Module 63, General Orthopaedist Level
This 16 year old, 220 pound male presented to the emergency room after
sustaining an acute injury to his right knee while playing baseball. The
patient related that he noticed acute onset of pain in the right knee after
striking out at bat. He heard a single clunk in his knee and noticed immediate
pain and swelling. On examination he was noted to have medial knee tenderness
with a mildly positive apprehension test. His ACL, PCL, MCL and LCL ligaments
were intact. He was placed into a knee immobilizer and told to follow up
in the Sports Medicine clinic. He presented to Sports Clinic 6 days later
with a reporting the knee "gave out" on him several times since
the accident. On physical exam of the patient, six days after injury the
knee was noted to have a large effusion. ROM was limited from 20 to 100
degrees of flexion. There was significant medial retinacular tenderness
with a mildly positive apprehension test.
Question 63A
This history, and physical examination is most consistent with a patellar
dislocation and tear of the medial retinaculum.
Question 63B
The
next part of the work up should be to obtain an MRI scan of the knee to
rule out meniscus tear.
Question 63C
This
type of injury is most common in girls.
Question 63D
Direct
trauma is the most common cause of patellar dislocations and the associated
fractures.
Question 63E
The
injury in this boy is a genetic disorder.
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