Congenital synostosis of the knee

Three congenital synostoses of the knee occurred in 2 patients. Complete bony epiphyseal fusion was present on the radiographs. This condition is a failure of joint formation in the early mesenchymal stage at 4--5 weeks gestation and appears as connected cartilaginous cell masses which later ossify. Involvement of other joints has been reported in the literature, but these may be the first documented cases of the condition in knee joints.