340 Emergency Medicine
(a)Rupture of the lateral collateral is caused by an unusual mecha-
nism and may be seen when a skier fails to maintain a snowplow and the
tips of his or her skis cross causing a varus stress. (c)Rupture of the ACL
usually includes a history of a poporsnapand immediate development of
a knee effusion. The Lachman test is used to identify ACL and PCL injuries.
(d)PCL injuries occur when the tibia is forced posteriorly relative to the
femur. (e)With meniscal injuries, patients typically complain that their
knee locks in place or they hear a clicking sound. These injuries are usually
caused by rotational force to a weight-bearing knee and are associated with
effusions.
310.The answer is c.(Rosen, p 527.)The best way to preserve an ampu-
tated part is to rinse it with normal saline to remove gross contamina-
tion, wrap it in sterile gauze moistened with saline or lactated ringers,
and place it in a sterile, water tight container.Thenstore this container
in ice water.
(a and d)Povidone-iodine is a strong antiseptic solution that is used
commonly in the hospital setting, particularly in the operating room to cre-
ate a sterile field. However, it is thought to be injurious to fibroblasts and
may limit wound healing. (b)The amputated part should not be placed
directly on ice or in ice water as this may also damage the tissue. (e)Replan-
tation of the thumb should be performed by a vascular surgeon in the oper-
ating room. There is an increased risk of tissue death the longer the severed
part is not properly stored.
311.The answer is d.(Tintinalli, pp 1726-1734.)Frequently, there is a
fractureto account for the presence of fat within the joint because the fat
has entered from the bone marrow cavity. The presence of fat globules may
be seen in the joint aspirate and even on the radiograph of the knee show-
ing a joint effusion with a fat-fluid level.
(a and b)Cruciate ligament tears are associated with early hemarthrosis.
(c)Meniscal tears are associated with effusions that develop gradually over
6 to 24 hours post injury. (e)Vascular injuries of the knee occur with frac-
tures and dislocations and are a medical emergency.
312.The answer is c.(Simon and Koenigsknecht, p 416.)The patient sus-
tained a posterior hip dislocation.The most common mechanism for this
to occur is during a motor vehicle collision in which a direct force is
applied to the flexed knee(eg, the patient’s knee hits the dashboard at
high velocity). The limb appears shortened, adducted, internally rotated,