Test yourself
Tendon tear or anisotropy? Heel-toe before you call it
5 questions. Pick an answer to see whether you are right and why. Your score appears at the end.
Question 1Why does a normal tendon look dark when the probe is tilted?
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Answer b. Tendon fibres reflect sound like a mirror. When the beam meets them at 90°, the echoes return to the probe and the tendon looks bright. At an angle, the echoes reflect away and the tendon looks dark. This is anisotropy.
Question 2A tendon has a dark area in long axis. You heel-toe the probe and the fibres turn bright. What is the diagnosis?
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Answer d. A dark area which turns bright when you correct the beam angle is anisotropy. A tear shows a defect which stays dark whatever the angle.
Question 3Which finding supports a full tendon tear?
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Answer b. In a full tear, the fibres are discontinuous, the ends separate, and gentle movement shows the ends do not move together. The other findings describe a normal tendon or anisotropy.
Question 4How do you use anisotropy to tell a tendon from a nerve in short axis?
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Answer d. Tendons are far more anisotropic than nerves. A small tilt makes a tendon go dark while a nerve stays visible. Colour Doppler and compression do not reliably separate them.
Question 5Which step reduces the risk of over-calling a tear?
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Answer d. Two planes and a comparison with the other side separate a true defect from anisotropy and normal variation. Increasing the gain does not correct the beam angle. The curvilinear probe gives less detail of superficial tendons.
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Four or five delegates per instructor, FAMUS-accredited faculty and long, supervised time on the probe.
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