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So this is a 41 year old patient who has pain centered

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at the first metacarpal phalangeal joint following trauma.

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Important concepts here,

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the presence of an injury on the NAR side of the first metacarpal

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phalangeal joint involving both the proper and

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accessory ulnar collateral ligaments.

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We see fluid signal intensity propagating

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between the ulnar tubercle of the

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proximal first feelings, um,

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across the retracted and torn ulnar collateral ligament

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interpose. Between the torn ulnar collateral ligament fibers.

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We see the adductor aosis, which is thicken and emus,

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bringing about the presence of a yoyo cy,

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which is the retracted U C L with the interpose

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OSIS fibers.

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Given this characteristic appearance on Corona images,

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as we follow the injury in the axial plane,

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we can see the retraction and bunching up of the fibers

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at the level of the first metacarpal head.

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So this is dual retracted U C L Interpose

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osis.

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This is an interposition syndrome extended lesion due to a

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full thickness of the ulnar collateral ligament and

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interposition of theosis.