Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Methods for the evaluation of the lumbar intervertebral disc vacuum phenomenon to predict postoperative residual lower back pain (#164)

SHUHEI OHYAMA 1 , Yasuchika Aoki 1 , Masahiro Inoue 1 , Hiroshi Takahashi 2 , Sumihisa Orita 3 , Kazuhide Inage 3 , Shiga Yasuhiro 3 , Koichi Nakagawa 4 , Seiji Ohtori 3
  1. Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Togane-city
  2. Department of Orthopaedic Surgery, University of Tsukuba, Tsukuba-city
  3. Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University., Chiba-city, Chiba
  4. Department of Orthopaedic Surgery, Toho University Sakura Medical Center, Sakura-city

Introduction: The lumbar intervertebral disc vacuum phenomenon (VP) is an important imaging finding that suggests severe disc degeneration. The severity of VP is associated with surgical outcomes after single-level transforaminal lumbar interbody fusion (TLIF).1,2 However, an appropriate method for the evaluation of VP to predict postoperative residual LBP is not well known.

This study aims to explore the appropriate method for the evaluation of the intervertebral disc vacuum phenomenon (VP) for predicting postoperative residual lower back pain (LBP) after a single-level TLIF for lumbar degenerative disease (LDD).

Methods: A total of 66 patients (67.8±10.2 years; 36 male and 30 female) with LDD and preoperative LBP (preoperative visual analogue scale (VAS) for LBP≥40) treated with single-level TLIF were enrolled in this study. The severity of the VP (SVP) score was evaluated at each lumbar intervertebral disc without fused disc using three methods of evaluation:1) SVP1 score, using Willhuber’s classification (0-5 point)3; 2) SVP2 score, using modified Willhuber’s classification (0-3 point); and 3) SVP3 score, using only the presence or absence of VP (0-1 point). Clinical outcomes were assessed using the VAS for LBP, lower extremity pain, and numbness; this scoring system was used for LBP in motion, as well as in the standing and sitting positions; the Oswestry disability index; Japanese Orthopaedic Association Back Pain Evaluation Questionnaire; Japanese Orthopaedic Association Score for intermittent claudication (JOA score for IC); and Nakai’s scoring system for the evaluation of surgical outcome. The patients were divided into a residual LBP group (R group) and a control group (C group) based on the postoperative VAS for LBP=25. The three SVP scores and preoperative clinical outcomes were compared between the two groups. Logistic regression analysis was performed with the presence of postoperative residual LBP as the dependent variable and SVP score as the independent variable. The best method of evaluation was selected based on the area under the curve (AUC).

Results: Of the 66 patients, 16 and 50 were assigned to the R and C groups. Each SVP score was significantly higher in the R group than in the C group. There were no significant differences in the preoperative clinical outcomes. The AUCs of the SVP1, SVP2, and SVP3 scores were 0.789, 0.802, and 0.788, respectively, with SVP2 showing the largest AUC. The cutoff was SVP2=8. Patients with SVP2>8 showed worse clinical outcomes than patients with SVP2≤8, except for VAS for LBP in sitting and JOA score for IC.

Discussion: The subchondral sclerosis of the endplate is a compensatory mechanism for the loss of the shock absorber function. A larger VP suggests a reduced shock absorber function of the intervertebral disc. Therefore, the SVP2 score, which was evaluated by excluding the subchondral sclerosis of the endplate subtype from Willhuber’s classification, was the most useful predictor of postoperative residual LBP. In conclusion, the most useful method for the evaluation of VP for predicting postoperative residual LBP is to evaluate VP severity based on the size of the VP (modified Willhuber’s classification).

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  1. 1. Ohyama S, Aoki Y, Inoue M, et al. Does vacuum phenomenon at non-fused discs affect the postoperative course after transforaminal lumbar interbody fusion in patients showing a positive value of difference in lumbar lordosis? J Orthop Sci 2023:S0949-2658(23)00007-6.
  2. 2. Ohyama S, Aoki Y, Inoue M, et al. Effect of Preoperative Severity and Location of Lumbar Intervertebral Disc Vacuum Phenomenon on Surgical Outcomes After Single-Level Transforaminal Lumbar Interbody Fusion. World Neurosurg 2023;173:e727–37.
  3. 3. Camino Willhuber G, Bendersky M, De Cicco FL, et al. Development of a New Therapy-Oriented Classification of Intervertebral Vacuum Phenomenon With Evaluation of Intra- and Interobserver Reliabilities. Global Spine J 2021;11:480–7.