Muscle Injuries in Sports: A New Evidence-Informed and Expert Consensus-Based Classification with Clinical Application

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.

Acute Hamstring Muscle Tears in Climbers-Current Rehabilitation Concepts

Acute hamstring injuries are often caused by the heel hook technique. This technique is unique to climbing and causes injury to muscular and inert tissues of the posterior thigh. The heel hook is used by climbers during strenuous ascent on overhanging walls and when crossing difficult terrain. The technique reduces the amount of upper body strength required during strenuous climbing because the climber's center of mass is retained within the base of support. The heel hook is stressful collectively for the hamstring muscle group and musculotendinous junction. Depending on injury severity, both conservative and surgical methods exist for the management of hamstring injuries. Contemporary approaches to rehabilitation primarily advocate the use of eccentric muscle strengthening strategies because of high rates of elongation stress associated with sprinting and team sports. However, there is reason to doubt whether this alone is sufficient to rehabilitate the climbing athlete in light of the high degree of concentric muscle strength required in the heel hook maneuver. This review examines the contemporary rehabilitation and strength and conditioning literature in relation to the management of acute hamstring musculotendinous injuries for the climbing athlete. The review provides a comprehensive approach for the rehabilitation and athletic preparation of the climbing athlete from the initial injury to full return to sports participation.

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

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Differentiation Between Tendinous, Myotendinous and Myofascial Injuries by L-BIA in Professional Football Players

Purpose

To differentiate by localized bioimpedance (L-BIA) measurements 24 h after injury, between tendinous, myotendinous junction (MTJ), and myofascial junction (MFJ) injuries, previously diagnosed by MRI exam. To evaluate by L-BIA, the severity of MTJ injuries graded from 1 to 3, and to determine the relationship between days to return to play (RTP) and L-BIA measurements.

Methods

3T MRI and tetra polar L-BIA was used to analyzed 37 muscle injuries 24 h after injury in 32 male professional football players, (23.5 ± 1.5 kg m^–2; 1.8 ± 0.1 m; 20–30 year.) between the 2016–2017 and 2017–2018 seasons. Muscle injuries were classified by The British Athletics Muscle Injury Classification (BAMIC). Percentage difference of L-BIA parameters [resistance (R), reactance (Xc), and phase angle (PA)] of the injured side were calculated considering contralateral non-injured side as the reference value.

Results

According to BAMIC classification and by MRI exam, we found tendinous (n = 4), MTJ (n = 26), and MFJ (n = 7) muscle injuries. In addition, MTJ injuries were grouped according to the severity of injury in grade 1 (n = 11), grade 2 (n = 8), and grade 3 (n = 7). Significant decrease (P < 0.01) was found in the L-BIA parameters R, Xc, and PA, in both MTJ and MFJ as well as in the different grades of MTJ injuries. In particular, in Xc (P < 0.001), which is related to muscle cell disruption. Regarding days to RTP, there was statistical significance among the three different grades of MTJ injuries (P < 0.001), especially when grade 1 was compared to grade 3 and grade 2 compared to 3.

Conclusion

L-BIA is a complementary method to imaging diagnostic techniques, such as MRI and US, to quantify MTJ and MFJ injuries. In addition, the increase in the severity of the MTJ injury resulted in higher changes of the Xc parameter and longer time to RTP.

A Histoarchitectural Approach to Skeletal Muscle Injury: Searching for a Common Nomenclature

In recent years, different classifications for muscle injuries have been proposed based on the topographic location of the injury within the bone-tendon-muscle chain. We hereby propose that in addition to the topographic classification of muscle injuries, a histoarchitectonic (description of the damage to connective tissue structures) definition of the injury be included within the nomenclature. Thus, the nomenclature should focus not only on the macroscopic anatomy but also on the histoarchitectonic features of the injury.

Calf muscle strain injuries in elite Australian Football players: A descriptive epidemiological evaluation

BACKGROUND

Calf muscle strain injuries (CMSI) show consistent rates of prevalence and re-injury in elite Australian Football players. An epidemiological evaluation is warranted to better understand the clinical presentation and recovery of CMSI.

PURPOSE

First, to describe the epidemiology of CMSI in elite Australian Football players. Second, to determine if recovery following injury is different according to: (a) injury type (index vs re-injury); (b) muscle injured (soleus vs gastrocnemius); and (c) mechanism of injury (running-related activity vs non running-related activity).

