My son was opening a door with a closed fist and someone pushed the door open from the other side which resulted in sharp force on the 2 middle knuckles of my sons hand. There is swelling and bruising over the 2 middle knuckles and he has difficulty making a fist or pushing the fingers backwards. Either move causes pain over the knuckle area. He can bend his fingers at the middle with no issues. Pain is isolated to the knuckles. Can this just be soft tissue injury or possible fracture?