Executive Editor: Chris Colton

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

Proximal phalanx - MCP joint - avulsion fracture

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Glossary

1 Principles top

Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Avulsion fractures

Avulsion fractures are the result of side-to-side (coronal) forces acting on the finger, putting the collateral ligament under sudden tension. The ligament is usually stronger than the bone, causing the ligament to avulse a fragment of bone at its insertion.
Avulsion fractures result in marked joint instability.
If the fracture is not displaced, nonoperative treatment is usually indicated (buddy taping to the adjacent finger). Displaced fractures, however, must be internally fixed.

View animation


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Avulsion fractures result in marked joint instability.
If the fracture is not displaced, nonoperative treatment is usually indicated (buddy taping to the adjacent finger). Displaced fractures, however, must be internally fixed.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Tension band principle

The tension band converts tensile forces into compression forces.
The presence of comminution is a contraindication for tension-band treatment.
In a case such as the illustrated fracture, the tension band will be applied in static mode.
Tension band wiring of this fracture has been shown to be effective and usually provides good results. The advantage of this technique is its limited soft-tissue disruption. The risk of fragmentation is also minimized.

2 Reduction top

Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Indirect reduction

Reduction is achieved by pulling the finger laterally, in the direction opposite to the forces that created the fracture, and into MCP flexion, as necessary, to approximate the fragment. The avulsed fragment is pushed into place by the surgeon’s thumb.

With tiny fragments, indirect reduction can be achieved by tightening the tension-band wire at the end of the fixation procedure.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Direct reduction

In displaced fractures, open reduction is often necessary.
A small pointed reduction forceps is used gently to reduce the fracture from palmar to dorsal and from proximal to distal. Application of excessive force can result in fragmentation. Do not use a forceps in tiny fragments.

Note
Anatomic reduction is important to prevent chronic instability, or posttraumatic arthritis.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Preliminary fixation

Hold the reduction by inserting a K-wire through the center of the fracture surface.
Check reduction using image intensification.

3 Wire fixation top

Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Drill a hole

A hole is drilled in the proximal phalanx, from dorsal to palmar.
The location of the drill hole should be the same distance from the fracture line as the avulsed fragment’s length.
Use a drill guide, for soft-tissue protection, and either a slow-spinning 1.5 mm drill, or a 1 mm K-wire.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Insert wire

Thread a 26-28 gauge stainless steel monofilament 0.6 mm wire through the drill hole.
A curved hemostat can be used to retrieve the wire from the palmar surface, sliding it very closely to the cortical bone in order to avoid damage to the digital nerve and artery.
Periosteal elevators can be used for protection.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Wire application

The wire must pass close to the bone and through the ligament in order to protect vascularity.

The wire is passed around the fragment and K-wire, and through the ligament attachment in a figure-of-eight mode.
This can be achieved by passing a syringe needle of appropriate diameter on the surface of the bone, deep to the ligament attachment, and then inserting one end of the wire into the tip of the needle. The needle and the wire are then carefully drawn through, guiding the wire along the correct track.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Tighten the wire

Once the fragment is reduced, the wire is tightened, cut short, and bent along the phalanx, in order to avoid soft-tissue irritation.
When tightening the wire, ensure that both ends are twisted into each other rather than twisting one end around the other straight end.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

This is achieved by using traction with the pliers to tighten the loop and the twisting, still under tension, to take out the slack.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Anchoring the K-wire

Check position of the K-wires under image intensification. If the tip of the wire is in contact with the far cortex, then retract the K-wire by about 2 mm, bend it through 180 degrees, cut the wire to form a small hook, and impact the bent tip into the bone.

 

Use image intensification finally to ensure anatomical reduction.

4 Alternative fixations top

Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Alternative: anchor screw

An alternative way of anchoring the figure-of-eight wire distally in the phalanx is the use of a screw instead of a drill hole.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Vertical fractures

In more vertical fractures, the K-wire gives the fragment additional stability and prevents secondary axial displacement.


Avulsion fracture of proximal phalanx MCP joint – Tension-band wiring enlarge

Small fragment

If the avulsed fragment is too small to risk further damage by passing a K-wire, a simple figure-of-eight tension band is used.

v1.0 2008-11-08