundamental features of myositis, including recent updates in terminology and consensus guidelines for IIMs; the most important MRI differential diagnostic considerations for myositis (i.e., myositis mimics); and new horizons, including the potential importance of artificial intelligence and multimodal integrated diagnostics in the evaluation of patients with muscle disorders.

Significant age-related differences between lower leg muscles of older and younger female subjects detected by ultrashort echo time magnetization transfer modeling

Magnetization transfer (MT) magnetic resonance imaging (MRI) can be used to estimate the fraction of water and macromolecular proton pools in tissues. MT modeling paired with ultrashort echo time acquisition (UTE-MT modeling) has been proposed to improve the evaluation of the myotendinous junction and fibrosis in muscle tissues, which the latter increases with aging. This study aimed to determine if the UTE-MT modeling technique is sensitive to age-related changes in the skeletal muscles of the lower leg. Institutional review board approval was obtained, and all recruited subjects provided written informed consent. The legs of 31 healthy younger (28.1 ± 6.1 years old, BMI = 22.3 ± 3.5) and 20 older (74.7 ± 5.5 years old, BMI = 26.7 ± 5.9) female subjects were imaged using UTE sequences on a 3 T MRI scanner. MT ratio (MTR), macromolecular fraction (MMF), macromolecular T2 (T2-MM), and water T2 (T2-W) were calculated using UTE-MT modeling for the anterior tibialis (ATM), posterior tibialis (PTM), soleus (SM), and combined lateral muscles. Results were compared between groups using the Wilcoxon rank sum test. Three independent observers selected regions of interest (ROIs) and processed UTE-MRI images separately, and the intraclass correlation coefficient (ICC) was calculated for a reproducibility study. Significantly lower mean MTR and MMF values were present in the older compared with the younger group in all studied lower leg muscles. T2-MM showed significantly lower values in the older group only for PTM and SM muscles. In contrast, T2-W showed significantly higher values in the older group. The age-related differences were more pronounced for MMF (-17 to -19%) and T2-W (+20 to 47%) measurements in all muscle groups compared with other investigated MR measures. ICCs were higher than 0.93, indicating excellent consistency between the ROI selection and MRI measurements of independent readers. As demonstrated by significant differences between younger and older groups, this research emphasizes the potential of UTE-MT MRI techniques in evaluating age-related skeletal muscle changes.

Muscle Healing in Sports Injuries: MRI Findings and Proposed Classification Based on a Single Institutional Experience and Clinical Observation

MRI plays a crucial role in assessment of patients with muscle injuries. The healing process of these injuries has been studied in depth from the pathophysiologic and histologic points of view and divided into destruction, repair, and remodeling phases, but the MRI findings of these phases have not been fully described, to our knowledge. On the basis of results from 310 MRI studies, including both basal and follow-up studies, in 128 athletes with muscle tears including their clinical evolution, the authors review MRI findings in muscle healing and propose a practical imaging classification based on morphology and signal intensity that correlates with histologic changes. The proposed phases, which can overlap, are destruction (phase 1), showing myoconnective tissue discontinuity and featherlike edema; repair (phase 2), showing filling in of the connective tissue gaps by a hypertrophic immature scar; and remodeling (phase 3), showing scar maturation and regression of the edema. A final healed stage can be identified with MRI, which is characterized by persistence of a slight fusiform thickening of the connective tissue. This information can be obtained from a truncated MRI protocol with three acquisitions, preferably performed with a 3-T magnet. During MRI follow-up of muscle injuries, other important features to be assessed are changes in muscle edema and specific warning signs, such as persistent intermuscular edema, new connective tear, and scar rupture. An understanding of the MRI appearance of normal and abnormal muscle healing and warning signs, along with cooperation with a multidisciplinary team, enable optimization of return to play for the injured athlete. ©RSNA, 2024 See the invited commentary by Flores in this issue.

Advanced MRI Approaches for Evaluating Common Lower Extremity Injuries in Basketball Players: Current and Emerging Techniques

Magnetic resonance imaging (MRI) can provide accurate and non-invasive diagnoses of lower extremity injuries in athletes. Sport-related injuries commonly occur in and around the knee and can affect the articular cartilage, patellar tendon, hamstring muscles, and bone. Sports medicine physicians utilize MRI to evaluate and diagnose injury, track recovery, estimate return to sport timelines, and assess the risk of recurrent injury. This article reviews the current literature and describes novel developments of quantitative MRI tools that can further advance our understanding of sports injury diagnosis, prevention, and treatment while minimizing injury risk and rehabilitation time. Innovative approaches for enhancing the early diagnosis and treatment of musculoskeletal injuries in basketball players span a spectrum of techniques. These encompass the utilization of T2, T1ρ, and T2* quantitative MRI, along with dGEMRIC and Na-MRI to assess articular cartilage injuries, 3D-Ultrashort echo time MRI for patellar tendon injuries, diffusion tensor imaging for acute myotendinous injuries, and sagittal short tau inversion recovery and axial long-axis T1-weighted, and 3D Cube sequences for bone stress imaging. Future studies should further refine and validate these MR-based quantitative techniques while exploring the lifelong cumulative impact of basketball on players' knees. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

[Muscle injuries: the importance of high-resolution dynamic sonography in diagnostics, treatment and monitoring]

BACKGROUND

Muscle injuries are common in football. Imaging diagnostics have a major role in establishing a diagnosis. The main diagnostic procedures are MRI and ultrasound. Both diagnostics have advantages and disadvantages, which should be balanced against each other.

NEW ULTRASONIC TECHNIQUES

The role of MRI as the gold standard is increasingly being replaced by high-resolution ultrasound techniques, and MRI imaging is not always useful. To detect complications in the early stages it is advised to perform regular ultrasound-imaging check-ups. The healing process can be monitored, and it offers additional options for ultrasound-guided interventions such as hematoma punctures and targeted infiltrations.

ADVANTAGES AND DISADVANTAGES

However, ultrasound imaging is highly user dependent. Experienced operators can eliminate this disadvantage, which makes ultrasound a superior imaging system in many areas, especially for dynamic examinations. Nevertheless, MRI imaging remains a necessary imaging method in certain areas.

A Novel Minimally Invasive Surgically Induced Skeletal Muscle Injury Model in Sheep

Sports-related muscle injuries account for 10-55% of all injuries, which is a growing concern, especially given the aging world population. To evaluate the process of skeletal muscle injury and compare it with muscle lesions observed in humans, we developed a novel in vivo model in sheep. In this model, muscle injury was induced by an ultrasound-guided transverse biopsy at the myotendinous junction of the medial gastrocnemius muscle. Twelve male sheep were examined at 3, 7, 14, and 28 days post-injury. Histological, immunofluorescence, and MRI analyses indicate that our sheep model could resemble key human clinicopathological features. Statistically significant differences (p < 0.05) were observed in collagen I, dMHC, α-SMA, and CD68 immunohistochemical detection when comparing injured and healthy muscles. The injured gastrocnemius muscle exhibited elevated levels of type I collagen, infiltration of CD68(+) macrophages, angiogenesis, and the emergence of newly regenerated dMHC(+) myofibers, which persisted for up to 4 weeks post-injury. Similarly, the progression of muscle injury in the sheep model was assessed using advanced clinical 3 T MRI and compared with MRI scans from human patients. The data indicate that the sheep muscle injury model presents features similar to those observed in human skeletal muscle injuries. This makes it a valuable large animal model for studying muscle injuries and developing novel therapeutic strategies.

