Introduction: Operations inside the spinal canal are afflicted with a certain number of iatrogenic dural lesions. Incidence figures in the literature vary from 1 to 17% and are mainly based on retrospective studies. The Swedish Spine Register, SweSpine, provides a good possibility to study the incidence in a prospective patient material.

Patients and Methods: During 5 years more than 9 000 patients had surgical treatment for lumbar disc herniation or lumbar spinal stenosis and were registered according to the protocol of the Swedish Spine Register. One year follow-up data were present for 74 % of the patients. Pre- and postoperative data are entirely based on questionnaires answered by the patient whereas surgical data are completed by the surgeon. Complication and re-operation registration is included.

Mean patient age for LDH was 45 (12–88) years, for spinal stenosis 68 (27–93) years and 56% of the disc herniation patients and 43% of the spinal stenosis patients were males. Most common level for LDH operation was L5/S1 followed by L4/L5 and for spinal stenosis L4/L5 followed by L3/L4.

The one-year result was studied.

Results: The incidence of dural lesion in lumbar disc herniation surgery was 2.7% and in spinal stenosis decompression 7.3%. The risk for dural lesion was more than doubled in patients with previous surgery which, thus, was a significant but also the only risk factor. At one year after surgery the result was similar for patients with and without dural lesion when VAS pain, ODI, SF-36 and patient graded global assessment were studied. Correlation between previous surgery and inferior outcome was seen but was not affected by the dural lesion as such. Three and 5% respectively in the groups were subjected to repeat surgery before discharge from the hospital.

The lost-to follow-up group (26%) had similar pre-operative demographics and the same incidence of dural lesion as those followed-up.

Conclusion: In a large prospectively studied material, the incidence of dural lesion in lumbar disc herniation surgery was 2.7% and in decompressive spinal stenosis surgery 7.3%. Previous surgery was a significant risk factor for dural lesion. The dural lesion as such did not negatively influence the one-year outcome.