Imaging of muscle injury in the elite athlete

Imaging of Acute Musculotendinous Injuries

Musculotendinous injuries represent a major concern in sports medicine, with significant implications for athlete recovery and performance. Ultrasound and magnetic resonance imaging, in particular, play a crucial role in diagnosing and monitoring these injuries, guiding treatment strategies, and estimating prognosis. Understanding the anatomy and distribution of connective tissue is fundamental to identifying and classifying musculotendinous injuries accurately. This review focuses on the imaging features of musculotendinous injuries and their evolution, emphasizing the role of connective tissue and the anatomical differences influencing injury patterns. It also examines current grading systems and their prognostic value, highlighting the need for muscle-specific subclassifications to improve accuracy in predicting return to play.

MRI and US in Hamstring Sports Injury Assessment: Anatomy, Imaging Findings, and Mechanisms of Injury

Most muscle tears occur in the lower extremities, especially in the hamstrings. The hamstring muscle complex consists of the semimembranosus (SM), semitendinosus (ST), and biceps femoris (BF) muscles. They originate from the ischial tuberosity, and while the BF inserts into the head of the fibula, the ST and SM muscles attach to the medial aspect of the tibia. The hamstrings are primarily hip extensors and knee flexors. Tears mostly occur during sport practice, particularly during forceful stretching or high-speed running, and typical sites are grouped and classified according to their location within the muscle anatomy. Sprint and stretching injuries typically affect the BF and SM, respectively. MRI and US are key complementary modalities for the diagnosis, treatment, and prognosis of hamstring injuries, as injury length, connective tissue involvement, and tear location determine evolution, recovery strategies, and return to play. ©RSNA, 2025.

Imaging of muscle injuries in soccer

Accurate diagnosis of muscle injuries is a challenge in everyday clinical practice and may have profound impact on the recovery and return-to-play decisions of professional athletes particularly in soccer. Imaging techniques such as ultrasound and magnetic resonance imaging (MRI), in addition to the medical history and clinical examination, make a significant contribution to the timely structural assessment of muscle injuries. The severity of a muscle injury determined by imaging findings has a decisive influence on therapy planning and affects prognosis. Imaging is of high importance when the diagnosis or grade of injury is unclear, when recovery is taking longer than expected, and when interventional or surgical management may be needed. This narrative review will discuss ultrasound and MRI for the assessment of sports-related muscle injuries in the context of soccer, including advanced imaging techniques, with the focus on the clinical relevance of imaging findings for the prediction of return to play.

Return-to-play criteria following a hamstring injury in professional football: a scoping review

The present scoping review aims to describe the available criteria to determine Return-To-Play (RTP), propose methodological considerations and new research questions, and provide information to help practitioners in professional football make informed decisions regarding RTP following a hamstring strain injury (HSI) in professional male football. The following electronic databases were searched: PubMed, MEDLINE, web of science and SPORTDiscus using keywords related to HSI in elite football. All types of studies in English reporting at least one RTP criterion for professional football players who sustained an HSI were included. In total, 19 studies met the inclusion criteria. RTP criteria were divided into three categories: clinical, strength and performance criteria. Clinical criteria were also divided into sub-categories: absence of pain, hamstring flexibility, medical staff clearance, psychological readiness, surgeon's opinion and imaging. Practitioners working in professional male football could benefit from using a combination of criteria in their RTP battery of tests.

Injuries of the Hamstring Tendons: MR Imaging Diagnosis

MR imaging evaluation of hamstring tendons reveals their association with subgluteal posterior hip pain, emphasizing the superiority of MR imaging over ultrasound due to the deep location of the hamstrings. This review encompasses various conditions, including overuse tendinopathy, metabolic disorders, and sports-related injuries prevalent in elite and recreational athletes. Practical MR imaging-guided approaches tailored to clinical needs and therapeutic options are discussed, highlighting MR imaging's crucial role in monitoring postinjury healing. Furthermore, potential residual complications are outlined, underscoring MR imaging's significance in diagnosing, treating, and evaluating hamstring tendon-related ailments comprehensively.

Current Concepts of MR Imaging Anatomy and Pathology of the Rectus Femoris Complex

The proximal origin of the rectus femoris from the anterior superior iliac spine, anterior inferior iliac spine and the supraacetabular sulcus comprises the proximal tendinous complex. A practical MR imaging-guided approach adapted to the anatomy of the proximal tendinous complex and the myoconnective transitions along the rectus femoris is critical in accurately evaluating and following rectus femoris injuries. This review presents various conditions, including avulsions, tendon tears, and myoconnecive lesions along the muscle that can result in loss of function and pain. Furthermore, different pathologies or "abnormal states" that can present with symptoms similar to myoconnective lesions are demonstrated.

