Traumatic injuries of thigh and calf muscles in athletes: role and clinical relevance of MR imaging and ultrasound

Guide to Muscular Injuries and Common Ligamentous Injuries Among Soccer Players

With over 250 million players worldwide, soccer is the most popular sport in the world. The overall number of players at professional, amateur, and recreational levels has increased along with an increase in player diversity, including age and sex. These increases in player numbers, as well as a variety of demographics, have resulted in an increase in soccer-related injuries. Injury in the professional setting can lead to time off the field and an effect on team results and earnings. Injury at the amateur and recreational levels can lead to time off work, away from other activities, and change in activities of daily living. We provide an extensive list of common injuries sustained by soccer players, their pathophysiology, diagnosis, treatment, and general guidelines on return to play.

3T 31P/1H calf muscle coil for 1H and 31P MRI/MRS integrated with NIRS data acquisition

PURPOSE

Our aim was to design and build a 3T 31P/1H calf coil that is capable of providing both good 31P and 1H transmit and receive performance, as well as being capable of accommodating a near-infrared spectroscopy (NIRS) device for simultaneous NIRS data and MRI/MRS acquisition.

METHOD

In this work, we propose a new 3T 31P/1H birdcage combination design consisting of two co-centrically positioned birdcages on the same surface to maximize transmit efficiency and sensitivity for both nuclei. The 31P birdcage is a high-pass birdcage, whereas the 1H birdcage is a low-pass one to minimize coupling. The diameter of the 31P/1H birdcage combination was designed to be large enough to accommodate a NIRS device for simultaneous NIRS data and MRI/MRS acquisition.

RESULTS

The one-layer coil structure of the birdcage combination significantly streamlines the mechanical design and coil assembly process. Full-wave simulation results show that the 31P and 1H are very well decoupled with each other, and the 1H and 31P SNR surpasses that of their standalone counterparts in the central area. Experiment results show that the inclusion of a NIRS device does not significantly affect the performance of the coil, thus enabling simultaneous NIRS and MRI readouts during exercise.

CONCLUSION

Our findings demonstrate the feasibility and effectiveness of this dual-tuned coil design for combined NIRS and MRS measurements, offering potential benefits for studying metabolic and functional changes in the skeletal muscle in vivo.

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.

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.

[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.

Imaging of Muscle Injuries

Ultrasound (US) and MR imaging are the most common imaging modalities used to assess sports muscle injuries. The site of the muscle injury can be located at the peripheral aspect of the muscle (myofascial), within the muscle belly (musculotendinous), and with tendon involvement (intratendinous). Tears that affect the intramuscular tendon have a worse prognosis in terms of recovery time. US is an excellent method to evaluate muscle injuries, with high spatial and contrast resolution. MR imaging can be reserved for evaluation of professional athletes, surgical planning, differential diagnosis, and assessment of deep located and proximal muscle groups.

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.

An experimental model of contusion injury in humans

INTRODUCTION

Contusion injuries are common in sport, but our knowledge of the responses to injury primarily come from animal studies and research using eccentric exercise. Therefore, the aim of this study was to develop a model of contusion injury in human participants and, additionally, investigate and compare physiological responses to four impact loads.

METHODS

Thirty-two males were exposed to a single impact of either 4.2, 5.2, 6.2 or 7.2kg, dropped from 67 cm, on to the vastus lateralis of one leg. Maximum voluntary and electrically induced quadriceps force, and pressure pain threshold were measured, and blood sampling carried out, prior to and 30min, 24, 48 and 72h post-impact. Magnetic resonance imaging was carried out 24h post-impact to quantify oedema.

RESULTS

Despite impact force with 7.2kg (1681.4 ± 235.6 N) not being different to 6.2kg (1690.7 ± 117.6 N), 7.2kg resulted in greater volume of oedema, voluntary force loss, pain and elevations in creatine kinase than the other loads. Although electrically induced force changed over time, post-hoc analysis failed to identify any changes. Interleukin-6 and prostaglandin-E2 did not change over time for any of the loads. Significant correlations were found between oedema volume, pressure pain threshold and maximum voluntary contraction force.

CONCLUSIONS

This is the first experimental study to investigate traumatic loading of skeletal muscle and the subsequent physiological responses associated with contusion injuries in humans. The absence of immediate elevations in creatine kinase and changes in electrically induced force suggest impact, with forces similar to those experienced in contact sport, does not cause significant, direct damage to skeletal muscle. However, the relationship between oedema volume, changes in pressure pain threshold and maximum voluntary contraction force suggests central inhibition plays a role in contusion-related muscle dysfunction.

Calf Strain in Athletes

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Calf strain is a common condition. In high-performance athletes, calf strain contributes to a substantial absence from competition.

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Player age and history of a calf strain or other leg injury are the strongest risk factors for calf strain injury and reinjury.

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Although the diagnosis is often clinical, magnetic resonance imaging and ultrasound are valuable to confirm the location of the strain and the grade of injury.

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Nonoperative treatment is effective for most calf strain injuries. Operative management, although rarely indicated, may be appropriate for severe cases with grade-III rupture or complications.

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Further investigation is necessary to elucidate the benefits of blood flow restriction therapy, deep water running, lower-body positive pressure therapy, platelet-rich plasma, and stem cell therapy for calf strain rehabilitation.

