Radiocarpal fracture-dislocations are rare injuries, and few studies in the literature have addressed this serious wrist injury. The trauma responsible for the radiocarpal fracture-dislocation probably involves:
-A position of dorsal hyperflexion in general;
-Torsion [9, 15, 8];
-Lateral inclination [9].
Several arguments support such a mechanism: anamnestic arguments. Y. Gerard [9], for example, specifies that in two cases the mechanism was well defined by the interrogation: trauma occurring on a hand supported on the palmar surface in dorsal flexion and complete pronation; experimental arguments, notably the work of Weiss [23] who attempted to reproduce the injury mechanism in cadavers. This would probably involve hyperextension and pronation; radiological arguments. Dislocation, comminution of the articular rim, and more or less comminuted cuneiform fracture are evidence of probable radial impaction, probably caused by forced flexion and torsion. The fracture of the ulnar styloid is evidence of a probable mechanism of detachment, possibly caused by lateral inclination and torsion. The lower radioulnar dislocation, sometimes associated, is evidence of a torsion mechanism [19].
Dorsal dislocation is by far the most frequent form. Our findings are consistent with those in the literature, but it should be noted that all forms can be encountered: palmar [3, 6, 7, 11, 14], radial [2], or combined: dorso-cubital [2]... Pure dislocations are exceptional: only 3 cases have been described: Destot [5], Bohler [3]. Associated fractures are typical, the most common being the posterior marginal fracture as well as an external wedge fracture that takes away a portion of the postero-inferior end of the radial styloid tip [4, 6, 8]. Radiocarpal dislocations can also be associated with intracarpal lesions [4] or perilunate injuries [9]. Neurological involvement is common in the literature; Moneim [4] described a ulnar nerve injury in two patients who recovered completely. The regressive involvement of the median nerve, which seems to be the most frequent [1, 5, 8, 10], is due to its stretching over the deformed skeleton. In severe and open trauma, the rate of neurological complications rises to 100%. Tendon injuries are exceptional - Nyquist [15] reported a case of flexor rupture at the wrist during a dislocation-fracture with anterior opening. Cutaneous opening was found in a few cases [3, 19] but mainly in Nyquist's series [15], which adds an infectious risk to often major osteoarticular and nerve lesions. Although Mugdal et al. [1] found four cutaneous openings in 12 cases, Nyquist et al. [10] described ten cases, with etiologies mainly limited to traffic accidents and falls. An in-depth study of the literature has shown no reported cases in sports practice. In Nyquist's series [10], patients were treated with debridement, open reduction supplemented by internal or external fixation. The majority of cases had ipsilateral limb fractures or dislocations, explaining the violence of the initial trauma. The median and/or ulnar nerve was contused in seven cases, requiring immediate decompression. Six patients were followed for an average of 15 months. Recovery was variable. Overall results were poor, regardless of treatment, with an average flexion-extension range of motion of 57°, and constant arthritic remodeling on follow-up radiographs. Surgical treatment involves longitudinal traction reduction, external or internal fixation to immobilize the joint, and synthesis of various associated bone injuries. The radiocarpal joint is then examined through the palmar wound by exploring the integrity of the tendinous, vasculonervous, and capsular elements. Careful debridement is necessary. The carpal tunnel and Guyon's canal can be decompressed as needed. Intraoperative radiography is used to identify carpal fractures or sprains of the interosseous ligaments, especially the scapholunate or lunotriquetral ligaments. If affected, capsuloligamentous surgery is necessary to prevent arthritic progression [4, 10, 13], which ensures good long-term results. A plaster cast can be associated for six to eight weeks [7, 12].
