Triphalangeal Thumb in the Typical Cleft Hand
Cong. horn.,36: 75-81, 1996 Original Triphalangeal Thumb in the Typical Cleft Hand Takayuki MIURAl and Emiko HORI12 'Health Service Center, Chukyo University, 101 Tokodate, Kaizu-cho, Toyota-shi, Aichi 470-03, Japan, and 2Department of Orthopaedic Surgery, Branch Hospital, Nagoya University, 1-1-20, Daiko-minami, Higashi-ku, Nagoya 461, Japan. ABSTRACT Ten hands of six patients with only a single digit retained on the radial side of the cleft were observed from a group of 63 patients with typical cleft hand. All patients were bilaterally involved, and five were complicated with cleft foot. There were two types of retained thumb: a triphalangeal thumb with characteristic metacarpal bone(s), six hands of four patients; and a normal diphalangeal thumb, four hands of two patients. The meta- carpal and distal phalangeal bone(s) of the triphalangeal thumb in typical cleft hand had signs of digital ray union: double epiphysis, deltametacarpal, bifurcated or perforated dis- tal phalanx. Key words: congenital hand anomaly, cleft hand, triphalangeal thumb, delta phalanx, double epiphysis, case report In 68 of 81 hands with typical cleft hand, observed in 63 patients from 1969 to 1993 at the Branch Hospital of Nagoya University, only the long finger was missing. The index and long fingers were absent in only 10 hands of six patients. The retained thumb in cases with only a single digit on the radial side of the cleft was triphalangeal in six hands, and diphalangeal in four. In this study the clinical features of the tripha- langeal thumb were compared with the diphalangeal thumb. These were found to have characteristic and interesting features which could help determine the embryonic failures of the typical cleft hand.
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