Bilateral multifocal muscular hemorrhage in the triceps surae during antiplatelet therapy: a case report

Hemorrhagic complications are often reported following antiplatelet therapy; however, simultaneous multifocal hemorrhages in both legs are uncommon. The patient was a 75-year-old man diagnosed with ST elevation myocardial infarction who underwent percutaneous coronary intervention in the right coronary artery. He was prescribed oral acetylsalicylic acid and ticagrelor. Three days after initial drug treatment, he complained of bilateral leg pain that was aggravated by walking and moving his ankle across a broad range of motion. No deep vein thrombosis was detected on Doppler ultrasonography; however, muscular hemorrhage was suspected according to musculoskeletal ultrasonography. Multifocal muscular hemorrhage was confirmed in the soleus and gastrocnemius muscles on magnetic resonance imaging. To reduce the risk of bleeding, we changed the medication from ticagrelor to clopidogrel. The patient performed leg elevation exercises, compression, and applied an ice pack. He also performed range of motion exercises and gait training in addition to receiving drug treatment. With these therapies, his pain score improved from 5 to 3 on a visual analog scale, without further complications. Multifocal muscular hemorrhage rarely occurs bilaterally; however, when it does occur, an appropriate treatment plan can be developed based on musculoskeletal ultrasonography.

Injury-associated levator ani muscle and anal sphincter ooedema following vaginal birth: a secondary analysis of the EMRLD study

OBJECTIVE

To determine whether all three components of the levator ani muscle (pubovisceral [= pubococcygeal], puborectal and iliococcygeal) and the external anal sphincter are equally affected by oedema associated with muscle injury after vaginal birth.

DESIGN

Observational cross-sectional study.

SETTING

Michigan Medicine, University of Michigan.

POPULATION

Primiparous women classified as high risk for levator ani muscle injury during childbirth.

METHOD

MRI scans obtained 6-8 weeks postpartum were analysed. Muscle oedema was assessed on axial and coronal fluid-sensitive magnetic resonance (MRI) scans. Presence of oedema was separately determined in each levator ani muscle component and in the external anal sphincter for all subjects. Descriptive statistics and correlation with obstetric variables were obtained.

MAIN OUTCOME MEASURES

Oedema score on fluid-sensitive MRI scans.

RESULTS

Of the 78 women included in this cohort, 51.3% (n = 40/78) showed muscle oedema in the pubovisceral (one bilateral avulsion excluded), 5.1% (n = 4/78) in the puborectal and 5.1% (n = 4/78) in the iliococcygeal muscle. No subject showed definite oedema on external anal sphincter. Incidence of oedema on the pubovisceral muscle was seven times higher than on any of the other analysed muscles (all paired comparisons, P < 0.001).

CONCLUSIONS

Even in the absence of muscle tearing, the pubovisceral muscle shows by far the highest incidence of injury, establishing that levator components are not equally affected by childbirth. External anal sphincter did not show oedema-even in women with sphincter laceration- suggesting a different injury mechanism. Developing a databased map of injured areas helps understand injury mechanisms that can guide us in honing research on treatment and prevention.

TWEETABLE ABSTRACT

Injury-associated levator ani muscle and anal sphincter oedema mapping on MRI reveals vulnerable muscle components after childbirth.

Non-uniform distribution of passive muscle stiffness within hamstring

Limited information is available on whether stiffness is different within and between the constituents of the hamstring, that is, the biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM). Therefore, understanding of hamstring injuries and stretching effect on hamstring stiffness is difficult. The present study primarily aimed to identify whether passive muscle stiffness differs between the BFlh, ST, and SM and between the proximal, middle, and distal sites within each muscle. Secondly, the effect of stretching exercise on the heterogeneity in passive muscle stiffness was examined. In the lengthened hamstring positions by extending the knee joint or flexing the hip joint, passive muscle shear modulus (a measure of stiffness) at the proximal, middle, and distal sites of the BFlh, ST, and SM was measured by using ultrasound shear wave elastography. Furthermore, before and after five repetitions of 90-seconds static stretching for the hamstring, passive muscle shear modulus at the proximal and distal sites of the SM was measured. The shear modulus was significantly higher in the SM than in the BFlh and ST and higher at the distal site than the proximal site in all muscles. After the stretching, the higher shear modulus at the distal site of the SM compared to the proximal site was still observed (pre-stretching: +80%, post-stretching: +81%). These findings indicate that passive muscle stiffness varies within the hamstring regardless of performing stretching exercise and that passive muscle stiffness is not highest at the proximal site of the SM where a stretching-type hamstring strain typically occurs.

Healing Process of Gastrocnemius Muscle Injury on Ultrasonography Using B-Mode Imaging, Power Doppler Imaging, and Shear Wave Elastography

OBJECTIVES

Muscle injury often occurs in sports activity. To avoid reinjury, it is important to determine the appropriate period until return to play after injury. The purpose of this study was to evaluate characteristics of the healing process for gastrocnemius muscle injury by B-mode imaging, power Doppler (PD) imaging, and shear wave elastography (SWE).

METHODS

Twenty patients with acute calf musculotendinous injury were enrolled. Scar thickness on B-mode imaging, new vessels according to PD grades, and SWE values in the muscle, musculotendinous junction, and tendon of the medial head of gastrocnemius were measured at 4, 8, and 12 weeks after injury.

