Instability of the Carpus – Axial Dislocation and Fracture-Dislocation: Review of the Literature

Fig. 1

Radial and ulnar columns with axial dislocation lines. AU axial ulnar, AR axial radial

Garcia-Elias et al. [3] describes three types of axial dislocation according to the affected column:

Radial axial (RA) (Fig. 2) with instability and proximal radial displacement of the radial column (first and second metacarpals, trapezium, trapezoid, scaphoid), while the ulnar column maintains stable relations with radius and ulna.

Fig. 2

Radial axial dissociation. AU axial ulnar, AR axial radial
Ulnar axial (UA) (Fig. 3) where the ulnar column (fourth and fifth metacarpals, hamate, triquetrum) is displaced proximal and ulnar, while the radial column maintains stable relations with the radius and ulna.

Fig. 3

Ulnar axial dissociation. AU axial ulnar, AR axial radial
Radioulnar axial (Fig. 4) with instability and displacement of both columns parting in opposite directions. Here, the third column (third metacarpal, lunate, capitate) is stable onto the radius and ulna, while the two other columns are displaced.

Fig. 4

Radioulnar axial dissociation. AU axial ulnar, AR axial radial

Garcia-Elias describes subgroups for the forms RA and UA:

For RA, three subgroups: peritrapezial/peritrapezoid, peritrapezial, transtrapezial
For UA, three subgroups: trans-hamatal/peri-pisiform, peri-hamatal/peri-pisiform, peri-hamatal/trans-triquetral

2 Mechanism

Several mechanisms have been suggested by different authors, but the common factor for this entity is the violence of the mechanism involved which has been reported throughout the literature.

According to Herzberg, axial dislocation is most often associated with blast injuries and open crush injuries. Garcia-Elias et al. [3] emphasizes the frequency of associated neurovascular and musculotendinous lesions: flexor/extensor injuries, thenar and hypothenar lacerations, median nerve, sensory and motor branches of ulnar nerve lesions, arterial injuries, fractures including metacarpal, hook of hamate, fracture avulsion of trapezium, pisiform, carpometacarpal dislocations and digital amputations.

Tabib [4] describes a case of radial axial dislocation and describes the mechanisms reported in the literature. These are most commonly manual work-related crush injuries or high kinetic energy accidents (motorcycle).

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