Risk Factors for Emboli in Adolescent Femur Fractures
Adolescents with femur fractures face significant embolic risk from both thromboembolic pulmonary embolism and fat embolism syndrome, with the fracture itself being the primary risk factor, compounded by surgery/trauma, immobilization, infection, central venous lines, and underlying conditions like systemic lupus erythematosus or thrombocytopenia.
Primary Risk Factors
Fracture-Related Factors
Femur fracture location and type: Intertrochanteric (50.3%) and femoral neck fractures (43.9%) are the most common sites associated with PE in femur fracture patients 1. Displaced transverse tibial fractures carry a 33% risk of fat embolism syndrome, while femoral fractures have a 75% incidence of FES 2.
Timing of embolic events: PE occurs remarkably early—57.1% of cases develop within the first 24 hours after injury and 89.3% within 48 hours 1. Fat embolism syndrome typically manifests within 36 hours of hospitalization 3.
Bilateral fractures: Bilateral femoral fractures significantly increase fat embolism risk 3.
Patient and Treatment Factors
Immobilization: Present in 38% of pediatric PE cases, making it the most frequently reported risk factor 4.
Surgery and trauma: Accounts for 22% of pediatric PE cases 4. Surgical intervention itself is a major risk factor, though early surgical stabilization paradoxically reduces FES incidence compared to conservative management 3, 2.
Central venous lines: Present in 23% of pediatric PE cases 4.
Infection: Found in 31% of pediatric PE cases 4.
Adolescent-Specific Risk Factors
Systemic lupus erythematosus: A major risk factor in adolescent PE patients 5.
Thrombocytopenia: Significantly increases PE risk in adolescents 5.
Long-term oral glucocorticoid use: Associated with increased PE risk in adolescent patients 5.
Hormonal contraception/pregnancy: Accounts for 15% of pediatric PE cases 4.
Malignancy: Present in 15% of pediatric PE cases 4.
Clinical Presentation Differences in Adolescents
Fever and chest pain: More common in adolescents compared to adults (P < 0.05) 5. Fever occurs in approximately 7% of PE cases overall 6, but appears more frequent in adolescents.
Dyspnea: Remains the most common symptom at approximately 80% 6.
Pleuritic chest pain: Occurs in 52% of PE cases 6.
Fat Embolism Syndrome Specific Features
Hypoxemia: Mean PO2 of 45 mm Hg at presentation 2.
Fever: Mean temperature of 39°C (102.2°F) 2.
Petechiae: Present in 40% of FES cases 2.
Duration: Less than 4 days in 86% of patients 2.
Critical Diagnostic Pitfalls
Delayed diagnosis: Mean diagnostic time is 7.8 ± 8.4 days in adolescents, with outpatient presentations having significantly longer delays (9.4 ± 7.5 days) compared to emergency department presentations (<1 day) 5.
Misdiagnosis as respiratory tract infection: The most common initial misdiagnosis in adolescent PE patients 5.
Low clinical suspicion: PE is seldom considered in adolescent patients by physicians, particularly in outpatient settings 5. However, 88% of adolescent PE cases score moderate-to-high probability on Wells score and 100% on revised Geneva score 5.
Prevention Strategies
Early surgical stabilization: Reduces FES incidence, with surgical correction providing greater risk reduction than conservative management 3.
Thromboprophylaxis: Low molecular weight heparin or fondaparinux should be employed 4. LMWH has become the main anticoagulant for VTE prevention in children due to convenient administration and predictable pharmacokinetics 4.
Mechanical prophylaxis: Thromboembolism stockings or intermittent compression devices should be used intra-operatively 4.
Maintaining hydration and normothermia: Essential preventive measures 4.
Expedited surgery and early mobilization: Reduces DVT risk 4.
Mortality and Morbidity Context
PE mortality without prophylaxis: 10% in femoral neck fracture patients without prevention 7.
PE mortality with prophylaxis: Reduced to 2-3.8% with appropriate thromboprophylaxis 7.
FES mortality in isolated fractures: 0% in otherwise healthy young patients with isolated femoral or tibial fractures 2. Early PE in femur fracture patients is not fatal when promptly recognized 1.
Incidence: PE occurs in 2.2% of femur fracture patients overall 1, with an incidence of 43.6 per 100,000 hospitalized adolescents 5.