RESULTS

Scar thickness was significantly larger at 8 and 12 weeks compared with 4 weeks (P < .01 for both). Power Doppler grades at 4 and 8 weeks were significantly higher compared with 12 weeks (P < .01 for both). Shear wave elastographic values in the muscle on the injury side were significantly higher at 8 and 12 weeks compared with 4 weeks (P < .01 for both), whereas those in the musculotendinous junction on the injury side were significantly higher at 12 weeks compared with 4 and 8 weeks (P < .01; P = .01, respectively).

CONCLUSIONS

B-mode imaging, PD imaging, and SWE can measure the healing process after musculotendinous injury of the gastrocnemius medial head.

Hamstring rehabilitation in elite track and field athletes: applying the British Athletics Muscle Injury Classification in clinical practice

Rationale

Hamstring injuries are common in elite sports. Muscle injury classification systems aim to provide a framework for diagnosis. The British Athletics Muscle Injury Classification (BAMIC) describes an MRI classification system with clearly defined, anatomically focused classes based on the site of injury: (a) myofascial, (b) muscle–tendon junction or (c) intratendinous; and the extent of the injury, graded from 0 to 4. However, there are no clinical guidelines that link the specific diagnosis (as above) with a focused rehabilitation plan.

Objective

We present an overview of the general principles of, and rationale for, exercise-based hamstring injury rehabilitation in British Athletics. We describe how British Athletics clinicians use the BAMIC to help manage elite track and field athletes with hamstring injury. Within each class of injury, we discuss four topics: clinical presentation, healing physiology, how we prescribe and progress rehabilitation and how we make the shared decision to return to full training. We recommend a structured and targeted diagnostic and rehabilitation approach to improve outcomes after hamstring injury.

Imaging of hip and thigh muscle injury: a pictorial review

Muscle injuries of the hip and thigh are a highly relevant issue in competitive sports imaging. The gold standard in diagnostic imaging of muscle injuries is magnetic resonance imaging (MRI). Radiologists need to be familiar with typical MRI findings in order to accurately detect and classify muscle injuries. Proper interpretation of the findings is crucial, especially in elite athletes. In soccer players, muscle injuries of the hip and thigh are the most common reason for missing a game.The present pictorial review deals with the diagnostic assessment, especially MRI, of muscle injuries of the hip and thigh. Typical MR findings in muscle injuries include edema, hematoma, and tendinous avulsion as well as partial or complete muscle tear. To estimate the time to return to play, a grading into three groups-muscle strain, partial tear, complete tear-has traditionally been used. Taking into account the most recent literature, there are other prognostic factors such as the longitudinal length of a tear, the tendon's intramuscular component, or persisting edema.

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.

[Muscular injuries in the inguinal region including apophyseal injuries]

BACKGROUND

Muscular and apophyseal injuries in the inguinal region are a common cause of groin pain in athletes.

PURPOSE

Frequently occurring muscular and apophyseal injuries in the groin region are described.

MATERIAL AND METHODS

Fundamental studies and expert recommendations are discussed. Examination protocols for routine clinical practice are presented.

RESULTS

The exact diagnosis and classification of muscular or apophyseal injuries in the inguinal region are the basic prerequisites for the initiation of a targeted treatment and thus crucial for the return to sport time. These injuries are occurring with increasing frequency in both professional and recreational sports.

CONCLUSION

In addition to the clinical examination and the history of the course of the injury, MRI plays an important role in the evaluation of muscular and apophyseal injuries in the inguinal region.

Soft tissue pseudotumours: a pictorial review with emphasis on MRI

Background

Several tumour-like conditions of the soft tissues may be encountered in clinical practice, or when patients undergo radiologic examinations. Al-though advances in cross sectional imaging (ultra-sound, MDCT and MRI) play a pivotal role in the correct evaluation of tumour-like lesions, a systematic approach is needed to achieve a definitive diagnosis or limit the differential diagnosis. Clinical history, physical examination and anatomic location are of paramount importance.

Methods

In this pictorial essay we review some of the most frequent benign soft tissue conditions which may be mistaken for malignancy and thus lead to need-less referrals, unnecessary biopsies and great anxiety to the patients and their carers.

Level of evidence

IV.

MR Imaging of Muscle Trauma: Anatomy, Biomechanics, Pathophysiology, and Imaging Appearance

Muscle is an important component of the muscle-tendon-bone unit, driving skeletal motion through contractions that alter the length of the muscle. The muscle and myotendinous junction (MTJ) are most commonly injured in the young adult, as a result of indirect mechanisms such as overuse or stretching, direct impact (penetrating or nonpenetrating), or dysfunction of the supporting connective tissues. Magnetic resonance (MR) imaging is widely used for assessment of muscle injuries. This review illustrates the MR imaging appearance of a broad spectrum of acute, subacute, and chronic traumatic lesions of muscle, highlighting the pathophysiology, biomechanics, and anatomic considerations underlying these lesions. Concentric (shortening) contractions are more powerful, but it is eccentric (lengthening) contractions that produce the greatest muscle tension, leading to indirect injuries such as delayed-onset muscle soreness (DOMS) and muscle strain. Strain is the most commonly encountered muscle injury and is characteristically located at the MTJ, where maximal stress accumulates during eccentric exercise. The risk of strain varies among muscles based on their fiber composition, size, length, and architecture, with pennate muscles being at highest risk. Direct impact to muscle results in laceration or contusion, often accompanied by intramuscular interstitial hemorrhage and hematoma. Disorders related to the muscle's collagen framework include compartment syndrome, which is related to acute or episodic increases in pressure, and muscle herniation through anatomic defects in the overlying fascia. The healing response after muscle trauma can result in regeneration, degeneration with fibrosis and fatty replacement, or disordered tissue proliferation as seen in myositis ossificans. In athletes, accurate grading of the severity and precise location of injury is necessary to guide rehabilitation planning to prevent reinjury and ensure adequate healing. In elite athletes, MR imaging grading of muscle trauma plays an increasingly important role in recently developed comprehensive grading systems that are replacing the imprecise three-grade injury classification system currently used. ^©RSNA, 2017.