Pictorial Review of Paediatric Limp

A limp is an abnormal, uneven or laboured gait typically resulting from pain, weakness, or structural deformity involving the hip, lower limb, spine or abdominopelvic abnormalities. Limps in children are common and have diverse causes that can be benign to life-threatening including trauma, congenital malformations, and neoplastic diseases. Diagnosis involves identifying gait abnormality thoroughly examining history and physical exam, assessing tenderness and range of motion, and completing targeted lab and radiographic studies. We present an imaging review of various usual and unusual causes of limp in different age groups such as in toddlers (1-3 years), children (4-10 years), and adolescents (11-16 years) with a comprehensive literature review.

Classification of myo-connective tissue injuries for severity grading and return to play prediction: A scoping review

OBJECTIVES

To conduct a systematic literature search to identify currently used classifications of acute non-contact muscle injuries in sporting adults.

DESIGNS

Scoping review.

METHODS

A systematic literature search from January 1, 2010 to April 19, 2022 of Medline and SPORTDiscus yielded 13,426 articles that were screened for eligibility. Findings from included studies were qualitatively synthesized. Classifications and their grading, as well as outcomes and definitions were extracted.

RESULTS

Twenty-four classifications were identified from the 37 included studies, most of which had low evidence study designs. Majority (57 %) of classifications were published after 2009 and were mostly developed for hamstring or other lower limb injuries. The six most cited classifications accounted for 70 % of the reports (BAMIC, modified Peetrons, Munich, Cohen, Chan and MLG-R). Outcome reporting was sparse, making it difficult to draw conclusions. Still, significant relationships between grading and time to return to play were reported for the BAMIC, modified Peetrons, Munich and Cohen classifications. Other classifications either had a very low number of reported associations, reported no associations, reported inconclusive associations, or did not report an assessment of the association. Other outcomes were poorly investigated.

CONCLUSIONS

There is no agreed-upon use of muscle classification, and no consensus on definitions and terminology. As a result, reported outcomes and their relationship to severity grading are inconsistent across studies. There is a need to improve the generalizability and applicability of existing classifications and to refine their prognostic value. High-level evidence studies are needed to resolve these inconsistencies.

Magnetic resonance classification proposal for medial gastrocnemius muscle injuries

Calf muscle injuries are common among athletes and occupational populations, with highly variable recovery times that are challenging to be predicted at the initial clinical evaluation. Specifically, in distal gastrocnemius muscle injuries, an ultrasound-based severity classification has shown to be useful for estimating the recovery time. According to the location of lesions and the recognition of some US signs, four types of injuries of the distal gastrocnemius muscle were described. Since magnetic resonance imaging (MRI) has proven to be useful in diagnosing and prognosticating muscle injuries by assessing the extent of affected connective tissue, a specific MRI protocol involving T1-weighted and fluid-sensitive static and dynamic acquisitions has been developed aimed to characterize the four types of injuries. We here describe the characteristics of this new MRI protocol and the interpretation of images, which will be useful to improve the recognition of acute and delayed distal gastrocnemius muscle injuries. The proposed classification includes: myoaponeurotic muscle injury without aponeurotic discontinuities (type 1), myoaponeurotic muscle injury with aponeurotic discontinuities (type 2), isolated free aponeurosis discontinuity (type 3), and a mixed myoaponeurotic-aponeurotic injury pattern (type 4). A comprehensive understanding of the MRI features associated with each injury type, in conjunction with multidisciplinary team collaboration, is essential for optimizing the athlete's recovery and return to play.

Prognosticating Return-To-Play Time Following a Hamstring Strain Injury Using Early Flexibility Asymmetry and Musculoskeletal Ultrasound Imaging Outcomes: An Exploratory Study Among Canadian University Football Players

OBJECTIVE

Identify key flexibility and point-of-care musculoskeletal ultrasound (POCUS) measures for prognosticating return-to-play (RTP) following a first hamstring strain injury (HSI) and informing the clinical decision-making process.

DESIGN

Exploratory prospective cohort study.

SETTING

Sport medicine and rehabilitation clinic of a Canadian university.

PARTICIPANTS

One hundred and sixty-seven elite Canadian university football athletes followed over 5 seasons.

INTERVENTIONS

Clinical and POCUS measures collected within 7 days after HSI and preseason clinical measures.

MAIN OUTCOME MEASURES

Active knee extension (AKE) and Straight Leg Raise (SLR) to quantify hamstring flexibility, POCUS-related outcomes to characterize tissue alteration, and RTP until full sport resumption were documented (categorized as Early [1-40 days] or Late [>40 days] RTP).

