Pediatric Muscle Sprains/Strains

Disease/Disorder

Definition

Pediatric muscle strain is an injury in children resulting in muscle fiber overstretching or possible tears, commonly near the muscle-tendon junction commonly, caused by excessive stretch to the muscle or eccentric contraction. It is characterized by localized tenderness, swelling, loss of range of motion, weakness in the muscle, and a greater risk of injury to the muscle following strain.¹

Etiology

Pediatric muscle strains may occur throughout spontaneous activity with excessive stretching of a muscle or while the muscle is under load during stretch. Injury is more likely to occur in a muscle that crosses multiple joints and has a large component of fast-twitch fibers.¹

Epidemiology including risk factors and primary prevention

Muscle strains can affect children of all ages, but they are more common in adolescents who are actively involved in sports and physical activities.  Prevalence rates may vary depending on the sport and geographic region. Muscle strains and overuse injuries account for >23% of pediatric musculoskeletal sources of pain.^2,3

Risk factors include sports participation (especially contact sports), inadequate warm-up, muscle imbalance, overuse, and previous injuries.^4,5 Risk also increases at maturity offset or as time to peak height velocity (PHV) decreases (the closer to PHV, the higher the risk).³

Children and adolescents can be grouped into the following categories of muscle strain risk level based on physical activity level, age and maturation:

• Low risk: young/prepubescent children, children/adolescents involved in no physical activity or typical recreational activities³
• Moderate risk: older children, student athletes³
• High risk: adolescents (especially adolescent girls), athletes in league sports³

To reduce the risk of muscle strains, children should engage in proper warm-up and stretching routines before physical activities, use appropriate protective gear in sports, and avoid overtraining. Emphasis on nutrition and hydration is another key to muscle strain prevention.⁶

Patho-anatomy/physiology

A muscle strain occurs when there is excessive or abnormal stretching or tearing of muscle fibers or the associated tendon, known as overloading. It can happen in different parts of the muscle-tendon unit:

• Muscle Belly Strain: Involves the central portion of the muscle.
• Muscle-Tendon Junction Strain: Occurs at the interface between the muscle and tendon.
• Tendon Strain: Affects the tendon itself, which connects the muscle to the bone.

This can occur due to:

• Rapid or forceful muscle contractions beyond the muscle’s capacity.
• Inadequate warm-up leading to less flexible and more injury-prone muscles.
• Fatigue from repetitive use or overtraining.

Overloading causes microtrauma to muscle fibers and tendons. This can range from mild stretching to partial tearing of muscle fibers or the tendon. The severity of the strain depends on the extent of damage:

• Grade 1 Strain: Mild stretching or microscopic tearing of muscle fibers, often referred to as a “pulled muscle.”
• Grade 2 Strain: Partial tearing of muscle fibers, resulting in moderate pain and loss of function.
• Grade 3 Strain: Severe tearing or rupture of muscle fibers, causing significant pain and loss of function.⁷

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

• New onset/acute: Characterized by pain and swelling. There is a greater risk of additional injury at this stage.  Pathologically associated with tearing and subsequent necrosis of myofibrils, and potential formation of a hematoma in the space created in the torn muscle with proliferation of inflammatory cells.⁸
• Subacute: Pain and swelling are reduced. There is repair and remodeling, with phagocytosis of the necrotic tissue, regeneration of the myofibrils and concomitant production of connective scar tissue, along with neoformation of vessels and neural growth.⁸
• Chronic/stable:  Resolution of symptoms with continued remodeling, maturation of the regenerated myofibrils, contraction and reorganization of the scar tissue, and recovery of muscle functional capacity.⁸

Specific secondary or associated conditions and complications

All muscle strains have the potential to cause muscular rupture and hematoma formation. This can lead to increased tissue pressure and metabolic insult from tissue necrosis can lead to microvascular disruption, which in turn, can cause compartment syndrome. Hematoma formation during muscle strain can also lead to compression of veins causing thrombosis.⁹

Essentials of Assessment

History

When patients present with muscle pain of any kind it is important to gather a thorough history. Components may include but are not limited to inciting incident, location of symptoms, prior episodes of similar symptoms, quality and severity of pain, pain radiation, duration of symptoms, prior treatments, exacerbating factors, and other associated symptoms.

Physical examination

Physical examination begins with inspection of the area of strain. In pediatric muscle strain edema and/or ecchymosis is often present. On palpation, the muscle will frequently be tender. In more severe muscle strains it is possible to detect a gap in the area of injury. Range of motion should also be tested and will be commonly reduced following strain. A reduction of strength will also often be apparent on manual muscle testing. Sensory deficits or changes to muscle stretch reflexes should not be present.⁸

Functional assessment

Functional assessment of pediatric muscle strains is an essential part of the evaluation process to determine the extent of the injury, guide treatment decisions, and assess a child’s readiness to return to physical activities or sports. Key aspects of functional assessment include history and physical examination, pain assessment, functional testing, functional questionnaires, rehabilitation progression and a return-to-play assessment.

