Musculoskeletal Injuries Answers 339307.The answer is c.(Rosen, pp 538-539.)Avascular necrosis of the
scaphoidis seen in approximately 3% of scaphoid fractures. The typical
presentation of a scaphoid fracture is a FOOSH. On examination patients
have snuff box tendernessor tenderness with axial loading of the thumb.
Blood supply to the scaphoid is provided by a single artery that flows into
the distal portion of the bone leaving the proximal portion vulnerable in
the setting of a fracture. This increases the likelihood of complications, par-
ticularly avascular necrosis, in the setting of a poorly healed fracture.
(a)A fracture of the distal ulna would heal after 3 months. There is no
tenderness over the ulna on examination. (b)This individual likely had an
acute fracture of her scaphoid that she did not seek medical care for. The
fracture did not heal properly subsequently leading to avascular necrosis.
(d)A hematoma may have occurred at the time of injury from a venous
bleed. However, it would not be present 3 months later. (e)Lunate frac-
tures are rare but are also complicated by avascular necrosis. This patient
has snuffbox tenderness, which is more likely because of a scaphoid injury.
308.The answer is a.(Simon and Koenigsknecht, p 178.)Themedian
nerveruns through the carpal tunnel between the flexor carpi radialis and
the palmaris longus. It provides sensation to the palmar aspect of the radial
three and one-half fingers as well as the dorsal aspect of the tips of the
index and middle fingers and the radial half of the ring finger. Lunate dis-
locations are usually caused by hyperextension injuries. The lunateis usu-
ally displaced volarly or dorsally. The median nerve may be compressed
in the carpal tunnel by the lunate, and the patient may display signs of
acute carpal tunnel syndrome.
(b)Perilunate dislocations are the most common wrist dislocation.
(c)Scapholunatedislocation is sometimes defined by the “Terry Thomas” or
“Dave Letterman” sign, where there is a gap (> 3 mm) in the space between
the scaphoid and lunate (similar to a gap in the front teeth of these two peo-
ple).(d and e)These dislocations are rare.
309.The answer is b.(Simon and Koenigsknecht, pp 454-456.)The most
common mechanism of injury resulting in ligamentous injury is a valgus
stresswith an external rotary component on the flexed knee. This is com-
mon in skiing and football injuries. The MCLis commonly injured. On
stability testing of the knee, patients with MCL tears usually show insta-
bility with a valgus stress with the knee in 30 degrees of flexion.Liga-
mentous tears are also associated with hemarthrosis.