STUDY DESIGN

Descriptive epidemiological.

METHODS

Data retrieved from the Soft Tissue injury Registry of the Australian Football League were analyzed. Sixteen clubs submitted data on CMSI from 2014 to 2017. Data included: player characteristics, training and match history at the time of injury, MRI, and the time to reach recovery milestones.

RESULTS

One hundred and eighty-four CMSI were included (149 index injuries; 35 re-injuries). Soleus injuries were most prevalent (84.6%). Soleus injuries took 25.4 ± 16.2 days to return to play, whereas gastrocnemius injuries took 19.1 ± 14.1 days (P = .097). CMSI sustained during running-related activities took approximately 12 days longer to recover than injuries sustained during non running-related activities (P = .001). Compared to index injuries, re-injuries involved older players (P = .03) and significantly more time was taken to run at >90% of maximum speed, return to full training, and return to play (P ≤ .001). Almost all of the observed re-injuries involved soleus (91.4%).

CONCLUSION

Soleus injuries are more prevalent than gastrocnemius injuries in elite Australian Football players. Prognosis appears to be influenced by clinical factors, with CMSI sustained during running-related activities and re-injuries needing more time to recover.

Is It All About the Fascia? A Systematic Review and Meta-analysis of the Prevalence of Extramuscular Connective Tissue Lesions in Muscle Strain Injury

Background:

The fascia has been demonstrated to represent a potential force transmitter intimately connected to the underlying skeletal muscle. Sports-related soft tissue strains may therefore result in damage to both structures.

Purpose:

To elucidate the prevalence of connective tissue lesions in muscle strain injury and their potential impact on return-to-play (RTP) duration.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

Imaging studies describing frequency, location, and extent of soft tissue lesions in lower limb muscle strain injuries were identified by 2 independent investigators. Weighted proportions (random effects) were pooled for the occurrence of (1) myofascial or fascial lesions, (2) myotendinous lesions, and (3) purely muscular lesions. Study quality was evaluated by means of an adapted Downs and Black checklist, which evaluates reporting, risk of bias, and external validity.

Results:

A total of 16 studies (fair to good methodological quality) were identified. Prevalence of strain injury on imaging studies was 32.1% (95% CI, 24.2%-40.4%) for myofascial lesions, 68.4% (95% CI, 59.6%-76.6%) for myotendinous lesions, and 12.7% (95% CI, 3.0%-27.7%) for isolated muscular lesions. Evidence regarding associations between fascial damage and RTP duration was mixed.

Conclusion:

Lesions of the collagenous connective tissue, namely the fascia and the tendinous junction, are highly prevalent in athletic muscle strain injuries. However, at present, their impact on RTP duration is unclear and requires further investigation.

Effect of poor cooperation between coaching and medical staff on muscle re-injury in professional football over 15 seasons

Background

Muscle injury is the most common type of injury in football. Previous research has focused on traditional risk factors (eg, age, injury history, muscle imbalance/inflexibility) contributing to muscle re-injury. The effect of poor cooperation between the coaching and medical teams on the risk of re-injury remains unexplored in the sports medicine football literature.

Purpose

Examine the effect of poor cooperation between coaching and medical teams on muscle re-injury in professional football.

Methods

Retrospective review of the medical files of 97 footballers of a professional team in Dubai over 15 consecutive seasons (2002–2017). Medical team recorded all injuries in each player’s file. Data on the perceived level of cooperation between coaching and medical teams were available in the daily meeting notes from the head of the medical team. The level of perceived cooperation was ranked on a three-point Likert scale by the head of the medical team and depended on whether the coaching team accepted the player injury (excellent cooperation), brought some suggestion after discussion with the medical team (normal cooperation) or rejected it (poor cooperation).

Results

In total, 338 indirect muscle injuries (21 re-injuries) were recorded during 15 consecutive seasons., There was a significant increase in the mean number of total injuries (mean ± SE, 95% CI; 16±2, 12–21; P<0.0001), mean number of indirect muscle injuries (12±1, 95% CI 10–14; P<0.0001), and indirect muscle re-injuries (4±1, 95% CI 3–5; P<0.0001) during seasons with a poor perceived level of cooperation compared to seasons with a normal/excellent perceived level of cooperation.

Conclusion

Findings suggest that poor cooperation between coaching and medical teams may increase the risk of muscle re-injury in professional football. Future studies conducted in different clubs, leagues, countries, and even sports are required to further explore the effect of cooperation between coaching and medical teams on the risk of re-injury.

