Vertebral end-plate changes: Are they clinically significant for postoperative low back pain?

Emre Kacar; Rukan Karaca; Demet Gunduz; Ender Korfali

doi:10.4103/wajr.wajr_31_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 29 | Issue : 1 | Page : 22-26

Vertebral end-plate changes: Are they clinically significant for postoperative low back pain?

Emre Kacar¹, Rukan Karaca², Demet Gunduz³, Ender Korfali⁴
¹ Department of Radiology, Doruk Private Hospital, Bursa, Turkey
² Department of Radiology, Malatya Darende State Hospital, Malatya, Turkey
³ Department of Radiology, Suleyman Demirel University School of Medicine, Isparta, Turkey
⁴ Department of Neurosurgery, Uludag University School of Medicine, Bursa, Turkey

Date of Submission	11-Aug-2021
Date of Acceptance	07-Jul-2022
Date of Web Publication	15-Nov-2022

Correspondence Address:
Dr. Rukan Karaca
Department of Radiology, Malatya Darende State Hospital, Malatya
Turkey

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/wajr.wajr_31_21

Abstract

Background: Our aim was to assess the relationship between postoperative recurrent low back pain and vertebral body end-plate signal intensity changes on magnetic resonance imaging in disc herniation patients.
Materials and Methods: The preoperative magnetic resonance images of 748 patients were retrospectively reviewed. End-plate changes were separated into three groups according to the Modic classification. The postoperative clinical improvement was defined according to the Kawabata criteria. The localization and type of end-plate degeneration and improvement after the operation were analyzed with Pearson's Chi-square test.
Results: End-plate degeneration was found in 394 of 748 patients. Single-level and multiple-level end-plate changes were present in 70.4% and 29.6% of the patients, respectively. Type 2 (85.5%), type 1 (10.7%), and type 3 (3.8%) degenerations were encountered in order of frequency. The severities of the end-plate changes were mild, moderate, and severe in 63.2%, 32.7%, and 4.1% of the patients. Type 1 and type 2 degenerations correlated with clinical course in the postoperative period (P < 0.05).
Conclusions: Type 1 and type 2 degenerative end-plate changes seen on preoperative magnetic resonance scans can influence the clinical course and be an indicator of postoperative back pain.

Keywords: End-plate, Modic change, magnetic resonance imaging, vertebra

How to cite this article:
Kacar E, Karaca R, Gunduz D, Korfali E. Vertebral end-plate changes: Are they clinically significant for postoperative low back pain?. West Afr J Radiol 2022;29:22-6

How to cite this URL:
Kacar E, Karaca R, Gunduz D, Korfali E. Vertebral end-plate changes: Are they clinically significant for postoperative low back pain?. West Afr J Radiol [serial online] 2022 [cited 2023 Jun 1];29:22-6. Available from: https://www.wajradiology.org/text.asp?2022/29/1/22/361187

Introduction

Lumbar disc herniation is a localized displacement of intervertebral disc tissue that causes the most low back pain.^[1] Degenerative disc changes are responsible for part of the low back pain.^[2],[3] Magnetic resonance imaging (MRI) is generally the preferred radiological method for displaying disc morphology and relationship of the disc with the nerves. However, MRI can demonstrate end-plate changes, an indicator of disc degeneration.^[4],[5] Furthermore, degenerative disc changes in or around the operation level in patients operated for lumbar disc herniation are held responsible for postoperative recurrent low back pain and recurrent disc herniation development.^{[6],[7],[8],[9],[10]}

Our objective was to evaluate the relationship between postoperative end-plate changes identified with MRI and recurrent low back pain complaints in lumbar disc herniation patients.

Materials and Methods

Patient assessments

Our study was performed retrospectively. We evaluated 748 patients between 16 and 80 years of age (mean age: 44 years, 316 males and 432 females) operated for lumbar disc herniation between November 2008 and December 2013.

Patients with no previous spinal surgery history and who had undergone microdiscectomy for disc herniation were included in the study.