The direct muscular origin of the semitendinosus: a pitfall in categorization of proximal hamstring tendon tears

The ischial origin of the hamstring musculature is complex. While the conjoint tendon and semimembranosus are commonly discussed and understood by radiologists, there is a lesser-known origin of the semitendinosus along the inferior and medial surface of the ischium in the form of a broad direct muscular connection. This secondary origin is infrequently described in the radiology literature and is a potential pitfall during grading of semitendinosus injuries if the interpreting physician is unaware of its presence. In a proximal hamstring tendon tear, the direct muscular origin of the semitendinosus can be spared, torn along with the conjoint tendon, or remain intact and contribute to a vertical shearing injury of the semitendinosus myotendinous junction. Detailed knowledge of this anatomy and its imaging appearance in the setting of injury enables the reader to correctly diagnose these unique hamstring injuries.

Reinjury Following Return to Play

Radiologists are frequently called on for guidance regarding return to play (RTP) for athletes and active individuals after sustaining a musculoskeletal injury. Avoidance of reinjury is of particular importance throughout the rehabilitative process and following resumption of competitive activity. Understanding reinjury risk estimation, imaging patterns, and correlation of clinical and surgical findings will help prepare the radiologist to identify reinjuries correctly on diagnostic imaging studies and optimize management for a safe RTP.

Ultrasound imaging in professional soccer: when is it adequate?

Ultrasound imaging plays an important role in the diagnosis, monitoring and treatment of injuries in professional soccer players. With the rapid increase in the availability of hand-held portable ultrasound devices and the pressure to make timely and accurate diagnosis in professional soccer where return to play time is crucial, ultrasound imaging is an essential diagnostic tool. In this article, we discuss examples of injuries that can be adequately assessed by ultrasound imaging alone and injuries where ultrasound imaging provides a useful first step to guide further investigation and management.

Managing Lower Limb Muscle Reinjuries in Athletes: From Risk Factors to Return-to-Play Strategies

Muscle injuries and subsequent reinjuries significantly impact athletes, especially in football. These injuries lead to time loss, performance impairment, and long-term health concerns. This review aims to provide a comprehensive overview of the current understanding of muscle reinjuries, delving into their epidemiology, risk factors, clinical management, and prevention strategies. Despite advancements in rehabilitation programs and return-to-play criteria, reinjury rates remain alarmingly high. Age and previous muscle injuries are nonmodifiable risk factors contributing to a high reinjury rate. Clinical management, which involves accurate diagnosis, individualized rehabilitation plans, and the establishment of return-to-training and return-to-play criteria, plays a pivotal role during the sports season. Eccentric exercises, optimal loading, and training load monitoring are key elements in preventing reinjuries. The potential of artificial intelligence (AI) in predicting and preventing reinjuries offers a promising avenue, emphasizing the need for a multidisciplinary approach to managing these injuries. While current strategies offer some mitigation, there is a pressing need for innovative solutions, possibly leveraging AI, to reduce the incidence of muscle reinjuries in football players. Future research should focus on this direction, aiming to enhance athletes' well-being and performance.

Clinical applications of skeletal muscle diffusion tensor imaging

Diffusion tensor imaging (DTI) may allow the determination of new threshold values, based on water anisotropy, to differentiate between healthy muscle and various pathological processes. Additionally, it may quantify treatment monitoring or training effects. Most current studies have evaluated the potential of DTI of skeletal muscle to assess sports-related injuries or therapy, and training monitoring. Another critical area of application of this technique is the characterization and monitoring of primary and secondary myopathies. In this manuscript, we review the application of DTI in the evaluation of skeletal muscle in these and other novel clinical scenarios, with emphasis on the use of quantitative imaging-derived biomarkers. Finally, the main limitations of the introduction of DTI in the clinical setting and potential areas of future use are discussed.

Indirect Rectus Femoris Injury Mechanisms in Professional Soccer Players: Video Analysis and Magnetic Resonance Imaging Findings

OBJECTIVE

To describe injury mechanisms and magnetic resonance imaging (MRI) findings in acute rectus femoris (RF) injuries of soccer players using a systematic video analysis.

DESIGN

Descriptive case series study of consecutive RF injuries from November 2017 to July 2022.

SETTING

Two specialized sports medicine hospitals.

PARTICIPANTS

Professional male soccer players aged between 18 and 40 years, referred for injury assessment within 7 days after a RF injury, with an available video footage of the injury and a positive finding on an MRI.

INDEPENDENT VARIABLES

Rectus femoris injury mechanisms (specific scoring based on standardized models) in relation to RF muscle injury MRI findings.

MAIN OUTCOME MEASURES

Rectus femoris injury mechanism (playing situation, player/opponent behavior, movement, and biomechanics), location of injury in MRI.

RESULTS

Twenty videos of RF injuries in 19 professional male soccer players were analyzed. Three different injury mechanisms were seen: kicking (80%), sprinting (10%), and change of direction (10%). Isolated single-tendon injuries were found in 60% of the injuries. Of the kicking injuries, 62.5% included complete tendon ruptures, whereas both running injuries and none of the change of direction injuries were complete ruptures. The direct tendon was involved in 33% of the isolated injuries, and the common tendon was affected in all combined injuries.

CONCLUSIONS

Rectus femoris injuries typically occur during kicking among football players. Most of the RF injuries involve a complete rupture of at least one tendon. Kicking injuries can also affect the supporting leg, and sprinting can cause a complete tendon rupture, whereas change of direction seems not to lead to complete ruptures.

MR evaluation of the posteromedial corner of the knee: association of posterior horn medial meniscus tear with posterior oblique ligament and distal semi-membranosus tendon tear

OBJECTIVE

To assess if posterior oblique ligament and distal semi-membranosus tendon tears are associated with posterior horn medial meniscus tears on MRI.

METHODS

From January 1, 2018 to December 31, 2019, 56 patients who met the inclusion criteria were enrolled in this study. Of the 56 patients, 43 patients who had a posterior horn of medial meniscus tear were included in the study group. A control group of 13 individuals was formed for comparison. Two radiologists reviewed the MR images and recorded the presence and grades of posterior oblique ligament and distal semi-membranosus tendon tears. We used the independent t-test and one-way ANOVA to compare the tear grades. Interobserver agreement was analyzed using a Cohen's κ coefficient (κ value) for categorical variables.