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.

Anatomy of proximal attachment, course, and innervation of hamstring muscles: a pictorial essay

Hamstring injuries are very common in sports medicine. Knowing their anatomy, morphology, innervation, and function is important to provide a proper diagnosis, treatment as well as appropriate prevention strategies. In this pictorial essay, based on anatomical dissection, the detailed anatomy of muscle-tendon complex is reviewed, including their proximal attachment, muscle course, and innervation. To illustrate hamstrings' role in the rotational control of the tibia, the essay also includes the analysis of their biomechanical function.Level of evidence V (expert opinion based on laboratory study).

Image guided injection therapies in athletes-Do they work and what should we be using?

In the modern management of the injured elite athlete, the goals of guided injection therapies have extended beyond simple reduction of pain to enhancement of tissue healing and accelerated return to competition, faster than natural healing can allow. This article will review the injection therapies which are frequently used in elite sports injury management and describe other less commonly used injection therapies that are available to the treating clinician and athlete. The evidence base, where available, for each treatment option will be summarised.

Italian consensus conference on guidelines for conservative treatment on lower limb muscle injuries in athlete

Provide the state of the art concerning (1) biology and aetiology, (2) classification, (3) clinical assessment and (4) conservative treatment of lower limb muscle injuries (MI) in athletes. Seventy international experts with different medical backgrounds participated in the consensus conference. They discussed and approved a consensus composed of four sections which are presented in these documents. This paper represents a synthesis of the consensus conference, the following four sections are discussed: (i) The biology and aetiology of MIs. A definition of MI was formulated and some key points concerning physiology and pathogenesis of MIs were discussed. (ii) The MI classification. A classification of MIs was proposed. (iii) The MI clinical assessment, in which were discussed anamnesis, inspection and clinical examination and are provided the relative guidelines. (iv) The MI conservative treatment, in which are provided the guidelines for conservative treatment based on the severity of the lesion. Furthermore, instrumental therapy and pharmacological treatment were discussed. Knowledge of the aetiology and biology of MIs is an essential prerequisite in order to plan and conduct a rehabilitation plan. Another important aspect is the use of a rational MI classification on prognostic values. We propose a classification based on radiological investigations performed by ultrasonography and MRI strongly linked to prognostic factors. Furthermore, the consensus conference results will able to provide fundamental guidelines for diagnostic and rehabilitation practice, also considering instrumental therapy and pharmacological treatment of MI. Expert opinion, level IV.

New MRI muscle classification systems and associations with return to sport after acute hamstring injuries: a prospective study

OBJECTIVES

To determine agreement between modified Peetrons, Chan acute muscle strain injury classification and British Athletics Muscle Injury Classification (BAMIC) and to investigate their associations and ability to predict time to return to sport (RTS).

METHODS

Male athletes (n=176) with acute hamstring injury and MRI (1.5T) ≤5 days were followed until RTS. MRIs were scored using standardised forms.

RESULTS

For MRI-positive injuries there was moderate agreement in severity grading (κ = 0.50-0.56). Substantial variance in RTS was demonstrated within and between MRI categories. Mean differences showed an overall main effect for severity grading (p < 0.001), but post hoc pairwise comparisons for BAMIC (grade 0a/b vs. 1, p = 0.312; 1 vs 2, p = 0.054; 0a/b vs 2, p < 0.001; 1 vs 3, p < 0.001) and mean differences for anatomical sites (BAMIC a-c, p < 0.001 [a vs b, p = 0.974; a vs c, p = 0.065; b vs c, p = 0.007]; Chan anatomical sites 1-5, p < 0.077; 2A-C, p = 0.373; 2a-e, p = 0.008; combined BAMIC, p < 0.001) varied. For MRI-positive injuries, total explained RTS variance was 7.6-11.9% for severity grading and BAMIC anatomical sites.

CONCLUSIONS

There was wide overlap between/variation within the grading/classification categories. Therefore, none of the classification systems could be used to predict RTS in our sample of MRI-positive hamstring injuries.

KEY POINTS

• Days to RTS varied greatly within the grading and classification categories. • Days to RTS varied greatly between the grading and classification categories. • Using MRI classification systems alone to predict RTS cannot be recommended. • The specific MRI classification used should be reported to avoid miscommunication.

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.