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Difficulty: MediumOrthopedic Surgery

Match each of the following specific orthopedic injuries with its most commonly associated acute neurovascular deficit as assessed on physical examination.

  • Midshaft humeral fractureInability to extend the wrist and fingers against resistance
  • Anterior shoulder dislocationLoss of pinprick sensation over the lateral aspect of the proximal arm
  • Posterior hip dislocationWeakness in ankle dorsiflexion and decreased sensation over the dorsal foot
  • Supracondylar humerus fracture (anterolateral displacement)Inability to flex the distal interphalangeal joint of the index finger and interphalangeal joint of the thumb

Answer

Midshaft humeral fracture matches with inability to extend the wrist and fingers. Anterior shoulder dislocation matches with loss of sensation over the lateral proximal arm. Posterior hip dislocation matches with weakness in ankle dorsiflexion. Supracondylar humerus fracture matches with inability to flex the distal joints of the thumb and index finger.
Each specific fracture or dislocation puts a predictable peripheral nerve at risk due to close anatomical proximity. The radial nerve is intimately associated with the midshaft humerus; the axillary nerve courses just inferior to the glenohumeral joint capsule; the sciatic nerve lies directly posterior to the hip joint; and the median/anterior interosseous nerve crosses anterior to the supracondylar region of the humerus.

Step-by-Step Solution

1
Identify the precise anatomical location and mechanism of each listed orthopedic injury.
Determined that the injuries involve the mid-diaphysis of the humerus, the anterior glenohumeral joint, the posterior acetabulum/femoral head, and the distal humerus metaphysis, respectively.
Understanding the exact location of the bony or ligamentous disruption is necessary to identify adjacent structures at risk.
2
Correlate the injury location with adjacent peripheral nerves and their expected downstream motor and sensory deficits.
Mapped the midshaft humerus to the radial nerve (wrist extension), the anterior shoulder to the axillary nerve (lateral arm sensation), the posterior hip to the sciatic nerve (ankle dorsiflexion via the common peroneal nerve branch), and the anterolaterally displaced distal humerus to the anterior interosseous nerve (distal thumb/index flexion).
This establishes the clinical presentation expected for each specific neurovascular complication on physical examination.

Key Concept

Neurovascular complications of common orthopedic fractures and dislocations
Estimated Time:1m 30s
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Orthopedic Surgery

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