RESULTS

The mean grades for the posterior oblique ligament and distal semi-membranosus tendon tears were significantly higher in the study group (all, p < 0.001). Interobserver agreement between the two readers was substantial in assessing the grade of posterior oblique ligament tear (κ = 0.653±0.087) and almost perfect in assessing the grade of distal semi-membranosus tendon tear (κ = 0.876±0.060).

CONCLUSION

Posterior oblique ligament and distal semi-membranosus tendon tears are significantly associated with posterior horn of medial meniscus tear and medial meniscus posterior root tears, and the peel-back mechanism could be related to this association.

ADVANCES IN KNOWLEDGE

Presenting this paper could adjust radiologist search patterns and potentially help orthopedists with management and pre-surgical planning for the posteromedial corner injury of the knee.

Mechanisms of Hamstring Injury in Professional Soccer Players: Video Analysis and Magnetic Resonance Imaging Findings

OBJECTIVE

To describe the injury mechanisms and magnetic resonance imaging (MRI) findings in acute hamstring injuries of male soccer players using a systematic video analysis.

DESIGN

Descriptive case series study of consecutive acute hamstring injuries from September 2017 to January 2022.

SETTING

Two specialized sports medicine hospitals.

PARTICIPANTS

Professional male soccer players aged between 18 and 40 years, referred for injury assessment within 7 days after an acute hamstring injury, with an available video footage of the injury and positive finding on MRI.

INDEPENDENT VARIABLES

Hamstring injury mechanisms (specific scoring based on standardized models) in relation to hamstring muscle injury MRI findings.

MAIN OUTCOME MEASURES

Hamstring injury mechanism (playing situation, player/opponent behavior, movement, and biomechanical body positions) and MRI injury location.

RESULTS

Fourteen videos of acute hamstring injuries in 13 professional male soccer players were analyzed. Three different injury mechanisms were seen: mixed-type (both sprint-related and stretch-related, 43%), stretch-type (36%), and sprint-type (21%). Most common actions during injury moments were change of direction (29%), kicking (29%), and running (21%). Most injuries occurred at high or very high horizontal speed (71%) and affected isolated proximal biceps femoris (BF) (36%). Most frequent body positions at defined injury moments were neutral trunk (43%), hip flexion 45-90 degrees (57%), and knee flexion <45 degrees (93%). Magnetic resonance imaging findings showed that 79% were isolated single-tendon injuries.

CONCLUSIONS

According to a video analysis, most hamstring injuries in soccer occur during high-speed movements. Physicians should suspect proximal and isolated single-tendon-most often BF-hamstring injury, if represented injury mechanisms are seen during game play. In addition to sprinting and stretching, also mixed-type injury mechanisms occur.

Past, present, and future in sports imaging: how to drive in a three-lane freeway

KEY POINTS

• Morphological evaluation of SRIs is still nowadays the clinical standard in daily practice.• New functional imaging modalities show potential to add valuable physiopathological information about the insights of SRIs in specific clinical scenarios.• In the era of personalized medicine, AI algorithms may help athletes and all professionals involved in their care to improve the evaluation of SRIs through a definitive quantitative metric approach.

A Review on Biological Effects of Ultrasounds: Key Messages for Clinicians

Ultrasound (US) is acoustic energy that interacts with human tissues, thus, producing bioeffects that may be hazardous, especially in sensitive organs (i.e., brain, eye, heart, lung, and digestive tract) and embryos/fetuses. Two basic mechanisms of US interaction with biological systems have been identified: thermal and non-thermal. As a result, thermal and mechanical indexes have been developed to provide a means of assessing the potential for biological effects from exposure to diagnostic US. The main aims of this paper were to describe the models and assumptions used to estimate the "safety" of acoustic outputs and indices and to summarize the current state of knowledge about US-induced effects on living systems deriving from in vitro models and in vivo experiments on animals. This review work has made it possible to highlight the limits associated with the use of the estimated safety values of thermal and mechanical indices relating above all to the use of new US technologies, such as contrast-enhanced ultrasound (CEUS) and acoustic radiation force impulse (ARFI) shear wave elastography (SWE). US for diagnostic and research purposes has been officially declared safe, and no harmful biological effects in humans have yet been demonstrated with new imaging modalities; however, physicians should be adequately informed on the potential risks of biological effects. US exposure, according to the ALARA (As Low As Reasonably Achievable) principle, should be as low as reasonably possible.

Measuring direct and indirect tendon parameters to characterize the proximal tendinous complex of the rectus femoris in football and futsal players

Objective: To present unprecedented radiological parameters that characterize the angle between the direct and indirect tendons of the proximal rectus femoris (RF) and its inclinations and to evaluate the population variability according to demographic variables. Materials and methods: From September 2019 to July 2021, using MRI multiplanar reconstructions of the proximal thigh/hip, two blinded radiologists measured the direct and indirect tendon angle and the inclination of each tendon in different planes. The intra- and inter-observer agreements were assessed with Bland-Altman analysis and intraclass correlation coefficient (ICC). The correlations between radiological parameters and demographic variables were evaluated using linear regression, Student's t-test, and analysis of variance. Results: We performed 112 thigh/hip MRI scans on 91 football players of different age, gender, and disciplines (football and futsal). For observer 1 (the reference), the mean direct and indirect tendon angle was 56.74° ± 9.37, the mean indirect tendon slope was -7.90° ± 7.49, and the mean direct tendon slope was 22.16° ± 5.88. The three measurements showed inter- and intra-observer agreement (mean differences ∼0). No correlation was observed between age and the parameters. Likewise, no statistically significant differences were found for gender, dominant limb, examined limb, and sport. Conclusion: There is an inter- and intra-observer agreement in the measurements of the direct and indirect tendon angle and the inclination of each tendon. There is population variability in the proximal tendinous complex unrelated to demographic factors. These results allow further detection of morphological patterns that represent a risk factor for lesions in the RF in professional football and futsal players and other sports.

Imaging of common hip pathologies in runners

Running is an increasingly popular sport and form of exercise. Because of the importance of the hip in the biomechanics involved with running, forming the primary connection between the axial and appendicular skeleton of the lower extremities, accurate diagnosis and reporting of hip pathology are vital for appropriate management. This review provides an overview of the most common hip pathologies and injuries encountered in runners. Radiologic studies, primarily conventional radiography and magnetic resonance imaging (MRI) provide useful diagnostic information and should be used in combination with clinical findings to help guide therapeutic management.

