After reading Heinrik's respose I just wanted to throw this out there. My dad had hip pain for a long time that when tested they could never find anything. Well he had a mild stroke and was down for awhile..not working etc and during this time his pain was mild or not there at all. When he did recover and went back to work his pain started returning. After much testing..therapy etc it was mentioned by someone to not carry a wallet for awhile. Well blessings aboud that was the culprit!!! Just thought I would mention this to you...might not help but you never know! Good luck to you!
Hi,
Cancer or arthritis may show up on the bone scan and it may be hard to distinguish them. Hence, if the pain was present and the bone scan was normal, I would start having doubts that the problem is indeed in the joint. If the PSA is always undetectable, it would be unlikely to develop bone metastasis in the interim with these values.
I would consider that the problem may be around the soft-tissues or the muscles around the hip. I think a visit to a rehabilitation or sports specialist would help detect which specific muscle groups would be involved. The simplest scenario I could think of is postural- he may be placing undue stress on some muscles due to the way he sits, stands, walks.
Try to recall any changes with his activities during the period without the pain and the present time and this may also help find the problem.