The effect of rotatory subluxation of the scaphoid on radio-scaphoid contact.

The effect of progressive rotatory subluxation of the scaphoid on radio-scaphoid contact area was examined in a cadaveric model. Five degrees of subluxation reduced the contact area of the proximal pole by 44%, with a shift to the dorsal lip of the radius. At 20 degrees of subluxation the contact area was reduced by 77%, with a shift radially to the dorsal lip of the radial styloid. These findings explain the progression of radio-scaphoid arthritis from the radial styloid to the remainder of the fossa and reemphasize the importance of operative reduction of a scapho-lunate disassociation in the prevention of degenerative arthritis.