Knee dislocation with vascular injury (ICD-10 S83.1 with vascular injury code as applicable)
Mimics and co-injuries
Mimics and co-injuries
Osgood-Schlatter apophysitis
Chronic anterior tibial tubercle pain
No acute deformity
ACL injury
Hemarthrosis
Pivot injury mechanism
Meniscal tear
Locking or catching
Tibial shaft fracture (ICD-10 S82.2)
Acute compartment syndrome of leg (ICD-10 T79.A2)
Laboratory Tests
Minimal labs for isolated closed injury
Laboratory strategy
No routine labs for isolated closed fracture with stable vitals
Targeted labs for operative pathway or high risk
If open fracture or planned urgent OR
Complete blood count for baseline and bleeding concern
Electrolytes and creatinine for perioperative planning
Coagulation studies if anticoagulants or liver disease
If compartment syndrome concern
Creatine kinase trend support for rhabdomyolysis risk
Creatinine for renal risk
Venous blood gas if systemic illness concern
PITFALLS
Pitfalls
Normal labs do not exclude compartment syndrome
Creatine kinase can be normal early in compartment syndrome
Diagnostic Tests
Scoring Systems
Classification and implications
Ogden classification for tibial tubercle fractures
Type I
Through secondary ossification center
Often less displaced
Often nonoperative if aligned and extensor mechanism intact
Type II
Extends into junction with proximal tibial epiphysis
Higher displacement risk
Often operative if displaced
Type III
Intra-articular extension into tibial plateau
Hemarthrosis common
Typically operative for articular congruity
Type IV
Through proximal tibial physis
Growth plate injury considerations
Often operative and closer pediatric ortho follow-up
Type V
Periosteal sleeve avulsion pattern
Can appear subtle on radiographs
MRI useful if diagnosis unclear
Gustilo-Anderson open fracture
Grade I
Wound <1 cm
Minimal contamination
Grade II
Wound 1 to 10 cm
Moderate soft tissue injury
Grade III
Wound >10 cm or high energy
Extensive contamination or soft tissue loss
Vascular injury possible
Salter-Harris classification when physeal injury present
Growth disturbance risk increases with higher grade
Gentle handling and avoidance of repeated manipulations
Radiographs
X-ray approach
Knee radiographs
AP view
Lateral view
Sunrise or merchant view if patellar injury concern
Long bone principle
Tibia and fibula views including knee and ankle if pain extends distally
Key radiographic features
Displacement of tibial tubercle fragment
Proximal tibial physeal extension
Tibial plateau intra-articular extension
Patella alta indicator for patellar tendon injury
Post-immobilization imaging
Repeat radiographs if alignment changes suspected
MRI
MRI indications
Radiographs negative with high clinical suspicion
Pain over tibial tubercle with extensor weakness
Suspected periosteal sleeve avulsion
Soft tissue assessment
Patellar tendon injury
Meniscus injury
ACL or collateral ligament injury
Contraindications and practical limits
Metallic implants compatibility
Need for sedation in younger children
CT
CT indications
Suspected intra-articular extension
Large effusion or hemarthrosis
Type III pattern on radiographs
Surgical planning support
Fragment comminution mapping
Articular step-off assessment
Radiation considerations
Pediatric dose optimization
Shared decision with orthopedics for borderline cases
Disposition
Ortho urgency and location of care
Disposition framework
Discharge with urgent follow-up
Closed injury
Neurovascularly intact
Pain controlled with oral regimen
Extensor mechanism intact
Minimal displacement and stable immobilization
Admission or observation
Uncontrolled pain
Need for serial compartment checks
Unreliable follow-up or unsafe home setting
Urgent orthopedics in ED
Displaced fracture
Extensor mechanism failure
Intra-articular extension
Open fracture
Neurovascular compromise
Compartment syndrome concern
Transfer criteria
No pediatric orthopedics coverage for likely operative injury
Need for emergent fasciotomy capability
Mobility and restrictions
Non weight-bearing
Crutches or walker fitting
Wheelchair if unable to safely use crutches
Knee immobilized in extension
Avoid knee flexion until specialist plan
Treatment
Immediate life-saving interventions
Immediate priorities
Limb ischemia pathway if present
If pulseless or rapidly worsening perfusion, immediate orthopedics and vascular involvement
If ischemia signs, avoid delays for advanced imaging when transfer or OR is needed
Compartment syndrome pathway if suspected
If concern, remove constrictive wraps
If concern, keep limb at heart level
If concern, urgent orthopedics for compartment pressure consideration and fasciotomy readiness
Open fracture immediate actions
Cover wound with sterile saline-moistened dressing
Antibiotics within 60 minutes when feasible
Tetanus prophylaxis per status
Immobilization and Splinting
Immobilization selection
Knee immobilizer
Full extension
Rapid application for stable patterns
Posterior long leg splint
Full extension
Preferred with marked swelling or instability
Position and principles
Knee extension to relax extensor mechanism tension
Avoid circumferential casting in acute swelling phase
Distal padding over malleoli and heel
Post-application checks
Pain trend
Dorsalis pedis pulse
Posterior tibial pulse
Toe capillary refill
Sensation in foot distributions
Toe and ankle motor function
Reduction
Reduction considerations
Typical management
Closed reduction not routinely performed in ED for tibial tubercle fractures
Definitive management often immobilization and orthopedic fixation decision
If gross displacement with threatened skin and orthopedics directs attempt
Traction and countertraction
Gentle longitudinal traction
Avoid repeated forceful attempts
Post-reduction requirements
Immediate neurovascular re-check
Immediate post-reduction radiographs
Immobilization in extension
Analgesia and anesthesia options