Muscle Injury Around the Shoulder

Acute shoulder tendon and intra-articular injuries are common and their imaging well described. However, a subset of patients present with more unusual acute shoulder muscle injury. Of these, pectoralis major muscle injuries are encountered the most often and are increasingly prevalent due to a focus on personal fitness, particularly bench-press exercises. Other muscle injuries around the shoulder are rare. This article reviews the anatomy, mechanism of injury, and the imaging findings in relation to injuries of these muscles around the shoulder. We focus on pectoralis major injury but also review proximal triceps, latissimus dorsi, teres major, and deltoid muscle injuries, providing imaging examples.

Epigenetic Alterations in Sports-Related Injuries

It is a well-known fact that physical activity benefits people of all age groups. However, highly intensive training, maladaptation, improper equipment, and lack of sufficient rest lead to contusions and sports-related injuries. From the perspectives of sports professionals and those performing regular–amateur sports activities, it is important to maintain proper levels of training, without encountering frequent injuries. The bodily responses to physical stress and intensive physical activity are detected on many levels. Epigenetic modifications, including DNA methylation, histone protein methylation, acetylation, and miRNA expression occur in response to environmental changes and play fundamental roles in the regulation of cellular activities. In the current review, we summarise the available knowledge on epigenetic alterations present in tissues and organs (e.g., muscles, the brain, tendons, and bones) as a consequence of sports-related injuries. Epigenetic mechanism observations have the potential to become useful tools in sports medicine, as predictors of approaching pathophysiological alterations and injury biomarkers that have already taken place.

Agonist-antagonist muscle strain in the residual limb preserves motor control and perception after amputation

Background

Elucidating underlying mechanisms in subject-specific motor control and perception after amputation could guide development of advanced surgical and neuroprosthetic technologies. In this study, relationships between preserved agonist-antagonist muscle strain within the residual limb and preserved motor control and perception capacity are investigated.

Methods

Fourteen persons with unilateral transtibial amputations spanning a range of ages, etiologies, and surgical procedures underwent evaluations involving free-space mirrored motions of their lower limbs. Research has shown that varied motor control in biologically intact limbs is executed by the activation of muscle synergies. Here, we assess the naturalness of phantom joint motor control postamputation based on extracted muscle synergies and their activation profiles. Muscle synergy extraction, degree of agonist-antagonist muscle strain, and perception capacity are estimated from electromyography, ultrasonography, and goniometry, respectively.

Results

Here, we show significant positive correlations (P < 0.005–0.05) between sensorimotor responses and residual limb agonist-antagonist muscle strain. Identified trends indicate that preserving even 20–26% of agonist-antagonist muscle strain within the residuum compared to a biologically intact limb is effective in preserving natural motor control postamputation, though preserving limb perception capacity requires more (61%) agonist-antagonist muscle strain preservation.

Conclusions

The results suggest that agonist-antagonist muscle strain is a characteristic, readily ascertainable residual limb structural feature that can help explain variability in amputation outcome, and agonist-antagonist muscle strain preserving surgical amputation strategies are one way to enable more effective and biomimetic sensorimotor control postamputation.

People who undergo limb amputation can have issues with controlling movement and perception of residual limbs. This, in turn, can impact the success of neuroprosthetic strategies, which use signals from the body to control a prosthetic limb. Here, we wanted to understand how sensory signals within the muscle help to preserve movement and limb perception following amputation. We used ultrasound imaging and other methods to measure muscle activity and limb perception in fourteen people who have undergone lower limb amputations. We show that the level at which the relationship between pairs of related muscles is preserved is associated with more natural control of limb movement after amputation. Developing surgical techniques that preserve this relationship may help people living with amputations to naturally perceive and control their residual limbs, and ultimately may improve controllability of assistive prosthetic devices.

Song et al. study the relationship between agonist-antagonist muscle strain (AMS) and motor control and perception in lower limb amputees, with some receiving a myoneural interface intervention. The authors report that the degree of AMS within the residual limb is associated with preserved motor control and perception.

Three-dimensional turbo spin-echo (TSE) MRI assessment of indirect acute muscle injuries in athletes: comparison with two-dimensional TSE MRI

OBJECTIVE

To evaluate three-dimensional (3D) turbo spin-echo (TSE) magnetic resonance imaging (MRI) for the assessment of acute muscle injuries in elite athletes in comparison with two-dimensional (2D) MRI.

METHODS

Elite athletes with clinically suspected acute muscle injury of the thigh who underwent both 2D and 3D MRI protocols on the same day were retrospectively included. Two musculoskeletal radiologists independently assessed 2D and 3D MRIs, with both techniques evaluated separately 1-month apart. Muscle injuries were evaluated using the BAMIC and the INSEP classifications. A second assessment of injuries was performed by each reader 2 months after the initial readings. Agreement was determined using weighted kappa statistics. The level of diagnostic confidence in classifying injuries was also assessed for both MRI protocols.

RESULTS

A total of 40 athletes were included. Intra-reader agreement when comparing injury grades from 2D vs. 3D for both INSEP and BAMIC classifications was almost perfect for both readers and ranged between 0.84 and 0.98. Inter-reader agreement was substantial to almost perfect and ranged from 0.78 to 0.93 for the 2D protocol, and from 0.78 to 0.95 for the 3D protocol. Intra-reader agreement for each MRI protocol separately was almost perfect to perfect for both readers and ranged between 0.84 and 1.00. Diagnostic confidence for grading injuries improved for both readers when using the 3D protocol.

CONCLUSIONS

Compared to 2D MRI, 3D TSE MRI is a reliable technique for acute muscular injury assessment, providing faster acquisition times and improving the diagnostic confidence.

KEY POINTS

• Compared to 2D MRI, 3D TSE MRI is a reliable technique for the assessment of acute muscular injuries. • 3D TSE MRI has the advantage of faster total acquisition times, thinner sections, and multiplanar reconstruction, improving the confidence for structural assessment including connective tissue involvement.

Navigating the complexity of calf injuries in athletes: a review of MRI findings

The calf muscle group is a common area for injury within the professional athlete population. Anatomical and biomechanical differences between the different component muscles vary their individual predispositions to and patterns of injury. However, there is a common unifying factor: injuries involving tendinous components have greater clinical implications with regards to rehabilitation, potential intervention, length of time to return to play, and re-injury rates. As such, accurate understanding of the underlying anatomy and subsequent interpretation of the injury patterns carry significant clinical ramifications. Ultrasound is a useful tool but has limitations, particularly when assessing soleus. As such, magnetic resonance imaging remains the workhorse in calf injury investigation.

