Six months ago, I had a microdiscectomy to remove pieces of a damaged disc in my lumbar spine. I’ve started having sciatica down the left leg again. How can this happen if the disc was removed?

As you described, microdiscectomy only removes fragments or portions of the damaged disc. Recurrent herniation of the remaining disc is still possible. In fact, this happens in about 10 percent of the patients who have this surgery.

The return of your sciatica could be from disc reherniation at the same level. Or it could be a new disc herniation at a slightly different level. Scar tissue called fibrosis is also a possible cause of your symptoms. Arthritis can actually be one other reason for your new symptoms.

None of these problems can be diagnosed on the basis of just your symptoms. Further testing is advised. See your surgeon and report your symptoms. Early diagnosis and treatment may result in better long-term results.