Musculoskeletal Injuries Answers 333that is characterized by a symmetric, progressive polyarthritis. Unlike
osteoarthritis(e), rheumatoid arthritis has systemic manifestations.
294.The answer is a.(Simon and Koenigsknecht, pp 453-460.)The cruci-
ate ligaments are two internal bands extending from the tibia to the femur,
one anteriorly and the other posteriorly. They control anteroposterior and
rotary stability of the knee and prevent hyperextension. The ACL is the
most frequently injured ligament in the knee.It has a rich blood supply
which accounts for the high incidence of hemarthrosiswhen the ligament
is injured. A history that includes a poporsnapat the time of injury (eg,
during a sudden turn in direction while playing sports) suggests a rupture
of the ACL until proven otherwise, particularly when associated with the
rapid development of a knee effusion.
The PCL (b)is significantly stronger than the ACL and collateral liga-
ments. Therefore, injury to it is rare and is usually associated with severe
knee injuries. (c and d)The medial and LCL are often injured with exces-
sive valgus (knee forced medially relative to leg) and varus (knee forced lat-
erally relative to leg) forces, respectively. The patella ligament (e)runs from
the patella to the tibial tuberosity and functions to help extend the leg at
the knee. The ligament is commonly injured when an individual falls on a
partially flexed knee.
295.The answer is e.(Simon and Koenigsknecht, p 566.)The patient’s
diagnosis is an Achilles tendon rupture.The individual gives a history of
a sudden excruciating pain and having heard or felt a poporsnap.This
entity is most common in sedentary, middle-aged men or in athletes. The
diagnosis can be made with the Thompson test.The patient is placed in
the prone position. With normal function, squeezing the calf produces plan-
tar flexion of the foot. With a complete tear of the Achilles tendon, plantar
flexion will not occur. If doubt remains, magnetic resonance imaging (MRI)
or ultrasound can be used to confirm the diagnosis.
Homan sign (a)is traditionally used to help diagnose a DVT. It is con-
sidered positive when passive dorsiflexion of the ankle elicits sharp pain in
the calf. However, this sign is neither sensitive nor specific for DVT. Lach-
man test (b)is used to detect an injury of the ACL of the knee. McMurray
test(c)is used to detect an injury to the meniscus of the knee. A ballotable
patella(d)signifies a significant knee effusion.