Sequence of the Essex-Lopresti lesion--a high-speed video documentation and kinematic analysis

Abstract

Background and purpose: The pathomechanics of the Essex-Lopresti lesion are not fully understood. We used human cadavers and documented the genesis of the injury with high-speed cameras.

Methods: 4 formalin-fixed cadaveric specimens of human upper extremities were tested in a prototype, custom-made, drop-weight test bench. An axial high-energy impulse was applied and the development of the lesion was documented with 3 high-speed cameras.

Results: The high-speed images showed a transversal movement of the radius and ulna, which moved away from each other in the transversal plane during the impact. This resulted into a transversal rupture of the interosseous membrane, starting in its central portion, and only then did the radius migrate proximally and fracture. The lesion proceeded to the dislocation of the distal radio-ulnar joint and then to a full-blown Essex-Lopresti lesion.

Interpretation: Our findings indicate that fracture of the radial head may be preceded by at least partial lesions of the interosseous membrane in the course of high-energy axial trauma.

Figure 1.

An Essex-Lopresti lesion: comminuted fracture of the radial head, resulting in proximalization of the radius and dislocation of the unstable distal radio-ulnar joint.

Figure 2.

Schematic drawing of the setup of a specimen in the test bench.

Figure 3.

Part 1 of the sequence of development of an Essex-Lopresti lesion. A. Unloaded specimen. B. Loading leads to slight impaction and bending of radius and ulna, and thereby to a transverse movement of the radial and ulnar shaft away from each other (see increasing distance between radial and ulnar shaft), leading to tension of the interosseous membrane (IOM). C. Due to the rising tension in the IOM, the IOM ruptures and ulna and radius separate further. D. A slight proximalization of the radius—and thereby of the radial head—is detectable (see movement of radial head in relation to the black line).

Figure 4.

Part 2 of the sequence of development of an Essex-Lopresti lesion. A. The intraosseous membrane is completely ruptured. Radius moves downwards (proximal direction), leading to fracture of the radial head and increasing displacement (again in relation to the black line). B–D. The lesion progresses to a dislocation of the distal radio-ulnar joint, then to a full Essex-Lopresti lesion.

Figure 5.

Curve representing force over time in specimen 2. * marks the moment of failure of the interosseous membrane, as in Figure 3C. ** marks the moment of fracture and proximalization of the radius, as in Figure 4B. The irregular lines in-between can be explained by dislocation movements of the radial head before the fracture, resulting in complete longitudinal instability.