Sixty-one cases of the infantile type of tibia vara and ten cases of the adolescent type are reported.

The infantile type: The roentgenographic changes may pass through six stages, depending on the maturity of the skeleton and the degree of growth disturbance. In three patients the development of tibia vara from a state of physiological bow legs was verified roentgenographically. Changes typical of tibia vara do not appear before the age of one year. Early osteotomy is imperative. With correction of the varus deformity into the physiological valgus position, osteotomy gives permanent cure, even of excessive deformity, if performed before the age of eight years. Without operative treatment the disease usually progresses. If osteotomy is delayed beyond the age of eight years serious deformity may occur. In neglected cases, first seen after the patient is nine years old, recurrence can be prevented by epiphyseodesis of the lateral condyle of the tibia and the upper end of the fibula in connection with osteotomy. Excessive laxity of the ligaments of the knee can be corrected by osteotomy and elevation of the medial condyle of the tibia. Microscopic findings in infantile tibia vara and infantile coxa vara suggest that necrosis of cartilage plays an important role in the pathogenesis of both these conditions. They should be grouped together under a common heading.

The adolescent type: The deformity first appears at the age of eight to eleven years. Tomography has shown an osseous bridge between the metaphysis and the epiphysis.