Can a pt be a candidate for TKR if they have chronic knee pain without severe arthritis? I've had 4 previous surgeries & still have debilitating pain.

No. Pain can be mechanical (worn or broken joint), inflammatory (something irritating or infecting the joint), neuropathic (nerve problem), or functional (normal joint but brain senses pain). First, find out which type of pain. TKR is only done for completely worn out joint. So, no.