Cases with moderate or severe facet joint degeneration in preoperative MRI examinations, spinal stenosis, spondylolisthesis, epidural fibrosis, and postoperative spondylodiscitis were excluded from the study.

The age, gender, history (diabetes, hypertension, and trauma), smoking, occupation, and body structure parameters of the patients were recorded. Sensory deficit, motor deficit, reflex deficit, and straight leg raise test results of the patients were evaluated. Operation level and postoperative follow-up time were recorded. Whether reoperation was performed and the reason for reoperation was evaluated.

Radiological assessments

A standard MRI protocol was followed for all patients. MR images were acquired on a 1.5T scanner using the Cervical-thoracic-lumbar (CTL) Spine Phase-Array Coil (Magnetom Vision Plus, Siemens, Erlangen, Germany). Following the acquisition of scout images, routine conventional images of the lumbar vertebrae were acquired for anatomical and morphological assessments. The following sequences were obtained:

Sagittal spin-echo (SE), T1-weighted (repetition time [TR]/echo time [TE]/flip angle [FA]: 600/12/90°),

Sagittal fast SE (FSE), T2-weighted (TR/TE/FA: 4480/130/90°),

Axial SE, T1-weighted (TR/TE/FA: 660/15/90°),

Axial FSE, T2-weighted (TR/TE/FA: 4900/120/90°).

Slice thickness was 3 mm for sagittal images and 5 mm for axial images. The cross-sectional gap was 1 mm, and the FOV was 130 × 250 and 125 × 250 for the axial and sagittal images, respectively. The matrix was 240 × 512 pixels. Contrast agents were not used. All images were evaluated by the same radiologist with 10 years of experience.

The types and intensity of end-plate changes were investigated on sagittal and axial T1- and T2-weighted MR images. The classification of Modic et al. was used to identify the type of end-plate change:^[11]

Type 1: Hypointense on T1-weighted imaging, hyperintense on T2-weighted imaging [Figure 1]b
Type 2: Hyperintense on T1- and T2-weighted imaging [Figure 1]c
Type 3: Hypointense on T1- and T2-weighted imaging [Figure 1]d.

Figure 1: (a) Normal lumbar MRI. (A1) Sagittal midline 500/17 (TR ms/TE ms), 4 mm thick image of the lower lumbar spine. (A2) Sagittal midline 2000/90 (TR ms/TE ms), 4 mm thick image. (b) Type 1 change in a male with low back pain. Hypointense T1-weighted image, hyperintense T2-weighted image. (B1) Sagittal midline 500/17 (TR msec/TE ms), 4 mm thick image of the lower lumbar spine. There is decreased signal intensity of the inferior aspect of L4 as well as the superior aspect of L5. (B2) Sagittal midline 2000/90 (TR ms/TE ms), 4 mm thick image. There is increased signal of the adjacent portions of the L4 and L5 vertebral bodies. (c) Type 2 change in a male with low back pain. Hyperintense T1-weighted and T2-weighted images. (C1) Sagittal midline 500/17 (TR ms/TE ms), 4 mm thick image through the lower lumbar spine. There is increased signal of the adjacent portions of the L4 and L5 vertebral bodies. (C2) Sagittal midline 2000/90 (TR msec/TE msec), 4 mm thick image. There is increased signal of the adjacent portions of the L4 and L5 vertebral bodies. (d) Type 3 change in a male with low back pain. Hypointense T1-weighted and T2-weighted images. (D1) Sagittal midline 500/17 (TR ms/TE ms), 4 mm thick image through the lower lumbar spine. There is decreased signal of the adjacent portions of the L1 and L2 vertebral bodies (white arrow). There is increased signal of the adjacent portions of the L5 and S1 vertebral bodies (Type 2 change – black arrow). (D2) Sagittal midline 2000/90 (TR msec/TE ms), 4-mm-thick image. There is decreased signal of the adjacent portions of the L1 and L2 vertebral bodies (white arrow). There is increased signal of the adjacent portions of the L5 and S1 vertebral bodies (Type 2 change – black arrow). MRI: Magnetic resonance imaging

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The intensity of end-plate changes was evaluated according to the craniocaudal axis as follows:

Mild: Less than 25% of the corpus vertebrae height
Moderate: More than 26% and <50% of the corpus vertebrae height
Severe: More than 50% of the corpus vertebrae height.