Hamstring Injuries in Professional Soccer Players: Extent of MRI-Detected Edema and the Time to Return to Play

Background:

Discrepancies exist in the literature regarding the association of the extent of injuries assessed on magnetic resonance imaging (MRI) with recovery times.

Hypothesis:

MRI-detected edema in grade 1 hamstring injuries does not affect the return to play (RTP).

Study Design:

Retrospective cohort study.

Level of Evidence:

Level 4.

Methods:

Grade 1 hamstring injuries from 22 professional soccer players were retrospectively reviewed. The extent of edema-like changes on fluid-sensitive sequences from 1.5-T MRI were evaluated using craniocaudal length, percentage of cross-sectional area, and volume. The time needed to RTP was the outcome. Negative binomial regression analysis tested the measurements of MRI-detected edema-like changes as prognostic factors.

Results:

The mean craniocaudal length was 7.6 cm (SD, 4.9 cm; range, 0.9-19.1 cm), the mean percentage of cross-sectional area was 23.6% (SD, 20%; range, 4.4%-89.6%), and the mean volume was 33.1 cm³ (SD, 42.6 cm³; range, 1.1-161.3 cm³). The mean time needed to RTP was 13.6 days (SD, 8.9 days; range, 3-32 days). None of the parameters of extent was associated with RTP.

Conclusion:

The extent of MRI edema in hamstring injuries does not have prognostic value.

Clinical Relevance:

Measuring the extent of edema in hamstring injuries using MRI does not add prognostic value in clinical practice.

MRI detection of soleus muscle injuries in professional football players

OBJECTIVES

To describe magnetic resonance imaging (MRI) characteristics of soleus muscle injuries in symptomatic professional football players stratified according to both the Munich consensus statement and the British Athletics Muscle Injury Classification (BAMIC), and to investigate the association between specific MRI features and the "return to play" (RTP).

MATERIALS AND METHODS

Professional football players with an episode of acute posterior calf pain and impaired function, subsequent to sports activity, underwent ultrasound followed by MRI examination reviewed by two different radiologists with more than 10 years of experience in the musculoskeletal system. MRI features and RTP outcome were evaluated for all types of injuries.

RESULTS

During a 36-month period, a total of 20 professional football players were evaluated. According to the Munich consensus, 11 were type 3A, 8 were type 3B, and 1 was type 4, whereas according to the BAMIC, 11 lesions were considered grade 1, 4 grade 2, 4 grade 3, and 1 grade 4. RTP data were available for all patients (mean 3.3 ± 1.6 weeks). Both the Munich consensus and the BAMIC correlated with RTP (Spearman correlation = 0.982 and p < 0.0001 and 0.886 and p < 0.0001 respectively). Extension of edema was an independent prognostic factor for RTP in two different models of multivariate regression analysis (p = 0.044 model A; p = 0.031 model B).

CONCLUSIONS

The Munich consensus and BAMIC grading systems are useful tools for defining the patient's prognosis and proper rehabilitation time after injury. The MRI feature that we should carefully look for is the extension of edema, as it seems to significantly affect the RTP.

Connective tissue injury in calf muscle tears and return to play: MRI correlation

Objective

The aim of our study was to assess a group of patients with calf muscle tears and evaluate the integrity of the connective tissue boundaries and interfaces. Further, we propose a novel MRI grading system based on integrity of the connective tissue and assess any correlation between the grading score and time to return to play. We have also reviewed the anatomy of the calf muscles.

Materials and methods

We retrospectively evaluated 100 consecutive patients with clinical suspicion and MRI confirmation of calf muscle injury. We evaluated each calf muscle tear with MRI for the particular muscle injured, location of injury within the muscle and integrity of the connective tissue structure at the interface. The muscle tears were graded 0–3 depending on the degree of muscle and connective tissue injury. The time to return to play for each patient and each injury was found from the injury records and respective sports doctors.

Results

In 100 patients, 114 injuries were detected. Connective tissue involvement was observed in 63 out of 100 patients and failure (grade 3 injury) in 18. Mean time to return to play with grade 0 injuries was 8 days, grade 1 tears was 17 days, grade 2 tears was 25 days and grade 3 tears was 48 days (p<0.001).

Conclusion

The integrity of the connective tissue can be used to estimate and guide the time to return to play in calf muscle tears.