The child’s pain is assessed using scales like the Visual Analog Scale (VAS) or Numeric Rating Scale (NRS). They help gauge the severity of pain and monitor changes over time.

Functional tests specific to the affected muscle or muscle group are performed to evaluate the child’s ability to perform movements related to their sport or daily activities.

Functional assessments may include tasks like squatting, jumping, or running, depending on the sport or activity involved.

Pediatric-specific questionnaires can be used to assess a child’s functional status and activity level. Examples include the Pediatric Outcomes Data Collection Instrument (PODCI) and the Lower Extremity Functional Scale (LEFS). More examples and further details can be found in the Supplemental assessment tools section below.¹⁰

Monitoring the child’s progress during rehabilitation is a crucial part of a functional assessment. This includes evaluating their ability to perform therapeutic exercises, gradually increase intensity, and regain functional movements.

Though there is no consensus on formal return-to-sport assessments, functional assessment can help determine when a child can safely return to sports or physical activities. Assessment typically includes a series of sport-specific drills and exercises to ensure the injured muscle can withstand the demands of the activity without the risk of re-injury.¹¹

Laboratory studies

In the evaluation of pediatric muscle strains, laboratory tests are not considered a routine part of the diagnostic process. Muscle strains are primarily diagnosed based on a thorough clinical history and physical examination. Labs such as creatine kinase (CK), inflammatory markers (CRP & ESR) and complete blood count (CBC) are useful in specific situations depending on the severity of the strain or to rule out other conditions (i.e., infection, systemic inflammatory conditions).¹²

Imaging

While imaging modalities are not typically necessary for diagnosing pediatric muscle strain, they can be done to aid in identifying the extent and site of lesion, prognostication of recovery time, return to pre-injury sporting, and risk of recurrence. Ultrasound imaging allows a dynamic diagnostic assessment of the muscle, though it is examiner dependent. MRI can also be utilized for a more detailed assessment of possible edema and hematoma formation but is a static exam.⁸

Supplemental assessment tools

Several pediatric-specific questionnaires are used to assess a child’s functional status after a musculoskeletal injury. These are designed to evaluate various aspects of physical function, pain, and overall well-being. Here are a few examples

Pediatric Quality of Life Inventory (PedsQL): The PedsQL is a comprehensive questionnaire that assesses a child’s quality of life across physical, emotional, social, and school functioning domains. It is used to measure how an injury affects a child’s overall well-being.

Pediatric Outcomes Data Collection Instrument (PODCI): The PODCI is specifically designed to assess functional outcomes in children with musculoskeletal conditions and injuries. It covers various domains, including upper extremity, lower extremity, and sports and physical functioning.

Pediatric Injury Functional Outcome Scale (PIFOS): The PIFOS is focused on evaluating functional outcomes following pediatric injuries. It assesses a child’s ability to perform activities of daily living and participation in sports and recreational activities.

Child Health Assessment Questionnaire (CHAQ): Originally developed for children with juvenile idiopathic arthritis, the CHAQ assesses physical function and overall well-being. It includes questions about a child’s ability to perform everyday tasks.

Pediatric Orthopedic Society of North America (POSNA) Musculoskeletal Functional Health Questionnaire: This questionnaire evaluates functional health in children with musculoskeletal conditions. It includes questions about pain, physical function, and overall well-being.

Lower Extremity Functional Scale for Pediatrics (LEFS-P): This questionnaire focuses on lower extremity function and assesses a child’s ability to perform various activities related to walking and lower limb function.¹¹

Early predictions of outcomes

Predicting outcomes for pediatric muscle strains can be challenging because they depend on several factors outlined here.

• Severity: Muscle strains are graded as mild, moderate, or severe. Mild strains may heal relatively quickly with rest and basic care, while severe strains can lead to more prolonged recovery and potential complications.
• Location: Some muscles are more critical for function than others. Strains in muscles that are essential for activities like walking or arm movement may have a more significant impact on a child’s daily life and recovery.
• Age: Younger children often recover more quickly than older children and adolescents. Pediatric bodies have a remarkable capacity for healing, but the recovery process may vary depending on the child’s age. 
• Follow-Up Care: Regular follow-up with a healthcare provider is essential to monitor the child’s progress. Adjustments to the treatment plan may be needed based on how the injury is healing. 
• Rehabilitation: Physical therapy and rehabilitation exercises can help restore strength, flexibility, and function in the affected muscle. Compliance with rehabilitation exercises is often a key factor in determining the long-term outcome.

