hi...It means due to wear and tear effect, our spine-cervical/lumbar are prone to develop abnormal biomechanics and weight bearing mechanism. normally intervertebral disk acts as a shock
absorber during weight loading..as part of ageing, the intervertebral disk loses its jelly like consistency and its height collapses...this leads to more work on other parts of spine namely facets..so they become large in size....eventually they restrict the space for the nerve roots which are coming out from the spinal cord
and lead to decreased blood supply to the spinal cord and nerves causing pain..also they will cause the spine to move forwards causing further nerve root compression
your father requires surgery- posterior lumbar decompression and fusion with pedicel-screw system...