Match each upper extremity fracture or dislocation pattern with its most classically associated neurovascular complication.
- Lunate dislocationAcute median nerve compression leading to paresthesias in the radial three and a half digits
- Hook of hamate fractureUlnar nerve compression leading to weakness of the intrinsic hand muscles and numbness in the small finger
- Monteggia fracture-dislocationPosterior interosseous nerve injury leading to inability to extend the fingers without sensory loss
- Scaphoid waist fractureInterruption of retrograde blood supply leading to avascular necrosis of the proximal bone fragment
Answer
Lunate dislocation pairs with acute median nerve compression; Hook of hamate fracture pairs with ulnar nerve compression; Monteggia fracture-dislocation pairs with posterior interosseous nerve injury; Scaphoid waist fracture pairs with interruption of retrograde blood supply.
Each pair correctly matches an upper extremity injury to its anatomical neurovascular consequence. Anterior dislocation of the lunate pushes the bone into the carpal tunnel, compressing the median nerve. The hook of the hamate sits adjacent to Guyon's canal, making fractures there a prime cause of ulnar nerve palsy. Monteggia fractures result in radial head dislocation, which stretches the posterior interosseous nerve (PIN) as it pierces the supinator muscle, leading to isolated motor deficits. Finally, the scaphoid is supplied by blood vessels that enter distally and travel proximally; a fracture at the waist interrupts this flow, causing avascular necrosis of the proximal fragment.
Step-by-Step Solution
Key Concept
Neurovascular complications of forearm and wrist injuries