SURGICAL ANATOMY OF THE FOOT. 311 



internal sesamoid bone is to be felt. Lastly, the expanded ends of the bones forming the last 

 joint of the great toe are to be felt. On the outer side of the foot the most posterior bony 

 point is the outer tuberosity of the os calcis, with the ridge separating the posterior from the 

 outer surface of the bone. * In front of this the greater part of the external surface of the os 

 calcis is subcutaneous ; on it, below and in front of the external malleolus, may be felt the pero- 

 neal ridge, when this process is present. Farther forward, the base of the fifth metatarsal bone 

 forms a prominent and well-defined landmark, and in front of this the shaft of the bone, with 

 its expanded head, and the base of the first phalanx may be defined. The sole of the foot is 

 almost entirely covered by soft parts, so that but few bony parts are to be made out, and these 

 somewhat obscurely. The hinder part of the under surface of the os calcis and the heads of the 

 metatarsal bones, with the exception of the first, which is concealed by the sesamoid bones, 

 may be recognized. 



Surgical Anatomy. Considering the injuries to which the foot is subjected, it is surpris- 

 ing how seldom the tarsal bones are fractured. This is no doubt due to the fact that the tarsus 

 is composed of a number of bones, articulated by a considerable extent of surface and joined 

 together by very strong ligaments, which serve to break the force of violence applied to this 

 part of the body. When fracture does occur, these bones, being composed for the most part 

 of a soft cancellous structure, covered oaly bv a. thiri shell f pnr- g 



- i TrjS' f * - 1 " -***4 IT 1 * 



the iractures are producea by 



comminuted, especially as most of the iractures are producea by afreet "violence. And na 

 only a very scanty amount of soft parts over them, the fractures are very often compound, and 

 amputation is frequently necessary. 



When fracture occurs in the anterior group of tarsal bones, it is almost invariably the result 

 of direct violence ; but fractures of the posterior group, that is. of the calcaneum and astrag- 

 alus, are most frequently produced by falls from a height on to the feet ; though fracture of 

 the os calcis may be caused by direct violence or by muscular action. The posterior part of the 

 bone, that is. the part behind the articular surfaces, is almost always the seat of the fracture, 

 though some few cases of fracture of the sustentaculum tali and of vertical fracture between 

 the two articulating facets have been recorded. The neck of the astragalus, being the weakest 

 part of the bone, is most frequently fractured, though fractures may occur in any part and 

 almost in any direction, either associated or not with fracture of other bones. 



In cases of club-foot, especially in congenital cases, the bones of the tarsus become altered 

 in shape and size, and displaced from their proper positions. This is especially the case in con- 

 genital equino-varus. in which the astragalus, particularly about the head, becomes twisted and 

 atrophied, and a similar condition may be present in the other bones, more especially the navic- 

 ular. The tarsal bones are peculiarly liable to become the seat of tubercular caries from com- 

 paratively trivial injuries. There are several reasons to account for this. They are composed 

 of a delicate cancellated structure, surrounded by intricate synovial membranes. They are situ- 

 ated at the farthest point from the central organ of the circulation and exposed to vicissitudes 

 of temperature ; and, moreover, on their dorsal surface are thinly clad with soft parts which 

 have but a scanty blood-supply. And finally, after slight injuries, they are not maintained in a 

 condition of rest to the same extent as similar injuries in some other parts of the body. Caries 

 of the calcaneum and astragalus may remain limited to the one bone fora long period, but when 

 one of the other bones is affected, the remainder frequently become involved, in consequence of 

 the disease spreading through the large and complicated synovial membrane which is more or 

 less common to these bones. 



Amputation of the whole or a part of the foot is frequently required either for injury or 

 disease. The principal amputations areas follow: (1) Syme's: amputation at the ankle-joint 

 by a heel-flap, with removal of the malleoli and sometimes a thin slice from the lower end of 

 the tibia. (2) Roux's: amputation at the ankle-joint by a large internal flap. (3) PirogofFs 

 amputation : removal of the whole of the tarsal bones, except the posterior part of the os calcis 

 and a thin slice from the tibia and fibula including the two malleoli. The sawn surface of the 

 os calcis is then turned up and united to the similar surface of the tibia. (4) Subastragaloid 

 amputation : removal of the foot below the astragalus through the joint between it and the os 

 calcis. This operation has been modified by Hancock, who leaves the posterior third of the os 

 calcis and turns it up against the denuded surface of the astragalus. This latter operation is of 

 doubtful utility and is rarely performed. (5) Chopart's or medio-tarsal : removal of the ante- 

 rior part of the foot with all the tarsal bones except the os calcis and astragalus ; disarticula- 

 tion being effected through the joints between the scaphoid and cuboid in front, and the astrag- 

 alus and os calcis behind. (6) Lisfranc's: amputation of the anterior part of the foot through 

 the tarso-metatarsal joints. This has been modified by Hey, who disarticulated through the 

 joints of the four outer metatarsal bones with the tarsus, and sawed off the projecting internal 

 cuneiform ; and by Skey, who sawed off the base of the second metatarsal bone and disarticu- 

 lated the others. 



The bones of the tarsus occasionally require removal individually. This is especially the 

 case with the astragalus and os calcis for disease limited to the one bone, or again the astragalus 

 may require excision in cases of subastragaloid dislocation, or, as recommended by Mr. Lund, 

 in cases of inveterate talipes. The cuboid has been removed for the same reason by Mr. Solly. 

 But both these two latter operations have fallen very much into disuse, and have been super- 

 seded by resection of a wedge-shaped piece of bone from the outer side of the tarsus. Finally, 

 Mickulicz and Watson have devised operations for the removal of more extensive portions of 

 the tarsus. Mickulicz' s operation consists in the removal of the os calcis and astragalus, along 



