External bipolar thermal annuloplasty as an adjunct to Lumbar microdiscectomy for Carragee Type i and III annular defects: a matched cohort study

Abstract

Lumbar microdiscectomy is an established treatment for symptomatic lumbar disc herniation; however, persistent pain and functional limitation may occur, particularly in patients with annular defects. Research question Is adjunctive external bipolar thermal annuloplasty (EBTA) associated with improved outcomes after lumbar microdiscectomy in patients with Carragee Type I and III annular defects? Material and methods This retrospective single-center matched cohort study included 60 patients with symptomatic single-level lumbar disc herniation and intraoperatively confirmed Carragee Type I or III annular defects. Thirty patients underwent microdiscectomy with adjunctive EBTA and were matched 1:1 with 30 patients treated with microdiscectomy alone based on age, sex, operated level, Carragee classification, baseline VAS-leg, VAS-back, and Oswestry Disability Index (ODI) scores. Outcomes were assessed preoperatively and at 6 and 12 months. Exploratory clinical relevance was assessed using MCID thresholds of ≥4.7 points for VAS-leg and >20 points for ODI. Results Both groups improved significantly in VAS-leg, VAS-back, and ODI scores (p < 0.001). Compared with controls, the EBTA group had significantly lower VAS-leg, VAS-back, and ODI scores at both follow-ups. VAS-back decreased from 5.84 ± 1.17 to 1.20 ± 0.49 at 12 months in the EBTA group and from 5.96 ± 1.08 to 2.06 ± 0.72 in controls. EBTA was also associated with earlier return to work and higher satisfaction, without increased complications. Mean ODI improvement exceeded the MCID threshold in both groups, whereas VAS-leg exceeded the threshold at both follow-ups only in the EBTA group. Discussion and conclusion Adjunctive EBTA was associated with greater improvements in leg pain, back pain, and disability without increased perioperative morbidity. These exploratory findings require confirmation in larger prospective studies.