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Knee ligament injuries
Shoulder & Clavicle
AC separation
Biceps tendon rupture
Clavicle fracture
Humerus proximal fracture
Rotator cuff tear
Scapular fractures
Shoulder dislocations
SLAP tear
Sternoclavicular dislocation
Arm & Elbow
Compartment syndrome (anterior, lateral, deep - superficial posterior)
Coronoid process fracture
Elbow dislocations
Epicondylar fracture
Humeral shaft fracture
Intercondylar and condylar region fracture
Olecranon fracture
Radial head fracture (Mason I-IV)
Supracondylar fracture (pediatric and adult)
Triceps tendon rupture
Forearm, Wrist & Hand
Carpal bones fractures
Carpal dislocations and ligament injuries
Distal radius and ulna fracture
Fight bite (human bite over MCP)
Finger dislocations by joint
Finger open fractures - amputations
Forearm fractures
Hand and finger tendon and ligament injuries
Hand tendon injuries
Metacarpal fractures
Nail bed injuries
Phalangeal fractures
Tuft fracture
Spine
Cervical spine fracture (C1-C7)
Cord syndromes
Sacrum and coccyx fracture
Thoracic and lumbar spine fracture
Pelvis & Hip
Acetabular fractures
Hip dislocations
Pelvis fractures
Proximal femur fractures
Thigh & Knee
Distal femur fractures
Femoral shaft fractures
Knee dislocation
Knee ligament injuries
Patellar dislocation
Patellar fracture
Patellar tendon rupture
Pes anserine bursitis
Prepatellar bursitis
Quadriceps tendon rupture
Tibial plateau fracture
Tibial spine fracture
Tibial tubercle fracture
Leg & Shin
Achilles tendon rupture
Fibular shaft fracture
Proximal fibula fracture
Stress fracture (tibia-fibula)
Tibial and Fibular shaft fracture
Tibial shaft fracture
Toddler's fracture
Ankle
Ankle dislocation
Ankle fractures
Ankle sprain
Maisonneuve fracture (proximal fibula and syndesmosis)
Peroneal tendon dislocation or tear
Peroneal tendon tear or dislocation
Subtalar dislocation
Syndesmotic injury (high ankle sprain)
Foot
Calcaneus fracture
Cuboid fracture
Cuneiform fractures
Dancer's fracture (5th MT spiral shaft)
Jones fracture (5th MT base - metadiaphyseal junction)
Lisfranc injury (tarsometatarsal dislocation)
March fracture (metatarsal stress fracture)
Metatarsal fractures (1st-5th)
Navicular fracture
Plantar fascia rupture
Talus fracture
Tibialis posterior tendon dysfunction
Toe dislocations
Knee ligament injuries
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Clinical Assessment Checklist
Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Immediate threats
Limb-threatening and life-threatening priorities
▶
Suspected knee dislocation or multiligament injury
▶
Vascular injury risk
▶
Popliteal artery injury risk despite palpable pulses
Peroneal nerve injury risk
▶
Foot drop risk
Open injury
▶
Contamination and antibiotic timing pathway
Compartment syndrome
▶
Escalate for pain out of proportion or escalating analgesic needs
Septic arthritis mimic
▶
Fever or toxic appearance triggers urgent joint infection pathway
Neurovascular first-pass
Neurovascular status baseline
▶
Pulses
▶
Dorsalis pedis
Posterior tibial
Perfusion
▶
Capillary refill
Skin temperature
Skin color
Motor
▶
Ankle dorsiflexion
Great toe extension
Ankle plantarflexion
Sensory
▶
Dorsal first web space
Plantar foot
Lateral foot
If hard signs of vascular injury, immediate vascular and ortho escalation
▶
Expanding hematoma
Active bleeding
Pulseless limb
Limb ischemia
Hemodynamic and pain trajectory
Stability and analgesia readiness
▶
Persistent hypotension triggers alternate diagnosis search
▶
Polytrauma
Hemorrhage elsewhere
Severe pain with swelling and tense effusion
▶
Hemarthrosis possibility
Fracture or osteochondral injury possibility
Key concepts
Time-critical risk patterns
▶
