Question
The result of the MRI Scan done had the results:
Small cental disc protrusions at L4-L5 and L5-S1 causing mild thecal indentation.Incidentally noted ileal condensations bilaterally. There is a mild marrow edema around left SI Joint. Sacroilitis or sprain will have to be excluded.

Answer
Small cental disc protrusions at L4-L5 and L5-S1 causing mild thecal indentation.Incidentally noted ileal condensations bilaterally. There is a mild marrow edema around left SI Joint. Sacroilitis or sprain will have to be excluded.
This means that your spinal cord cover (thecal sac) has pressure on it from a disc protrusion.
Think about a jelly donut with the jelly coming out and pressing on your spinal cord.
the second finding tells me that your SI joint is involved.