52 yr old male, 5'10", 190 lbs, recent back pain. I just received my MRI report and it states Bone marrow: mild L4, moderate L5 and moderate S1 degenerative subchondral marrow change. IMPRESSION: L3-L4 minimal broad left posterlateral disc buldge. L4-L5 and L5-S1 mild annular disc buldging. What does this mean?