Unicondylar fractures of the middle phalanx can be transverse, short or long oblique, or comminuted. Typically they are the results of a sports injuries, caused by axial load combined with lateral angulation of the finger.
Condylar fractures tend to be very unstable and should usually be treated operatively. If conservative treatment is attempted, secondary displacement, leading to angulation of the finger, often ocurrs.
Short and long oblique fractures
Short oblique fractures typically originate in the intercondylar notch.
Long oblique fractures more often originate through one of the condyles, splitting proximally towards the diaphyseal cortex on the side of the uninjured condyle.
Outcome of fractures of the middle phalanx is usually more favourable than in the proximal phalanx. This is largely due to the fact that limitation of DIP joint motion is not as great a problem as similar limitations in the PIP and MP joints.
However, since fragments in this segment are generally smaller than in the proximal phalanx, management and stabilization can be more of a challenge.
Consequences of malunion (pain or deformity), or of degenerative joint disease, at the DIP joint can well be dealt with by arthrodesis, which is a procedure with very predictable outcome.
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.