. >> and joining us is marshall lewis and he is chief of the department of physical medicine at st. luke's. >> thank you. >> dr. johnson talked a little bit about pain. can you define it more? >> i think chronic pain is defined partly by time. when pain lasts more than three months but also the debilitating nature of kron ig pain is very serious as it may not get better so severity is another defend of it. >> what are some of the common causes? >> some of the common causes, in our clinic, motor vehicle accidents, sports injuries. involved in athletics or n college and certainly trauma. overtime may have a fall or accident that causes them to get a fracture. sometimes it doesn't heal completely. >> so when they come to you, they are at their wits end? >> literally. some of them are limping into the clinic. besides being understanding, the most important thing for me to figure out is what happened and what is causing the pain. >> and have they tried a variety of things and bunch of doctors and nothing is working? >> often. many times patients will have gone through local walgreens and