ABNORMAL CONDITIONS OF THE FOOT. 



347 



FOOT, ABNORMAL CONDITIONS OF 

 THE. The dislocation of any of the bones of 

 the foot is an accident of.unfrequent occur- 

 rence, particularly of the tarsus and metatarsus, 

 where the ligaments are powerful, and the joints 

 very limited in their motions. \Vhen a dis- 

 placement does occur here, the violence neces- 

 sary to produce it is often so great, that the 

 foot is destroyed . Cases, however, are met with 

 where a dislocation of one or more of these 

 bones has been successfully treated without loss 

 of the limb. Sir A. Cooper mentions several 

 instances. The astragalus alone, without the 

 other bones of the foot, is never thrown back- 

 wards, nor is it ever thrown directly inwards 

 nor directly outwards, but it may be dislocated 

 forwards on the instep and then may incline 

 inwards, so as to be situated below and in front 

 of the inner malleolus, or it may incline out- 

 wards and be placed below and in front of the 

 outer malleolus ; the rest of the foot in the 

 latter case is thrown inwards, and in the former 

 outwards. 



In these cases there is what Boyer calls a 

 double luxation of the astragalus, for this bone 

 is not only expelled by violence from the mor- 

 tise-shaped cavity formed for it by the bones 

 of the leg, but is at the same time driven from 

 the space formed between the os calcis and os 

 naviculare, where it naturally rests or plays in 

 standing or progression. 



Most of the ligamenlary ties which bind it 

 to the other bones of the foot and leg are vio- 

 lently ruptured, yet in these cases the surgeon 

 almost invariably finds great difficulty in ex- 

 tracting the bone from its new situation, and to 

 return it back to its original space in general is 

 quite impracticable. 



One reason for the difficulty the surgeon 

 experiences in replacing the luxated astragalus 

 may, we imagine, be found in this, that the 

 bones once expelled by violence, the muscles 

 attached to the tendo Achillis, and, indeed, 

 all those of the leg before and behind, act so 

 on the foot as to have a powerful and effective 

 influence in effacing the interspace between the 

 os calcis and articulating surfaces of the tibia 

 and fibula, so that there is now no room for 

 its return. 



Moreover, it should be recollected that the 

 astragalus is sometimes only partially luxated, 

 and perhaps at the same time has revolved on 

 its long axis in such a way that it shall be 

 placed as it were on its side, as we have known 

 an example, in which the pulley-shaped sur- 

 face of the astragalus looked outwards, the 

 peroneal articular surface looked downwards 

 towards the os calcis, and the facet for arti- 

 culation with the tibial malleolus was placed 

 upwards in contact with that part of the tibia 

 which was naturally shaped for articulation with 

 the upper part of the trochlea of the astra- 

 galus : when the astragalus is thus rotated on 

 its longitudinal axis, a broader part of the bone 

 is wedged in between the tibia and os calcis 

 than the vertical height of the astragalus would 

 measure, and hence there is difficulty in re- 

 storing the bone or removing it. Fig. 161 re- 

 presents the simple dislocation. More than 



Fig. 161. 



one example is mentioned by Sir A. Cooper 

 in which this bone was removed entire after a 

 compound dislocation of it, and yet a very 

 tolerable use of the foot was regained. 



A heavy weight falling upon the foot will 

 sometimes displace the double articulation be- 

 tween the first and second row of tarsal bones. 

 When this accident has occurred, the appear- 

 ance which the limb assumes bears a striking 

 resemblance to the internal variety of the club- 

 foot. In fact this state of the parts really con- 

 stitutes neither more nor less than the pied-bot, 

 with the exception of the difference of the 

 cause, the state of ligamentous connections, 

 and the facility of reduction. 



Dislocation of the other tarsal bones is very 

 rare, yet Sir A. Cooper has seen the inner 

 cuneiform bone displaced in two instances, in 

 neither of which could the bones be reduced. 

 See also Diet, des Sciences Medicales, art. 

 Pied. 



The joints of the toes, as they are more 

 moveable and their ligaments more lax, are 

 more easily dislocated than the other joints of 

 the foot, and especially the great toe, which 

 has more extent of motion than the rest, and is 

 more exposed to the influence of accident. 



Congenital displacement of the bones of the 



