So Mephibosheth ate at David's table like one of the king's sons. Mephibosheth had a young son named Mica, and all the members of Ziba's household were servants of Mephibosheth. And Mephibosheth lived in Jerusalem, because he always ate at the king's table, and he was crippled in both feet. You never read in here that David was able to cure the cripple and make him able to walk. We cannot walk a life that is perfect before our King.
Humans are always cripples.
Our best efforts are not enough. There are more deep lessons to be learned from this beautiful story if we continue to plumb its depths. Once Mephibosheth savored an unbroken companionship with his father. 6000 years ago Adam walked in close daily fellowship with his father. Disaster struck suddenly and Mephibosheth suffered when his nurse dropped him.