It’s important to note that most pediatric muscle strains have a good prognosis, especially when they are promptly diagnosed and appropriately managed. With proper care, many children can return to their normal activities and sports over time. However, the exact outcome can vary widely from case to case, so it’s crucial to consult with a healthcare provider for a personalized assessment and treatment plan for a child with a muscle strain.

Environmental

Environmental factors can play a role in pediatric muscle strains, either as contributing factors to the injury or as factors that influence the recovery process.

• Weather Conditions: Extreme temperatures can affect susceptibility. Cold weather may require extra warm-up, and hot weather can lead to dehydration-related strains.¹³ 
• Nutrition: Proper diet aids muscle health and recovery, lowering the risk of strains.¹⁴
• Sleep Hygiene: Inadequate sleep increases susceptibility to muscle strains.¹⁴

Social role and social support system

The social role and social support system can play a significant role in the experience of pediatric muscle strains. 

• Family Support: Crucial for emotional aid and ensuring treatment adherence.
• Medical Professionals: Diagnose, treat, and monitor recovery.
• Coaching Staff: Assist in rehabilitation and safe return to activities.
• Mental Health Support: Addresses emotional challenges related to the injury.
• School Support: Provides educational accommodations. 

The social support system surrounding a child with a muscle strain can have a profound impact on their physical and emotional well-being. A strong support network can enhance the child’s motivation, adherence to treatment plans, and overall recovery process. It is essential for parents, caregivers, coaches, and healthcare professionals to collaborate to ensure the child receives the necessary support and care.

Professional issues

Pediatric athletes, particularly at higher levels of competition, may be under significant outside pressure to return to sport following a muscle strain sooner than medically recommended. However, it is important that full range of motion and strength are regained before returning to sports activities. Recurrences of injuries may result in more serious complications such as myositis ossificans.¹⁵

Rehabilitation Management and Treatments

Available or current treatment guidelines

Acute treatment is based on the model of protection, rest, ice, compression, and elevation. Active and passive stretching can be beneficial. In the three-to-seven-day period post injury, isometric training may also promote muscle recovery; isotonic exercises can be initiated if isometric training can be performed without pain.  After this stage, athletes may benefit from sport specific rehabilitation which aims to improve motor abilities, muscle resistance and strength. Surgery is indicated if there is a complete lesion of the muscle or the muscle tendon conjunction or a subtotal lesion with persistent pain and loss of strength after conservative management.⁷

At different disease stages

• New onset/acute (initial 48-72 hours)
• R.I.C.E. (rest, ice, compression, elevation)
• Protect the injured muscle and minimize further damage¹⁶
• Moderate exercise (active and passive stretching) as tolerated
• Consider manual therapy consisting of massage to aid in drainage of inflammatory catabolites¹⁶
• Overall, children are advised to rest and avoid activities that exacerbate pain¹⁶
• Subacute (3-7 days after injury)
• Physical therapy can be incorporated. Muscle stretching (passive, assisted or active), pain-free isometric exercise, modalities such as ultrasound, thermotherapy, and low or high intensity laser therapy^16,17
• OTC pain medications as needed¹⁶
• Intermediate phase (several weeks to months)
• Focus is on functional rehabilitation and general athletic reconditioning¹⁶
• Strength training, balance and coordination training¹⁶
• Sport-specific training¹⁶
• Final stage: full recovery/Return to sport¹⁶
• Gradual return to full activity¹⁶
• Utilization of rehab strategies to prevent recurrence or new injuries¹⁶

Coordination of care

Coordination of care in pediatric muscle strains involves various professionals and support systems working together in a interdisciplinary team:

• Primary Care Physician (PCP): Initial diagnosis and monitoring.
• Pediatric Orthopedic/Physiatrist Specialist: Expertise for complex cases.
• Physical Therapist: Rehabilitation and recovery. 
• Athletic Trainer: Safely returning to activities.
• Mental Health Professional: Emotional support. 
• Parents/Caregivers: Communicate, support, and ensure adherence. 
• School Personnel: Notify teachers and administrators for educational support. 
• Coaches: Collaborate for safe sports re-entry. 

Patient & family education

Patients and families should be educated that muscle strain injuries typically have an excellent prognosis and complications are rare. Treatment includes the “P.R.I.C.E model” of protection, rest, ice, compression, and elevation. Lastly, too much fatigue and lack of warm up exercise can help to precipitate further muscle strain injuries.⁸

Measurement of treatment outcomes

To measure treatment outcomes in pediatric muscle strains, assessments cover three main areas.

Impairment-Based

• Pain: Using scales like visual analog scale (VAS) or numerical rating scale (NRS).
• Range of Motion: Assessing joint flexibility.
• Strength Testing: Evaluating muscle strength.
• Functional and Endurance Tests: Measuring overall muscle function and endurance.
• Imaging: Visualizing muscle injury and healing progress.

