1 Principles topenlarge
While dislocations and ligament injuries are common throughout the hand,
they are most common at the proximal interphalangeal (PIP) joint.
The spectrum of these injuries ranges from minor stretching (sprains) to complete disruptions of the ligaments.
Dislocations of the PIP joint are classified according to the direction of displacement of the middle phalanx. They can be palmar, dorsal, lateral, or lateral rotatory.
The collateral ligament usually tears at one of two locations:
a) at its attachment to the proximal phalanx
b) at its attachment to the volar plate and middle phalanx.
Often, these injuries are accompanied by a partial lesion of the volar plate.
Lateral subluxation can be accompanied by a condylar fracture, or a plateau fracture (either as an avulsion fracture, or as an impaction fracture).
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.
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 topenlarge
In cases of associated dislocation, start by reducing the dislocation.
Apply traction to the finger, with the PIP joint in slight flexion, to relax the flexor tendons and the lateral band.
Then, maintaining the traction, deviate the finger laterally...
...and rotate towards the contralateral side.
In the majority of cases, the collateral ligament regains its natural anatomical position after reduction.
Reduction is achieved by pulling the finger laterally, in the direction opposite to the forces that created the fracture, and into MP 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.
In displaced fractures, open reduction is often necessary.
A dental pick is used gently to reduce the fracture from palmar to dorsal and from proximal to distal. Application of excessive force can result in fragmentation.
Anatomical reduction is important to prevent chronic instability, or posttraumatic degenerative joint disease.
Hold the reduction by inserting a K-wire through the center of the fracture
Check reduction using image intensification.
Pearl: use K-wire to reduce fracture
An alternative is to insert the K-wire in the avulsed fragment, and then, using the K-wire as a joystick, simultaneously to reduce the fragment and preliminarily hold it with the wire.
3 Fixation topenlarge
Drill a hole
A hole is drilled in the middle 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.
Thread a 0.6 mm stainless steel monofilament wire through the drill
A fine, 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.
The wire is passed through the drill hole and then around the fragment and
K-wire, 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.
Anchoring the K-wire
Check the position of the K-wire using 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.
Tighten the wire
Once the fragment is reduced, the wire loop 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 around each other rather than twisting one end around the other straight end.
This is achieved by using traction with the pliers to tighten the loop and the twisting, still under tension, to take up the slack.
In more vertical fractures, the K-wire gives the fragment additional stability and prevents secondary axial displacement.
Use image intensification finally to ensure anatomical reduction.
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.
Alternative: 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.