Dachshund leg injury HELP!?

last night I went to hand my younger brother our male dachshund. I thought he had the dog, but he didn't and I dropped him from about 4 feet up on his back leg. He yiked about five times and stopped. It is about 8 hours later and he is still hobbling around on 3 legs. As far as we can tell there is no swelling or bleeding. He does not seem to be in great distress and we can still pet him. He has shown signs of improvement and is now putting some weight on the leg, but very little. This dog had a hip replacement before we owned him. He is about 4 years old. Is it necessary that we take him into the vet or can we wait? If he has a broken leg what would be some signs that he needs medical help?