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. CASES Case 1: Female with bilateral cleft hand. She was the first child and had no relatives with congenital anomalies. Her right hand retained the thumb, ring finger and small finger only; the ring finger was webbed with the small finger. Her left hand retained the thumb, index finger, ring finger and small finger. The thumb was webbed with 76 T. Miura and E. Horii a b Fig. 7 a: Right hand retained the thumb, ring finger and small finger only. The thumb of the left hand was webbed with the index finger, and synostosis between the distal phalanges of the thumb and index finger was present. The thumb of the right hand had a triangular extra phalanx and the base of the bone was on the ulnar side. b: The distal phalanx was bifurcated as seen in Wassel’s type 1 duplicated thumb. The first metacarpal bone was delta shaped and had a continuous epiphysis running from the proximal to the distal end (longitudinally bracketed epiphysis). Triphalangeal thumb in the typical cleft hand 77 the index finger; synostosis between the distal phalanges of the thumb and index finger was present (Fig. la). Both feet were cleft foot. The thumb of her right hand had a triangular extra phalanx in the interphalangeal joint, and the base of the bone was on the ulnar side (triphalangeal thumb). The distal phalanx of the right thumb was bifurcated as seen in Wassel’s type 1 duplicated thumb (Miura, 1981). The first metacarpal bone was delta-shaped and had a continuous epiphysis running from the proximal to the distal end along the shortened side (Fig. lb). Case 2: Female with bilateral cleft hand. She was the second child and had no relatives with congenital anomalies. Both hands retained the thumb, ring finger and small finger only. Both feet were cleft foot. The thumbs of both hands had triangular extra phalanx in the interphalangeal joint, and the base of the bone was on the ulnar side (triphalangeal thumb) (Fig. 2). The distal phalanx of the right thumb was perforated in an incipient form of polydactyly (Kelikian, 1974, Miura, 1976b, 1981). The first metacarpal bone was longer than normal and had two epiphyses, one at the distal and one at the proximal end (Miura, 1978). Case 3: Male with bilateral cleft hand. He was the second child and had no relatives with congenital anomalies. Both hands retained the thumb, ring finger and small finger only. Both feet were cleft foot. Four metacarpal bones were found and two of them corresponded with the ring fiiger. The thumb was normal diphalangeal and the first metacarpal bone had one epiphysis at the proximal end (Fig. 3). Case 4 Female with bilateral cleft hand. She was the first child and had no relatives with congenital anomalies. Both hands retained the thumb, ring finger and small finger only. Both feet were cleft foot. There were five metacarpal bones. One proximal phalangeal bone which corresponded to both the second and third metacarpal bones was crossed and fused to the proximal phalanx of the ring finger. The distal phalanx of the ring finger was bifurcated in the manners of a duck bill (Miura, 1981). The metacarpal bone of the right thumb was Fig. 8 The thumbs of both hands had triangular extra phalanx,. and the base of the bone was on the ulnar side. The first metacarpal bone was longer than normal and had two epiphyses. 78 T. Miura and E. Horii Fig. 9 The thumbs of both hands were normal diphalangeal and the first metacarpal bone had one epiphysis at the proximal end. Fig. 10 The proximal phalanx of the long finger which corresponded to both the second and third metacarpal bone was crossed and fused to the proximal phalanx of the ring finger. The distal phalanx of the ring finger was bifurcated. The thumbs of both hands were diphalangeal. bifurcated. The thumbs of both hands were diphalangeal, but there was a wide interphalangeal joint space of the left thumb (Fig. 4). Case 5: Female with bilateral cleft hand. She was the third child and had no relatives with congenital anomalies. Both hands retained the thumb, ring finger and small finger only. Both feet were cleft foot. Cleft lip and palate were complicated. The thumbs of both hands had a triangular extra phalanx in the interphalangeal joint, and the base of the bone was on the ulnar side (triphalangeal thumb). There were five metacarpal bones; the Triphalangeal thumb in the typical cleft hand 79 3 Fig. 11 The thumbs of both hands had a triangular extra phalanx, and the base of the bone was on the ulnar side. There were five metacarpal bones; the second metacarpal bone was fused to the first metacarpal bone at the distal end. The first metacarpal bone had two epiphyses. a0c? Fig. 12 Right hand retained the thumb, index finger, ring finger and small finger. The thumb was webbed with the index finger. The thumb of the left hand had a triangular extra phalanx, and the base of the bone was on the ulnar side. The first metacarpal bone was delta shaped. second metacarpal bone was fused to the first metacarpal bone at the distal end. The first metacarpal bone had two epiphyses, one at the distal which joined with the second metacarpal bone and one at the proximal end (Miura, 1976a) (Fig. 5). The third and fourth metacarpal bones corresponded with the ring finger, and the distal phalanx of the ring finger was bifurcated in the manner of a duck bill (Miura, 1981). Case 6: Male with bilateral cleft hand. He was the second child and had no relatives with congenital. anomalies. His left hand retained the thumb, ring finger and small finger only. His right hand retained the thumb, index 80 T. Miura and E. Horii finger, ring finger and small finger. The thumb was webbed with the index finger, and the ring finger was webbed with the small finger. The thumb of his left hand had a triangular extra phalanx in the interphalangeal joint, and the base of the bone was on the ulnar side (triphalangeal thumb). Only three metacarpal bones were found in his left hand, and the first metacarpal bone was delta shaped. In his right hand four metacarpal bones and rudimental third metacarpal bone were found (Fig. 6). DISCUSSION Ten hands from 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 six patients were bilaterally involved; five were complicated with cleft foot. Six hands of four patients (Cases 1, 2, 5, and 6) had a triangular extra phalanx in the interphalangeal joint of the radial digit (triphalangeal thumb). The base of the triangular extra phalanx was on the ulnar side (Miura, 1976b). The metacarpal bones of these triphalangeal thumbs showed signs of digital union. The radial digit in two hands from one patient (Case 5) had two metacarpal bones which were fused at the distal end. In the two hands of another patient (Case 2), the first metacarpal bones had two epiphyses, one at the distal end, like a second metacarpal, and one at the proximal end, like a first metacarpal. These were longer than normal first metacarpals and looked more like a second metacarpal (Miura, 1984). In other two patients (Cases 1 and 6) the first metacarpal bone was delta-shaped, delta phalanx was frequently associated with syndactyly and polydactyly (Wood, 1977), and syndactyly between the thumb and index finger was found on the opposite hands. The distal phalangeal bones of these triphalangeal thumbs also showed signs of digital union. One of the distal phalangeal bones (Case 2) was perforated as like an incipient form of polydactyly (Kelikian, 1974). Another of the distal phalangeal bones (Case 1) was bifurcated like Wassel’s type 1 duplicated thumb. Four hands of two patients (Cases 3 and 4) had normal diphalangeal thumbs.