Chapter 20 – Lower Extremity Trauma




Abstract




Usually results from high-energy mechanisms (i.e. high speed MVC), but low-energy mechanisms (falls) are possible in elderly patients as well.1





Chapter 20 Lower Extremity Trauma


Ryan LaFollette and Jeffery Hill



Femur



Mechanism of Injury


Usually results from high-energy mechanisms (i.e. high speed MVC), but low-energy mechanisms (falls) are possible in elderly patients as well.1



Physical Examination




  • Obvious external deformity of the thigh is common with femur fractures.1, 2



  • Palpate the compartments of the thigh to assess the degree of hematoma formation and screen for possible compartment syndrome (Figure 20.1).



  • Neurovascular exam:




    • Popliteal, dorsalis pedis, and posterior tibial pulses distal to the site of fracture pre- and post-reduction, splinting, or application of traction.



    • Calculate Ankle Brachial Indices (ABIs) if diminished pulses are found on initial examination.



    • Assess for sensory and motor deficits in sciatic and peroneal nerve distributions pre- and post-reduction and traction/splinting.2






Figure 20.1 Compartments of the thigh


(adapted from the 1921 German edition of Anatomie des Menschen by Hermann Braus)


Femoral Shaft Fractures




  • Anatomic considerations: The femoral shaft extends from 5 cm distal from the lesser trochanter to 6 cm proximal to the adductor tubercle.




    • Three soft tissue compartments (see Figure 20.1): anterior, medial, posterior




  • Types of fractures:




    • Spiral, transverse, or oblique fractures



    • Comminuted



    • Open




  • Imaging: AP and lateral plain x-rays of the femur, as well as imaging of the ipsilateral hip and knee.



  • Associated injuries/complications:




    • Ipsilateral femoral neck fracture: 1–9% incidence with 20–50% missed on initial evaluation.1, 3



    • Bleeding – closed fractures can result in significant bleeding (1–1.5 L) into the soft tissue compartments of the thigh. However, this bleeding is usually not sufficient in and of itself to result in hypotension.1, 2



    • Thigh Compartment Syndrome is relatively uncommon due to the large size of the compartment.2 Suspect this condition when physical examination reveals a tense compartment with palpation, pain out of proportion to exam, and associated neurovascular compromise.



    • Anterior compartment is most commonly affected.



    • Urgent consultation with an orthopedic surgeon is needed as definitive management is surgical with fasciotomy.2




  • Neurovascular:




    • Sciatic nerve injuries are uncommon in blunt mechanisms of injury. Higher incidence of injuries noted with penetrating trauma.2



    • Peroneal nerve injuries are uncommon as a result of the fracture itself but can result from traction/splinting.




  • Management:




    • Non-operative management is by placement of a long leg cast. Preferred when multiple medical comorbidities preclude operative management.1



    • Surgical management within 24 hours is preferred with intramedullary (IM) nailing vs. open reduction and internal fixation (ORIF) with plate fixation.1




Distal Femur Fractures




  • Represent <1% of all fractures and 3–6% of all femur fractures (though frequency increases with periprosthetic fractures).1




    • Bimodal distribution with increased incidence in young, healthy males (usually as a result of high-energy mechanism of injury) and elderly osteopenic females (usually as a result of low-energy mechanism of injury).4




  • AO/Orthopedic Trauma Association Classification:1




    • Type A – Extra-articular (supracondylar)



    • Type B – Partial articular with extension into the medial or lateral condyle (partial condylar)



    • Type C – Intra-articular with extension into the intercondylar region (intercondylar)




  • Imaging: AP and lateral x-ray are adequate for visualization, though CT may be needed to evaluate for intra-articular extension and can help with operative planning.




    • Consider angiography if diminished distal pulses on exam.




  • Associated injuries:




    • Ligamentous injuries to the knee in 20% of patients.2



    • Vascular injury – thrombosis, pseudoaneurysm, and dissection of femoral artery/popliteal artery.



    • Nerve injury – overall uncommon, but peroneal nerve injury is possible.




  • Management:




    • Operative therapy is common, but non-operative management is considered for non-displaced fractures, non-ambulatory patients, non-reconstructable injuries, or patients with comorbidities precluding operative management.5



    • Non-operative management includes a hinged knee brace with immediate range of motion and non-weight bearing for 6 weeks.4




Traction vs Splinting


Stabilization of midshaft femur fractures through traction or splinting may improve analgesia.6 It may also improve bony/soft tissue alignment and could benefit resuscitation if there is a large femoral compartment bleed as a result of the fracture (Table 20.1).2, 7