Back pain assessments

Postoperative recovery in year one was defined according to the criteria of Kawabata criteria^[12] and called the clinical course:

Excellent: Asymptomatic, normal physical examination (neurologically intact)
Good: Significant improvement in symptoms and physical examination (minor sensory deficit and paresis grade 4/5 with improvement at least one grade)
Fair: Minimal improvement in symptoms and physical examination (minor sensory deficit, mild atrophy, and paresis grade 3/5 or 4/5 with improvement of at least one grade)
Poor: No improvement or worse symptoms and physical examination (major complaints, marked deficits, and atrophy).

The relationship between end-plate changes identified with preoperative MRI and clinical course was studied in patients. In addition, the relationship between the clinical course of the patients, their demographic information and the reasons for reoperation were examined.

Statistical analysis

Statistical analyses of the research were obtained from the SPSS for Windows version 10.0, SPSS Inc., (Chicago, Illinois, US) Statistics module. Pearson's Chi-square test was applied to understand the level, intensity, type of end-plate changes, and postoperative improvement. The significance level was accepted as P < 0.05 in all tests.

Results

The mean age of 748 patients included in this study was 45.1 ± 0.4 years (minimum 16 years, maximum 80 years, and median 44 years). The mean follow-up time for the operation date was 24.18 ± 10.34 months (minimum 15 months, maximum 48 months, and median 19 months).

The postoperative clinical progress of the patients in terms of age, gender, history, smoking, and professional group and body structure parameters were shown in [Table 1]. Age, history, smoking, and professional group parameters of the patients were not found to have any effect on the clinical progress (P > 0.05). Female gender and obese body structure were found to have an impact on clinical progression (P < 0.05).

Table 1: Clinical course according to parameters such as age, gender, history, smoking, occupation, and constitution

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Six hundred and thirty-two patients underwent single-level lumbar microdiscectomy and 116 patients underwent two-level lumbar microdiscectomy [Table 2]. Single-level lumbar microdiscectomy was performed at the levels L2–L3 (n = 15), L3–L4 (n = 30), L4–L5 (n = 339), and L5–S1 (n = 248). Two-level lumbar microdiscectomy was performed at the levels L3–L4 and L4–L5 (n = 92), and L4–L5 and L5–S1 (n = 24).

Table 2: Surgical procedure and details

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In the preoperative MR images of a total of 748 patients, no end-plate changes were observed in 354 patients (47.4%), and changes were identified in 394 patients (52.6%). There were end-plate changes in a total of 502 disc levels in the patients with degeneration. While 277 of these patients (70.4%) had degeneration at a single level, 117 (29.6%) had degeneration at multiple levels. The end-plate degeneration levels were found to be L5–S1 (49%), L4–L5 (38.6%), L3–L4 (10.1%), L2–L3 (1.9%), and L1–L2 (0.4%), in order of frequency. There was a significant difference in the postoperative clinical course between the patient groups with and without end-plate changes (P < 0.05).

Type 1, type 2, and type 3 end-plate degenerations were observed in 42 (10.7%), 337 (85.5%), and 15 (3.8%) patients, respectively [Table 3]. Type 1 and type 2 end-plate changes were observed to be parameters that had an unfavorable effect on the clinical course in the postoperative period (P < 0.05). Type 3 end-plate changes were not found to have a statistically significant effect on the clinical progress of the patients (P > 0.05) [Table 3].

Table 3: Relationship between end-plate changes and clinical course

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Reoperation was performed in 78 of the cases (10.4%). The reason for reoperation was recurrent disc herniation in 38 cases (48.1%), epidural fibrosis in 23 cases (29.5%), and new-level disc herniation in 17 cases (21.8%). It was found that the detected end-plate changes did not have a significant effect on the causes of reoperation in cases who underwent reoperation (P > 0.05).

