There are several common reasons why the knees do not come together: First, osteoarthritis of the knee joint, which leads to increased wear and tear of the medial joint space and even bony defects, causing the knee joint to turn sideways. Second, epiphyseal injury of the knee and proximal tibial fracture, both of which can lead to inversion deformity of the knee joint and inability to bring the knee joint together. Third, osteochondrosis, commonly seen in rickets, is prone to calf flexion in the lower extremities with weight bearing, leading to knee valgus. Fourth, elongation of the lateral collateral ligament of the knee, common in horseback riders, can lead to inversion deformity of the knee, increased spacing between the femoral condyles on both sides, and joint pain when arthritis occurs.