The functional and molecular effects of problematic alcohol consumption on skeletal muscle: a focus on athletic performance

Background: Chronic alcohol misuse is associated with alcoholic myopathy, characterized by skeletal muscle weakness and atrophy. Moreover, there is evidence that sports-related people seem to exhibit a greater prevalence of problematic alcohol consumption, especially binge drinking (BD), which might not cause alcoholic myopathy but can negatively impact muscle function and amateur and professional athletic performance.Objective: To review the literature concerning the effects of alcohol consumption on skeletal muscle function and structure that can affect muscle performance.Methodology: We examined the currently available literature (PubMed, Google Scholars) to develop a narrative review summarizing the knowledge about the effects of alcohol on skeletal muscle function and exercise performance, obtained from studies in human beings and animal models for problematic alcohol consumption.Results: Exercise- and sport-based studies indicate that alcohol consumption can negatively affect muscle recovery after vigorous exercise, especially in men, while women seem less affected. Clinical studies and pre-clinical laboratory research have led to the knowledge of some of the mechanisms involved in alcohol-related muscle dysfunction, including an imbalance between anabolic and catabolic pathways, reduced regeneration, increased inflammation and fibrosis, and deficiencies in energetic balance and mitochondrial function. These pathological features can appear not only under chronic alcohol misuse but also in other alcohol consumption patterns.Conclusions: Most laboratory-based studies use chronic or acute alcohol exposure, while episodic BD, the most common drinking pattern in amateur and professional athletes, is underrepresented. Nevertheless, alcohol consumption negatively affects skeletal muscle health through different mechanisms, which collectively might contribute to reduced sports performance.

[CME-Sonography 105: Ultrasound in Sports Injuries]

CME-Sonography 105: Ultrasound in Sports Injuries Abstract. Muscle injuries are frequent in athletes and in the general population. For therapy and prognosis, it is important to understand the total extent of the injury and to be aware of possible complications. In most cases ultrasound is a useful tool for diagnostics of muscle injuries. However, muscle ultrasound is not as common as joint ultrasound; this article discusses the possibilities of high-resolution dynamic ultrasound in diagnostics and its limitations.

Diagnosis and follow-up MRI evaluation of tennis leg:New understanding of the pathogenesis and imaging

OBJECTIVES

To evaluate the Magnetic resonance imaging (MRI) findings of patients with a clinical diagnosis of tennis leg and to explore the pathogenesis of tennis leg.

METHODS

A retrospective review of 58 (45 men, 13 women; age range, 7-81 years; mean age, 46.7 years) patients with a clinical diagnosis of tennis leg at our hospital during a 64-month period (May 2014 through Sep 2019) was conducted. All patients underwent MRI scan. Follow-up MRI was performed on 4 patients. Images findings, including integrity of the myotendinous junction and tendon of the gastrocnemius and soleus, and presence of fluid collection were analyzed.

RESULTS

MRI revealed fluid collection between the medial head of the gastrocnemius and soleus in 44 cases (72.1%). In 25 cases (41.0%), the collected fluid spread to around the medial border of fascia cruris. Fifty-five cases (90.2%) had edema or disruption of the gastrocnemius, with most cases (n = 55) showing edema or disruption of the medial head of the gastrocnemius at the myotendinous junction. Twenty-two (36.1%) cases had edema or disruption of the soleus, with most cases (n = 17) showing edema or disruption of the soleus at the myotendinous junction. Plantaris tendon disruption was observed in 7 cases (11.5%). A thick area of reparative tissue at the distal myotendinous junction of the medial head of the gastrocnemius was observed in all 4 MRI patients followed up.

CONCLUSION

Abnormalities of the medial head of the gastrocnemius at the myotendinous junction and tendon appear to be more common than those of the plantaris tendon. Reparative tissue at the distal myotendinous junction of the medial head of the gastrocnemius may be an important specific indication of chronic tennis leg injury.

Ultrasound Imaging in Sport-Related Muscle Injuries: Pitfalls and Opportunities

Muscle injuries occur frequently in athletes, accounting for more than one-third of sport-related trauma. Athletes most affected by these injuries are those practicing football and track and field, with hamstrings and gastrocnemius-soleus as the mainly involved sites. Muscle injuries lead to loss of competitions, long recovery times and risk of re-injury with a consequent increase of the management costs. It is therefore advisable to make an accurate and timely diagnosis to establish appropriate interventions for proper healing in the shortest time. In this context, ultrasound imaging is widely used for diagnosis of musculoskeletal disorders because of several advantages including absence of radiation, portability, good spatial resolution, and the ability to perform dynamic tests. The aim of this review is to address the role of US in the evaluation of athletes with muscle injuries. US may play a pivotal role for the management of sport-related muscle injuries because it is fast and relatively cheap, allowing dynamic muscle assessment and time series evaluation of the healing process.

Indirect Structural Muscle Injuries of Lower Limb: Rehabilitation and Therapeutic Exercise

Muscle injuries are the most common trauma in team and individual sports. The muscles most frequently affected are those of the lower limb, and in particular hamstrings, adductors, rectus femoris and calf muscles. Although several scientific studies have tried to propose different rehabilitation protocols, still too often the real rehabilitation process is not based on scientific knowledge, especially in non-elite athletes. Moreover, the growing use of physical and instrumental therapies has made it increasingly difficult to understand what can be truly effective. Therefore, the aim of the present paper is to review proposed therapeutic algorithms for muscle injuries, proposing a concise and practical summary. Following a three-phase rehabilitation protocol, this review aims to describe the conservative treatment of indirect structural muscle injuries, which are the more routinely found and more challenging type. For each phase, until return to training and return to sport are completed, the functional goal, the most appropriate practitioner, and the best possible treatment according to current evidence are expressed. Finally, the last section is focused on the specific exercise rehabilitation for the four main muscle groups with a structured explanatory timetable.

Diagnostic performance of the Strength and Pain Assessment (SPA) score for non-contact muscle injury screening in male soccer players

OBJECTIVES

The aims of this study were to develop a clinical-feature based scoring system for muscle injury screening and to assess its diagnostic accuracy when large number of injuries are suspected.

METHODS

A prospective diagnostic accuracy study was performed according to the Standards for Reporting of Diagnostic Accuracy (STARD) criteria. The diagnostic accuracy of the Strength and Pain Assessment (SPA) score (index test) was assessed in relation to muscle ultrasonography (reference standard). A large (n = 175) number of male soccer players met the inclusion/exclusion criteria: clinical assessment (i.e., evaluation of pain onset modality, location, distribution, impact on performance, and manual muscle strength testing) and ultrasonography were performed in all players after 48 hours from the sudden or progressive onset of muscle pain during or after a soccer competition.

RESULTS

91 of 175 cases (52%) were classified as functional muscle disorders, while signs of muscle tear were observed in the remaining 84 of 175 (48%) cases that were classified as structural muscle injuries. The median (1st - 3rd quartile) value of the SPA score was significantly (P < 0.001) lower in the functional disorder group [9 (9-10)] compared to the structural injury group [12 (12-13)]. The area under the Receiver Operating Characteristic curve for different cutoff points of the SPA score was 0.977 (95% confidence intervals: 0.957-0.998) and the optimal cutoff value of the SPA score providing the greatest sensitivity and specificity (respectively, 99% and 89%) was 11.