Knee dislocation equals vascular injury risk until proven otherwise
Multiligament injury equals unstable knee and high associated injury risk
Locked knee suggests displaced meniscal tear and urgent specialist pathway
History
Mechanism and trajectory
Injury mechanism mapping
▶
Noncontact pivot or deceleration
▶
ACL tear pattern
Dashboard injury or hyperflexion
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PCL tear pattern
Valgus with external rotation
▶
MCL injury pattern
Varus stress
▶
LCL or PLC injury pattern
Hyperextension or high-energy trauma
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Multiligament injury pattern
Knee dislocation pattern
Time course
▶
Immediate swelling within 2 hours
▶
Hemarthrosis pattern
ACL tear or intra-articular fracture pattern
Delayed swelling
▶
Meniscal tear pattern
Functional impact
▶
Ability to bear weight
Instability or giving way episodes
Locking or inability to fully extend
Audible or felt events
▶
Pop sensation
Prior knee history
▶
Previous ligament reconstruction
Prior instability episodes
Prior meniscal surgery
Bleeding and clotting context
▶
Anticoagulants or antiplatelets
Bleeding disorders
Associated injuries and symptoms
▶
Numbness or foot drop symptoms
Cold foot symptoms
Calf pain or swelling symptoms
Hip or ankle pain symptoms
Red flags
Red-flag clusters
▶
Gross deformity at injury or spontaneous reduction history
▶
Knee dislocation concern
Severe pain with progressive swelling
▶
Compartment syndrome concern
Fever or systemic symptoms
▶
Septic arthritis concern
Open wound near joint
▶
Traumatic arthrotomy concern
Physical Exam
Inspection and palpation
General knee survey
▶
Effusion
▶
Tense hemarthrosis appearance
Ecchymosis
Deformity
Abrasions or lacerations
▶
Open joint risk
Patellar position abnormality
▶
Patellar dislocation history
Palpation map
▶
Medial joint line tenderness
Lateral joint line tenderness
MCL tenderness
LCL tenderness
Fibular head tenderness
Tibial plateau tenderness
Patellar tendon tenderness
Quadriceps tendon tenderness
Range of motion and extensor mechanism
Function and motion
▶
Active extension
▶
Extensor mechanism integrity screen
Passive extension block
▶
Locked knee screen
Flexion limitation pattern
Effusion special signs
▶
Ballottement
Ligament stability tests
ACL tests
▶
Lachman
▶
High sensitivity for ACL tear in acute setting
Anterior drawer
▶
Lower sensitivity in acute swelling and guarding
Pivot shift
▶
Often limited acutely by pain and guarding
PCL tests
▶
Posterior drawer
Posterior sag sign
Quadriceps active test
MCL tests
▶
Valgus stress test at 30 degrees
▶
Isolated MCL laxity pattern
Valgus stress test in full extension
▶
Combined injury concern
LCL tests
▶
Varus stress test at 30 degrees
Varus stress test in full extension
PLC and rotational tests
▶
Dial test
Posterolateral drawer
External rotation recurvatum test
Neurovascular re-check
Distal neurovascular findings
▶
Pulses and perfusion
Common peroneal nerve motor and sensory
Tibial nerve sensory and plantarflexion
If ABI < 0.9, urgent vascular imaging pathway :contentReference[oaicite:0]{index=0}
PITFALLS
Common pitfalls
▶
Normal pulses do not exclude popliteal artery injury after knee dislocation
Guarding reduces exam accuracy in acute setting
Concomitant fracture or osteochondral injury with ligament tears
Differential Diagnosis
Primary ligament patterns
ACL tear
▶
ICD-10 S83.51- anterior cruciate ligament sprain or tear
Noncontact pivot with immediate swelling
PCL tear
▶
ICD-10 S83.52- posterior cruciate ligament sprain or tear
Dashboard mechanism
MCL tear
▶
ICD-10 S83.41- medial collateral ligament sprain or tear
Valgus injury
LCL tear
▶
ICD-10 S83.42- lateral collateral ligament sprain or tear