Table 20.1 Types of traction


































Traction Splints Cutaneous Traction Skeletal Traction
Description/ Example KTD Splint/Hare Traction Foam padded boot with weighted distraction Temporary traction pin placed into distal femur/proximal tibia with weighted distraction9
Complications Peroneal nerve injury, skin breakdown, pain8 Skin breakdown Skin infection, osteomyelitis, septic arthritis (0.7% w/proper technique), fracture, regional neuromuscular injury, ligamentous injury6, 10
Indications Pre-hospital temporary stabilization of isolated midshaft femur fractures In-hospital stabilization of midshaft or distal femur fractures In-hospital stabilization of diaphyseal femur fractures
Contraindications Ipsilateral hip dislocation, multiple ipsilateral leg fractures Ligamentous knee injury, multiple ipsilateral leg fractures6 Existing fractures at pin placement sites


Pediatric Femur Fractures




  • Thorough history and physical examination are mandated to evaluate for the potential for non-accidental trauma as a cause of the fracture.



  • There is typically no difference in the type of fracture observed in non-accidental trauma vs. accidental trauma.11



  • Non-accidental trauma is more likely in patients 0–18 months of age.11, 12



  • If the child is old enough to run, they are old enough to fall and sustain a femur fracture (a fall with twisting rotational force can lead to spiral midshaft femur fracture).11



Knee


Physical Examination: Evaluate for fracture/deformity of the distal femur, patella, and proximal tibia, dislocation, or subluxation of the knee joint, as well as significant ligamentous injury.




  • Inspect for deformity, wounds, skin changes, or any other abnormality.



  • Careful evaluation for joint effusion as lipohemarthrosis is the most sensitive indicator of knee fracture.13



  • Neurovascular examination distal to the site of the injury – evaluate dorsalis pedis and posterior tibial pulses with ABIs if diminished pulses are present.



  • Active range of motion (normal is 10° of extension with 130° of flexion).13



  • Palpation along medial and lateral joint lines, varus and valgus testing, assessment of patellar tendon/quadriceps tendon function.



Tibial Plateau Fractures


Anatomic Considerations: The tibial plateau is comprised of the medial and lateral condyle of the proximal articular surface of the tibia. The plateau slopes 10° from anterior to posterior.14





Table 20.2 Schatzker classification of tibial plateau fractures












































Schatzker Classification Morphologic Description Condyle Involved Mechanism of Injury Energy
I Lateral Split Fracture Lateral Condyle Lower
II Lateral Split Fracture with Medial Depression (Split-Depression Fracture) Lateral Condyle Lower
III Lateral Depression Fracture Lateral Condyle Lower
IV Medial Condyle Fracture Medial Condyle High
V Bicondylar Medial and Lateral Condyle High
VI IV or V Fracture with Disruption of Metaphysis and Diaphysis Either High




Figure 20.2 Non-displaced bicondylar tibial plateau fracture (Schatzker Class V)


(image: Jeffery Hill, MD Med)


Mechanism of Injury




  • Axial and rotational forces (falls from height).



  • Direct blows to the proximal tibia (pedestrian struck):




    • Forceful abduction causing lateral tibial plateau fractures.



    • Forceful adduction causing medial tibial plateau fractures.




Segond Fracture




  • Avulsion fracture of the lateral tibial plateau that is frequently associated with ACL disruption.13, 15



  • Mechanism of injury: Flexion of the knee with excessive internal rotation and varus stress.



Reverse Segond Fracture




  • Elliptical avulsion fracture of the medial proximal tibia associated with tears of medial meniscus and PCL.16



  • Uncommon (0.64% of fractures seen in acute knee trauma presentations).15 Usually found in association with other fractures in the bones of the knee.



Imaging Considerations




  • Lateral tibial plateau fractures are commonly missed in the Emergency Department.17



  • AP and lateral x-rays are the initial imaging of choice (79% sensitive for the detection of lateral tibial plateau fractures).16




    • Oblique views increase sensitivity to 85%.16



    • Plateau view: AP view with a 10° tilt to account for anterior to posterior slope of the tibial plateau.17



    • Layering of lipohemarthrosis on lateral x-ray is highly suggestive of fracture.13, 17




  • CT can identify fractures not seen on x-ray and assists in operative planning of severely comminuted fractures.2, 14



Complications and Associated Injuries




  • Tibial plateau fractures are often associated with ligamentous injuries and joint instability.2



  • Peroneal nerve injuries are possible.



  • Popliteal artery injuries – typically from the high energy mechanism of injury, usually associated with Schatzker type IV fractures.2, 17



  • Compartment syndrome is an uncommon complication from isolated tibial plateau fracture.2



Management




  • Initial stabilization of fracture site with knee immobilizer and non-weight bearing status until evaluated by orthopedist.



  • Non-operative management: Hinged knee brace and partial weight bearing.17




    • Considered for patients with minimally displaced fractures, nonambulatory patients, or low energy mechanism of injury with stable varus/valgus alignment.




