AAHS ASPN ASRM - 2013 Annual Meeting - American Association ...

Mechanics of Injury
The mechanism of injury most commonly associated with pilon fractures of the PIP joint is a sudden axial loading to the extended
digit. These injuries include dorsal , volar and combined rimmed fractures which permits a widening of the shattered base.
Cadaveric studies in our lab identified dorsal fracture –dislocations and the pilon fracture s as the most common injuries sustained
when an sudden axial load was applied to a digit. Dorsal fracture –dislocations were most common when a fully extended PIP was
axially impacted . This is due in part to the laxity of the collateral ligaments when the joint is in full extension, permitting increased dorsal
translation of the middle phalanx and an increased load on its volar surface and the volar plate. With a hyperextension moment on the PIP
joint, the base of the middle phalanx is forced dorsally resulting in a shearing of its volar base on the proximal phalangeal head and a dorsal
dislocation of the joint. With flexion of the PIP joint the base of the proximal phalanx is more firmly seated and axial loading resulted in a
significant increase in the number of pilon fractures generated following injury, both the intrinsic and extrinsic tendon systems act as deforming
forces on the joint. The strong sublimus insertion causes a flexion moment on the distal portion of the middle phalanx, while the lateral
bands tend to collapse the joint in flexion and rotate the proximal end of the middle phalanx dorsally. These forces explain the difficulty in
maintaining a concentric reduction. To maintain a reduction, treatment must re-balance these forces . To allow motion of the injured joint,
the stabilizing forces must be realized throughout the full arc of motion.
Treatment Options for Pilon Fractures
Extensive comminution makes anatomic restoration of the articular surface impossible.
The goal is restoration of a congruent gliding surface.
1. Splinting- results in stiffness
2. Traction
dynamic traction external fixator
span the pip joint and permit early active motion
orthotic traction splint
passive motion only
ORIF
Standard ORIF- increase complications
Limited ORIF to restore central depression
bone graft- as needed
Dynamic external fixator
Volar Arthroplasty
Boney reconstruction of Dorsal rim
Dynamic external fixator
Hemi-Hamate Chondral Arthroplasty
Dynamic external fixator
Technique of Application of PIP Dynamic Distraction External Fixation:
Manual closed reduction is performed on the injured digit. If closed reduction of the proximal interphalangeal joint is unattainable,
a percutaneous reduction can be accomplished using minimal incisions with fluroscopic guidance. Concentric reduction of the joint must be
obtainable prior to frame application. The dynamic distraction splint is assembled using three 0.045-inch K-wires placed parallel to each other
and perpendicular to the lateral axis of the digit (figure). The lateral axis of the finger is a plane where the dorsal forces acting on the skin are
perfectly balanced by the palmar forces, resulting in minimal soft tissue gliding and important feature in pin placement to reduce pin tract
infection. Using a mini C-arm fluoroscopy for pin placement, the first K-wire is placed through the rotational center of the head of the proximal
phalanx as seen on the lateral fluoroscopic view. The free ends of the wire on both sides are bent at right angles and distally along the
long axis of the digit. The ends of the wire are formed into hooks for application of the dental loop rubber bands.
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