No known hereditary tendency; boys affected three times more frequently than girls
Manifestations:
(1) Hard bony swellings affecting the inner or outer aspects of the knee and ankle of one lower extremity, especially talus (2) Unilateral knock knee deformity (3) Pain, deformity, and restricted motion
Chief Roentgen Manifestations:
(I) Irregular deposition of calcium in the cartilage on one side of an epiphyseal ossification center, more often medially (2) The individual lesion is an osteochondroma
Chief Clinical
Other
important
Differential
Details:
Knee may be involved before the ankle lesion appears
Variants:
Capital femoral epiphysis affected, round bones of the wrist and distal ulna involved
Fig. A. Progressive involvement in a lo-mo-old girl with unilateral knock knee deformity and prominent bony swelling along the medial aspect of the right knee. The unilateral valgus deformity is apparent. There are small round clusters of calcium distal and medial to the distal femoral epiphyseal ossification center. Fig. B Pneumoarthrogram (figure reversed) shows the clusters of calcium within the cartilage of the epiphysis. Histologically this was an osteochondroma. Fig. C. At age 3 both epiphyseal centers in the right knee are affected. The valgus deformity has been partially corrected by surgical removal of part of the osteochondroma. The right ankle is radiographically normal. Fig. D. At 5 yr of age, an osteochondroma protrudes from the medial aspect of the distal tibia1 epiphysis (arrow). 174