RESULTS

A total of 19 and 14 athletes were included in the Early RTP (mean RTP = 28.84 ± 8.62 days) and Late RTP groups (mean 51.93 ± 10.54 days), respectively, after having been diagnosed with a first HSI. For the clinical results, height and a greater flexibility asymmetry measure with the AKE or SLR when compared with both ipsilateral preseason and acute contralateral values significantly increases the chance of facing a long delay before returning to play (ie, RTP). For the POCUS-related results, the Peetrons severity score, extent of the longitudinal fibrillary alteration, and novel score lead to similar results.

CONCLUSIONS

Early hamstring flexibility asymmetry following acute HSI, particularly the AKE, along with some POCUS-related measures are valuable in prognosticating late RTP following among Canadian university football athletes.

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.

Isolated spontaneous non-insertional tear of the iliopsoas tendon in an elderly patient: significance of ultrasound imaging

Isolated spontaneous tears in the non-insertional portion of the iliopsoas tendon without any underlying injury are uncommon, especially among elderly individuals. We describe the case of an 88-year-old man who experienced right groin pain caused by a spontaneous non-insertional tear in the iliopsoas tendon identified through ultrasound and confirmed via MRI. Ultrasound revealed hypoechogenicity in the non-insertional portion of the iliopsoas tendon, leading to quick identification and conservative treatment and resulting in positive functional outcomes. This case report emphasises the significance of considering spontaneous non-insertional iliopsoas tendon tears when evaluating cases of acute groin pain. This finding underscores the effectiveness of ultrasound as an initial diagnostic tool for the early cost-effective diagnosis of soft tissue injuries around the hip joint, especially in low-resource settings. Timely detection and management can help avoid unnecessary operative interventions and facilitate faster and better recovery.

Biomaterials-Based Technologies in Skeletal Muscle Tissue Engineering

For many clinically prevalent severe injuries, the inherent regenerative capacity of skeletal muscle remains inadequate. Skeletal muscle tissue engineering (SMTE) seeks to meet this clinical demand. With continuous progress in biomedicine and related technologies including micro/nanotechnology and 3D printing, numerous studies have uncovered various intrinsic mechanisms regulating skeletal muscle regeneration and developed tailored biomaterial systems based on these understandings. Here, the skeletal muscle structure and regeneration process are discussed and the diverse biomaterial systems derived from various technologies are explored in detail. Biomaterials serve not merely as local niches for cell growth, but also as scaffolds endowed with structural or physicochemical properties that provide tissue regenerative cues such as topographical, electrical, and mechanical signals. They can also act as delivery systems for stem cells and bioactive molecules that have been shown as key participants in endogenous repair cascades. To achieve bench-to-bedside translation, the typical effect enabled by biomaterial systems and the potential underlying molecular mechanisms are also summarized. Insights into the roles of biomaterials in SMTE from cellular and molecular perspectives are provided. Finally, perspectives on the advancement of SMTE are provided, for which gene therapy, exosomes, and hybrid biomaterials may hold promise to make important contributions.

[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.

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.

Diffusion tensor imaging and quantitative T2 mapping to monitor muscle recovery following hamstring injury

MRI examinations are accurate for diagnosing sports-related acute hamstring injuries. However, sensitive imaging methods for assessing recovery of these injuries are lacking. Diffusion tensor imaging (DTI) and quantitative T2 (qT2) mapping have both shown promise for assessing recovery of muscle micro trauma and exercise effects. The purpose of this study was to explore the potential of DTI and qT2 mapping for monitoring the muscle recovery processes after acute hamstring injury. In this prospective study, athletes with an acute hamstring injury underwent a 3-T MRI examination of the injured and contralateral hamstrings including DTI and qT2 measurements at three time points: (1) within 1 week after sustaining the injury, (2) 2 weeks after time point 1, and (3) return to play (RTP). A linear mixed model was used for time-effect analysis and paired t-tests for the detection of differences between injured and uninjured muscles. Forty-one athletes (age 27.8 ± 7 years; two females and 39 males) were included. Mean RTP time was 50 (range 12-169) days. A significant time effect was found for mean diffusivity, radial diffusivity, and the second and third eigenvalues (p ≤ 0.001) in the injured muscles. Fractional anisotropy (p = 0.40), first eigenvalue (p = 0.02), and qT2 (p = 0.61) showed no significant time effect. All DTI indices, except for fractional anisotropy, were significantly elevated compared with control muscles right after the injury (p < 0.001). Values normalized during the recovery period, with no significant differences between control and injured muscles at RTP (p values ranged from 0.08 to 0.51). Mean qT2 relaxation times in injured muscles were not significantly elevated compared with control muscles at any time point (p > 0.04). In conclusion, DTI can be used to monitor recovery after an acute hamstring injury. Future work should explore the potential of DTI indices to predict RTP and recovery times in athletes after an acute strain injury.