Varus injury
Posterolateral corner injury
▶
Rotational instability pattern
High association with PCL injury
Important co-injuries and mimics
Knee dislocation with spontaneous reduction
▶
ICD-10 S83.1- dislocation of knee
Vascular injury risk
Tibial plateau fracture
▶
Occult fracture risk with normal X-ray
Patellar dislocation with MPFL injury
▶
ICD-10 S83.0- dislocation of patella
Meniscal tear
▶
ICD-10 S83.24- tear of medial meniscus
ICD-10 S83.25- tear of lateral meniscus
Locking or extension block pattern
Extensor mechanism rupture
▶
Quadriceps tendon rupture
Patellar tendon rupture
Septic arthritis
▶
Fever and severe pain with limited ROM
DVT
▶
Calf swelling and tenderness
Hip pathology referral pain
▶
Limited hip ROM or groin pain
Laboratory Tests
Minimal labs for uncomplicated soft tissue injury
Routine labs
▶
Typically not required in isolated stable ligament injury
Labs when specific triggers present
Infection concern
▶
CBC with differential
▶
Leukocytosis supports but does not confirm septic arthritis
CRP
▶
Elevated supports inflammatory or infectious process
ESR
Hemarthrosis aspiration planned
▶
INR
▶
Anticoagulated patient safety check
Platelets
Polytrauma or operative pathway
▶
Type and screen
BMP
▶
Baseline renal function for contrast imaging considerations
Arthrocentesis studies when septic arthritis concern
Synovial fluid studies
▶
Cell count with differential
▶
High WBC supports septic arthritis
Gram stain
Culture
Crystals
Glucose and protein as adjuncts
Diagnostic Tests
Scoring Systems
Clinical decision rules and grading
▶
Ottawa Knee Rule for radiographs after acute trauma :contentReference[oaicite:1]{index=1}
▶
Age 55 years or older
Isolated patellar tenderness
Tenderness at fibular head
Inability to flex to 90 degrees
Inability to bear weight 4 steps immediately and in ED
Meta-analysis pooled sensitivity about 98% for fracture :contentReference[oaicite:2]{index=2}
MCL and LCL grading concept
▶
Grade I
▶
Pain with firm endpoint
Grade II
▶
Laxity with endpoint
Grade III
▶
Laxity without endpoint
Multiligament injury suspicion flags
▶
Laxity in multiple planes
Instability in full extension
Neurovascular symptoms
Radiographs
Plain films in acute knee trauma
▶
Knee series
▶
AP
Lateral
Sunrise or merchant view when patellar injury suspected
Indications anchored to decision rules
▶
Ottawa Knee Rule positive :contentReference[oaicite:3]{index=3}
Key radiographic clues
▶
Tibial plateau fracture signs
Segond fracture
▶
ACL-associated avulsion clue
Fibular head avulsion
▶
PLC injury clue
MRI
MRI for internal derangement
▶
Indications
▶
Suspected ligament tear with significant instability
Suspected meniscal tear with locking
Persistent pain or swelling with negative radiographs
Diagnostic utility
▶
Best test for suspected meniscus or ligament tear after negative radiographs :contentReference[oaicite:4]{index=4}
Timing considerations
▶
Early MRI may better visualize certain associated soft tissue injuries after acute trauma :contentReference[oaicite:5]{index=5}
Contraindications
▶
Non-MRI compatible implants
Unstable patient requiring immediate stabilization pathway
CT
CT knee applications
▶
Occult fracture concern
▶
Tibial plateau fracture suspicion with normal X-ray
Surgical planning for intra-articular fracture
CT angiography in vascular injury concern
▶
If ABI < 0.9 or abnormal pulses after suspected dislocation, vascular imaging pathway :contentReference[oaicite:6]{index=6}
Disposition
Discharge versus admission or urgent referral
Copy
Discharge criteria
▶
Stable vitals
No neurovascular deficit
No concern for knee dislocation or multiligament instability
Pain controlled with oral meds
Safe ambulation plan with brace and crutches
