Faculty Bibliography

Study DesignConsensus-based classification development utilizing a modified Delphi process.ObjectivesTo develop a practical, standardized classification system to quantify surgical invasiveness in minimally invasive degenerative lumbar spine procedures.MethodsAn international panel of 45 spine surgeons from the AO Spine Knowledge Forum - Degenerative participated in a three-stage, modified Delphi consensus process. First, candidate determinants of invasiveness were identified through evaluation of existing indices and literature review, then refined through iterative expert rounds. The scale was applied to standardized case scenarios, with internal review by the AO Spine Knowledge Forum - Degenerative and external review by the AO Spine MISS Task Force. Finally, a consensus survey reached ≥75% agreement on all final factors for inclusion in the grading scale.ResultsThe final classification system included nine factors: operative time, number of approaches, blood loss, instrumentation, muscle dissection/access, anesthesia, number of levels, fusion technique, and revision status. Consensus was achieved on all components of the scale following iterative refinement. Each factor was scored from 0 (least invasive) to 2 (most invasive), generating a cumulative invasiveness score. Application of the scale across representative procedures demonstrated a spectrum ranging from least invasive (endoscopic 1-level discectomy) to most invasive (thoracic-to-pelvis fixation). Procedures were stratified into minimally invasive, less invasive, and more invasive categories.ConclusionsMISS-INC (L) is a proposed, consensus-based classification that quantifies surgical invasiveness among minimally invasive lumbar spine procedures. It offers a user-friendly framework for communication, research, and patient counseling, with further validation against clinical outcomes representing an important next step.

OBJECTIVE:Bracing after lumbar discectomy surgery (LDS) is a controversial topic with paucity of related scientific literature. Previous surveys on spine surgeons' preferences were limited both in geographical coverage and number of respondents. The aim of this study is to fill this gap in the literature. METHODS:An international online survey among AO Spine members regarding the postoperative recommendations for bracing (PoBr), activity restriction (AR), and associated factors, was performed. RESULTS:A total of 703 spine surgeons participated in the survey of which 34% recommended PoBr, with half of them reported usage for 4 weeks. Main influencing variables were being from Europe/South Africa region, greater extent of bony decompression, and larger amount of excised disc material. Seventy-nine percent of the respondents recommended postoperative AR. Prolonged standing, prolonged sitting, and driving were usually restricted for 2 weeks. Bending, twisting, lifting, and low-intensity physical activities for 3 months, while high-intensity physical activities and direct contact sports for 6 months were restricted. CONCLUSION/CONCLUSIONS:Despite recent literature insights showing limited evidence of efficacy, 34% and 80% of a large cohort of international surgeons practice bracing and recommend AR after LDS for variable durations. Extensive bony decompression and radical discectomy significantly influenced the decision to brace, similarly endoscopic approaches and radical discectomy influenced the decision to restrict activity. These findings emphasize the persistent evidence-practice gap and the wide variability on the global level. More randomized controlled trials are warranted on this topic to reach an evidence-based recommendation.

OBJECTIVE:Lumbar discectomy is one of the most frequently undertaken procedures for the management of lumbar disc herniation. However, it may be complicated by recurrent disc herniation, with reported rates as high as 25%. To the authors' knowledge, this study is the largest systematic review to date, analyzing the clinical and radiographic risk factors for recurrent disc herniation. METHODS:A systematic literature search of Embase and PubMed/Medline, covering the period from inception to October 1, 2025, was conducted to identify case-control or cohort studies reporting risk factors for recurrent disc herniation. Risk factors were classified into baseline, clinical, and radiographic risk factors. Meta-analysis was performed for any reported risk factor with data from 3 or more studies. The assessment included an evaluation of publication bias and heterogeneity. RESULTS:A total of 51 studies published during the search timeframe, comprising 52,479 patients, met the inclusion criteria. Recurrent disc herniation occurred in 6,794 patients (12.9%). Significant risk factors for disc herniation included high body mass index (BMI) (standard mean difference [SMD], 0.48; 95% confidence interval [CI], 0.26-0.70), diabetes (odds ratio [OR], 1.48; 95% CI, 1.23-1.77), increased sagittal range of motion (SMD, 2.15; 95% CI, 0.35-3.94), and Modic changes (OR, 2.97; 95% CI, 2.20-4.01). No other significant predictors for recurrent disc herniation were identified. CONCLUSION/CONCLUSIONS:In conclusion, patients with high BMI, diabetics, increased sagittal range of motion, and presence of Modic changes are at increased risk of recurrent disc herniation. Future prospective studies are needed to validate the risk factors identified in this study associated with recurrent disc herniation.

OBJECTIVE:This study aimed to characterize international practice patterns in the surgical management of primary lumbar disc herniation (LDH) among AO Spine surgeons. METHODS:A cross-sectional online survey was distributed in September 2024 to AO Spine members. The questionnaire collected detailed information on demographic characteristics, surgical indications, preferred techniques, and approaches for primary LDH treatment. Data on specialty, practice setting, fellowship training, and surgical case volume were analyzed using univariate and multivariate logistic regression to identify significant associations between surgeon characteristics and treatment preferences. RESULTS:A total of 714 surgeons participated, representing diverse regions: North America (9.0%), Latin America (18.7%), Europe & Southern Africa (34.7%), Middle East & Northern Africa (12.8%), and Asia Pacific (24.8%). Neurological status was the most critical factor influencing early operative treatment in nonurgent cases, while bladder/bowel dysfunction and severe motor deficits were the primary indications in urgent scenarios. The majority of respondents (54.2%) preferred a mini-open technique-using either a surgical microscope or loupes-with partial laminotomy (58.1%) and partial discectomy (63.2%) being the most frequently performed procedures. Regional variations and differences in surgeon training were significantly associated with the choice of surgical approach and overall case volume. CONCLUSION/CONCLUSIONS:The findings reveal substantial variability in the surgical management of primary LDH across regions and specialties. This comprehensive dataset underscores the need for standardized, evidence-based guidelines to harmonize treatment strategies and optimize patient outcomes.

Low back pain is a leading cause of disability worldwide, with intervertebral disc herniation contributing substantially to its burden. Most patients improve with conservative care, often associated with disc resorption. Although increasingly recognized as a major determinant of recovery, the mechanisms underlying resorption remain poorly understood. Herniated disc tissue induces immune cell infiltration and release of cytokines and proteolytic enzymes, yet standard anti-inflammatory treatments may paradoxically impede this process. Outcomes are also influenced by physical therapy, lifestyle, herniation characteristics, and immunological background, but predictive biomarkers are lacking. This review summarizes the current knowledge gap and explores strategies to harness intrinsic healing for personalized management.