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.

[Imaging of muscle injuries in sports medicine]

BACKGROUND

Early diagnosis of muscle injuries is indispensable in order to initiate appropriate treatment and to facilitate optimal healing.

PURPOSE

The aim of this review is to provide an update on imaging of muscle injuries in sports medicine with a focus on ultrasound and magnetic resonance imaging (MRI) and to present experimental approaches in addition to routine diagnostic procedures.

MATERIALS AND METHODS

A PubMed literature search for the years 2012-2022 using the following keywords was performed: muscle, muscle injury, muscle imaging, muscle injury classification, delayed onset muscle soreness, ultrasound, MRI, sodium MRI, potassium MRI, ultra-high-field MRI, injuries of athletes.

RESULTS

Imaging is crucial to confirm and assess the extent of sports-related muscle injuries and may help establishing treatment decisions, which directly affect the prognosis. This is of importance when the diagnosis or grade of injury is unclear, when recovery is taking longer than expected, and when interventional or surgical management may be necessary. In addition to established methods such as B‑mode ultrasound and ¹H‑MRI, individual studies show promising approaches to further improve the imaging of muscle injuries in the future. Prior to the integration of contrast-enhanced ultrasound and X‑nuclei into clinical routine, additional studies are needed to validate these techniques further.

CONCLUSION

B‑mode ultrasound represents an easily available, cost-effective modality for the initial diagnosis of muscle injuries. MRI is still considered the reference standard and enables an accurate morphological assessment of the extent of the injury. There are still no imaging approaches available for the objective determination of the optimal point of return to play.

Diagnosis and Treatment of Myogenous Temporomandibular Disorders: A Clinical Update

Myogenous temporomandibular disorders (M-TMDs) are the most common chronic orofacial pain, affecting the masticatory muscles and, thus, jaw movement. While a concise diagnosis is crucial to formulate a rational treatment plan, the similarities in clinical presentations that M-TMDs share with other neuromuscular disorders affecting the temporomandibular joint (TMJ) could easily confuse physicians. In addition to the basics, such as thorough history taking and meticulous clinical examinations, different imaging techniques are useful adjuncts to facilitate the diagnostic process. This review presents an overview of the current understanding on a variety of diagnostic and treatment modalities for M-TMD patients. It is essential to highlight that there is not a single treatment for all, and the benefits of multidisciplinary strategies have been noted for the effective management of myogenous TMD pain. Treatment modalities ranging from conservative to minimally invasive options are discussed in this review.

Microwave Antenna System for Muscle Rupture Imaging with a Lossy Gel to Reduce Multipath Interference

Injuries to the hamstring muscles are an increasing problem in sports. Imaging plays a key role in diagnosing and managing athletes with muscle injuries, but there are several problems with conventional imaging modalities with respect to cost and availability. We hypothesized that microwave imaging could provide improved availability and lower costs and lead to improved and more accurate diagnostics. In this paper, a semicircular microwave imaging array with eight antennae was investigated. A key component in this system is the novel antenna design, which is based on a monopole antenna and a lossy gel. The purpose of the gel is to reduce the effects of multipath signals and improve the imaging quality. Several different gels have been manufactured and evaluated in imaging experiments. For comparison, corresponding simulations were performed. The results showed that the gels can effectively reduce the multipath signals and the imaging experiments resulted in significantly more stable and repeatable reconstructions when a lossy gel was used compared to when an almost non-lossy gel was used.

Management of anterior thigh injuries in soccer players: practical guide

Most of the anterior thigh injuries are contusions or strains, however, some of these injuries can be career ending. Early diagnosis and correct treatment are key to successful outcome. Analyzing injury mechanism and adding both clinical and imaging findings, clinicians can make the right treatment decisions already often in the acute phase of the injury. Low grade contusions and muscle strains are treated well with planned rehabilitation, but complete tendon injuries or avulsions can require operative treatment. Also, neglected minor injuries could lead to chronic disabilities and time lost from play. Typical clinical presentation of anterior thigh injury is swelling and pain during hip flexion or knee extension. In more severe cases a clear gap can be palpated. Imaging methods used are ultrasound and magnetic resonance imaging (MRI) which are helpful for clinicians to determine more exact the extent of injury. MRI can identify possible tendon retractions which may need surgery. Clinicians should also be aware of other traumatic lesions affecting anterior thigh area such as myositis ossificans formation. Optimal treatment should be coordinated including acute phase treatment with rest, ice, and compression together with designed return-to-play protocol. The anatomical structure involved lines the treatment pathway. This narrative review describes these more common reasons for outpatient clinical visits for anterior thigh pain and injuries among soccer players.

