THE FOOT. 577 



inward. Division of the plantar fascia is also often necessary. The main principles 

 of treatment are to stretch the contracted tissues forcibly, either by manual or instru- 

 mental force, and then maintain the foot in its corrected position, often at first by 

 plaster of Paris and later by apparatus, until the weakened opposing muscles have 

 resumed their functions. This often takes so long that transplanting of tendons has 

 been resorted to; thus the tendon of the tibialis anterior has been detached from its 

 insertion on the inner side of the foot and transplanted to the outer side, so that the 

 contracting force on the inner side of the foot is weakened, while the correcting force 

 of the abducting muscles has been increased. 



If equinus is present either tenotomy of the tendo calcaneus (Achillis) or forcible 

 stretching of it allows the heel to descend. 



Talipes Valgus. In talipes valgus the foot is abducted or everted. It is 

 sometimes associated with equinus and sometimes with calcaneus. It is more usually 

 an acquired than a congenital deformity. It is a deformity that has weakness as its 

 primary cause and most marked characteristic. This weakness is either a more or 

 less general one affecting the ligaments and muscles, as shown by its occurring in 

 adolescents, or else primarily a muscular one caused by spinal infantile paralysis 

 (anterior poliomyelitis) (Fig. 596). 



From what has been said of the normal movements of the joints (page 569 and 

 ante) it is evident that a weakness of either the muscles or ligaments shows itself first 



FIG. 596. Paralytic talipes valgus. FIG. 597. Flat-foot. 



by an eversion of the foot called the pronated foot which is followed by a descent of 

 the tarsal arch or flat-foot and later by a more complete eversion or pes valgus: 

 They are the three stages of the same process. 



When a young person with apparently normal feet is subjected to excessive 

 strain, as by long standing, etc., the muscles and ligaments are unable to bear th6 

 burden. The muscles give way first and the foot everts, mainly at the subastragaloid 

 joint, thus is produced the pronated foot. The patient, unable to support the body 

 weight sufficiently on the weakened muscles, relaxes them and allows the body- 

 weight to be borne on the ligaments. This excess of weight on the ligaments sup- 

 porting the arch causes them to give way and the arch descends and flat-foot results; 

 The process often stops here in the adolescent form or even if rheumatism is th6 

 weakening element (Fig. 597). 



When paralysis usually of the extensors and tibialis posterior is the cause,' 

 then the ligaments not being so much affected may maintain the arch intact, but the 

 whole foot is drawn outward by the peroneal and flexor muscles, aided also by the 

 centre of gravity being shifted inward. The deformity is increased by walking and 

 a true valgus results. 



In the pronated foot and flat-foot of adolescents pain is often marked so that the 

 relaxation of the inverting muscles is often accompanied by spasm of the everting 

 muscles and the peronei muscles are frequently found markedly contracted. In 

 paralytic valgus the eversion of the foot relaxes the peronei and they gradually 

 shorten. It should be noted that the contraction of the peroneal muscles in one case 

 is active, in the other passive. 

 37 