Non-opioid base
Paracetamol 15 mg/kg PO
Ibuprofen 10 mg/kg PO
Opioid titration
Morphine 0.05 mg/kg IV
Repeat every 10 minutes to effect
Regional anesthesia option
Femoral nerve block if trained operator and protocol
Ropivacaine 0.2 percent
Maximum 3 mg/kg total dose
Aspirate before incremental injection
Procedural sedation if required
Ketamine IV 1 mg/kg
Additional 0.5 mg/kg IV every 5 to 10 minutes as needed
Continuous cardiorespiratory monitoring
Airway equipment and suction at bedside
ACEP procedural sedation guidance adherence (ACEP Level B)
Open fracture medications and timing
Antibiotics and tetanus
Antibiotics timing
First dose within 60 minutes when feasible
Continue per orthopedics and operative plan
Antibiotics selection
Gustilo I or II
Cefazolin 2 g IV
Repeat every 8 hours
Gustilo III or heavy contamination
Cefazolin 2 g IV
Repeat every 8 hours
Gentamicin 5 mg/kg IV
Once daily dosing strategy per local protocol
Severe beta-lactam allergy
Clindamycin 600 mg IV
Repeat every 8 hours
Tetanus prophylaxis
Clean minor wound with immunization up to date
No booster if last dose within 10 years
Dirty wound or open fracture
Booster if last dose 5 years or more
Add tetanus immune globulin if unknown or incomplete series
DVT prophylaxis when relevant
Thrombosis risk planning
Pediatric isolated immobilization
Pharmacologic prophylaxis not routine
Consider hematology or ortho guidance if major risk factors
Adult or near adult with prolonged immobilization
Risk assessment
Prior VTE
Active cancer
Known thrombophilia
Estrogen therapy
Marked obesity
If high risk and low bleeding risk, follow local prophylaxis protocol
Special Populations
Pregnancy
Pregnancy considerations
Imaging safety
X-ray acceptable with shielding when possible
CT only if benefits outweigh risks and affects management
Analgesia selection
Paracetamol preferred
NSAID avoidance in later pregnancy per obstetric guidance
Opioid short course if required with counseling
VTE risk
Elevated baseline risk in pregnancy
Early obstetric input for prophylaxis decisions if immobilization prolonged
Geriatric
Older adult considerations
Mechanism differences
Lower energy mechanisms possible with osteopenia
Baseline mobility and fall risk
Physiotherapy needs and assistive device safety
Medication risks
Opioid delirium and constipation risk
NSAID renal and bleeding risk
Admission threshold
Higher likelihood of unsafe discharge if non weight-bearing
Pediatrics
Pediatric priorities
Typical demographic
Adolescent age range
Sports related jumping mechanisms
Physeal considerations
Growth plate involvement risk in higher Ogden types
Avoid repeated manipulations
Compartment syndrome vigilance
Lower threshold for serial exams
Early escalation with increasing pain or agitation
Weight-based dosing
Paracetamol 15 mg/kg PO
Ibuprofen 10 mg/kg PO
Morphine 0.05 mg/kg IV titration
Background
Epidemiology
Epidemiology
Frequency
Reported 0.4 to 2.7 percent of pediatric fractures
Rare overall compared with other knee injuries
Typical population
Adolescent males predominance
High association with jumping and sprint sports
Complication frequency
Acute compartment syndrome reported in a minority of cases
Vascular injury uncommon but limb-threatening when present
Pathophysiology
Mechanism and anatomy
Avulsion at tibial tubercle apophysis from quadriceps contraction via patellar tendon
Vulnerable phase during partial closure of proximal tibial physis in adolescence
Intra-articular extension possible into tibial plateau in higher grade injuries
Vascular risk
Injury to anterior tibial recurrent vessels can contribute to compartment syndrome
Extensor mechanism disruption
Loss of active knee extension with displaced avulsion
Therapeutic Considerations
Management rationale
Immobilization in extension reduces traction on avulsed fragment
Operative fixation indications
Displacement
Extensor mechanism failure
Intra-articular extension
Open fracture
Compartment syndrome
Nonoperative pathway considerations
Stable alignment
Intact extensor mechanism
Reliable follow-up and adherence to non weight-bearing
Compartment syndrome surveillance
Early recognition prevents irreversible muscle and nerve injury
Escalation triggers override normal imaging timelines
Patient Discharge Instructions
Copy discharge instructions
Discharge instructions
Immobilizer and care
Keep knee immobilizer or splint on at all times
Keep splint dry
Do not insert objects inside splint
Activity
Non weight-bearing on injured leg
Crutches or walker use as instructed
Elevation above heart when resting
Swelling control
Ice 15 to 20 minutes at a time
Repeat every 2 to 3 hours while awake for first 48 hours
Pain plan
Paracetamol 1000 mg every 6 hours as needed
Ibuprofen 400 mg every 6 to 8 hours with food as needed
Opioid only if prescribed for breakthrough pain
Return to ED now
Increasing pain not controlled with medication
Numbness or tingling in foot or toes
Foot becoming cold, pale, or blue
Increasing tightness of leg or severe pain with toe movement
New weakness moving toes or ankle
Splint too tight or causing severe pressure pain
Fever or drainage from any wound
Follow-up
Orthopedics within 24 to 72 hours if displaced or extensor weakness
Orthopedics within 5 to 7 days if stable and improving
Return earlier if symptoms worsen
References
Evidence-based sources and guidelines
Reference set
Pediatric Orthopaedic Society of North America resources on tibial tubercle fractures
AAOS general fracture care principles and immobilization guidance
Standard orthopedic trauma texts for Ogden classification and operative indications
ATLS principles for initial trauma assessment and limb threat evaluation
ACEP procedural sedation guidance for ED sedation safety (ACEP Level B)
ACEP acute pain management principles for multimodal analgesia (ACEP Level B)
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