[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.

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.

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.

Rehabilitation of a patient with bilateral rectus abdominis full thickness tear sustained in recreational strength training: a case report

STUDY DESIGN

Case Report.

BACKGROUND

Abdominal wall muscle injuries have been reported in handball, tennis, and baseball; however, a bilateral full-thickness tear of the rectus abdominis muscle and its rehabilitation have not previously been described. This report aims to describe a case of an acute bilateral full-thickness rectus abdominis tear simulating an acute abdomen that presented to an emergency department.

CASE DESCRIPTION

A 25-year-old male (169 cm, 84 kg) was transferred to the emergency room due to severe lancinating (Numerical Pain Rating 10/10) abdominal pain that occurred during weight training at a gym. An orthopedic surgeon, an internist, and a general surgeon assessed him for internal and surgical emergencies. The magnetic resonance imaging of his abdomen revealed a bilateral full-thickness tear of the rectus abdominis muscle. The patient was given an option of surgical repair of the RA, but he refused. Six weeks later, he attended our sports medicine department. A criteria-based rehabilitation program was planned, with weekly follow-ups.

OUTCOMES

The patient could walk pain-free at 4^th week and jog at 10^th week of rehabilitation. Significant improvements in the range of movement of the trunk, pain levels and functional capacity were noted at discharge and 6 and 12-month follow-ups.

DISCUSSION

Clinical management of this patient is described in detail, with emphasis on diagnostic ultrasonography. The structured rehabilitation program used for this patient resulted in a return to pre-injury level function.

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.

Sonographic demonstration of a spontaneous rectus sheath hematoma following a sneeze: a case report and review of the literature

Spontaneous rectus sheath hematoma (SRSH) is an uncommon cause of acute abdominal pain characterized by bleeding within the rectus sheath; it is a benign condition and, in most cases, it is treated conservatively. Bleeding of the abdominal wall is an unusual condition that is quite challenging to identify promptly and can be easily overlooked during a routine physical examination. In daily practice, anticoagulant therapy is one of the main risk factors for hemorrhagic events. In this respect, we report a rare case of spontaneous hematoma of the abdominal wall (diagnosed and monitored through an ultrasound examination) that arose after sneezing in a patient receiving anticoagulant treatment.

Diaphragm echodensity in mechanically ventilated patients: a description of technique and outcomes

Background

Acute increases in muscle sonographic echodensity reflect muscle injury. Diaphragm echodensity has not been measured in mechanically ventilated patients. We undertook to develop a technique to characterize changes in diaphragm echodensity during mechanical ventilation and to assess whether these changes are correlated with prolonged mechanical ventilation.

Methods

Diaphragm ultrasound images were prospectively collected in mechanically ventilated patients and in 10 young healthy subjects. Echodensity was quantified based on the right-skewed distribution of grayscale values (50th percentile, ED50; 85^th percentile, ED85). Intra- and inter-analyzer measurement reproducibility was determined. Outcomes recorded included duration of ventilation and ICU complications (including reintubation, tracheostomy, prolonged ventilation, or death).

Results

Echodensity measurements were obtained serially in 34 patients comprising a total of 104 images. Baseline (admission) diaphragm ED85 was increased in mechanically ventilated patients compared to younger healthy subjects (median 56, interquartile range (IQR) 42–84, vs. 39, IQR 36–52, p = 0.04). Patients with an initial increase in median echodensity over time (≥ + 10 in ED50 from baseline) had fewer ventilator-free days to day 60 (n = 13, median 46, IQR 0–52) compared to patients without this increase (n = 21, median 53 days, IQR 49–56, unadjusted p = 0.03). Both decreases and increases in diaphragm thickness during mechanical ventilation were associated with increases in ED50 over time (adjusted p = 0.03, conditional R² = 0.80) and the association between increase in ED50 and outcomes persisted after adjusting for changes in diaphragm thickness.

Conclusions

Many patients exhibit increased diaphragm echodensity at the outset of mechanical ventilation. Increases in diaphragm echodensity during the early course of mechanical ventilation are associated with prolonged mechanical ventilation. Both decreases and increases in diaphragm thickness during mechanical ventilation are associated with increased echodensity.