Reliable follow-up within appropriate window
Urgent orthopedics or sports medicine referral
▶
Suspected ACL tear with instability
Suspected PCL tear with significant posterior laxity
Grade III MCL or LCL injury
Suspected PLC injury
Locked knee
Immediate ED escalation or admission
▶
Suspected knee dislocation
Neurovascular deficit
ABI abnormal
Compartment syndrome concern
Open joint or traumatic arthrotomy concern
Septic arthritis concern
Follow-up timing suggestions
▶
Locked knee or large unstable tear suspicion
▶
Within 24 to 72 hours
Suspected ACL or PCL tear without vascular concern
▶
Within 1 to 2 weeks
Grade I to II collateral ligament sprain
▶
1 to 2 weeks with rehab plan
Treatment
Immediate life-saving interventions
Immediate stabilization triggers
▶
If suspected knee dislocation, immediate reduction if deformity present and limb threatened
▶
Post-reduction neurovascular reassessment
Post-reduction immobilization in long leg splint
Vascular evaluation pathway regardless of symptom improvement
If pulseless or ischemic limb, immediate vascular and ortho escalation
If open joint suspected, antibiotics and urgent ortho pathway
Immobilization and Splinting
Brace and immobilization strategy
▶
Knee immobilizer for gross instability
▶
Short-term use
▶
Transition to hinged brace when safe
Hinged knee brace for collateral ligament injuries
▶
Valgus or varus protection
Crutches and weight-bearing plan
▶
Weight-bearing as tolerated for stable sprains
Partial or non-weight-bearing for significant instability or fracture concern
Immobilization principles
▶
Avoid prolonged total immobilization when not required
▶
Early rehab emphasis in soft tissue knee injuries :contentReference[oaicite:7]{index=7}
Elevation and compression for swelling
Re-check neurovascular status after bracing
Reduction
Reduction pathways
▶
Knee dislocation reduction principles
▶
Gentle traction and reversal of deforming force
Avoid repeated forceful attempts
Immediate reassessment of pulses and motor
Patellar dislocation reduction principles
▶
Extension with medial pressure
Post-reduction stability and effusion reassessment
Analgesia and anesthesia options
▶
Multimodal pain control ladder
▶
Acetaminophen
▶
1000 mg PO every 6 to 8 hours
Maximum 4000 mg per 24 hours
Ibuprofen
▶
400 to 600 mg PO every 6 to 8 hours
Maximum 2400 mg per 24 hours
Naproxen
▶
250 to 500 mg PO every 12 hours
Opioid for breakthrough pain
▶
Hydromorphone
▶
1 to 2 mg PO every 4 to 6 hours as needed
Avoid with concurrent sedatives when possible
Oxycodone
▶
5 mg PO every 4 to 6 hours as needed
Procedural sedation when reduction required
▶
Airway readiness and monitoring
▶
Continuous pulse oximetry
▶
Capnography when available
▶
Titrated sedative dosing to effect
Open fracture medications and timing
Open injury pathway when suspected
▶
Antibiotics as early as feasible
▶
Cefazolin IV
▶
2 g every 8 hours
3 g every 8 hours if weight 120 kg or more
If severe beta-lactam allergy
▶
Clindamycin IV
▶
900 mg every 8 hours
Tetanus prophylaxis based on immunization status
Sterile dressing and splint
Urgent orthopedics consultation and transfer triggers
DVT prophylaxis when relevant
VTE risk considerations
▶
Lower limb immobilization
Limited mobility
Prior VTE
Malignancy
Pregnancy or postpartum
Prophylaxis alignment with local protocol
▶
If high risk and prolonged immobilization, specialist or institutional pathway
Special Populations
Pregnancy
Pregnancy considerations
▶
Imaging selection
▶
Radiographs with shielding when needed
MRI without gadolinium preferred for soft tissue assessment when appropriate
Analgesia choices
▶
Acetaminophen preferred first-line
NSAID avoidance in later pregnancy based on obstetric guidance
