Regarding lumbar traction. It sounds like the client is still in the acute phase and is simply not ready for traction, if you have tried the modifications already suggested. A minimum of 6 weeks for early scar formation is required, sometimes much longer. For each phase of healing it is appropriate to ascertain whether he/she tolerates flexion or extesnion and if too symptomatic it may be that neutral is the only posture tolerated at this time without adding additional stress via position or traction. The literature can come across as idealistic and clinical reality can be different. Wikipedia reference-linkMRI's are not perfect tests, they have false positives and false negatives. I have had several over the course of 11 years and can state the same with regards to radiographs and CT scans-there is some common ground in serial tests and there is also a wide range in the Radiologist's report. With respect to your client, it might be appropriate to slow it down, reduce short term expectations and cotinue with a common-sense gentle approach. If pain is severe and protracted, communication with referring physician is essential. Perhaps an epidural will help, ongoing patient education is essential. These are a few "off the cuff" thoughts. Additional medical testing may be waranted, rare pehnomenon like discitis could be at work, requiring anti-biotics.
Best of luck.
Jerry hesch, MHS, PT