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1. There is a disc in-between the vertebrae works as a shock-absorber function, the disc contains good amount of water content.
2. This water content is lost in in degenerative disc diseases and gets merited in different directions posteriorly.
3.There is
nerve compression ( pressure effect on the nerve ) with herniated /
slipped disc (case pressure effect).And the-cal sac compression at different levels of
lumbar vertebrae.
4.There is anterior movement / listhesis of L5 over S1 and the
osteophyte growth causing pressure effect on the spinal chord.
5.Rest all can be treated conservatively with exercise and
physiotherapy , but listhsis might need operative procedure with trans pedicular screw fixation might be needed to align the spine. Good luck.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.