Executive Editor: Chris Colton

Authors: Renato Fricker, Matej Kastelec, Fiesky Nuñez, Terry Axelrod

Thumb - Distal phalanx: Base - Dislocation

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Glossary

1 Principles top

Typically, hyperextension of the finger causes dorsal, or, rarely, palmar dislocation. enlarge

Mechanism of the injury

The majority of these uncommon injuries are caused by sporting accidents.
Typically, hyperextension of the finger causes dorsal, or, rarely, palmar dislocation.
In both cases, disruptions of the collateral ligament and the volar plate will be present.
In palmar dislocations, there will be an additional terminal extensor tendon disinsertion.


In the lateral view, the middle and distal phalanges should be collinear. Any axial malalignment is a clear indication of ... enlarge

Recognizing subluxation

Diagnosis is based on

  1. the clinical history of the trauma and mechanism of the injury
  2. the clinical examination of the patient
  3. the x-rays


AP and lateral x-rays are necessary for diagnosis. Be careful to avoid interposition of other fingers in the x-rays.

In the lateral view, the middle and distal phalanges should be collinear. Any axial malalignment is a clear indication of subluxation.

2 Closed reduction top

If the joint is stable after reduction, nonoperative treatment is usually indicated. enlarge

Dorsal subluxation

The majority of these dislocations can be reduced by applying traction, flexion and dorsal pressure on the base of the distal phalanx.
If the joint is stable after reduction, nonoperative treatment is usually indicated.


In the case of palmar dislocation, apply traction and extension. Then apply pressure with the thumb on the palmar aspect of ... enlarge

Palmar subluxation

In the case of palmar dislocation, apply traction and extension. Then apply pressure with the thumb on the palmar aspect of the base of the distal phalanx.
Rarely, the terminal extensor tendon, or the flexor digitorum profundus, may be interposed in the DIP joint. This is an indication for ORIF.
If the joint is stable after reduction, nonoperative treatment is usually indicated.

3 Approach top

In order to avoid unnecessary radiation from image intensification, mark the planned track of the K-wire with a skin ... enlarge

Indication

In high-demand patients, K-wire fixation enables immediate return to many activities.

Marking K-wire track
In order to avoid unnecessary radiation from image intensification, mark the planned track of the K-wire with a skin marker (or methylene blue) on the distal phalanx, in both the AP and the lateral aspects.


Make a 1 cm horizontal incision just beneath the free border of the nail, over the center of the distal phalanx. enlarge

Make a 1 cm horizontal incision just beneath the free border of the nail, over the center of the distal phalanx.
Bluntly dissect the subcutaneous tissues to the tip of the distal phalanx.

4 Inserting the K-wire top

Due to the conical shape of the tip of the distal phalanx, there is a risk of skidding of the K-wire, either in the lateral, ... enlarge

Pitfall: slipping K-wire

Due to the conical shape of the tip of the distal phalanx, there is a risk of skidding of the K-wire, either in the lateral, palmar, or dorsal directions.


To prevent the K-wire from skidding while introducing it, either a 16 gauge hypodermic needle or a 1.0 mm drill guide can be ... enlarge

Pearl: preventing slippage

To prevent the K-wire from skidding while introducing it, either a 16 gauge hypodermic needle or a 1.0 mm drill guide can be used. Each finds good purchase on the tip of the distal phalanx and will ensure that the K-wire is inserted in the center and along the longitudinal axis of the phalanx.


If a K-wire is mistakenly inserted at an angle to the axis of the phalanx, we recommend leaving it in until a second K-wire ... enlarge

Pitfall: K-wire in wrong plane

If a K-wire is mistakenly inserted at an angle to the axis of the phalanx, we recommend leaving it in until a second K-wire has been inserted in the correct orientation. This will prevent the wire from going unintentionally along the wrong track.


The K-wire is now advanced across the DIP joint into the middle phalanx, as far as its base. Be careful not to penetrate the ... enlarge

Fully insert the K-wire

The K-wire is now advanced across the DIP joint into the middle phalanx, as far as its base. Be careful not to penetrate the PIP joint.


There are two methods for completing K-wire fixation. Each method has its advantages and disadvantages. enlarge

Cut the K-wire

There are two methods for completing K-wire fixation. Each method has its advantages and disadvantages.

K-wire beneath the skin
Cut the K-wire just distal of the tip of the distal phalanx. Retract it by about 5 mm (be careful not to pull the tip of the wire back through the fracture plane), bend it through 180 degrees and then bury it in the bone to avoid soft-tissue irritation.
This method has the advantage that the patient may speedily regain full use of the finger.
However, removal of the K-wire requires another minor surgical procedure under local anesthesia.

K-wire protrusion through the skin
Cut the K-wire so that it protrudes through the skin, about 1 cm from the tip of the finger. Bend its end to form a tight U-configuration to prevent catching on clothing, etc.
Leaving the K-wire to protrude through the skin in this way has the advantage of its being easy to remove. The disadvantages are patient discomfort and risk of pin-track infection.

v1.0 2008-11-08