"Tennis Leg": A State-of-the-Science Review

BACKGROUND

Tennis leg (TL), a musculotendon injury to the gastrocnemius, has been associated with the eponymous sport since 1883. This article examines the historical context of TL as a sports compared with an occupational injury. This was juxtaposed with the history of tennis elbow, a tendon injury to the upper extremity also associated with sport.

METHODS

Bibliometric databases (PubMed, Web of Science [WOS], Hathi Trust) were keyword-searched; relevant citations were investigated in depth.

RESULTS

The search yielded 71 citations for TL (PubMed). The majority (n = 43) were key word linked to sport terms; only one was linked to work-related search terms. Furthermore, none of the top four cited publications (Web of Science) alluded to work-related risk factors in TL in full textual analysis. Hathi Trust yielded the earliest work-related case, reported in a non-biomedical source. Tennis elbow was more frequently reported (n = 189 citations in PubMed) and more frequently linked (n = 193; 9.7%) to occupational search terms.

CONCLUSION/APPLICATION TO PRACTICE

The history of TL, juxtaposed with tennis elbow, demonstrates how nosology can influence but does not wholly explain disease attribution, potentially to the detriment of taking into account occupational causality. The lack of recognition of occupational factors revealed in this literature search was notable because TL occurred most commonly in males of working age. By providing perspective on how historical context and nosology can affect the conceptualization of disease, this review may help inform prevention, treatment, and regulatory policy.

Muscle Madness and Making a Case for Muscle-Specific Classification Systems: A Leap from Tissue Injury to Organ Injury and System Dysfunction

Despite the recent publication and subsequent clinical application of several muscle injury classification systems, none has been able to address the varying and often unique/complex types of injuries that occur in different muscles. Although there are advantages of using a unified classification, there are significant differences between certain muscles and muscle groups. These differences may complicate the clinical effectiveness of using a unified injury classification. This narrative explores the difficulties in using a single classification to describe the heterogeneous nature of muscle injuries. Within that context, the possibility of viewing muscles and muscle injuries in the same manner as other biological tissues, structures, organs, and systems is discussed. Perhaps, in addition to a unified classification, subclassifications or muscle specific classifications should be considered for certain muscles. Having a more specific (granular) approach to some of the more commonly injured muscles may prove beneficial for more accurately and effectively diagnosing and treating muscle injuries. Ideally, this will also lead to more accurate determination of the prognosis of specific muscle injuries.

MRI in acute muscle tears in athletes: can quantitative T2 and DTI predict return to play better than visual assessment?

OBJECTIVES

To assess the ability of quantitative T2, diffusion tensor imaging (DTI) and radiologist's scores to detect muscle changes following acute muscle tear in soccer and rugby players. To assess the ability of these parameters to predict return to play times.

METHODS

In this prospective, longitudinal study, 13 male athletes (age 19 to 34 years; mean 25 years) underwent MRI within 1 week of suffering acute muscle tear. Imaging included measurements of T2 and DTI parameters. Images were also assessed using modified Peetrons and British athletics muscle injury classification (BAMIC) scores. Participants returned for a second scan within 1 week of being determined fit to return to play. MRI measurements were compared between visits. Pearson's correlation between visit 1 measurements and return to play times was assessed.

RESULTS

There were significant differences between visits in BAMIC scores (Z = - 2.088; p = 0.037), modified Peetrons (Z = - 2.530; p = 0.011) and quantitative MRI measurements; T2, 13.12 ms (95% CI, 4.82 ms, 21.42 ms; p = 0.01); mean diffusivity (0.22 (0.04, 0.39); p = 0.02) and fractional anisotropy (0.07 (0.01, 0.14); p = 0.03). BAMIC scores showed a significant correlation with return to play time (Rs = 0.64; p = 0.02), but modified Peetrons scores and quantitative parameters did not.

CONCLUSIONS

T2 and DTI measurements in muscle can detect changes due to healing following muscle tear. Although BAMIC scores correlated well with return to play times, in this small study, quantitative MRI values did not, suggesting that T2 and DTI measurements are inferior predictors of return to play time compared with visual scoring.

KEY POINTS

• Muscle changes following acute muscle tear can be measured using T2 and diffusion measurements on MRI. • Measurements of T2 and diffusion using MRI are not as good as a radiologist's visual report at predicting return to play time after acute muscle tear.

The management of proximal rectus femoris avulsion injuries

Injuries to the quadriceps muscle group are commonly seen in sporting activities that involve repetitive kicking and high-speed sprinting, including football (soccer), rugby and athletics.

The proximal rectus femoris is prone to avulsion injuries as rapid eccentric muscle contraction leads to asynchronous muscle activation and different force vectors through the straight and reflected heads.

