Trispiral tomographic staging of Kienböck's disease.

Trispiral tomography enhances the staging of Kienböck's disease and aids in surgical planning. The clinical records, plain x-rays, and trispiral tomograms of 105 patients with Kienböck's disease were reviewed. When tomograms were used, upward revision of the classification stage was indicated in 73% of patients with stage I or stage II disease and in 10% of those with stage III disease. On tomograms, 91% of patients had lunate fractures, compared with 55% on plain films. The most common lunate fracture seen on trispiral tomograms was a transverse shear fracture that represented lunate collapse; the next most common was a midcoronal fracture that may be displaced, causing fragment extrusion palmarly or dorsally. The most common instability pattern was nondissociative proximal row flexion, seen in stage III. Indices of carpal collapse and ulnar translation may be useful in following up patients, but values vary widely among patients.