This is what happens. The first sign is a feeling of tightness in the joint but no real pain. The joint feels a little puffy to the touch. As the hours pass, the joint becomes hot to the touch. Fully flexing or extending the joint becomes painful.
Weight bearing becomes difficult.
By this time, the joint is visibly swollen. As the bleeding continues and the swelling increases, all movement in the joint is lost. The joint becomes fixed in a slightly flexed position in an attempt to relieve the interior pressure in the joint. The pain at this point can be excruciating. The bleeding slows after several days when the joint is so full of blood that the pressure inside the joint cavity is equal to the pressure inside the broken blood vessels.