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Difficulty: Very hardOrthopedic Surgery

Match the following complex orthopedic injuries with their defining pathophysiologic mechanism, critical diagnostic finding, or absolute surgical management principle.

  • Essex-Lopresti fracture-dislocationRadial head excision is strictly contraindicated; requires preservation or arthroplasty to prevent proximal radial migration and distal radioulnar joint dissociation.
  • Bado Type I Monteggia fracture-dislocationSurgical management demands anatomic restoration of ulnar length and alignment to allow for indirect reduction of the anteriorly displaced radiocapitellar joint.
  • Hawkins Type III talar neck fractureAssociated with a near-certain risk of avascular necrosis of the talar body due to complete disruption of the artery of the tarsal canal and deltoid branches.
  • Lisfranc joint complex injuryCharacterized by pathognomonic plantar ecchymosis; diagnosis is frequently missed unless weight-bearing or stress radiographs of the foot are obtained.
  • Juvenile Tillaux fractureSalter-Harris III fracture of the anterolateral distal tibia, occurring uniquely in adolescents due to the asymmetric medial-to-lateral fusion of the distal tibial physis.

Answer

The correct pairings correlate highly specific orthopedic trauma patterns with their core biomechanical or clinical tenets: Essex-Lopresti requires radial head preservation; Monteggia demands ulnar length restoration; Hawkins III carries near-certain AVN risk; Lisfranc injuries require stress views and present with plantar ecchymosis; and Juvenile Tillaux fractures occur due to asymmetric medial-to-lateral physeal closure.
Each specific injury pattern relies on a unique anatomic vulnerability or biomechanical principle tested at the highest levels of the USMLE Step 2 CK. The Essex-Lopresti lesion couples a radial head fracture with interosseous membrane disruption, making radial head preservation absolute to prevent catastrophic wrist collapse. Monteggia fractures are driven by ulnar shortening; fixing the ulna indirectly fixes the radial dislocation. The talus receives retrograde blood flow; a Hawkins III injury disrupts all supplying anastomoses, making AVN almost inevitable. Lisfranc injuries are notoriously missed on static films and are clinically hallmarked by plantar ecchymosis. Finally, the Juvenile Tillaux fracture is a purely pediatric phenomenon dictated by the asymmetric, medial-to-lateral fusion timeline of the distal tibial physis.

Step-by-Step Solution

1
Analyze the management requirements of longitudinal radioulnar dissociation (Essex-Lopresti).
Identify that the radial head acts as a critical secondary block to proximal radial migration.
Because the interosseous membrane is torn, the radius will migrate proximally if the radial head is excised, causing severe wrist impingement.
2
Evaluate the biomechanics of a Monteggia fracture-dislocation.
Determine that ulnar fixation is the primary surgical goal.
The radial head dislocation is secondary to the foreshortening of the fractured ulna; restoring ulnar length reduces the radiocapitellar joint.
3
Assess the vascular supply of the talus in the context of a Hawkins III fracture.
Identify the near 100% risk of avascular necrosis (AVN).
Complete displacement of both the subtalar and tibiotalar joints severs the artery of the tarsal canal and the deltoid branches, destroying the retrograde blood supply to the talar body.
4
Identify the diagnostic pitfalls of midfoot trauma.
Recognize that Lisfranc injuries require weight-bearing imaging.
The injury often reduces spontaneously at rest; applying physiological axial load reveals the pathologic diastasis between the first and second metatarsals.
5
Correlate skeletal maturation with pediatric ankle fractures.
Match Juvenile Tillaux fracture with asymmetric physeal closure.
Because the medial physis closes earlier than the lateral physis in adolescents, external rotation forces cause an avulsion of the remaining open anterolateral epiphysis.

Key Concept

Advanced principles of orthopedic trauma, including eponymous fracture biomechanics, occult injury diagnosis, and region-specific vascular vulnerability.
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Topics

Orthopedic Surgery

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