Radiocarpal joint dislocations are uncommon, with an incidence of ~0.2% of all wrist injuries.1 They nearly always result from high-energy trauma that causes extremes of hyperextension and pronation, such as a fall from a height or motor vehicle crash and are most frequently seen in young, active men.2 The mechanism of injury is thought to be a severe shear or rotational insult that transmits the force from lateral to medial through the platform of the radius.3 The majority of these dislocations involve associated injuries—particularly radial styloid fractures—with purely ligamentous injuries being extremely rare.4 Conservative treatment may be appropriate for some cases of radiocarpal dislocation with no intracarpal damage, but most surgeons prefer surgical intervention for optimal outcomes and to reduce the risk for carpal instability.3-5
Definitions
- A radiocarpal joint dislocation occurs when the articular surface of the proximal scaphoid, lunate, and/or triquetrum is displaced off the articular surface of the distal radius.
Hand Surgery Resource’s Dislocation Description and Characterization Acronym
D O C S
D – Direction of displacement
O – Open vs closed dislocation
C – Complex vs simple
S – Stability post reduction
D – Direction of displacement
- The primary description and characterization of radiocarpal joint dislocations are done by noting the direction of the displacement of the carpal relative to the distal radius: dorsal, lateral, and volar.6 Dorsal dislocations are the most common; volar dislocations are rare.7,8
- In one study of 26 radiocarpal dislocations, only 1 (4%) was in the volar direction, with the 25 others being dorsal.8
- The degree of displacement of the carpal further characterizes radiocarpal dislocations. In a true complete dislocation, the articular surface of the proximal carpal is no longer in contact with the articular cartilage of the distal radius. If there is partial contact of the cartilaginous surfaces, this is not a true dislocation but rather a joint subluxation.6
O – Open vs closed
- The majority of radiocarpal joint dislocations are closed; the skin is intact, and there is no route for bacteria to contaminate the joint space.
- Open radiocarpal joint dislocations are rare, but when they do occur, are usually dorsal dislocations with a volar opening. These cases always require urgent irrigation, debridement, open reduction, and ligament repair.9
C – Complex vs simple
- Most radiocarpal joint dislocations are simple, meaning that reduction is easily achieved under digital anesthetic block and is not blocked by soft tissue being interposed in the joint between the carpal and radial joint surfaces.
- Complex (irreducible) radiocarpal joint dislocations are extremely rare, but do occur on some occasions.
S – Stability
- Radiocarpal joint dislocations are usually reducible but the significant ligamentous and/or fracture damage associated with these dislocations means the dislocation is never perfectly and anatomically aligned by closed reduction alone. To achieve a truly stable outcome, the initial reduction must be followed by ligament repair/reconstruction and ORIF of any associated radial styloid fractures.12,13
Related anatomy4,8
- Extensor tendons – extensor carpi radialis longus, extensor carpi radialis brevis, extensor pollicis longus, extensor digitorum, extensor indices, extensor digiti minimi, extensor carpi ulnaris
- Flexor tendons – flexor digitorum superficialis, flexor digitorum profundus, flexor carpi radialis, flexor carpi ulnaris, flexor pollicis longus
- Abductor pollicis longus tendon
- Radial collateral ligament
- Radioscaphocapitate ligament
- Radiolunate ligament (short and long)
- Radioscapholunate ligament
- Radioscaphoid ligament
- Radiotriquetral ligament
- Osteology of the distal radius and carpal(s) involved
- Anatomic studies have identified the short radiolunate and radioscaphocapitate ligaments as the primary stabilizers of the carpus in resisting volar and ulnar translocation, respectively.8
- The short and long radiolunate ligaments, and the radioscapholunate and radioscaphocapitate ligaments are all typically ruptured in pure radiocarpal dislocations.4
Overall incidence
- Radiocarpal dislocations with or without associated fracture are typically reported to account for 0.2% of all wrist injuries1, but some studies have disputed this incidence rate.
- In a review of 438 patients with a distal radius fracture or wrist dislocation over 5 years, 12 (2.7%) presented with a radiocarpal dislocation in which the entire carpus moved relative to the articular surface of the distal radius.2
- Another suggested that radiocarpal dislocations could actually represent 20% of all wrist injuries.10
- Radiocarpal dislocations most often occur in young active men aged 20-40 years and nearly always involve high-energy trauma. These injuries can involve bone, ligament, and/or soft-tissue disruption, while pure dislocations are extremely rare.2,3
Related Injuries/Conditions
- Fractures of the scaphoid, lunate, and/or triquetrum
- Fractures of the distal radius
- Volar surface ligament injuries
- Dorsal surface ligament injuries
- Extensor tendon ruptures
- Flexor tendon ruptures
- Letenneur (volar margin) fracture of the distal radius13
- Barton (dorsal margin) fracture of the distal radius13