494 THE INFERIOR EXTREMITY 



and produces a prominence on the medial border of the foot in 

 front of the medial malleolus. The downward displacement 

 of the talus is accompanied by lateral deviation of the foot, 

 and the body-weight is carried on the collapsed longitudinal 

 arch. 



Deformities of the Foot. Talipes may be either a 

 congenital or an acquired deformity and may affect one or both 

 feet. In Congenital Talipes the foot develops in the faulty 

 attitude and the bones are therefore modified in shape, while 

 some of the soft structures are lengthened and others are 

 shortened. In Acquired Talipes, which usually results from 

 acute anterior poliomyelitis and occasionally from cerebral 

 palsy or nerve injuries, the attitude of the foot depends on the 

 over-action of some muscle or muscles following parsesis or 

 paralysis and atrophy of its antagonists. 



Four primary deformities are recognised: (i) Talipes Equinus, 

 in which the heel is raised and the toes are pointed ; (2) Talipes 

 Calcaneus, in which the foot is dorsi-flexed and the long axis 

 of the calcaneus becomes nearly vertical ; (3) Talipes Varus, 

 in which the foot is inverted ; (4) Talipes Valgus, in which the 

 foot is everted. Combinations of these primary deformities 

 may occur, including Talipes Equino-varus by far the 

 commonest of all the varieties of talipes Equino-valgus, 

 Calcaneo-varus and Calcaneo-valgus. 



(1) Talipes Equinus. When the condition is congenital, 

 the muscles of the posterior compartment of the leg and the 

 plantar aponeurosis are shortened secondarily to the faulty 

 position. When the condition is acquired, it is caused by the 

 tonus of the muscles of the posterior compartment, which are 

 unopposed owing to paralysis or parsesis of the muscles of the 

 anterior compartment of the leg. All the anterior muscles are 

 not necessarily involved and one or more of them may escape. 



(2) Talipes Calcaneus. When the condition is congenital, 

 the tendons of the muscles of the anterior compartment of the 

 leg are shortened, while the muscles of the posterior compartment 

 are overstretched. When the condition is acquired, it is caused 

 by the tonus of the muscles of the anterior compartment, which 

 are unopposed owing to paralysis of the posterior muscles. As 

 in the other varieties of acquired talipes, the degree of the 

 deformity depends on the extent of the paralysis, the condition 

 being most marked when both the superficial and the deep 

 muscles are affected. 