  • Operative management for displaced fractures or joint instability.



Tibial Spine Fracture




  • Uncommon fractures of the intercondylar eminence that are more commonly seen in adolescents (8–14 years) and is roughly the equivalent of an ACL tear in an adult.2, 14



  • Examination: May have a block to full knee extension due to fracture fragment or tense hemarthrosis.14



  • Imaging: Standard AP and lateral views are typically sufficient, but may need plateau or tunnel view to fully identify fractures.14, 18



  • Management:




    • Reduction: Extend knee to within 20° of full extension and observe for fracture reduction.18



    • Aspiration of hemarthrosis can improve reduction and decrease patient pain.18



    • Immobilization in 0–20° of flexion with knee immobilizer.




Knee Dislocation


Classification (Kennedy Classification) based on direction of tibia in relation to the femur – Anterior (most common), Posterior, Lateral, Medial, Rotatory (rare).2



Mechanism of Injury




  • High-energy: MVC with dashboard causing axial load on flexed knee (2/3 of cases), falls from height.2



  • Low-energy: Rotational component, patients with morbid obesity are at increased risk.



Examination




  • May see obvious deformity, severe ecchymosis, and swelling, but should consider any grossly unstable knee following a trauma to be a dislocation until proven otherwise.2




    • 50% of injuries spontaneously reduce prior to presentation.




  • Distal vascular exam is crucial, but may be insufficient for detecting arterial injuries.




    • Sensitivity of pulse exam for popliteal injury is 80%.19




Associated Injuries (Figure 20.3)




  • Popliteal artery injuries (dissection, thrombosis):




    • Popliteal artery injuries are common (up to 50% incidence) with anterior/posterior dislocations.20



    • Have a high index of suspicion and a low threshold for ordering CT angiography.



    • 86% of patients with a delay in repair >8 hours undergo amputation.2




  • Nerve injuries: Tibial and common peroneal nerve injuries in 16–40% of cases.2



  • Severe ligamentous and soft tissue disruption are likely with any knee dislocation.





Figure 20.3 Obese patient with low mechanism of injury and diminished lower extremity pulses on exam. AP and Lateral Knee films with tibial spine and proximal fibula fracture. CTA of lower extremity with complete occlusion of popliteal artery


(images courtesy of Peter Toth, MD)


Imaging




  • AP and lateral x-rays may be normal in appearance if dislocation reduced prior to presentation.



  • CT angiography:




    • Should be performed for all patients with signs of ischemia prior to reduction, even if pulse returns to normal after reduction.2, 21



    • Consider for all patients with suspected dislocation, even if pulse examination is normal.2




  • Intraoperative angiography: For patients with persistent signs of ischemia after reduction.2, 21



Initial Management




  • Reduction by exerting longitudinal traction on the lower leg and directing the tibia anteriorly or posteriorly (depending on the initial direction of the dislocation).2



  • Post-reduction, splint with a long leg posterior splint in 15–20° of flexion.2, 20



Definitive Management


Surgical repair emergently for irreducible dislocations, open fracture/dislocations, or persistent vascular compromise.14, 20



Patella Dislocations




  • Lateral dislocation is most common (Figure 20.4).



  • Mechanism of injury: Direct blow (less common) or twisting motion of lower extremity with foot planted and knee flexed.2, 22



  • Imaging:




    • Diagnosis is typically apparent based on clinical examination alone if patella is still displaced.



    • Post-reduction x-ray is recommended to identify associated fractures.




  • Initial management:




    • Lateral dislocations reduced by flexing the ipsilateral hip while extending the knee and pushing the dislocated patella medially.2



    • Horizontal or intra-articular dislocations require operative reduction.2



    • Post-reduction, place patient in a knee immobilizer with full weight bearing and follow up with orthopedic surgery.2






Figure 20.4 Patella dislocation


(image courtesy of Hellerhoff, reproduced here under CC BY-SA 3.0 license creativecommons.org/licenses/by-sa/3.0)


Patella Fractures


Mechanism of injury is most commonly from a direct blow to the patella. It can also be indirect from contraction of the quadriceps.2, 23



Examination – Superior Displacement of the Patella (“High Riding”)


Test extensor function of the quadriceps to ensure it is intact.



Imaging – AP, Lateral, and “Sunrise” Views (Figure 20.5)


Displacement seen best on lateral view and correlates with disruption of extensor function.23





Figure 20.5 Horizontal patella fracture


(image courtesy of Hellerhoff, reproduced here under CC BY-SA 3.0 license creativecommons.org/licenses/by-sa/3.0)


Initial Management




  • Consider aspiration of tense hemarthrosis.



