Nileshkumar M. Chaudhari
Dislocation of the radiocarpal joint, with or without
Radial styloid fracture
Dorsal or volar rim avulsion fractures
In the category of carpal instability nondissociative
This topic does not include articular shear fractures (“Barton” variants), perilunate dislocations, or instability related to distal radius malunion or rheumatoid arthritis.
Proximal carpal row linked to distal radius by the volar (radioscaphocapitate [RSC], short radiolunate [SRL], long radiolunate[LRL]) and dorsal (dorsal radiocarpal [DRC]) extrinsic wrist ligaments
Radiocarpal dislocation requires either near-global ligament disruption or a fracture that disrupts the stability of the osseous insertion of the ligaments.
Volar ligaments are typically avulsed from their origin on the distal radius.
One report of avulsion distally from the carpal insertions1
If a radial styloid fracture is greater than one-third the width of the scaphoid fossa, the RSC and LRL origins usually remain attached to the fractured fragment.2
DRC and capsule may avulse small fragments from the dorsal distal radius.
Role of extrinsic wrist ligaments
Palmar structures provide majority of restraint against dorsal (61%) and volar (48%) translation of the carpus.3
SRL is the primary stabilizer against volar translation.4
Intercarpal ligament injury
Ulnar styloid fracture
Distal radioulnar joint (DRUJ) disruption
Secondary ulnar translation
Mechanism of injury
Typically high-energy injuries
The radial-based extrinsic ligaments (RSC, SRL, LRL), typically torn during radiocarpal dislocation, tighten with and resist pronation, suggesting that forceful pronation is a part of the injury mechanism.2
Identification of associated traumatic injuries
Swelling and pain
Offset of the hand in the direction of dislocation
Obtain a complete neurovascular examination.
Radiographs of the elbow, forearm, wrist, and hand
In chronic cases or cases with delayed presentation, stress radiographs (distraction, radial deviation, and ulnar deviation) may help establish the diagnosis.
Computed tomography (CT) scanning may help with fracture characterization.
Direction of dislocation (dorsal, volar, radial, and ulnar)18
Most useful classification system because it can guide treatment.
Type I—radial styloid fracture absent or small (lesser than one-third width of scaphoid fossa)
Typically all ligaments are torn.
Type II—large (greater than one-third width of scaphoid fossa) radial styloid fracture (Figure 23.3 A and B)
Volar extrinsic ligaments intact and attached to radial styloid
▲ One report of ligaments avulsed from fractured styloid13
Type I—ligamentous injury limited to the radiocarpal ligaments
Type II—addition of intercarpal ligamentous lesion(s)
Limitations of current classification systems
Rely on radiographs, so cannot prove pattern of ligamentous injury13
Fail to account for postreduction stability and ulnar-sided pathology13
Measured using carpal-radial distance21
Distance between the center of the proximal capitate and a line bisecting the radius (mean: 5.7 ± 1.4 mm)
Carpal-radial distance ≥ 9 mm represents ulnar carpal translation.
Type I—entire carpus (including scaphoid) translates ulnarly22
Type II—scaphoid stays with radius, remaining carpus translates ulnarly22
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