Background: Publications concerning recurrent disc disease quote percentage recurrence without regard to the times of recurrence and the influence of longer follow-up.

Objective: To assess the use of survival analysis to measure revision rate after lumbar microdiscectomy.

Design: A retrospective analysis of the hospital records of all patients undergoing lumbar microdiscectomy over a nine-year period was undertaken. Patients who had a repeat microdiscectomy at the same level as the index procedure were designated ‘revisions’. The overall revision rate was calculated for the average length of follow-up. A survival analysis was then carried out using the life table method, as described by Murray et al for follow-up of hip arthroplasty.

Subjects: Seven hundred and twenty-nine patients underwent primary microdiscectomy during this time period, average age 40 years.

Results: Twenty-seven patients had a revision microdiscectomy during the study period. This gave an overall revision rate of 3.7% at average follow up of five years, one month. Using survival analysis the revision rate was 5.5% at eight years of follow up, number at risk 51.

Conclusions: Survival analysis gives a more accurate estimation of the true recurrence rate for patients undergoing lumbar microdiscectomy. The method would allow better comparison between different interventions for intervertebral disc herniation.