CONCLUSION

This study found that the SPA score has high diagnostic accuracy for structural muscle injuries and could be used as a valid screening tool in soccer players presenting with sudden or progressive onset of muscle pain during or after a competition.

Update on sports imaging

Sports Imaging has dramatically increased in the past decade with increasing number of adolescents, young and middle-aged adults participating in non-competitive/hobby sports. Therefore, sports injuries are no longer confined to elite athletes. Furthermore, newer forms of sports such as mountain climbing, pickle ball and curling etc. are gaining popularity. Majority of the injuries in sports medicine are from musculoskeletal trauma. Therefore, it is imperative that the musculoskeletal radiologist becomes familiar with various sports related injury patterns as these are commonly encountered in daily practice. This update aims to briefly encapsulate the major aspects of sports imaging. It includes the imaging manifestations of various types of musculoskeletal injuries on different modalities (commonly US and MRI) and briefly mentions the various image guided interventions, performed both on the sports field and in the hospital setting.

Ultrasonographic and Histological Correlation after Experimental Reconstruction of a Volumetric Muscle Loss Injury with Adipose Tissue

Different types of scaffolds are used to reconstruct muscle volume loss injuries. In this experimental study, we correlated ultrasound observations with histological findings in a muscle volume loss injury reconstructed with autologous adipose tissue. The outcome is compared with decellularized and porous matrix implants. Autologous adipose tissue, decellularized matrix, and a porous collagen matrix were implanted in volumetric muscle loss (VML) injuries generated on the anterior tibial muscles of Wistar rats. Sixty days after implantation, ultrasound findings were compared with histological and histomorphometric analysis. The muscles with an autologous adipose tissue implant exhibited an ultrasound pattern that was quite similar to that of the regenerative control muscles. From a histological point of view, the defects had been occupied by newly formed muscle tissue with certain structural abnormalities that would explain the differences between the ultrasound patterns of the normal control muscles and the regenerated ones. While the decellularized muscle matrix implant resulted in fibrosis and an inflammatory response, the porous collagen matrix implant was replaced by regenerative muscle fibers with neurogenic atrophy and fibrosis. In both cases, the ultrasound images reflected echogenic, echotextural, and vascular changes compatible with the histological findings of failed muscle regeneration. The ultrasound analysis confirmed the histological findings observed in the VML injuries reconstructed by autologous adipose tissue implantation. Ultrasound can be a useful tool for evaluating the structure of muscles reconstructed through tissue engineering.

Foreign body misdiagnosed as myofascial herniation of tibialis anterior muscle

Following a trip-and-fall injury, a 22-year-old male was misdiagnosed with myofascial herniation of his tibialis anterior muscle. After a diagnostic work-up, the correct diagnosis was identified: a foreign body in the tibialis anterior. His case describes the physical examination and diagnostic imaging findings expected in myofascial herniation while highlighting the ramifications of an incomplete differential diagnosis.

Hamstring strains in professional rugby players result in increased fascial stiffness without muscle quality changes as assessed using shear wave elastography

INTRODUCTION

Hamstring strain injury is common among sports injuries. A previous history of this injury is considered a strong predictor of recurrent hamstring strain injury. Fascial tissue reportedly becomes stiffer after hamstring strain injury. However, the association between fascial stiffness and previous hamstring strain injury has not been investigated in clinical studies. We aimed to determine whether a previous history of hamstring strain injury affects fascial tissue and muscle tissues using shear wave elastography.

METHOD

In eleven male professional rugby players, the stiffness as a shear modulus (kPa) of fascial tissue and muscle was measured on the specific injured area measured by magnetic resonance imaging (MRI) at resting position by using shear wave elastography. The side-to-side differences between the injured and the uninjured side were analyzed. The length and area of the muscle scar tissue were evaluated by MRI in relation to fascial stiffness.

RESULTS

The shear elastic modulus of fascia was stiffer in the injured vs. the uninjured side; however, no difference was observed in the muscle. No significant relationship was detected between the length and area of the muscle scar tissue (all P > 0.05).

DISCUSSION

Rugby players with a previous history of hamstring strain injury exhibited passive stiffness of fascial tissues in the injured leg, regardless of the length or area of the muscle scar tissue. However, the passive stiffness of muscles was same between the injured and the uninjured leg.

CONCLUSION

The results can be beneficial to consider future risk for hamstring strain injuries.

Sports injuries at the Rio de Janeiro 2016 Summer Paralympic Games: use of diagnostic imaging services

OBJECTIVE

To describe the occurrence of imaging-depicted sports-related injuries (bone, muscle, tendon, and ligament injuries) during the Rio 2016 Summer Paralympic Games.

METHODS

Descriptive data on all imaging examinations by using radiography, ultrasonography (US), and MRI were collected and retrospectively analyzed centrally by five musculoskeletal radiologists according to imaging modality, country of origin of the athletes, type of sport, type of disability, and type and location of injury.

RESULTS

We report 109 injuries in 4378 athletes. A total of 382 radiologic examinations were performed in 261 athletes, including 118 (31%) radiographic, 22 (6%) US, and 242 (63%) MRI examinations. Para athletes from Africa had the highest utilization rate (20.1%, 67 out of 333). Athletes from Europe underwent the most examinations with 29 radiographic, 12 US, and 66 MRI examinations. The highest utilization rate of imaging modalities by sport was among Judo para athletes (16.7%, 22 out of 132). Most injuries were reported in athletics discipline (37.6%, 41 out of 109). Most injuries were also reported among para athletes with visual impairment (40 injuries, 36.7% of all injuries). Bone stress injuries were most common among para athletes with visual impairment (6 out of 7). Para athletes with visual impairment were also more prone to bone stress injuries than traumatic fractures, unlike para athletes with neurologic and musculoskeletal impairments.

CONCLUSIONS

Imaging was used in 6.0% of para athletes. MRI comprised 63% of imaging utilization. Identification of patterns of injuries may help building future prevention programs in elite para athletes.

KEY POINTS

• The highest imaging utilization rates were found among para athletes competing in Judo, sitting volleyball, powerlifting, and football. • Utilization of diagnostic imaging at the Rio 2016 Paralympic Games demonstrated similar trends to what was observed at the Rio 2016 Olympic Games. • Comparison of the rate of imaging-depicted injuries between Olympic and Paralympic athletes is limited due to inherent differences between the two athlete populations and the manner in which injury risk in the Paralympic athlete varies dependent on impairment type, which is not the case for the Olympic athlete.

