42 
Split-Hand and Split-Foot Deformities 
herself. Of the five deformed children of IV, 23, four have cross-bones in each and 
the fifth in one hand, and this in spite of the fact that the father's hands are free 
from it (Figs. 22, 23). 
Cross-bones of a somewhat different character have been reported by many 
writers*' ^' and have been discussed by Perthes. Such cross-bones are 
obviously displaced phalanges, lying across the head of the 3rd metacarpal or 
articulating with phalanges of the second row. The method in which such cross- 
bones, as are figured in v. Bergmaun's Surgery (Figs. 183, 184), are formed is 
strictly comparable to the method of production of a distal bony syndactyly. 
The hand shown in Fig. 10 shows a very similar condition, though more advanced. 
In this figure though the 1st phalanges appear to be united, yet when screened 
there was a doubt about it. The main cross-bone in this figure can only be 
interpreted as the 1st phalanx of the 4th finger, and the shorter piece, perhaps 
united with it, as the corresponding phalanx of the 5 th. A similar explanation 
Avill not apply to the t} pe shown in Figs. 6 and 7, for complete sets of phalanges 
spring from the triple joints. Moreover the presence of two epiphyses precludes 
the possibility of interpreting the cross-boue as one phalanx. A further ex- 
planation must consequently be sought. Now there can be but two possibilities, 
for either the cross-bone is an entirely new formation or it is developed from the 
representatives of parts normally present. In regard to the last there are two 
explanations, the cross-bone may represent phalanges or metacarpals. The latter 
is excluded by such hands as the left of V, 45, in which all the metacarpals are 
present. The cross-bone may thus be said to represent either united phalanges 
or to be an entirely new formation. If the former view is adopted the phalanges 
concerned must necessarily be those normally situated further to the radial side 
of the hand than the position of the cross-bone itself ; for instance in the right 
hand of V, 45 (Fig. 14) they should come from the 2nd and 3rd digits, and in V, 41 
(Fig. 6) from the Srd and 4th. There is no difficulty in the way of accepting this 
displacement, for such cross-bones are the only possible representatives of the 
phalanges corresponding to those fingers which lie between the space bridged by 
the cross-bone and the thumb (compare the hand of V, 40 (Fig. 13) and the 
subsequent explanation of her deformity). The view that the cross-bone is 
developed from ossifying centres which normally represent phalanges is by far 
the most plausible and is further supported by the following considerations. In 
all the cross-bones there is a strong resemblance between the extremities of 
the bones and the bases of 1st phalanges. In the right hand of V, 40 (Fig. 12), 
the cross-bone is bent and indicates such a union. In the hands of V, 42 
(Figs. 18, 19) a cross-bone on the left side (Fig. 19) is replaced on the right 
(Fig. 18) by the proximal half of a 1st phalanx. Lastly there can be no doubt 
that in the cross-bones shown in Figs. 10 and 13 phalanges are represented, and 
when this is taken into consideration with the fact that cross-bones in other 
families can only receive rational explanation in this way further evidence is 
hardly wanting. Our conclusion is that in the hands of V, 41 (Figs. 6, 7) 
