Severe Left Foraminal Stenosis At L5s1,bilateral Pars Defects ,spondylolysis Sublaxtion

severe left foraminal stenosis at l5s1,bilateral pars defects ,spondylolysis sublaxtion of l5 exiting left l5 nerve is tightly positioned between the posterior margin of the disc and the inferior margin of the left l5 pedicle ,pt,shots, no back pain just sciatic pain down left leg, am time is fine afternoon is when dis comfort ,66 years old non smoker,non drinker,5"10 215 lbs doctor say i am good good overall shape,single fusion?