Activity Participation-Based

• Functional Outcome Measures: Assessing daily living activities.
• Return-to-Play Assessment: Determining readiness for sports.
• Patient-Reported Outcomes (PROs): Using questionnaires for self-reported function and quality of life.

Environmentally based

• Environmental Assessments: Identifying barriers or facilitators to participation.
• Social Participation: Measuring engagement in social, school, and community activities. Environmental Modifications: Evaluating the impact of accommodations.
• Patient and Family Satisfaction: Gathering feedback on healthcare and support.
• Healthcare Resource Utilization: Assessing medical visits and costs.

These measures provide a comprehensive view of treatment outcomes and help tailor care for pediatric muscle strains.

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

Physicians should provide patients as well as families with evidence-based information on pediatric muscle strain including definition, common causes, possible complications, prognosis, and treatment options through the acute, subacute, and chronic stages of injury.

Education should include that the diagnosis is typically made clinically and imaging is not usually required. Thankfully, pediatric muscle strains have a good prognosis. However, patients and families should be cautioned against returning to activity too soon as reinjury is more common prior to complete resolution of symptoms.

Cutting Edge/Emerging and Unique Concepts and Practice

Advancements in pediatric muscle strain management are continually shaping the field. 

• Regenerative Therapies: Cutting-edge approaches like stem cell therapy and platelet-rich plasma (PRP) treatments are being explored for their potential to enhance muscle healing and reduce scar tissue formation in pediatric patients.¹⁸
• Shockwave Therapy: Extracorporeal shockwave therapy (ESWT) is gaining recognition for its potential to stimulate healing, reduce pain, and improve muscle function in pediatric muscle strains.¹⁹

More research is needed to be able to understand how each of these promising modalities will be incorporated in a guidelines-oriented fashion in the management of pediatric muscle strains.

Gaps in the Evidence-Based Knowledge

Our understanding of pediatric muscle strains has notable gaps, impeding prevention, diagnosis, and treatment. These gaps include missing prevalence data, hindering at-risk group identification and prevention strategies. Long-term outcomes, delayed complications, and age-specific guidelines are understudied. Insufficient research exists on risk factors, preventive measures’ effectiveness, and psychological impacts on children. Further, standardized treatments, advanced diagnostics, and tailored rehab protocols for pediatric patients are lacking. Research mostly focuses on sports injuries, leaving non-sports strain prevention unexplored. Bridging these gaps is crucial for enhancing care and outcomes for children with muscle strains.

References

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6. Valovich McLeod TC, Decoster LC, Loud KJ, et al. National Athletic Trainers’ Association position statement: prevention of pediatric overuse injuries. J Athl Train. 2011;46(2):206-220. doi:10.4085/1062-6050-46.2.206 Prevention
7. Maffulli N, Del Buono A, Oliva F, et al. Muscle Injuries: A Brief Guide to Classification and Management. Transl Med UniSa. 2014;12:14-18. Published 2014 Sep 1.  Patho-anatomy/pathophysiology, Current treatment guidelines
8. Fernandes TL, Pedrinelli A, Hernandez AJ. MUSCLE INJURY – PHYSIOPATHOLOGY, DIAGNOSIS, TREATMENT AND CLINICAL PRESENTATION. Rev Bras Ortop. 2015 Dec 8;46(3):247-55. doi: 10.1016/S2255-4971(15)30190-7. PMID: 27047816; PMCID: PMC4799202. symptoms acute – chronic. Physical exam. Family education. Imaging
9. Alessandrino F, Balconi G. Complications of muscle injuries. J Ultrasound. 2013 Mar 2;16(4):215-22. doi: 10.1007/s40477-013-0010-4. PMID: 24432177; PMCID: PMC3846951. complications.
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16. Maffulli N, Del Buono A, Oliva F, et al. Muscle Injuries: A Brief Guide to Classification and Management. Transl Med UniSa. 2014;12:14-18. Published 2014 Sep 1. Treatment at different stages
17. Contraindications for use of therapeutic laser – practical pain management. Practical Pain Management. January 28, 2012. Accessed October 10, 2023. https://www.practicalpainmanagement.com/treatments/complementary/lasers/contraindications-use-therapeutic-laser. Treatment at different stages
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19. Zissler A, Steinbacher P, Zimmermann R, Pittner S, Stoiber W, Bathke AC, Sänger AM. Extracorporeal Shock Wave Therapy Accelerates Regeneration After Acute Skeletal Muscle Injury. Am J Sports Med. 2017 Mar;45(3):676-684. doi: 10.1177/0363546516668622. Epub 2016 Oct 13. PMID: 27729321.

Author Disclosure

Erika Trovato, DO
Nothing to Disclose

Malav Shah, MD
Nothing to Disclose

Matthew Slitzky, DO
Nothing to Disclose

Brandon Roberson, MD
Nothing to Disclose

Bryan Lebron-Solis, DO
Nothing to Disclose