The Role of Magnetic Resonance in the Diagnosis of Chronic Exertional Compartment Syndrome

Chronic compartment syndrome is a common and often underdiagnosed exercise-induced condition, accounting on average for a quarter of cases of chronic exertional pain in the leg, second only to the fracture/tibial stress syndrome spectrum. It traditionally occurs in young runner athletes, although more recent studies have demonstrated a considerable prevalence in low-performance practitioners of physical activity, even in middle-aged or elderly patients. The list of differential diagnoses is extensive, and sometimes it is difficult to distinguish them only by the clinical data, and subsidiary examinations are required. The diagnosis is classically made by the clinical picture, by exclusion of the differential diagnoses, and through the measurement of the intracompartmental pressure. Although needle manometry is considered the gold standard in the diagnosis, its use is not universally accepted, since there are some important limitations, apart from the restricted availability of the needle equipment in Brazil. New protocols of manometry have recently been proposed to overcome the deficiency of the traditional ones, and some of them recommend the systematic use of magnetic resonance imaging (MRI) in the exclusion of differential diagnoses. The use of post-effort liquid-sensitive MRI sequences is a good noninvasive option instead of needle manometry in the diagnosis of chronic compartment syndrome, since the increase in post-exercise signal intensity is statistically significant when compared with manometry pressure values in asymptomatic patients and in those with the syndrome; hence, the test can be used in the diagnostic criteria. The definitive treatment is fasciotomy, although there are less effective alternatives.

Use of Magnetic Resonance Imaging for Orthopedic Trauma and Infection in the Emergency Department

Conditions affecting the musculoskeletal system constitute a significant portion of medical emergencies in the United States, with traumatic injury and infection being two of the most common etiologies. Although physical examination and plain radiographs are often sufficient to guide diagnosis and treatment, there are myriad traumatic and infectious pathologies that are commonly missed or simply not detectable on plain radiographs. Advanced imaging is subsequently warranted for additional workup.Magnetic resonance imaging (MRI) has become an increasingly used imaging modality for musculoskeletal complaints in the emergency department due to its superior visualization of soft tissues, focal edematous changes, and occult osseous insults often not visible on plain radiographs. Although multiple studies have evaluated its utility in the workup of emergency musculoskeletal complaints, there remains a dearth of literature examining the use of MRI for certain occult diagnoses.Radiologists, emergency clinicians, and orthopedic surgeons must be knowledgeable of the indications for MRI in the emergency setting, as delayed diagnosis may contribute to increased morbidity and possibly mortality. This review summarizes the use of MRI in diagnoses relating to trauma or infection among patients presenting to the emergency department with a musculoskeletal complaint.

Acromioclavicular Joint Injuries in Professional Ice Hockey Players: Epidemiologic and MRI Findings and Association With Return to Play

Background:

Acromioclavicular joint (ACJ) injuries are common in ice hockey players and are traditionally evaluated with conventional radiography, which has recognized limitations in the accurate characterization of the spectrum of soft tissue injuries and severity/grade of injury sustained.

Purpose:

To evaluate the epidemiologic, clinical, and magnetic resonance imaging (MRI) findings in professional ice hockey players who have sustained acute ACJ injuries.

Study Design:

Case series; Level of evidence, 4.

Methods:

A retrospective review was performed of professional National Hockey League (NHL) players referred for MRI evaluation of acute ACJ injuries. All MRI scans were assessed for status of the ACJ, ligamentous stabilizers, and surrounding musculature. MRI-based overall grade of ACJ injury (modified Rockwood grade 1-6) was assigned to each case. Data regarding mechanism of injury, player handedness, clinical features, and return to play were evaluated.

Results:

Overall, 24 MRI examinations of acute ACJ injuries (23 patients; mean age, 24 years) were reviewed. We found that 50% of injuries were sustained during the first period of play, and in 75% of cases, injuries involved the same side as player shooting handedness. Analysis of MRI scans revealed 29% (7/24) grade 1 ACJ injuries, 46% (11/24) grade 2 injuries, 21% (5/24) grade 3 injuries, and 4% (1/24) grade 5 injuries. Trapezius muscle strains were seen in 79% and deltoid muscle strain in 50% of cases. Nonoperative management was used for 23 injuries; 1 patient (grade 5 injury) underwent acute reconstructive surgery. All players successfully returned to professional NHL competition. Excluding cases with additional injuries or surgery (n = 3) or convalescence extending into the offseason (n = 3), we found that the mean return to play was 21.4 days (7.2 games missed). No statistically significant difference was observed in return to play between nonoperatively treated grade 3 injuries (mean, 28.3 days) and grade 1 or 2 injuries (mean, 20.1 days). However, grade 3 injuries were associated with a greater number of NHL scheduled games missed (mean, 12.7) compared with lower grade injuries (mean, 6.1) (P = .027).

Conclusion:

The spectrum of pathology and grading of acute ACJ injuries sustained in professional ice hockey can be accurately assessed with MRI; the majority of injuries observed in this study were low grade (grades 1 and 2). Although grade 3 injuries were associated with a greater number of games missed, similar return-to-play results were observed between nonoperatively treated grade 3 and grade 1 or 2 ACJ injuries.

Return to Play and Recurrence After Calf Muscle Strain Injuries in Elite Australian Football Players

BACKGROUND

Calf muscle strain injuries (CMSI) are prevalent in sport, but information about factors associated with time to return to play (RTP) and recurrence is limited.

PURPOSE

To determine whether clinical and magnetic resonance imaging (MRI) data are associated with RTP and recurrence after CMSI.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data of 149 CMSI reported to the Soft Tissue injury Registry of the Australian Football League were explored to evaluate the impact of clinical data and index injury MRI findings on RTP and recurrence. Clinical data included age, previous injury history, ethnicity, and the mechanism of injury.

RESULTS

Irrespective of the anatomical location, players with CMSI with severe aponeurotic disruption (AD) took longer to RTP than players with CMSI with no AD: 31.3 ± 12.6 days vs 19.4 ± 10.8 days (mean ± SD; P = .003). A running-related mechanism of injury was associated with a longer RTP period for CMSI overall (adjusted hazard ratio [AHR], 0.59; P = .02). The presence of AD was associated with a longer RTP period for soleus injuries (AHR, 0.6; P = .025). Early recurrence (ie, ≤2 months of the index injury) was associated with older age (AHR, 1.3; P = .001) and a history of ankle injury (AHR, 3.9; P = .032). Older age (AHR, 1.1; P = .013) and a history of CMSI (AHR, 6.7; P = .002) increased the risk of recurrence within 2 seasons. The index injury MRI findings were not associated with risk of recurrence.

CONCLUSION

A running-related mechanism of injury and the presence of AD on MRI were associated with a longer RTP period. Clinical rather than MRI data best indicate the risk of recurrent CMSI.

