01Approach to the Critical Patient/attcp25

Immediate stabilization and red flags

›Threat recognition

›Airway compromise from neck trauma or expanding hematoma

›Respiratory distress with chest wall pain and hypoventilation

›Hemodynamic instability

›Rapidly expanding swelling or ecchymosis

›Severe pain out of proportion to exam

›Neurovascular compromise distal to injury

›Suspected compartment syndrome

Key decision points

›Determine alternative diagnosis

›If high-energy mechanism, fracture or dislocation pathway

›If focal bony tenderness, imaging pathway

›If tendon gap or loss of function, tendon rupture pathway

›If fever or systemic symptoms, infection pathway

›Determine severity

›Grade I strain suspected with mild pain and minimal strength loss

›Grade II strain suspected with functional limitation and weakness

›Grade III strain suspected with complete loss of function or palpable defect

Monitoring and analgesia priorities

›Analgesia strategy

›Pain score and functional limitation tracking

›Early multimodal non-opioid analgesia when safe

›Sedation avoidance unless procedure required

›Limb safety

›Distal pulses and capillary refill

›Distal motor and sensory function

›Compartment firmness and pain with passive stretch

02History/hx36

Presentation pattern

›Symptom narrative

›Sudden pain during eccentric contraction

›Pain after unaccustomed activity or overload

›Delayed onset pain after exercise

›Cramping sensation during activity

Mechanism and timing

›Injury context

›Sprinting or jumping mechanism

›Lifting or twisting mechanism

›Direct blow mechanism

›Pop sensation

›Immediate functional loss

Risk factors and modifiers

›Predisposition

›Prior strain in same muscle group

›Inadequate warm-up

›Sudden training load increase

›Poor flexibility or fatigue

›Dehydration or heat exposure

›Fluoroquinolone exposure for tendon risk mimic

›Comorbidities and meds

›Anticoagulant or antiplatelet use

›Bleeding disorder

›Statin use with myopathy risk

›Sickle cell disease with rhabdomyolysis risk

›Diabetes with neuropathy masking severity

03Physical Exam/exam27

Focused musculoskeletal exam

›Local assessment

›Point tenderness in muscle belly or musculotendinous junction

›Swelling pattern and symmetry

›Ecchymosis distribution

›Palpable defect suggesting higher grade tear

›Range of motion

›Pain with active contraction

›Pain with passive stretch

›Limitation pattern suggesting joint pathology mimic

›Strength testing

›Pain limited weakness

›True weakness compared with contralateral side

›Inability to generate force suggesting rupture

Neurovascular and compartment screen

›Distal status

›Pulses and capillary refill

›Sensation in distal dermatomes

›Motor function in distal myotomes

›Compartment syndrome features

›Pain with passive stretch

›Tense compartment

›Progressive paresthesia

›Weakness

PITFALLS

›Common misses

›Normal skin appearance early in compartment syndrome

›Referred pain from spine or hip mimicking strain

04Differential Diagnosis/ddx23

Must not miss

›Limb threatening and life threatening

›Compartment syndrome ICD-10 T79.A

›Acute arterial occlusion ICD-10 I74

›Septic arthritis ICD-10 M00

›Necrotizing soft tissue infection ICD-10 M72.6

›Rhabdomyolysis ICD-10 M62.82

›Deep vein thrombosis ICD-10 I82

Common mimics and associated injuries

›Structural injuries

›Fracture ICD-10 S12-S92 range by site

›Dislocation ICD-10 S03-S93 range by site

›Tendon rupture SNOMED concept tendon rupture

›Ligament sprain ICD-10 S13-S93 range by site

›Muscle contusion ICD-10 S70-S90 range by site

›Medical causes of muscle pain

›Statin myopathy

›Electrolyte disturbance related cramps

›Viral myositis

›Inflammatory myopathy

Clinical clues for separation

›Pattern recognition

›Focal bony tenderness with axial loading suggesting fracture

›Joint effusion and limited passive range suggesting intra-articular pathology

›Palpable tendon gap and loss of specific function suggesting rupture

›Systemic symptoms suggesting infection or inflammatory condition

05Laboratory Tests/lt22

No routine labs for uncomplicated strain

›Selective testing strategy

›No labs for mild localized pain with benign exam

›Labs only when red flags, severe injury, systemic symptoms, or exertional syndrome concern

