Recent Knowledge on the Cleft Hand : it's Pathologic Pattern and Scope

Cleft hand is an anomaly in which the primary feature is oligodactyly, and it is considered an important congenital malformation. The authors have analyzed the cases they have handled and developed an independent classification based on the number of defective digits. It has been ascertained that the clinical symptoms correlate with the number of defective digits, and a regular pattern was observed. Study of cases considered to be in the main stream led us to feel that polydactyly of the middle finger is the developmental mechanism for this entity. That is, we feel that the polydactylous partner on the radial side is transpositioned to the index finger while the same on the ulnar side is transfered to the ring finger, which is followed by fusion of the respective rays resulting in the loss of the middle finger.

Generally when refferring to the central fingers, it often the case that reference is being made to the index, middle and ring fingers. The kind of morphological anomalies that develop when cleft hand changes similar to the those of the middle finger occur in the index or ring finger are shown by schematic diagrams. As a result, in the case of index finger involvment, in addition to cleft hand of the index finger, there is development of Wassel VII type polydactyly of the thumb and single type triphalangeal thumb can be considered, while in the case of the ring finger, the occurence of polydactyly of the little finger in addition to cleft hand of the ring finger can be considered.

Pursuit of such changes in the clinical cases from the standpoint of morphology or symptoms, indicates that many cases which had been difficult to diagnose in the past had findings which agreed with the above, which surved to confirm the presence of such a developmental course.

That is, cleft hand is not a diagnosis to be assigned to a fixed morphological condition, but indicates a set scope, and from the standpoint of site it involves not only the middle finger, but it is obvious it can develop in any of the other central fingers as well. However, attention should be paid to the fact that the cleft hand changes which develop in the index and ring fingers present an entirely different morphology from that of the concept entertained in the past.

The above developmental mechanism is an anomaly in the distribution of digital rays which occurs to the formation of polydactyly within the hand plate, considered to be based upon this anomaly. It is presumed to be a typical congenital anomaly which occurs during the hand plate formation stage.