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So we'll discuss thumb dislocations.

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So dislocation of the thumb at the carp metacarpal

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articulation is rare.

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It typically only occurs dorsally

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because of the other structures that prevent it from

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a palmar subluxation or dislocation.

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It's related to axial compression force

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to a flexed first metacarpal bone.

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The typical treatment is open reduction internal fixation.

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Because of the predisposition to recurrence,

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there's ligament reconstruction that's performed.

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Now, the more common lesions that we see at the base

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of the thumb are the Bennet type fracture

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or fracture subluxation.

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So this is a more common lesion.

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It is also related to axial compression

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to a flexed first metacarpal.

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There is disruption of the dorsal ligaments

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and it strips the volar ligaments from the

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metacarpal attachments.

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So with regards to thumb basilar fractures,

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these are fractures that occur at the base of the

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metacarpal bone.

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Along the carpal metacarpal articulation,

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they can be considered anomaly as four types.

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There's an epi basal, there's a Bennet lesion,

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there's a Rolando lesion,

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and there's a more comminuted fracture.

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These account for 80% of thumb metacarpal fractures,

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typically in the dominant upper extremity in 75%.

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They could be unstable when there's greater than 30 degrees

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angulation because of pull of the abductor lysis longus

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with an intact vol oblique ligament,

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and thus represent surgical lesions.

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So here's a drawing showing a representation of a fracture

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that demonstrates subluxation

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or dislocation of the main metacarpal shaft fragment

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and a smaller evulsion fragment that remains attached

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to the trapezium and the index metacarpal.

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And here's a radiograph of a typical Ben fracture

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where there's a fracture at the base of the metacarpal.

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The triangular shaped fracture fragment

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maintains its anatomic position,

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but the rest of the metacarpal is now subluxed.

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So these are relatively common intraarticular fractures at

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the base of the thumb related to axial blow

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to a partially flexed first metacarpal.

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They can have an oblique

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or parametal configuration that separates the major part

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of the bone from a fragment at the volar ulnar aspect

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of the metacarpal base.

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They may have a deep anterior oblique ligament

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that holds the fragment in anatomic position

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and maintains the metacarpal fragment to the trapezium.

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The metacarpal base then sublux is radially

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proximally and dorsally.

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The preferred treatment is to have an anatomic reduction in

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percutaneous pinning,

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but there are complications such as malunion,

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joint instability and osteoarthritis.

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Here we have a drawing

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of a Rolando fracture showing the communed Y

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or T-shaped fracture dislocation at the base

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of the thumb metacarpal.

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So with the Rolando fracture, we have this communed Y

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or T-shaped intraarticular fracture.

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It has a worse prognosis

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because it's more complex, it's more difficult to treat.

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And the treatment, particularly

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for these three part type Rolando fractures is

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open reduction internal fixation.

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Severe combintion may preclude adequate open reduction.