Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis.
OBJECTIVE
To clarify quantitatively the 3-dimensional deformity of the carpus in scaphoid nonunion on the basis of fracture location.


METHODS
Three-dimensional computed tomography was used to examine 20 patients with scaphoid nonunion. Displacements of the distal and proximal fragments of the scaphoid, lunate, triquetrum, and capitate were visualized and quantified using a 3-dimensional image-matching technology. Cases were categorized as distal fracture (16 cases) or proximal fracture (4 cases) based on the location of the fracture line relative to the dorsal apex of the scaphoid ridge where the dorsal scapholunate interosseous ligament is attached.


RESULTS
The displayed distal scaphoid fractures showed that the proximal fragment of the scaphoid, lunate, and triquetrum rotated into extension and supination. The distal fragment of the scaphoid and capitate translated dorsally without notable rotation. The deformity in proximal fractures was less remarkable than that in distal fractures. Most distal scaphoid nonunions had dorsal intercalated segment instability deformity patterns, whereas a dorsal intercalated segment instability occurred in only 1 case of a proximal fracture.


CONCLUSIONS
Whether the fracture line passes distal or proximal to the dorsal apex of the scaphoid determines the subsequent carpal deformity. Dorsal translation of the distal fragment might be one of the factors in the development of degenerative change at the radial styloid.
Oka
Kunihiro
K
Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan. oka-kunihiro@umin.ac
Moritomo
Hisao
H
Murase
Tsuyoshi
T
Goto
Akira
A
Sugamoto
Kazuomi
K
Yoshikawa
Hideki
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D002348:Carpal Bones / Q000000981:diagnostic imaging*; D005260:Female; D005599:Fractures, Ununited / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D021361:Scaphoid Bone / Q000000981:diagnostic imaging* / Q000293:injuries*; D014057:Tomography, X-Ray Computed