Ultrasonographic Imaging and Anti-inflammatory Therapy of Muscle and Tendon Injuries Using Polymer Nanoparticles

Ultrasonography is a reliable diagnostic modality for muscle and tendon injuries, but it has been challenging to find right diagnosis of minor musculoskeletal injuries by conventional ultrasonographic imaging. A large amount of hydrogen peroxide (H2O2) are known to be generated during tissue damages such as mechanical injury and therefore H2O2 holds great potential as a diagnostic and therapeutic marker for mechanical injuries in the musculoskeletal system. We previously developed poly(vanillyl alcohol-co-oxalate) (PVAX), which rapidly scavenges H2O2 and exerts antioxidant and anti-inflammatory activity in H2O2-associated diseases. Based on the notion that PVAX nanoparticles generate CO2 bubbles through H2O2-triggered hydrolysis, we postulated that PVAX nanoparticles could serve as ultrasonographic contrast agents and therapeutic agents for musculoskeletal injuries associated with overproduction of H2O2. In the agarose gel phantom study, PVAX nanoparticles continuously generated CO2 bubbles to enhance ultrasonographic echogenicity significantly. Contusion injury significantly elevated the level of H2O2 in skeletal muscles and Achilles tendons. Upon intramuscular injection, PVAX nanoparticles significantly elevated the ultrasound contrast and suppressed inflammation and apoptosis in the contusion injury of musculoskeletal systems. We anticipate that PVAX nanoparticles hold great translational potential as theranostic agents for musculoskeletal injuries.

Imaging of Muscle Injuries in Sports Medicine: Sports Imaging Series

In sports-related muscle injuries, the main goal of the sports medicine physician is to return the athlete to competition-balanced against the need to prevent the injury from worsening or recurring. Prognosis based on the available clinical and imaging information is crucial. Imaging is crucial to confirm and assess the extent of sports-related muscle injuries and may help to guide management, which directly affects the prognosis. This is especially important 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. Several imaging techniques are widely available, with ultrasonography and magnetic resonance imaging currently the most frequently applied in sports medicine. This state of the art review will discuss the main imaging modalities for the assessment of sports-related muscle injuries, including advanced imaging techniques, with the focus on the clinical relevance of imaging features of muscle injuries. ^© RSNA, 2017 Online supplemental material is available for this article.

A Porcine Urinary Bladder Matrix Does Not Recapitulate the Spatiotemporal Macrophage Response of Muscle Regeneration after Volumetric Muscle Loss Injury

Volumetric muscle loss (VML) results in irrecoverable loss of muscle tissue making its repair challenging. VML repair with acellular extracellular matrix (ECM) scaffolds devoid of exogenous cells has shown improved muscle function, but limited de novo muscle fiber regeneration. On the other hand, studies using minced autologous and free autologous muscle grafts have reported appreciable muscle regeneration. This raises the fundamental question whether an acellular ECM scaffold can orchestrate the spatiotemporal cellular events necessary for appreciable muscle fiber regeneration. This study compares the macrophage and angiogenic responses including the remodeling outcomes of a commercially available porcine urinary bladder matrix, MatriStem™, and autologous muscle grafts. The early heightened and protracted M1 response of the scaffold indicates that the scaffold does not recapitulate the spatiotemporal macrophage response of the autograft tissue. Additionally, the scaffold only supports limited de novo muscle fiber formation and regressing vessel density. Furthermore, scaffold remodeling is accompanied by increased presence of transforming growth factor and α-smooth muscle actin, which is consistent with remodeling of the scaffold into a fibrotic scar-like tissue. The limited muscle formation and scaffold-mediated fibrosis noted in this study corroborates the findings of recent studies that investigated acellular ECM scaffolds (devoid of myogenic cells) for VML repair. Taken together, acellular ECM scaffolds when used for VML repair will likely remodel into a fibrotic scar-like tissue and support limited de novo muscle fiber regeneration primarily in the proximity of the injured musculature. This is a work of the US Government and is not subject to copyright protection in the USA. Foreign copyrights may apply. Published by S. Karger AG, Basel.

Hamstring Reinjuries Occur at the Same Location and Early After Return to Sport: A Descriptive Study of MRI-Confirmed Reinjuries

BACKGROUND

Despite relatively high reinjury rates after acute hamstring injuries, there is a lack of detailed knowledge about where and when hamstring reinjuries occur, and studies including imaging-confirmed reinjuries are scarce.

PURPOSE

To investigate the location, radiological severity, and timing of reinjuries on magnetic resonance imaging (MRI) compared with the index injury.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A MRI scan was obtained ≤5 days after an acute hamstring index injury in 180 athletes, and time to return to sport (RTS) was registered. Athletes with an MRI-confirmed reinjury in the same leg ≤365 days after RTS were included. Categorical grading and standardized MRI parameters of the index injury and reinjury were scored by a single radiologist (with excellent intraobserver reliability). To determine the location of the reinjury, axial and coronal views of the index injury and reinjury were directly compared on proton density-weighted fat-suppressed images.

RESULTS

In the 19 athletes included with reinjury, 79% of these reinjuries occurred in the same location within the muscle as the index injury. The median time to RTS after the index injury was 19 days (range, 5-37 days; interquartile range [IQR], 15 days). The median time between the index injury and reinjury was 60 days (range, 20-316 days; IQR, 131 days) and the median time between RTS after the index injury and the reinjury was 24 days (range, 4-311 days; IQR, 140 days). More than 50% of reinjuries occurred within 25 days (4 weeks) after RTS from the index injury and 50% occurred within 50 days after the index injury. All reinjuries with more severe radiological grading occurred in the same location as the index injury.

