Kienböck's disease with congenital capitohamate coalition in an ulnar ray defect: a case report.

We report a patient who developed Kienböck's disease with congenital capitohamate coalition and absence of the little finger: an ulnar ray abnormality of the hand without hypoplasty or defect of the ulna at the forearm. Kienböck's disease combined with an ulnar ray abnormality is a rare situation and the force distribution is unclear. The etiology of the Kienböck's disease is still obscure, so numerous surgical procedures have developed. Capitohamate fusion is one of them, but the case reported here highlights the fact that capitohamate fusion may be a questionable treatment for Kienböck's disease.