Hi killerback
"Status Post complete L4-5 Laminectomy"
They are just noting the laminectomy you have had in the past.
"There is no evidence of residual dural sac compression on todays exam however there is loss of normal epidural fat consistent with an element of epidural scar. There does not appear to be arachnoiditis or focal root encasement."
The dural sac is a membrane that encases the spinal cord the disk is not touching it. Epidural fat is fat in the spinal canal.
Arachnoiditis is a debilitating condition characterized by severe stinging and burning pain and neurologic problems. It is caused by an inflammation of the arachnoid lining—one of the 3 linings that surround the brain and spinal cord
"Right posterolateral outer annular tear L3-4"
There is a tear in the outer case of the disk that is on the right and towards the back and of the disk.
"Posterior element hypertrophy at this interspace results in some compromise of the posterolateral aspects of the dural sac without a definite central canal or lateral recess stenosis."
Posterior element hypertrophy is a weakening and thinning of the soft tissie (ligaments) that cross the two vertabra. with some compression of the dural sac but without stenosis wich is anarrowing of the spinal canal.
" Multilevel lower lumbar facet arthropathy"
The facet joints are small joints towards the back of the vertebral body that limit and guide joint motion. Arthropathy means arthritis