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<v ->Now as you know, some tendons are pressed against bones.

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They wrap around the bones.

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They're called wrap-around tendons.

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Here are a partial list of some of the tendons

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I would include in that category.

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Where they are pressed against bone

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they often sit in grooves,

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and they change directions rather abruptly.

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So tendonosis, tenosynovitis, tendon tearing,

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erosion of grooves and marrow edema may be seen

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in this example showing you the peroneus longus

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as it extends into the cuboid groove.

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And by the way, one thing,

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depending upon the position of the foot,

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the peroneus longus doesn't always sit in that groove.

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It may sit aside that groove.

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So it depends upon the position of the foot.

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Similarly, if we look at the tibialis posterior tendon

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at the level of the medial malleolus,

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there is a rather shallow groove that we can see here.

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Occasionally it's deep.

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Here again, however, the tendon changes directions.

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Tendonosis, tendon tears, tenosynovitis

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and reactive marrow edema may develop

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in these areas of wraparound tendons.

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And one other point about wraparound tendons,

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as tendons change direction

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they have a supporting system to keep them in place.

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And that supporting system consists

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of retinacula or reflection pulleys

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holding the tendon against the bone surface.

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I wanted to show you one example of this.

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This is the superior peroneal retinaculum

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that we talked a bit about it yesterday.

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Here we can see the peroneus brevis in front

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the peroneus longus tendon behind,

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the typical appearance of what they look like.

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The peroneus brevis tendon does become elongated

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in this location and sometimes it can simulate a split tear

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of the peroneus brevis.

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So those are the retinacula

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and problems can occur in those retinacula,

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because sometimes the forces transmitted

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by those traversing tendons

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will put force on the retinaculum,

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so the retinaculum tears, or the bone avulses.

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And one of the characteristic avulsions we will see

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is an avulsion fracture at the fibular attachment

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of the superior peroneal retinaculum,

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often associated with peroneal tendon dislocation,

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in this case, a split tear of the peroneus brevis.

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With this element, the lateral element dislocated laterally

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accounting for this fracture,

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the peroneus longus tendon sitting in pretty normal place

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behind the fibula.

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Here's another example.

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This is an avulsion fracture

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involving the superior peroneal retinaculum

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with anti-lateral dislocation of the peroneal tendons.

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And this sort of phenomenon

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of this fracture and dislocations,

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there is an association with calcaneal fractures.

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So you should always look at this particular area

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of the fibula when you're dealing with patients

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with calcaneal fractures.

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Now there is another condition, slightly different,

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that relates to displacement of the peroneal tendons.

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And this is known as intrasheath subluxation,

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where the peroneal tendons undergo torsion

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but not dislocation.

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Here's a beautiful example showing you

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here's the peroneus brevis tendon

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located abnormally lateral to the longus,

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the muscle, the peroneus brevis muscle

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still located medially.

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So this is a torsion of the peroneal tendons

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within the sheath, without an example of a dislocation.