DVT risk higher in pregnancy
▶
Lower threshold for prophylaxis discussion in immobilized patients
Geriatric
Older adult considerations
▶
Higher fracture probability with low-energy trauma
Lower threshold for radiographs and occult fracture evaluation
Anticoagulation associated hemarthrosis risk
Opioid sensitivity and delirium risk
Baseline mobility and falls risk planning
Pediatrics
Pediatric considerations
▶
Physeal injury and tibial spine avulsion mimicking ACL tear
Growth plate protection in exam and splinting
Nonaccidental trauma screening when history inconsistent
Weight-based analgesia
▶
Acetaminophen 15 mg per kg PO every 6 hours
Ibuprofen 10 mg per kg PO every 6 to 8 hours
Background
Epidemiology
Frequency and context
▶
ACL injury common in pivot sports
Meniscal tears commonly co-occur with ACL injuries
Ottawa Knee Rule reduces unnecessary radiography with high sensitivity :contentReference[oaicite:8]{index=8}
Pathophysiology
Mechanism to structure mapping
▶
ACL
▶
Anterior tibial translation restraint
Rotational stability role
PCL
▶
Posterior tibial translation restraint
MCL
▶
Valgus stability restraint
LCL and PLC
▶
Varus and external rotation restraint
Hemarthrosis physiology
▶
Intra-articular bleeding after acute ligament rupture or osteochondral injury
Therapeutic Considerations
Early management principles
▶
Protection and symptom control
▶
PRICER approach for soft tissue knee injuries :contentReference[oaicite:9]{index=9}
Avoid prolonged immobilization when not indicated :contentReference[oaicite:10]{index=10}
Early supervised rehabilitation as cornerstone for many ligament injuries
Definitive management overview
▶
ACL management options and shared decision-making framework in AAOS guideline :contentReference[oaicite:11]{index=11}
MRI role for suspected ligament or meniscus tear after negative radiographs :contentReference[oaicite:12]{index=12}
Patient Discharge Instructions
Copy discharge instructions
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Discharge instructions set
▶
Rest and swelling control
▶
Elevation above heart level when resting
Ice 15 to 20 minutes up to every 2 to 3 hours for first 48 hours
Compression wrap if comfortable and not causing numbness
Brace and crutches plan
▶
Brace on when walking
Crutches until walking without limp or per follow-up plan
Activity and weight-bearing
▶
Weight-bearing as tolerated unless told otherwise
Avoid pivoting and twisting
Pain plan
▶
Acetaminophen and NSAID alternating if safe
Opioid only for breakthrough pain if prescribed
Follow-up
▶
Sports medicine or orthopedics within recommended window
Return to ED now for
▶
New numbness or weakness in foot
Foot becoming cold, pale, or blue
Increasing swelling with severe worsening pain
Inability to move toes
Fever with worsening knee pain and inability to bend or straighten
Redness spreading or drainage from a wound
Chest pain or shortness of breath
References
Clinical guidelines and evidence sources
Source set :contentReference[oaicite:13]{index=13}
▶
AAOS Clinical Practice Guideline
▶
Management of Anterior Cruciate Ligament Injuries
▶
Published 2022 :contentReference[oaicite:14]{index=14}
ACR Appropriateness Criteria
▶
Acute Trauma to the Knee :contentReference[oaicite:15]{index=15}
Ottawa Knee Rule performance summaries
▶
Meta-analysis pooled sensitivity about 98% :contentReference[oaicite:16]{index=16}
MRI role after negative radiographs in suspected internal derangement :contentReference[oaicite:17]{index=17}
NICE CKS knee assessment referral triggers :contentReference[oaicite:18]{index=18}
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.
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Knee ligament injuries