Risk factors for injury include previous rectus femoris muscle or hamstring injury, reduced flexibility of the quadriceps complex, injury to the dominant leg, and dry field playing conditions.

Magnetic resonance imaging (MRI) is the preferred imaging modality as it enables the site of injury to be accurately located, concurrent injuries to be identified, preoperative grading of the injury, and aids surgical planning.

Non-operative management is associated with highly variable periods of convalescence, poor return to preinjury level of function and high risk of injury recurrence.

Operative treatment of proximal rectus femoris avulsion injuries with surgical repair or surgical tenodesis enables return to preinjury level of sporting activity and high functional outcomes.

Surgical tenodesis of proximal rectus femoris avulsion injuries may offer an avenue for further reducing recurrence rates compared to direct suture anchor repair of these injuries.

Cite this article: EFORT Open Rev 2020;5:828-834. DOI: 10.1302/2058-5241.5.200055

Management of hamstring injuries: current concepts review

Injuries to the hamstring muscle complex are common in athletes, accounting for between 12% and 26% of all injuries sustained during sporting activities. Acute hamstring injuries often occur during sports that involve repetitive kicking or high-speed sprinting, such as American football, soccer, rugby, and athletics. They are also common in watersports, including waterskiing and surfing. Hamstring injuries can be career-threatening in elite athletes and are associated with an estimated risk of recurrence in between 14% and 63% of patients. The variability in prognosis and treatment of the different injury patterns highlights the importance of prompt diagnosis with magnetic resonance imaging (MRI) in order to classify injuries accurately and plan the appropriate management. Low-grade hamstring injuries may be treated with nonoperative measures including pain relief, eccentric lengthening exercises, and a graduated return to sport-specific activities. Nonoperative management is associated with highly variable times for convalescence and return to a pre-injury level of sporting function. Nonoperative management of high-grade hamstring injuries is associated with poor return to baseline function, residual muscle weakness and a high-risk of recurrence. Proximal hamstring avulsion injuries, high-grade musculotendinous tears, and chronic injuries with persistent weakness or functional compromise require surgical repair to enable return to a pre-injury level of sporting function and minimize the risk of recurrent injury. This article reviews the optimal diagnostic imaging methods and common classification systems used to guide the treatment of hamstring injuries. In addition, the indications and outcomes for both nonoperative and operative treatment are analyzed to provide an evidence-based management framework for these patients. Cite this article: Bone Joint J 2020;102-B(10):1281-1288.

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.

Biological Basis of Treatments of Acute Muscle Injuries: A Short Review

Muscle strains occur frequently in recreational and professional sports. This article considers various treatment options in a biological context and reviews evidence of their efficacy. Treatments reviewed include the PRICE principle (P: rotection, R: est, I: ce, C: ompression, E: levation), early mobilization, physical therapy, hematoma aspiration, platelet-rich plasma injections, use of nonsteroidal anti-inflammatory drugs, corticosteroids, and local anesthetics, cellular therapies, and surgery.

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.

Abdominal wall sonography: a pictorial review

The anterior abdominal wall, which is composed of three layers (skin and adipose tissues; the myofascial layer; and the deep layer, consisting of the transversalis fascia, preperitoneal fat, and the parietal peritoneum), has many functions: containment, support and protection for the intraperitoneal contents, and involvement in movement and breathing. While hernias are often encountered and well reviewed in the literature, the other abdominal wall pathologies are less commonly described. In this pictorial review, we briefly discuss the normal anatomy of the anterior abdominal wall, describe the normal ultrasonographic anatomy, and present a wide range of pathologic abnormalities beyond hernias. Sonography emerges as the diagnostic imaging of first choice for assessing abdominal wall disorders, thus representing a valuable tool for ensuring appropriate management and limiting functional impairment.

Diagnostic biomarkers of muscle injury and exertional rhabdomyolysis

Early recognition of muscle injury, up to development of exertional rhabdomyolysis (ER), is essential for many clinical and practical reasons, such as planning the suitable period of recovery and deciding an appropriate time for return to exercise. Albeit magnetic resonance imaging (MRI) remains the reference technique for assessing muscle injuries, and ultrasonography (US) may be a complementary approach for easy, inexpensive and fast screening, the potential drawbacks of both techniques may be overcome by some laboratory tests, which may help guiding both diagnostic reasoning and clinical decision making. Current evidence attest that creatine kinase remains the most validated test across the clinical spectrum of muscles injuries, as its measurement may be helpful for screening subjects with suggestive signs and symptoms, its concentration substantially reflects the amount of injured muscle and its kinetics appears suitable, combined with clinics and results of imaging testing, for making decisions on return to exercise. Relatively low cost and widespread availability are additional advantages of this test. In athletes with ER, myoglobin assessment may provide adjunctive useful information, due to high predictive value for development of acute kidney injury. Regarding other historical biomarkers, namely aldolase and lactate dehydrogenase, the kinetics, correlation with injury severity, laboratory standardization and availability make their measurement unsuitable and redundant. Some innovative biomarkers have also been tested in recent years, including fatty acid-binding proteins and carbonic anhydrase III, myosin light chain 3 and muscle micro RNAs. However, their clinical effectiveness, standardization, availability in clinical laboratories and costs are still regarded as major drawbacks.

