Purpose: In most large series of congenital differences there are always a few hypoplastic hands which do not fit into any common classification system and are hidden as isolated cases among typical cleft hands, symbrachydactyly, oligodactyly, ectrodactyly and radial polydactyly. Treatment has been individualized. There are no detailed reports in the literature outlining the principles of treatment and outcomes.
Methods: A series of 35 hypoplastic hands in 32 children has been collected from the senior author’s large database of congenital hand differences collected over 30 years of practice. Radiographs, kodacrome slides, digital images, medical records and plastic casts were available for review. Videotapes of several patients playing musical instruments were also analyzed.
Results: All hands were hypoplastic and contained a thumb and one or two digits. There were no associated malformations and in 29 children the deficiency was unilateral. All family histories were unremarkable. A classification system similar to that used for routine radial polydactyly was developed and a teratologic sequence became clear. The deviation of the thumb was always in a radial direction and the polydactyly most often branched at the phalangeal level. Phalanges with longitudinal epiphyseal brackets were common and all types of intermediate thumb phalanges were seen. The degree of complexity was proportional to the level of polydactyly. Surgery was performed on all patients and included initial syndactyly release, secondary rotation-recession osteotomies, radial clinodactyly correction and frequently re-separation of the central web space. Remarkable function was achieved in all hands despite their limited pinch strength, digital span, loss of volumetric grip and small size.
Conclusions: For the first time a group of previously “unclassifiable”two and three fingered hands with radial polydactyly is presented with a classification system which impacts upon treatment. Staged construction consists of initial separation and creation of a well-lined web space, secondary optimal repositioning of the rays with metacarpal osteotomies, and finally thumb clinodactyly correction when the thumb is larger. All are completed by school age. Re-widening of web spaces to improve span were commonly performed later in childhood or during the adolescent years. The adaptive function of these compromised hands has been remarkable and will be demonstrated.