Diagnosis and prognosis for exercise-induced muscle injuries: from conventional imaging to emerging point-of-care testing

With the development of modern society, we have witnessed a significant increase of people who join in sport exercises, which also brings significantly increasing exercise-induced muscle injuries, resulting in reduction and even cessation of participation in sports and physical activities. Although severely injured muscles can hardly realize full functional restoration, skeletal muscles subjected to minor muscle injuries (e.g., tears, lacerations, and contusions) hold remarkable regeneration capacity to be healed without therapeutic interventions. However, delayed diagnosis or inappropriate prognosis will cause exacerbation of the injuries. Therefore, timely diagnosis and prognosis of muscle injuries is important to the recovery of injured muscles. Here, in this review, we discuss the definition and classification of exercise-induced muscle injuries, and then analyze their underlying mechanism. Subsequently, we provide detailed introductions to both conventional and emerging techniques for evaluation of exercise-induced muscle injuries with focus on emerging portable and wearable devices for point-of-care testing (POCT). Finally, we point out existing challenges and prospects in this field. We envision that an integrated system that combines physiological and biochemical analyses is anticipated to be realized in the future for assessing muscle injuries.

Sports-related lower limb muscle injuries: pattern recognition approach and MRI review

Muscle injuries of the lower limbs are currently the most common sport-related injuries, the impact of which is particularly significant in elite athletes. MRI is the imaging modality of choice in assessing acute muscle injuries and radiologists play a key role in the current scenario of multidisciplinary health care teams involved in the care of elite athletes with muscle injuries. Despite the frequency and clinical relevance of muscle injuries, there is still a lack of uniformity in the description, diagnosis, and classification of lesions. The characteristics of the connective tissues (distribution and thickness) differ among muscles, being of high variability in the lower limb. This variability is of great clinical importance in determining the prognosis of muscle injuries. Recently, three classification systems, the Munich consensus statement, the British Athletics Muscle Injury classification, and the FC Barcelona-Aspetar-Duke classification, have been proposed to assess the severity of muscle injuries. A protocolized approach to the evaluation of MRI findings is essential to accurately assess the severity of acute lesions and to evaluate the progression of reparative changes. Certain MRI findings which are seen during recovery may suggest muscle overload or adaptative changes and appear to be clinically useful for sport physicians and physiotherapists.

Sports Imaging of Team Handball Injuries

Team handball is a fast high-scoring indoor contact sport with > 20 million registered players who are organized in > 150 federations worldwide. The combination of complex and unique biomechanics of handball throwing, permitted body tackles and blocks, and illegal fouls contribute to team handball ranging among the four athletic sports that carry the highest risks of injury. The categories include a broad range of acute and overuse injuries that most commonly occur in the shoulder, knee, and ankle. In concert with sports medicine, physicians, surgeons, physical therapists, and radiologists consult in the care of handball players through the appropriate use and expert interpretations of radiography, ultrasonography, CT, and MRI studies to facilitate diagnosis, characterization, and healing of a broad spectrum of acute, complex, concomitant, chronic, and overuse injuries. This article is based on published data and the author team's cumulative experience in playing and caring for handball players in Denmark, Sweden, Norway, Germany, Switzerland, and Spain. The article reviews and illustrates the spectrum of common handball injuries and highlights the contributions of sports imaging for diagnosis and management.

Ultrasonographic and magnetic resonance images of a gluteus maximus tear

The diagnosis of a gluteal muscle tear or strain is based on clinical findings. However, for an accurate diagnosis, imaging examinations are also needed. Herein, we describe the case of a patient with a gluteus maximus muscle tear confirmed by ultrasonography (US) and magnetic resonance imaging (MRI). A 58-year-old woman complained of dull pain in the left lateral gluteal region that she had been experiencing for 8 days. In the axial US image, retraction of the left gluteus maximus muscle was noted around its insertion site in the iliotibial band. On an MRI, a partial tear in the left gluteus maximus was observed at its insertion site in the left iliotibial band. In addition, fluid infiltration due to edema and hemorrhage was observed. A partial left gluteal muscle tear was diagnosed. The patient was treated with physical therapy at the involved region and oral analgesics. She reported relief from the pain after 1 month of treatment. Based on this experience, we recommend US or MRI for accurate diagnosis of muscle tear or strain.

Intra-session and inter-rater reliability of spatial frequency analysis methods in skeletal muscle

Spatial frequency analysis (SFA) is a quantitative ultrasound (US) method originally developed to assess intratendinous tissue structure. This method may also be advantageous in assessing other musculoskeletal tissues. Although SFA has been shown to be a reliable assessment strategy in tendon tissue, its reliability in muscle has not been investigated. The purpose of this study was to examine the reliability of spatial frequency parameter measurement for a large muscle group within a healthy population. Ten participants with no history of lower extremity surgery or hamstring strain injury volunteered. Longitudinal B-mode images were collected in three different locations across the hamstring muscles. Following a short rest, the entire imaging procedure was repeated. B-mode images were processed by manually drawing a region of interest (ROI) about the entire muscle thickness. Four spatial frequency parameters of interest were extracted from the image ROIs. Intra- and inter-rater reliabilities of extracted SFA parameters were performed. Test-retest reliability of the image acquisition procedure was assessed between repeat trials. Intraclass correlation coefficients showed high intra- and inter-rater reliability (ICC(3,1) > 0.9 for all parameters) and good to moderate test-retest reliability (ICC(3,1) > 0.50) between trials. No differences in parameter values were observed between trials across all muscles and locations (p > 0.05). The high reliability metrics suggest that SFA will be useful for future studies assessing muscle tissue structure, and may have value in assessing muscular adaptations following injury and during recovery.

Correlating clinical assessment and MRI findings in diagnosing calf injuries in elite male Australian rules footballers

OBJECTIVE

Calf complex injuries represent a significant injury burden among Australian Rules athletes. To date, there has been limited research correlating clinical and radiological findings of pathology within the calf. The objective of this study is to determine how accurately magnetic resonance imaging (MRI) findings correlate with clinical measures of calf muscle complex pathology in elite male athletes.

MATERIALS AND METHODS

A prospective cohort study was conducted on Australian rules elite athletes. A cohort of 45 athletes underwent a high-load training session of approximately 10 km of running. Athletes were then assessed by a sports physiotherapist who made a diagnosis of no pathology, delayed onset muscle soreness, strain or other. Subsequently, the athletes underwent MRI of their bilateral calf complexes. Radiologists interpreted the MRI findings and radiological diagnosis were correlated with clinical diagnosis.

RESULTS

A total of 90 calf MRIs were performed. Correlation of clinical and radiological diagnosis occurred in 57 cases. Of the 33 cases which did not correlate, there were 4 radiologically significant acute calf strains in clinically asymptomatic athletes, 3 of which involved old scar tissue.

CONCLUSION

MRI may detect clinically insignificant injuries within the calf complex. If an athlete does not have any clinically relevant symptoms, abnormal signal on MRI may represent a different diagnosis to muscle strain. Signal change on MRI proximal to scar tissue may represent reactive oedema. Clinical history and examination should be correlated with radiological findings is recommended when diagnosing calf injury in elite athletes.

Editorial for "Quantitative MRI Reveals Microstructural Changes in the Upper Leg Muscles After Running a Marathon"

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 5 J. Magn. Reson. Imaging 2020;52:418-419.