Why We Fuse Recurrent Lumbar Disc Herniations

This “Author 360” post was written by Gregor Fischer, MD and Markus Loibl, MD, two of the authors of a new study now in JBJS: Surgical Treatment of Recurrent Lumbar Disc Herniation: To Fuse or Not to Fuse. A Single-Center Analysis of Clinical and Radiographic Characteristics and Surgical Outcomes of 450 Patients.

Few decisions in our week generate as much disagreement as the one regarding a patient with a recurrent lumbar disc herniation. In our indication conferences, the same case could draw two confident and opposite recommendations from several experienced surgeons, and no one could point to a rule that settled it. What pulled us into this project was that absence: no clear guidance on whether instrumented fusion or a repeat microdiscectomy is the right call.

The literature offered little help. Current literature concludes that the two operations are equivalent, without ever saying who should undergo fusion, while prior reports share the same weaknesses: subjective outcome measures, heterogeneous pathologies, small fusion cohorts, follow-up too short to catch late failures of treatment, and almost no direct comparisons of repeat microdiscectomy versus fusion. Is repeat microdiscectomy avoiding fusion, or only deferring it?

That question requires data most centers do not have. Twenty years of prospectively collected data from our local spine registry yielded 450 patients with isolated recurrence at the index level. To our knowledge, this represents the largest comparative cohort of its kind, propensity-matched and with extended follow-up.

With respect to function, both treatment strategies were tied statistically. Both groups demonstrated improvement of >60% in the mean COMI (Core Outcome Measures Index) scores from baseline to 5 years, and fusion’s 1-year edge of lower COMI scores and a higher rate of reaching the minimal clinically important change did not reach significance.

Durability was another matter. Over a mean follow-up exceeding 7 years, 36.7% of patients in the repeat microdiscectomy group underwent reoperation versus 15.7% in the fusion group, and 73% of failures in the repeat microdiscectomy group were due to recurrent herniation requiring fusion in the end anyway.

That is our key message. A dramatically higher reoperation rate after repeat microdiscectomy, with favorable 1-year outcomes for fusion, suggests that primary instrumented fusion should be strongly considered in appropriately selected patients. Personalized decision-making is what matters: a body mass index (BMI) of ≥35 kg/m², which tripled the reoperation risk, and radiographic markers of degeneration lend support toward fusion at the first recurrence rather than after the second.

Ultimately, our study highlights the need for a stratified approach and an updated treatment algorithm that asks not which operation is better, but which operation is most suitable for this particular patient in this moment.

Gregor Fischer, MD is a junior attending spine surgeon in the Spine Center at the Schulthess Clinic in Zürich, Switzerland.