CONCLUSION

The majority of the hamstring reinjuries occurred in the same location as the index injury, early after RTS and with a radiologically greater extent, suggesting incomplete biological and/or functional healing of the index injury. Specific exercise programs focusing on reinjury prevention initiated after RTS from the index injury are highly recommended.

The correlation between the imaging characteristics of hamstring injury and time required before returning to sports: a literature review

Injuries to the hamstring muscles are common in athletes. Track and field, Australian football, American football and soccer are examples of sports where hamstring injuries are the most common. The purpose of this study was to investigate whether there is a correlation between a hamstring injury prognosis and its characteristics of imaging parameters. The literature search was performed in the databases PubMed and CINAHL, and eleven articles were included. Seven out of the 11 articles showed a correlation between the size of the hamstring injury and length of time required before returning to sports. Different authors have reported contrasting results about length of time required before returning to sports due to location of injury within specific muscle. Majority of the articles found hamstring strain correlated to an extended amount of time required before returning to sports.

Pathophysiological Concepts and Treatment of Camptocormia

Camptocormia is a disabling pathological, non-fixed, forward bending of the trunk. The clinical definition using only the bending angle is insufficient; it should include the subjectively perceived inability to stand upright, occurrence of back pain, typical individual complaints, and need for walking aids and compensatory signs (e.g. back-swept wing sign). Due to the heterogeneous etiologies of camptocormia a broad diagnostic approach is necessary. Camptocormia is most frequently encountered in movement disorders (PD and dystonia) and muscles diseases (myositis and myopathy, mainly facio-scapulo-humeral muscular dystrophy (FSHD)). The main diagnostic aim is to discover the etiology by looking for signs of the underlying disease in the neurological examination, EMG, muscle MRI and possibly biopsy. PD and probably myositic camptocormia can be divided into an acute and a chronic stage according to the duration of camptocormia and the findings in the short time inversion recovery (STIR) and T1 sequences of paravertebral muscle MRI. There is no established treatment of camptocormia resulting from any etiology. Case series suggest that deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) is effective in the acute but not the chronic stage of PD camptocormia. In chronic stages with degenerated muscles, treatment options are limited to orthoses, walking aids, physiotherapy and pain therapy. In acute myositic camptocormia an escalation strategy with different immunosuppressive drugs is recommended. In dystonic camptocormia, as in dystonia in general, case reports have shown botulinum toxin and DBS of the globus pallidus internus (GPi-DBS) to be effective. Camptocormia in connection with primary myopathies should be treated according to the underlying illness.

Gastrocnemius tendinosis--A frequent finding on MRI knee examination

OBJECTIVE

Gastrocnemius tendinosis (GT) is one potential cause for posterior knee pain, commonly overlooked on clinical examinations and imaging. This study assesses the frequency of GT on MR imaging in a convenience sample based on a database search and associations with other articular pathologies and clinical findings.

SUBJECTS AND METHODS

With IRB approval, retrospective review was completed on 300 randomly selected MR knee exams performed from February 2009 to June 2010. Following de-identification, axial T2 and sagittal PD images, with or without fat suppression, were reviewed by 2 radiologists. The gastrocnemius tendon femoral attachments were graded as normal, mild (few cysts, thickening, intermediate signal) or severe GT (multiple cysts, marrow edema, tear). Select associated MR findings of internal derangement were documented. Clinical charts were reviewed for clinical presentation, physical exam findings, and select demographics.

RESULTS

The inter-observer reliability for presence/grading of GT was very high (kappa statistic=0.97). Frequency of GT was 50.33%, most frequently involving medial head of gastrocnemius (63.6%). Grades of GT were 41.7% and 17.2% for mild and severe respectively. Univariate analysis showed statistically significant relationship between grade of GT with arthrosis (p=0.05) and clinical joint effusion (p=0.02). Multivariate analysis showed higher odds of severe GT for individuals with medial plus lateral GT. Statistical significance was noted for presence of both GT and ACL tear (13.9%; p=0.02).

CONCLUSION

Significant findings of our analysis included GT presented with predominant involvement of medial head of gastrocnemius tendon, mild in severity, strong association with ACL tear, presented frequently as posterior knee pain, limited joint motion and clinical joint effusion. However, there was no statistically significant association between demographic features and medical comorbidities in the patients. Increased understanding of frequency of GT allows more accurate reporting of MR knee exam and systematic search for associated abnormalities.

Imaging techniques for muscle injury in sports medicine and clinical relevance

Magnetic resonance imaging (MRI) and ultrasound are the imaging modalities of choice to assess muscle injuries in athletes. Most authors consider MRI as the reference standard for evaluation of muscle injuries, since it superiorly depicts the extent of injuries independently of its temporal evolution, and due to the fact that MRI seems to be more sensitive for the detection of minimal injuries. Furthermore, MRI may potentially allow sports medicine physicians to more accurately estimate recovery times of athletes sustaining muscle injuries in the lower limbs, as well as the risk of re-injury. However, based on data available, the specific utility of imaging (including MRI) regarding its prognostic value remains limited and controversial. Although high-quality imaging is systematically performed in professional athletes and data extracted from it may potentially help to plan and guide management of muscle injuries, clinical (and functional) assessment is still the most valuable tool to guide return to competition decisions.