Discussion

The most common complaint encountered in patients with symptomatic lumbar disc herniation is short-lasting low back pain attacks. Such attacks exist before the development of sciatic pain and are likely to disappear spontaneously or may have a chronic course lasting many years. Vertebral end-plate changes and facet joint degeneration in addition to a disc herniation may be associated with the pain in these patients.^[13],[14]

Several factors such as aging, genetics, autoimmunity, trauma, and biomechanical factors are responsible for disc degeneration.^[11],[15] In the degenerative process, the structure of the disc molecules is distorted, and the disc loses water, most significantly in the nucleus pulposus. The disc loses height, annular ruptures occur, and the annular integrity deteriorates.^[11],[16] The disc then bulges out from the intervertebral space. The nucleus pulposus may herniate from an annular rupture, causing a disc herniation. In addition, secondary changes occur in the facet joints, end plates, and subchondral bone marrow when the disc loses its stability.^[17]

End plates act as the interface between a rigid and a flexible part, consisting of the vertebral body and the intervertebral disk. They have to be strong to prevent vertebral fracture but are also porous so that they can be provided in the transfer of substances from the capillaries to the cells within the disc. Irritation of the nerve endings that terminate at the periphery of the annulus fibrosus and/or the inflammatory reaction caused by the diffusion into the nucleus pulposus of mediators such as cytokines that are formed in the vertebral end-plates during the degenerative process are thought to be responsible for the pain.^{[2],[3],[13],[18]}

Changes that occur in the end plate during the degenerative process are evaluated in three groups according to the Modic classification. The most common Modic change type and the distribution of the various types are not clear, and the prevalence varies from 0.5% to 62% in the literature. Age, race, occupation, and current back pain symptoms are all influencing factors. The pattern of the changes would be expected to vary significantly with age, a factor that has not been fully evaluated.^[19],[20]

Braithwaite^[21] and Weishaupt^[22] have demonstrated that type 1 and type 2 end-plate changes could be associated with low back pain. We demonstrated end-plate changes in 25.4% of the patients with recurrent low back pain symptoms and preoperative MR images. We found that 157 of 183 patients with recurrent low back pain (85.8%) had type 2 end-plate changes, whereas 23 (12.6%) and 3 (1.6%) had type 1 and type 3 end-plate changes, respectively. Type 1 and type 2 end-plate changes were observed to influence a moderate and severe clinical course in the postoperative period (P < 0.05). Statistically, the effect of type 2 end-plate changes on the clinical course was much more significant than that of type 1 end-plate changes. These values are consistent with literature data and indicate the significance of end-plate changes frequently identified with MRI in patients operated for lumbar disc herniation.

The symptoms are relieved with conservative therapy or spontaneously in the majority of patients with lumbar disc herniation. Surgical treatment is necessary for only 2% of symptomatic patients. The clinical recovery rate is 75%–95% in the early postoperative period and is reduced to 65%–75% in the long term.^[23],[24] The most common symptom in the long term after adequate decompression therapy is recurrent low back pain.^[25],[26] Parker et al.^[25] reported a recurrent low back pain complaint rate of 15%–25%. The rate of low back pain symptoms reported by Suri et al.^[26] was 29%–65%. Our data revealed similar rates to those reported in the literature. While satisfactory recovery was observed in 64% of our patients after surgical therapy, 36% had recurrent low back pain complaints.

The limitations of this study include all patients being operated on for disc herniation and the retrospective nature of the study. To reach a high number of subjects, we formed our study group from all patients who had undergone surgery. Second, the relationship between the location of the end-plate changes in corpus vertebrae and the side of the low back pain was not examined during the study. We also did not evaluate the relationship between the surgical procedure and low back pain.

Conclusions

Type 1 and type 2 end-plate changes detected in preoperative MR examinations may be an indicator of low back pain that may occur in the long term after lumbar disc herniation surgery. We found a relationship between the end-plate change and the postoperative clinical course of patients. In addition, we concluded that female gender and obesity may be a source of low back pain in the postoperative period.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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