2. In the va/gus, (see fig. 164), where the foot is turned in the opposite direction to that which has been just described, the whole state of the foot seems to be pretty nearly the exact converse of every thing there mentioned. The same bones are affected, and in the same tive degree ; and the same analogy which exists between the one condition and the phenomena of adduction, is found between the other and those of abduction. The dorsum faces more or less directly forwards, the plantar surface backwards, the inner side of the foot rests upon the ground, the outer is uppermost. The tibia frequently here participates in the deformity so far as to have a curve inwards, and the inner ankle consequently approaches to the ground. The double articulation between the first and second row of bones in this case also suffers the most. The astragalus sometimes projects in front, and lower than in the yams. The distortion is sometimes carried to such an tent that the foot is turned nearly upwards and at the side of the fibula. The os calcis is twisted outwards, with the heel elevated, its hollow inclining wards the ground. The scaphoid and cuboid bones are, as we have said, most displaced ; the first being nearest the ground, the last placed uppermost, and near the outer lus. The cuneiform bones, and the other bones of the foot,retain their relation to the bones to which they are articulated, their unnatural situation ing the result of the displacement of these. 3. The pcs equinus, (seefig.165,) so named from the resemblance in the position of the sus to that of the horse, differs from either of the others in its anato mical characters. \Then it has arrived at a con siderable pitch, the tibia is found partially dislo cated backwards upon the os calcis; the sca phoid and cuboid are carried backwards, to wards the sole of the foot, leaving the tipper part of the head of the astragalus and cuboides projecting; the cuneiform and metatarsal bones are displaced sometimes in a similar manner. Thus the whole foot is more arched than natural, independently of its altered position ; the sole is shortened and hollowed, the dorsum is elongated and projecting.
A very interesting history of yet another form of this disease by M. Holz of Strasburg, is given in the 13th vol. of the Lancet, in which the foot was turned completely back, having the dorsum restiog on the ground, the plantar surface being uppermost. The deformity was in both feet. NValking was not painful; the patient rested his weight on the tarsus; the metatarsus and toes did not touch the ground. Ile wore common half-boots, the toes of which pointed backwards and the heels forwards. The man died, and upon examination of bis feet the fol lowing state of parts was found. The skin of the dorsum upon which he trod was hard and callous. The bones of the leg were well formed ; the astragalus was dislocated forwards; the calcaneum forwards and outwards, and the cuboid downwards on the calcaneum. The dorsal surface of the foot was very convex, ex cepting at the spot which touched the ground ; the plantar surface very concave. The supe rior articular surface of the astragalus was turned directly forward and a little downward ; its posterior surface also looked forward, and the tibia rested on the inferior, in a great de gree, and on the small process of the calca neum. The connexion of the scaphoid with
the astragalus was more natural ; the scaphoid was, however, turned a little backward. The cuboid rested by its posterior part on the inferior surface of the os calcis. The articular surfaces of the astragalus and os calcis gave attachment to ligamentous fibres. The three cuneiform bones, the metatarsal bones, and the toes had not experienced any sensible change in their position.
The descriptions now given are of extreme cases in each of the species of deformity. Of course the degree of departure from the natural form varies in every case. In the varus, every intermediate shade between the extreme men tioned and the mere state of permanent adduc tion occurs. The state of fixed abduction may, in the same way, be called the milder extreme of the valgus, while the pes equinus shows its simplest form in the mere fixed extension of the foot.
We also find in some instances a combina tion of more than one form of the deformity in the same foot. The most frequent of these is the state of permanent extension, of the pes equinus, with the adduction of the metatarsal bones and phalanges, constituting a variety of the varus. (fig. 166.) The same complication of the pes equinus with the valgus is rare, but does sometimes occur. A congenital deformity, so far as we know not mentioned, has once fallen under our no tice, namely, a dislo cation of the tibia back wards upon the upper and posterior part of the os calcis, so that the prominence of the heel was entirely lost, and the foot flexed to such a degree, as that the dorsum lay in contact with the anterior part of the The alterations from the normal state of the ligaments, bones, mus cles, and articular sur faces, in these cases of deformity, are easily comprehended. The ligaments are of course elongated on the one side of the dislocated joint, and shortened on the other side ; the bones are altered in shape, occasionally, where pressure is produced by a neighbouring bone, and sometimes a portion of the bone is twisted, and drawn towards the unna tural situation of that one with which itarticulates. The muscles are elongated or shortened, accord ing as their points of attachment are, by the deformity, approximated or further separated. The articular surfaces undergo great alterations they are altered in shape and situation by the friction of the parts in contact producing a new synovial surface upon its new situation, while a part, or the whole of the natural joint loses its polished surface, and becomes adherent to the integuments, while, in many instances, the altered position of a bone brings it into contact with another, with which naturally it had no such relation, and here again a preternatural synovial articulation will form, in accordance with the same law of the animal economy, by which long-continued pressure will produce a synovial bursa. As a general observation, we may state, that the whole limb is smaller, shorter, and feebler than the sound one, and that this defect increases by comparison with the sound one, as the child grows. M. Cru veilhier has also found that individual bones are sometimes singly defective in their growth, while occasionally only the portion of a bone which is subjected to pressure is checked in its developement.