Spine Journal - 2026-09-01 - Journal Article; Comparative Study
Extraforaminal versus central lumbar disc herniations: clinical features and surgical outcome comparing data from a national spine registry (NORspine).
Dos Reis JABPR, Lønne G, Grundnes O, Alhaug OK
Topics
Key Takeaway
After propensity score matching, EDH and CDH patients achieved equivalent 12-month ODI (18.9 vs 17.4, p=NS) and satisfaction rates, despite EDH surgery requiring 17.9 additional operative minutes.
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Summary
This study used NORspine registry data to compare surgical outcomes between EDH and CDH patients undergoing lumbar discectomy. Before matching, EDH patients were older (57.1 vs 46.7 years) with worse baseline PROMs; after propensity score matching, preoperative differences resolved and 12-month ODI, NRS leg pain, NRS back pain, and satisfaction were statistically equivalent between groups. EDH procedures were longer (75.9 vs 58.0 min) but had fewer perioperative complications (0.4% vs 1.4%).
Key Limitation
The 229 EDH cases represent only 2.2% of the registry cohort, and herniation classification relied on MRI report categorization rather than standardized intraoperative or radiographic criteria, introducing potential misclassification bias.
Original Abstract
BACKGROUND CONTEXT
Previous studies indicate that extraforaminal disc herniations (EDH) tend to have a more acute onset and more pronounced radicular symptoms. Surgical outcomes for lateral disc herniations remain somewhat heterogeneous in the literature when compared with central disc herniations (CDH).
PURPOSE
We aim to compare clinical features and surgical outcomes between extraforaminal and central disc herniations.
DESIGN
Retrospective analysis of prospectively collected data from the Norwegian Spine Registry (NORspine).
PATIENT SAMPLE
A total of 11,341 patients were registered during the study period. We included 10,288 patients: 10,159 with CDH and 229 with EDH. Propensity score matching resulted in 2 groups of 214 patients each.
OUTCOME MEASURES
The primary outcome was the Oswestry Disability Index (ODI) score at 3 and 12 months postoperatively. Secondary outcomes were success at 3 and 12 months postoperatively, defined as ODI<22, a Global Perceived Effect (GPE) rating of "much improved" or "completely recovered," Numeric Rating Scale (NRS) for back and leg pain (0-10), as well as patient satisfaction, perioperative and postoperative complications.
METHODS
Patient groups were defined based on reported MRI findings, categorising cases as either CDH or EDH. We used Patient-Reported Outcome Measures (PROMs) derived from NORspine, specifically ODI, NRS back and leg pain and GPE, as well as surgical details, and clinical outcomes at 3 and 12 months, and recorded complications. To adjust for baseline differences between the groups, propensity score matching was used.
RESULTS
Patients in the EDH group were older (57.1 vs 46.7 years), had higher preoperative ODI scores (49.5 vs 46.6), and reported higher NRS scores for both leg pain (7.4 vs 7.1) and back pain (7.0 vs 6.5). At the 3-month follow-up, patients with EDH had higher ODI scores (21.9 vs 17.1; p<.001), higher NRS leg pain (3.1 vs 2.3; p<.001), and higher NRS back pain (3.5 vs 2.9; p<.001). At the 12-month follow-up, group differences had narrowed but remained statistically significant for ODI and NRS leg pain. Following propensity score matching, preoperative PROM differences were no longer statistically significant. NRS leg and back pain remained slightly worse in the EDH group at 3-month follow-up (3.0 vs 2.3; p=.011; 3.5 vs 2.6; p<.001). At 12- month follow-up, there was no statistically significant difference in PROMs between groups (ODI 18.9 vs 17.4; NRS leg pain 3.0 vs 2.4; NRS back pain 3.0 vs 3.1). Surgical duration was longer for EDH procedures (75.9 vs 58.0 minutes), although perioperative complications were less common in the EDH group (0.4% vs 1.4%). The proportions of patients reporting satisfaction at 3 and 12 months were similar across groups and did not differ significantly.
CONCLUSIONS
Patients with extraforaminal lumbar disc herniation experience substantial benefits from surgical intervention, including meaningful improvements in PROMs, comparable treatment success and patient satisfaction rates to those with central lumbar disc herniation.