Return to sport after muscle injury

Skeletal muscle injuries are among the most common sports-related injuries that result in time lost from practice and competition. The cellular response to muscle injury can often result in changes made to the muscle fibers as well as the surrounding extracellular matrix during repair. This can negatively affect the force and range of the injured muscle even after the patient's return to play. Diagnosis of skeletal muscle injury involves both history and physical examinations; imaging modalities including ultrasound and magnetic resonance imaging (MRI) can also be used to assess the extent of injury. Current research is investigating potential methods, including clinical factors and MRI, by which to predict a patient's return to sports. Overall, function of acutely injured muscles seems to improve with time. Current treatment methods for skeletal muscle injuries include injections of steroids, anesthetics, and platelet-rich plasma (PRP). Other proposed methods involve inhibitors of key players in fibrotic pathways, such as transforming growth factor (TGF)-ß and angiotensin II, as well as muscle-derived stem cells.

No association between fibrosis on magnetic resonance imaging at return to play and hamstring reinjury risk

BACKGROUND

Connective tissue scar (fibrosis) is a common finding on magnetic resonance imaging (MRI) after recovery from acute hamstring injuries. Fibrosis has been suggested as a predisposing factor for reinjury, but evidence from clinical studies is lacking.

PURPOSE/HYPOTHESIS

The aim of this study was to examine the association between the presence of fibrosis on MRI at return to play after an acute hamstring injury and the risk of reinjury. The hypothesis was that fibrous tissue on MRI was associated with an increased reinjury risk.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Magnetic resonance images were obtained from 108 consecutive athletes with modified Peetrons classification grade 1 or 2 hamstring injuries within 5 days of injury and within 7 days of return to play. The presence and extent of abnormally low signal intensity in the intramuscular tissue on MRI, suggestive of fibrosis, were assessed on both T1- and T2-weighted images. Reinjuries were recorded over a 1-year follow-up period. The association between fibrosis and reinjury risk was analyzed with a Cox proportional hazards model.

RESULTS

The MRIs of the initial injury showed 45 (43%) grade 1 and 63 (57%) grade 2 injuries. Median time of return to play was 30 days (interquartile range [IQR], 22-42 days). At return to play, 41 athletes (38%) had fibrosis on MRI with a median longitudinal length of 5.8 cm (IQR, 3.3-12.5 cm) and a median volume of 1.5 cm3 (IQR, 1.5-3.9 cm3). In athletes with fibrosis, 24% (10/41) sustained a reinjury, and in the subjects without fibrosis, 24% (16/67) had a reinjury, resulting in a hazard ratio of 0.95 (95% CI, 0.43-2.1; P=.898).

CONCLUSION

Fibrosis is commonly seen on MRI at return to play after grade 1 or 2 hamstring injuries but is not associated with reinjury risk.

Effect of photodynamic therapy on local muscle treatment in a rat muscle injury model: a controlled trial

Background

Muscle injury is common and is thought to account for 10%–50% of all sports-related injuries. The use of rest, ice, compression, and elevation is common in clinical practice, but many treatments over a long period are required to produce a therapeutic effect. We evaluated the utility of photodynamic therapy as a new treatment option for the acute stage of muscle injury.

Methods

Twenty 8-week-old Sprague-Dawley male rats underwent experimental injury of the right gastrocnemius muscle with a drop-mass method. After muscle injury was induced, a liposomally formulated indocyanine green derivative (7 mg/kg) near-infrared laser irradiation was performed at 18 h after injury. Local time-dependent changes in the treatment (n = 14) and no treatment (n = 14) groups were evaluated with in vivo imaging, histologic examination, and enzyme-linked immunosorbent assay methods.

Results

In vivo imaging fluorescence values were significantly higher in the no treatment group, whereas interleukin-6 and tumor necrosis factor-α levels were significantly higher in the treatment group at 18 h after injury. Histologic examination results revealed that the treatment group had less bleeding and more degeneration repair processes than the no treatment group at 24 h and 1 week after muscle injury.

Conclusions

These findings suggest that photodynamic therapy promotes a tissue-repairing effect during the early stage of muscle injury.

MRI findings of rotator cuff myotendinous junction injury

OBJECTIVE

The purpose of this article is to describe the MRI features of rotator cuff myotendinous junction injuries.

MATERIALS AND METHODS

We retrospectively identified MRI cases with myotendinous junction injury of the rotator cuff muscles and reviewed clinical, imaging, and surgical records. MR images were reviewed independently by two musculoskeletal radiologists to grade myotendinous junction injuries (strain, partial tear, or complete tear) and to assess for concurrent tendon tears (partial or full thickness) and bone changes (fracture or contusion).

RESULTS

The final study group comprised 16 subjects. The mean age was 38 years, with a majority of men (56%). The left shoulder was affected in 56% of subjects, with the dominant upper limb affected in 50%. The mean time between symptoms and MRI was 19 days. Subjects reported heavy lifting (19%), landing on the arm after a fall (19%), or prior shoulder therapeutic injection (25%). Myotendinous junction injuries affected the infraspinatus muscle (50%), followed by the supraspinatus (31%), subscapularis (25%), and teres minor (19%) muscles. About one fifth of subjects presented with more than one muscle affected, and 94% did not present with tears of the corresponding tendons. Most myotendinous junction injuries were strains (80%), followed by partial tears (20%). No complete tears were identified. There was no correlation between myotendinous junction injury and the presence of bone changes or the presence of tendon tears (p > 0.05).