Muscle injury and exertional syndrome labs

›Rhabdomyolysis evaluation

›Creatine kinase for severe exertional pain or weakness

›Serial CK trend if ongoing symptoms or high initial value

›Serum creatinine for kidney injury risk

›Acute kidney injury risk with dehydration or heat illness

›Potassium for hyperkalemia risk

›ECG correlation if abnormal

›Calcium for severe rhabdomyolysis physiology

›Early hypocalcemia possible

›Urinalysis for heme positive with few RBC pattern

›Myoglobinuria support

Bleeding risk labs

›Hematoma evaluation

›Hemoglobin for large expanding hematoma or anticoagulation

›INR for warfarin associated bleeding

›Platelet count if thrombocytopenia concern

Infection and inflammatory labs

›When systemic features present

›White blood cell count for systemic infection concern

›C-reactive protein for inflammatory or infectious concern

›Blood cultures if febrile and deep infection concern

06Diagnostic Tests/dt33

Scoring Systems

›Severity classification frameworks

›Clinical grading of muscle strain

›Grade I minimal fiber disruption and minimal strength loss

›Grade II partial tear with weakness and functional limitation

›Grade III complete tear with loss of function and possible defect

›Functional readiness markers

›Pain free full range of motion

›Symmetric strength on manual testing

›Sport specific movement without compensation

MRI

›MRI soft tissue characterization

›Indications

›Suspected grade II to III tear with major functional loss

›Persistent symptoms beyond expected recovery window

›Suspected tendon avulsion or deep hematoma

›Interpretation pearls

›Extent of edema and fiber disruption correlates with recovery time

›Proximal hamstring and adductor injuries often underestimated clinically

CT

›CT limited role

›Indications

›Concern for occult fracture when radiographs equivocal

›Deep pelvic or retroperitoneal hematoma concern

›Limitations

›Soft tissue tear characterization inferior to MRI

›Radiation exposure considerations

07Disposition/dispo20

ED course and observation

›Safe discharge features

›Pain controlled with oral medications

›Ambulation or limb use acceptable with support as needed

›No neurovascular deficit

›No compartment syndrome concern

›No concerning systemic symptoms

›Observation or admission triggers

›Suspected compartment syndrome

›Large expanding hematoma

›Rhabdomyolysis or acute kidney injury

›Uncontrolled pain despite ED therapy

›Inability to ambulate safely with home supports

Referral and follow-up

›Sports medicine or primary care follow-up

›Grade I to II reassessment within 3-7 days

›Rehab plan and progressive loading guidance

›Orthopedics or surgery consultation triggers

›Suspected grade III tear

›Tendon rupture or avulsion concern

›Compartment syndrome concern

›Persistent functional loss despite initial management

08Treatment/t58

Initial care and activity modification

›Early phase goals

›Pain reduction

›Maintain gentle mobility

›Prevent re-injury

›Return to function planning

›Relative rest and support

›Activity modification avoiding painful loading

›Compression wrap if swelling

›Elevation for edema reduction

›Short term crutches or brace if gait compromised

›Thermal therapy

›Ice for 10-20 minutes up to every 2-3 hours in first 24-48 hours

›Heat after acute phase for stiffness when swelling controlled

Analgesics and anti-inflammatory options

›Acetaminophen

›Adult dosing

›500-1000 mg PO every 6-8 hours as needed

›Maximum 3000 mg per 24 hours typical outpatient limit

›Hepatic risk precautions

›Lower maximum with chronic alcohol use or liver disease

›Ibuprofen

›Adult dosing

›400 mg PO every 6-8 hours as needed

›Maximum 1200 mg per 24 hours OTC

›Risk precautions

›Avoid or use caution with CKD, peptic ulcer disease, anticoagulation, pregnancy third trimester

›Naproxen

09Special Populations/sp22

Pregnancy

›Medication safety

›Acetaminophen preferred first line

›NSAID avoidance in third trimester

›Topical NSAID risk benefit discussion and limited area use

›Diagnostic considerations

›Lower threshold for DVT evaluation with unilateral swelling

›Pelvic pain mimics including obstetric causes

Geriatric

›Higher risk features

›Occult fracture mimic after low energy falls

›Anticoagulant associated hematoma risk

›Higher fall risk with sedating medications

›Medication cautions

›NSAID GI and renal risk

›Avoid muscle relaxants due to delirium and falls

Pediatrics

›Evaluation nuances

›Apophyseal avulsion injuries mimicking strain in adolescents

›Growth plate injury mimic near joints

›Nonaccidental trauma consideration when history inconsistent

›Dosing safety

›Weight based acetaminophen dosing per local pediatric standards

›Weight based ibuprofen dosing per local pediatric standards

›Avoid aspirin due to Reye syndrome risk

10Background/b18

Epidemiology

›Frequency patterns

›Common in sports with sprinting and jumping

›Hamstring, quadriceps, calf common locations

›Recurrence common with premature return to play

Pathophysiology

›Injury biology

›Fiber microtears at musculotendinous junction common

›Eccentric overload major mechanism

›Inflammatory phase followed by repair and remodeling

›Scar tissue and altered mechanics contribute to recurrence

Therapeutic Considerations

›Why relative rest

›Complete immobilization increases stiffness and delays recovery

›Early gentle motion supports alignment of healing fibers

›Why progressive loading

›Strength and tendon muscle unit capacity restoration reduces recurrence

›Eccentric strengthening improves tolerance to high load lengthening

›NSAID considerations

›Short course for analgesia balanced against bleeding and renal risks

›Prolonged high dose use may theoretically affect healing in some contexts

11Patient Discharge Instructions/pdi25

copy discharge instructions

›Diagnosis explanation

›Muscle strain meaning partial muscle fiber injury from overload

›Expected course mild strains often improve over days and recover over 1-3 weeks

›Home care

›Relative rest with gradual return to normal activity

›Ice 10-20 minutes up to every 2-3 hours for first 24-48 hours

›Compression wrap if swelling

›Elevation when resting

›Gentle range of motion as tolerated

›Medications

›Acetaminophen as directed on label or by clinician

›NSAID only if safe and not contraindicated

›Avoid mixing multiple NSAIDs

›Return precautions

›Increasing pain not relieved by medication

›New numbness or weakness

›Pale or cold limb or weak pulses

›Rapidly increasing swelling or tightness

›Severe pain with passive stretch

›Fever or feeling unwell

›Dark urine or markedly reduced urination

›Follow-up plan

›Recheck if not improving within 5-7 days

›Earlier follow-up for inability to bear weight or use limb normally

›Physical therapy referral if recurrent or prolonged symptoms

12References/r7

Clinical guidelines and consensus

›Emergency medicine and sports medicine guidance

›ACEP clinical policy general approach to acute musculoskeletal pain and imaging selection Level C

›Sports medicine consensus on muscle strain rehabilitation and return to play criteria

Evidence based sources

›Key reviews and resources

›Systematic reviews on hamstring strain rehabilitation and eccentric strengthening

›Reviews on ultrasound and MRI utility for grading muscle tears and prognostication

›Exertional rhabdomyolysis evaluation and management reviews for red flag presentations

Evidence & Review

Evidence & Review