In this study, MRIs were used to evaluate the results of two different surgical procedures for disc removal. The two operations included microdiscectomy and sequestrectomy. In a previous article by the same authors, the clinical results (changes in pain, function, and patient satisfaction) for these same two groups of patients were reported.
All patients included were between the ages of 18 and 60. They all had a single-level lumbar disc herniation. Both procedures were considered minimally invasive. This means they were done with a tiny incision, and the surgeon used a special operative microscope.
Microdiscectomy removes the entire disc. Sequestrectomy only removes loose pieces of the disc. These are fragments that have broken off. They are in the intervertebral space. The disc itself is not punctured or entered by any surgical instruments during a sequestrectomy.
Results after two years showed that functional outcomes were better after sequestrectomy. More patients with a microdiscectomy had further deterioration of the operative segment. MRI results confirmed the benefits of sequestrectomy over microdiscectomy.
Microdiscectomy caused greater post-operative disc degeneration. There was a loss of disc height and endplate changes with microdiscectomy. The endplate is a piece of fibrous cartilage between the disc and the vertebral bone. In fact, the rate of endplate degeneration doubled in the microdiscectomy group compared with the sequestrectomy group. These changes did not occur as a result of patient age or sex. The changes were not linked with the surgeon who did the surgery either. The size, location, and type of disc herniation weren’t factors determining endplate changes.
The major finding of this study was that changes in the endplate may be linked with poor results after microdiscectomy. Endplate degeneration (not disc protrusion) may be the real cause of failed-back surgery syndrome (FBSS).
FBSS refers to continued or worse back pain after surgical disc decompression via microdiscectomy or sequestrectomy. Since the disc isn’t penetrated by sequestrectomy, this procedure is less likely to cause endplate changes or FBSS.