Mesenchymal stem cell basic research and applications in dog medicine

The stem cells, owing to their special characteristics like self-renewal, multiplication, homing, immunomodulation, anti-inflammatory, and dedifferentiation are considered to carry an "all-in-one-solution" for diverse clinical problems. However, the limited understanding of cellular physiology currently limits their definitive therapeutic use. Among various stem cell types, currently mesenchymal stem cells are extensively studied for dog clinical applications owing to their readily available sources, easy harvesting, and ability to differentiate both into mesodermal, as well as extramesodermal tissues. The isolated, culture expanded, and characterized cells have been applied both at preclinical as well as clinical settings in dogs with variable but mostly positive results. The results, though positive, are currently inconclusive and demands further intensive research on the properties and their dependence on the applications. Further, numerous clinical conditions of dog resemble to that of human counterparts and thus, if proved rewarding in the former may act as basis of therapy for the latter. The current review throws some light on dog mesenchymal stem cell properties and their potential therapeutic applications.

Ultrasound imaging in musculoskeletal injuries-What the Orthopaedic surgeon needs to know

Patients with musculoskeletal complaints have either been ignored or advised investigations far beyond their means or comfort. Focusing attention only on spine and head restricted the evaluation in cases of trauma and were followed up only if the injuries were life threatening. In the same vein, the extremities often got overlooked or at best were evaluated only by plain radiographs. Soft tissue injuries were therefore often missed and not only raised the morbidity in the patient but also dissatisfaction towards the treating physician. Recent exponential improvement in medical ultrasound technology has revolutionised the field of musculoskeletal imaging. Cutting-edge technology using state-of-the-art machines and high-frequency transducers have placed it in a stronger position as compared to in the past in many aspects of musculoskeletal imaging. Also, with better techniques and understanding of the modality, under given set of circumstances MSK ultrasound has far reaching results allowing for detailed evaluation of soft tissues including nerves, ligaments and tendons.

Magnetic resonance imaging of muscle injury in elite American football players: Predictors for return to play and performance

Muscle injury accounts for about one-third of total sports-related injuries. The lower limb muscles have one of the highest predisposition for injury in high-level professional athletic sports, such as the National Football League. The commonest group of muscles injured among football players include the hamstrings, followed by the quadriceps. Muscle injuries lead to significant time, off the field and affect return to play. Sports physicians and teams have been keen on assessing such injuries and also relying on multiple tools to safely return the player back to the field. MRI plays a key role in evaluation, follow-up, and assessment for return to play (RTP). In this review, we will discuss details of muscle anatomy, incidence of muscle injuries, injury mechanisms, and use of MRI in assessment, grading, follow-up and in predicting the natural course of muscle injuries in the high-end athletic players. While the use of MRI is clear in diagnosis, and for follow up of muscle injuries, there is some limitation in its ability to predict RTP, based on current MRI classification systems. Footballers who have clinical injuries without MRI evidence of significant muscle injury (grade 0 and 1) have a shorter period of RTP. Injuries classified as high grade (3 and 4) on MRI do not correlate well with time to RTP. Further trials are required to improve the capability of MRI in its prediction of RTP.

Adult thigh muscle injuries-from diagnosis to treatment: what the radiologist should know

Muscle injuries are one of the major problems facing elite athletes, representing a significant source of time lost from competition, with substantial consequences for teams and athletes. There are considerable pressures for a rapid return, but players who return to competition too soon have an increased risk of recurrent muscle injuries, which are associated with longer lay-offs. Imaging plays a key role in achieving the correct diagnosis, and magnetic resonance imaging (MRI) has emerged as the method of choice for skeletal muscle imaging. Several authors have reported prognostic MRI features, but it is difficult to predict the exact length of time to return to full training afterwards due to considerable discrepancy and overlap between different injuries. Therefore, development of a universally applicable classification and grading system is challenging. This paper aims to: (a) review the contemporary role of imaging in the setting of muscle injuries, with special focus on thigh muscles; (b) list the most accepted terminology used to describe muscle injuries;