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1.There is straightening of the spine seen - which is due to the pain reflex caused by the
nerve compression the muscle gets stiff.
2.There is loss of hydration in the disc at the level mentioned - which is degenerative
disc disease.
3.There is a bulge noted at the L4-5 which is seen causing pressure effect on the exiting nerve.
4.Due to the foramina narrowing and nerve compressions the
back pain symptoms are seen , some time radiating to the legs.
5.In this case the treatment includes back exercises, followed by
physiotherapy - only when this fails operative might be needed - but no need in your case.
Good luck.
Hope i have answered your query,
any thing to ask ? do not hesitate to ask.
http://doctor.healthcaremagic.com/doctors/dr-ganesh/62888