Successful pars repair depends upon how much slip was present before surgery, how much “gap” (or distraction) of the fracture ends was noted prior to surgery, what the quality of the disc was and how precise the repair of the pars defect was performed. At this point, I really can’t tell without images how predictable your pars repair healing will be. If your pain is “really bad”, maybe X-rays with flexion-extension will be helpful and eventually a precise CT scan will be necessary.
Dr. Corenman