If X-rays taken for a knee injury show a radiolucent line at the supero-lateral corner of the patella, a comparison view of the other knee will confirm or rule out bipartite patella, since it is usually bilateral. 
Sometimes the injury involves the bipartite patella itself, which could be a separation of the fibrous or cartilage union at the bipartite patella. In those cases, a cylinder cast or knee immobilizer to rest the knee in extension for 4 to 6 weeks usually resolves the problem.