Here's what I would try if it were mine. Hold your left hand out, palm up, fingers toward the right, in front of your chest. Lay the chick's belly in your left hand, feet pointing back toward your body, overhanging your pinky finger/palm. Grasp the feet and legs between your right thumb and forefinger. Slowly lower your left hand (kinda bowling ball or lawn-dart starting motion) and let the bird dangle for just a few seconds. Twist your wrist outward, and the bird's reaction should be to lift its head/chest/body upward toward your hand. (keep your hand under, but not touching, and don't drop her! lol) When it does, you can re-grab the body. This will sometimes "reset" a slipped hip or knee joint. It won't hurt the bird, and I would think its worth a try.