Congenital Carpal Fusion Deformity With Metacarpal Phalangeal Agenesis

A 21-year-old woman presented with a left-hand deformity that had been present since birth. She had no clear family or genetic history. Physical examination revealed absence of the left metacarpal phalanges and four soft tissue bulges at the distal end of the wrist (Figure 1a). Digital radiography showed fusion of the lunate and triangular bones of the left wrist, fusion of the scaphoid with the distal row of carpal bones, and an irregular bone with an uneven distal margin. The metacarpals and phalanges were absent, and four round soft tissue shadows protruded at the end of the wrist's soft tissues (Figure 1b,c). A diagnosis of congenital carpal fusion deformity with agenesis of the metacarpal phalanges was made. Images of a 21-year-old woman with congenital carpal fusion deformity with agenesis of the metacarpal phalanges. (a) Physical examination revealed absence of the left metacarpal phalanges and four soft tissue bulges at the distal end of the wrist. (b, c) Digital radiography showed fusion of the lunate and triangular bones of the left wrist, as well as fusion of the scaphoid with the distal row of carpal bones, forming an irregular bone with an uneven distal margin. The metacarpals and phalanges were absent, and four round soft tissue shadows protruded at the distal end of the wrist. Congenital bone malformation refers to skeletal abnormalities caused by embryonic developmental disorders. Such malformations include agenesis, hypoplasia, or overdevelopment of bones, resulting from disruptions during early embryonic formation [1]. Carpal fusion deformity is rare and most commonly involves the lunate and triangular bones [2]. Devilliers Minnaar [3] classified these deformities into four types, with type IV showing complete fusion of the lunate and triangular bones, often combined with other bone fusion deformities, making it the rarest type. In this case, the deformity was not only characterized by multiple carpal fusion abnormalities but was also associated with agenesis of the metacarpal phalanges, a combination not previously reported in the literature. It is speculated that this may represent a distinct type of carpal developmental deformity. Cong Huang: writing–original draft and review (lead). Zilin Zhao: writing–review and editing (supporting). The authors have nothing to report. The authors have nothing to report. The patient provided written informed consent prior to taking part in this study. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.