CONCLUSION

Rotator cuff myotendinous junction injuries affect mostly the infra-spinatus and supraspinatus muscles, usually in a strain pattern and without tear of the corresponding tendon attachment.

Ultrasonographic findings in a large series of patients with knee pain

Background:

Musculoskeletal ultrasound (MSKUS) is becoming more and more popular in the evaluation of different musculoskeletal abnormalities. The aim of this retrospective study was to document the prevalence and spectrum of MSKUS findings at the painful knee.

Materials and Methods:

All the studies of MSKUS that were performed for the evaluation of knee pain during the previous 2 years at the Department of Radiology in Nazareth hospital were reviewed. Demographic and clinical parameters including age, gender, side, and MSKUS findings were documented.

Results:

Two hundred and seventy-six patients were included in the review. In 21 of them, both knees were evaluated at the same setting (total number of knees evaluated was 297). One hundred and forty-four knees were of the left side. Thirty-three pathologies were identified. 34% of the studies were negative. The most common MSKUS findings were medial meniscal tear (MMT) (20%), Baker's cyst (BC) (16%), and osteoarthritis (OA) (11%). Only one knee of all the knees evaluated in our study showed synovitis. Fifty-three knees (18% of all the knees evaluated) had more than one imaging finding, mosty two and while some had three findings. The most common combination of findings was MMT and BC (8 knees), MMT with OA (8 knees), and MMT with fluid (6 knee). In 67% of the patients who had simultaneous bilateral knee evaluation, at least one knee had no abnormal findings and in 43%, both knees were negative.

Conclusions:

MSKUS has the potential for revealing huge spectrum of abnormalities. In nearly 90% of the positive studies, degenerative/mechanical abnormalities were reported, with MMT, BC, and osteoarthritic changes being the most common.

Ultrasound findings of the painful ankle and foot

OBJECTIVES

To document the prevalence and spectrum of musculoskeletal ultrasound (MSKUS) findings at different parts of the foot.

MATERIALS AND METHODS

All MSKUS studies conducted on the foot during a 2-year period (2012-2013) at the Department of Radiology were reviewed. Demographic parameters including age, gender, and MSKUS findings were documented.

RESULTS

Three hundred and sixty-four studies had been conducted in the 2-year period. Ninety-three MSKUS evaluations were done for the ankle, 30 studies for the heel, and 241 for the rest of the foot. The most common MSKUS finding at the ankle was tenosynovitis, mostly in female patients; at the heel it was Achilles tendonitis, also mostly in female patients; and for the rest of the foot it was fluid collection and presence of foreign body, mainly in male patients. The number of different MSKUS abnormalities that were reported was 9 at the ankle, 9 at the heel, and 21 on the rest of the foot.

CONCLUSIONS

MSKUS has the potential for revealing a huge spectrum of abnormalities. The most common finding was collection/hematoma and foreign bodies at the foot, tenosynovitis at the ankle, and Achilles tendinitis at the heel.

Diagnosis and rehabilitation of gastrocnemius muscle tear: a case report

OBJECTIVE

This case study presents the epidemiology, etiology, diagnostic criteria, and therapeutic interventions for a common clinical condition - gastrocnemius injury.

CLINICAL FEATURES

A 44-year old male presented with acute calf pain with a palpable defect, loss of range of motion, and loss of strength after sustaining a soft tissue injury to the lower leg. The differential diagnosis of tear of the medial head of the gastrocnemius was confirmed by physical examination and diagnostic ultrasound imaging.

INTERVENTION AND OUTCOME

The patient was treated over a 6 week period. Initially, rehabilitation was approached using the PRICE principles for symptomatic relief, followed by stretching, strengthening, proprioception, and conditioning exercises. At 9-month follow-up post injury, there was no residual impairment in the gastrocnemius muscle function.

SUMMARY

This case demonstrates the importance of epidemiology, clinical assessment, and the use of diagnostic ultrasound and MRI imaging in the diagnosis of a tear of the medial head of the gastrocnemius muscle. With an accurate diagnosis and comprehension of classification of muscle injuries, management of gastrocnemius tears is straightforward.

Thoracic injuries in professional rugby players: mechanisms of injury and imaging characteristics

Professional rugby players are prone to traumatic thoracic injuries due to the use of minimal protective gear to cover the torso. In the 2007 Rugby World Cup, thoracic injuries occurred at a rate of 8.3 cases/1000 player-hours. CT and MRI play an important role in the diagnosis of these injuries. Vital internal organs, such as the heart, lungs, trachea, liver and large blood vessels lie within close proximity to the bony structures and what seems to be a simple rib fracture or clavicular dislocation can have potentially life-threatening complications that are not detected by conventional radiography. Cross-sectional imaging helps to determine the choice of treatment. Ultrasound offers a quick and dynamic imaging examination and allows high-resolution assessment of superficial tissues that complements conventional imaging. In this review article, we (1) presented data on incidence of thoracic injuries in professional rugby players; (2) described the anatomy of the joints comprising the thoracic cage and major muscles attached to the rib cage; (3) discussed indications and relevance for MRI and presented an optimised MRI protocol for assessment of suspected thoracic injury; and (4) illustrated various types of thoracic injuries seen in professional rugby players, including sternal contusion, retrosternal haematoma, manubriosternal disruption, sternoclavicular dislocation, rib fractures and injuries of the pectoralis major muscle.