Dados do Trabalho

Título

DORSORADIAL WRIST BUMP: THE DISAPPEARANCE OF THE ANATOMICAL SNUFFBOX AS A SIGN OF “SLAC” WRIST

Introdução e Objetivo

Biomechanical studies have shown that chronic injury to the scapholunate ligament associated with loss of secondary stabilizers causes the scaphoid to pronate and flex, thereby resulting in its dorsal radial projection within the scaphoid fossa of the radius. If left untreated, these patients can progress to scapholunate advanced collapse (SLAC).

Material e Método

Pointing to the sign of snuffbox disappearance, we aim to alert doctors that patients with SLAC wrists, in addition to the classic symptoms of pain, stiffness and loss of strength, will present with a loss of the normal contour of the dorsoradial edge of the wrist, along with an increased volume of that region. The osteophytes that form on the edge of the distal radius (at the scaphoid fossa), the rotatory subluxation of the scaphoid, causing protrusion of the proximal pole of the scaphoid, and the chronic inflammatory process can cause joint capsule thickening, synovitis, and edema of the radial extensor tendons.

Resultados

Thus, through direct arthroscopic visualization, we observed that the degenerative process of the SLAC (scapholunate advanced collapse) wrist starts at the dorsoradial region of the distal radius, progressing in an oblique fashion to volar and ulnar, different from what has been previously proposed. Due to this structural change of the region, it is clear that patients with moderate or severe SLAC lesions, on initial clinical assessment, present with a characteristic deformity of the wrist which we have called the disappearance of the anatomical snuffbox or the “dorsoradial wrist bump”.

Discussão

The anatomical snuffbox is a triangular region located in the dorsoradial portion of the wrist1. Its boundaries are defined by the tendons of the extensor pollicis longus (dorsally); extensor pollicis brevis and abductor pollicis longus (volarly); and the dorsoradial edge of the distal radius. Its floor is formed by the carpal bones (scaphoid and trapezium) and contains the dorsal branches of the radial artery and radial nerve (Figure 1). The anatomical snuffbox becomes more pronounced when the thumb is extended.1,2,3

Conclusão

We describe a clinical finding noted in these patients with disappearance of the anatomical snuffbox with the development of a “dorsoradial wrist bump”.