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Difficulty: HardOrthopedic Surgery

Match each patient presentation of a lower extremity orthopedic injury with the most likely associated neurovascular complication and physical exam finding.

  • Shortened, internally rotated, and adducted lower extremity after a motor vehicle dashboard injuryWeakness in both ankle dorsiflexion and plantar flexion, with sensory loss below the knee except along the medial aspect of the leg
  • Shortened, externally rotated, and abducted lower extremity following a forced abduction traumaWeakness in knee extension, diminished patellar reflex, and sensory loss over the anterior thigh and medial leg
  • Grossly unstable knee with multi-ligamentous disruption after a high-energy hyperextension injuryDiminished distal pulses, an ankle-brachial index less than 0.9, and a cool, pale distal extremity
  • Severe pain and localized tenderness over the proximal lateral aspect of the leg following a direct impactWeakness in ankle dorsiflexion and foot eversion, with intact inversion and sensory loss over the anterolateral leg and dorsum of the foot

Answer

The correct matches align each specific lower extremity mechanism of injury with its characteristic anatomical presentation and subsequent neurovascular compromise: posterior hip dislocation with sciatic neuropathy, anterior hip dislocation with femoral neuropathy, tibiofemoral dislocation with popliteal artery injury, and fibular neck fracture with common peroneal neuropathy.
Each correct pairing links the biomechanics of the orthopedic injury with the physical examination findings characteristic of the nearest neurovascular structure. Posterior hip dislocations compress the sciatic nerve; anterior hip dislocations stretch the femoral nerve; knee dislocations tether and tear the popliteal artery; and fibular neck fractures contuse the superficially wrapped common peroneal nerve.

Step-by-Step Solution

1
Analyze the dashboard injury presentation.
Identify a shortened, internally rotated, and adducted leg as a posterior hip dislocation.
Axial loading on a flexed hip drives the femoral head posteriorly out of the acetabulum, putting the posteriorly located sciatic nerve at risk.
2
Analyze the forced abduction injury presentation.
Identify a shortened, externally rotated, and abducted leg as an anterior hip dislocation.
Anterior displacement of the femoral head can stretch or compress the femoral nerve, which runs anteriorly over the hip joint.
3
Analyze the high-energy hyperextension knee injury.
Identify a grossly unstable knee as a tibiofemoral dislocation.
Knee dislocations severely stretch the popliteal artery, which is firmly tethered across the popliteal space, creating a high risk for intimal tear or transection.
4
Analyze the proximal lateral leg direct impact.
Identify this as a fibular neck fracture.
The common peroneal nerve wraps directly around the fibular neck superficially, making it highly vulnerable to direct trauma and fractures in this specific area.

Key Concept

Lower extremity orthopedic injuries have highly specific and predictable neurovascular complications based on anatomical relationships, such as the sciatic nerve in posterior hip dislocations, the popliteal artery in knee dislocations, and the common peroneal nerve in fibular neck fractures.
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Topics

Orthopedic Surgery

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