Executive Editor: Chris Colton

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

Thumb Proximal phalanx: Articular (head) - unicondylar fracture dislocation

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Glossary

1 Principles top

Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

These are rare unicondylar fractures that occur in the coronal plane and are associated with palmar, or dorsal, dislocations.
If the PIP joint is dislocated dorsally, a coronal dorsal fracture is present. If the PIP joint is dislocated palmarly, a coronal palmar fracture is associated.

Typically these fractures are the results of sports injuries, occurring as a result of axial loading associated with hyperflexion or hyperextension.
Condylar fractures tend to be very unstable and should usually be treated operatively. If conservative treatment is attempted, secondary displacement leads to angulation of the finger.

Caveat
These fractures are rare, but difficult to treat. There is an increased risk of joint stiffness resulting from these fractures.
It is wise to use magnifying loupes in these procedures. Gentle and precise handling throughout the procedure is mandatory.

2 Reduction top

Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Anatomical reduction mandatory

Articular fractures must be reduced anatomically, otherwise, the articular cartilage may be damaged, leading to painful degenerative joint disease and digital deformities.
This illustration shows how displacement may lead to abrasion and shearing of the articular cartilage, and also to instability.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Closed reduction of the dislocation

Dorsal dislocation
Apply traction to the finger with the PIP joint in partial flexion, and exert dorsal pressure on the displaced condyle in order to reduce the dislocation.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Palmar dislocation
Apply traction to the finger with the PIP joint in extension and exert palmar pressure on the displaced condyle in order to reduce the dislocation.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

In dorsal fragments

In dorsal fragments, part of the fracture line on the lateral aspect of the head is covered by the collateral ligament.
Flexing the PIP joint will draw back the collateral ligament, which can be further retracted with a hook to expose the dorsal fragment.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

In palmar fragments

In palmar dislocations, the collateral ligament complex is torn or partially torn. In most cases, the remnant of the collateral ligament can be retracted gently to reveal the palmar condylar fracture line.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Reduce the fracture

In order to gain better visualization of the fracture, use a syringe to clear out blood clot with a jet of Ringer lactate.
Gently reduce the fragment with a dental pick. Be careful to avoid fragmentation.

The opposite joint surface of the middle phalanx can be used as a template for reduction.

Small dorsal articular defect
If a small articular fragment is present, it can be excised. This will not compromise stability or flexion of the PIP joint.

Small palmar articular incongruency
Any incongruency on the palmar side is critical and can impede movement. It must be anatomically reduced and fixed.

3 Fixation top

Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Location of the drill holes

On the lateral intraarticular aspects of the condyles, there is a small ridge on each side. These are uniquely suited for screw placement, as the screws can be buried deep to the edge of the cartilage without violating the joint surface and avoiding causing irritation.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Drilling

Drill a gliding hole as perpendicularly to the fracture plane as possible, using a 1.0 mm drill bit for a 1.0 mm screw.
Use a 0.8 mm drill bit to drill a thread hole in the opposite fragment, just through the far (trans) cortex.

Dorsal fragment
In a dorsal fragment, fixation is from dorsal to palmar.

Palmar fragment
In a palmar fragment, fixation is from palmar to dorsal.


Unicondylar fracture dislocatino of proximal phalanx PIP joint – Lag screw fixation enlarge

Insert lag screw

Insert the lag screw. Carefully tighten the screw to achieve interfragmentary compression.

v1.0 2008-11-08