Prevalence and clinical relevance of endplate junction failure in lumbar disc herniation: a post-hoc subgroup analysis of 5-year follow-up prospective data.

OBJECTIVE: This study conducted a post-hoc exploratory subgroup analysis of 5-year follow-up data from a randomized controlled trial (RCT) to clarify the prevalence and clinical relevance of endplate junction failure (EPJF) in patients with lumbar disc herniation (LDH). METHODS: Patients diagnosed with LDH who underwent minimally invasive discectomy in our RCT were included. Based on MRI findings, operated discs with type 1 herniation (evidencing EPJF) were assigned to Group 1, and those with type 2 herniation (without EPJF) to Group 2. Demographic characteristics, radiological parameters, and clinical outcomes (assessed via patient-reported outcome measures [PROMs]) were compared between the two groups. RESULTS: A total of 135 patients (69.2%) were classified as type 1 herniation with EPJF. EPJF predominantly involved both endplates (48.1%), followed by the lower endplate junction (42.2%). Sixty discs (30.8%) with intact endplates without junction failure were classified as type 2 herniation. Both groups showed significant improvements in all PROMs at short-term (6 months) and long-term (5 years) follow-ups after surgery. Although Group 1 exhibited worse short-term Oswestry Disability Index (ODI) scores, European Quality of Life-5 Dimensions (EQ-5D) scores, and visual analog scale for back pain (VAS-back) (P < 0.05), long-term PROMs were comparable between the two groups. The 5-year cumulative symptomatic recurrence rate was significantly lower in Group 1 (4.7%) than in Group 2 (14.3%) (P = 0.031). CONCLUSIONS: This study reinforces evidence that EPJF is common in surgical LDH patients. While EPJF negatively affects short-term clinical outcomes, long-term outcomes are satisfactory with a lower symptomatic recurrence rate. CLINICAL TRIAL: This trial was registered at ClinicalTrials.gov on November 14, 2013 (registration number: NCT01997086; https://clinicaltrials.gov/ct2/show/NCT01997086).