  • Splint in full extension with knee immobilizer or posterior long leg splint.2 Weight bear as tolerated in full extension.2



Definitive Management


Nonoperative management for those patients with intact extensor function, intact articular surface, and <2 mm of displacement.2, 23



Evaluation for an Open Knee Joint


Any disruption of the skin surface near the knee joint should raise suspicion for the possibility of an open knee joint. These can occur as a result of simple lacerations, open fractures, or projectiles.




  • Patients with open joints should receive antibiotics and undergo urgent irrigation and debridement to decrease the possibility of septic arthritis.24, 25



Saline Load Test




  • Injection of sterile saline into the knee joint (either superomedial or inferomedial approach) until saline comes through the open wound or unable to continue to inject due to high pressure.24



  • The mean volume needed to detect an open knee joint is 64 mL in the inferomedial approach and 95 mL in the superomedial approach, but up to 175 mL of saline may be needed in order to detect 99% of open knee joints.



  • With advent of CT, saline load test is not as commonly used.



CT




  • Intraarticular air on CT is diagnostic of open knee joint. CT has a higher sensitivity and specificity than the saline load test and is recommended as the diagnostic modality of choice for open joints.25



  • One study found that patients with an absence of intra-articular air and no other signs of open joint did not experience septic arthritis.25



Proximal Third Tibial Fractures


Subcondylar tibial fractures are typically transversely or obliquely oriented and most importantly can extend intra-articularly and can be associated with tibial plateau fractures.2



Initial Management




  • Long leg posterior splint and orthopedic consultation.



  • Non-operative management for patients with non-displaced and non-angulated transverse fractures.2, 26



Tibial Shaft Fractures


Tibial shaft fractures are the most common leg fracture, and they can be associated with vascular injury, although this is rare.2



Anatomy




  • The interosseous membrane is a fibrous structure connecting most of the tibia and fibula, stabilizing their relative positions. Either the fibula or tibia may be fractured independently; however, the most common injury pattern is a both bone spiral fracture.27



  • Concurrent fractures of the distal tibia or deltoid ligament in combination with a proximal fibula fracture is concerning for interosseous membrane injury (Maisonneuve fracture) which requires surgical repair to stabilize the ankle mortise.28



Imaging


AP x-rays are adequate for diagnosis of mid-shaft injuries.



Vascular Injuries – Compartment Syndrome




  • Risk of compartment syndrome is 4.3% after closed tibia fractures (highest risk fracture).




    • This occurs most commonly in the anterior compartment, with deep peroneal nerve compression and neuropraxia.




  • If the compartment pressure is greater than the venous pressure, there is a risk of neurovascular compromise and high morbidity.



  • Compartment pressures >30 mmHg or delta pressure (calculated by subtracting the compartment pressure from the diastolic blood pressure) <30 mm Hg is suggestive of compartment syndrome.29, 30



  • In an awake patient, increasing pain is concerning. If comatose, use clinical suspicion with compartment pressure assessment and specialist consultation.



  • Open fractures are still at risk for compartment syndrome.



  • Patients at risk for compartment syndrome include younger patients, and missed compartment syndrome occurs more often in comatose and intoxicated patients.31



  • Penetration injury: ABI >0.9 and absence of soft or hard signs of vascular injury can reliably exclude vascular injury.32



  • Indications for admission include open fractures, concerns for compartment syndrome, or neurovascular compromise. Immobilization in a long posterior splint is warranted.



Proximal Fibula Fractures




  • Rarely isolated fracture; consider concomitant ankle fracture or knee ligamentous injury.



  • Management depends on other injuries, and isolated proximal fibula fractures rarely need operative repair.



  • Patients are usually appropriate for early mobilization.2



Ankle


The articular surface (mortise) consists of the medial malleolus (tibia), lateral malleolus (fibula), and posterior malleolus (tibia), making the trimalleolar structure which articulates inferiorly with the talus.




  • Most common injury is an inversion injury with progressive ligamentous to bony injury.



  • Treatment based on radiographic and clinical stability and amount of dislocation (Table 20.3).



  • Bimalleolar fractures (medial + lateral) typically require operative therapy and non-weight bearing status.



  • Axial load intra-articular fractures (pilon/plafond) require orthopedic evaluation and surgical intervention. Highly variable fracture patterns may require ORIF or ex-fix depending on soft tissue swelling and extent of displacement.



  • Non-displaced medial malleolar fracture




    • Management includes weight bearing as tolerated if the joint is stable. If the joint is unstable or significant pain is present, place in a splint and discuss need for non-weight bearing to prevent further articular damage.




  • Displaced fractures




    • If widened or unstable, reduce, place in short leg splint, and consult orthopedics.




Jan 10, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 20 – Lower Extremity Trauma
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