The Prevalence of Facet Tropism and Its Correlation with Low Back Pain in Selected Community-Based Populations

Semiautomatic Assessment of Facet Tropism From Lumbar Spine MRI Using Deep Learning: A Northern Finland Birth Cohort Study

STUDY DESIGN

This is a retrospective, cross-sectional, population-based study that automatically measured the facet joint (FJ) angles from T2-weighted axial magnetic resonance imagings (MRIs) of the lumbar spine using deep learning (DL).

OBJECTIVE

This work aimed to introduce a semiautomatic framework that measures the FJ angles using DL and study facet tropism (FT) in a large Finnish population-based cohort.

SUMMARY OF DATA

T2-weighted axial MRIs of the lumbar spine (L3/4 through L5/S1) for (n=1288) in the NFBC1966 Finnish population-based cohort were used for this study.

MATERIALS AND METHODS

A DL model was developed and trained on 430 participants' MRI images. The authors computed FJ angles from the model's prediction for each level, that is, L3/4 through L5/S1, for the male and female subgroups. Inter-rater and intrarater reliability was analyzed for 60 participants using annotations made by two radiologists and a musculoskeletal researcher. With the developed method, we examined FT in the entire NFBC1966 cohort, adopting the literature definitions of FT thresholds at 7° and 10°. The rater agreement was evaluated both for the annotations and the FJ angles computed based on the annotations. FJ asymmetry ( - was used to evaluate the agreement and correlation between the raters. Bland-Altman analysis was used to assess the agreement and systemic bias in the FJ asymmetry. The authors used the Dice score as the metric to compare the annotations between the raters. The authors evaluated the model predictions on the independent test set and compared them against the ground truth annotations.

RESULTS

This model scored Dice (92.7±0.1) and intersection over union (87.1±0.2) aggregated across all the regions of interest, that is, vertebral body (VB), FJs, and posterior arch (PA). The mean FJ angles measured for the male and female subgroups were in agreement with the literature findings. Intrarater reliability was high, with a Dice score of VB (97.3), FJ (82.5), and PA (90.3). The inter-rater reliability was better between the radiologists with a Dice score of VB (96.4), FJ (75.5), and PA (85.8) than between the radiologists and the musculoskeletal researcher. The prevalence of FT was higher in the male subgroup, with L4/5 found to be the most affected region.

CONCLUSION

The authors developed a DL-based framework that enabled us to study FT in a large cohort. Using the proposed method, the authors present the prevalence of FT in a Finnish population-based cohort.

Correlation of Hounsfield Units with Bone Mineral Density and T-Score in Chinese Adults

OBJECTIVE

To examine the association between vertebral cancellous Hounsfield units (HUs), age, bone mineral density, and T-score in a sample of Chinese adults.

METHODS

The study included a sample of 739 participants. Age, bone mineral density, and T-score of each participant were recorded, and HUs were measured in the L1-L4 vertebrae.

RESULTS

Data analysis revealed that HUs of vertebral cancellous bone across the pedicle level decreased with age, with women having higher values than men up to age 50 and vice versa thereafter. Furthermore, a positive correlation was found between HUs of vertebral cancellous bone across the pedicle level and bone mineral density/T-score in the L1-L4 vertebrae, but with a weaker correlation in the L4 vertebrae. Additionally, HU values for participants with osteoporosis were significantly lower than HU values for participants with osteopenia and normal bone health.

CONCLUSIONS

From the findings of this study, it can be concluded that HUs may be a potential predictor of bone health, with implications for presurgical assessment of the quality of bone-screw interfaces for spinal surgery.

Is there an anatomic basis for the different behavior of Lenke types 1AR and 1AL in idiopathic scoliosis? A study on facet joint tropism influence

INTRODUCTION

AIS type 1 Curves are sub-classified based on the tilt of L4 as 1AR and 1AL. These curves are different w.r.t their curve behavior, progression and level selection. Presently there is no known anatomic etiology for the different behavior. Facet tropism (FT) is defined as the asymmetry between the facet angle of the left and right facet joints. The purpose of this study was to evaluate the correlation between facet tropism in the lumbar segments and occurrence of type 1AR and 1AL curves in AIS patients.

METHODS

AIS patients with diagnosis of type 1 AR and 1AL right thoracic AIS curves who underwent posterior instrumented fusion were queried from a single institutions' database. Patients needed to have an MRI of their entire spine to be included. L2-3, L3-4 and L4-5 Facet angles (FA, angle made by the facet line with the mid-sagittal line at respected vertebral level) were calculated. FT was classified as follows: ≤ 5° (minimal), 6- 10° (mild) and ≥ 11° (severe). 1AR and 1AL curves were compared for FA, FT and FT grade at each lumbar segmental levels.

RESULTS

One hundred nineteen patients were included (77 females, mean age-13.85 years, mean BMI- 21.63, 73 1AL and 46 1AR). The mean thoracic Cobb was 52.5 ± 9.8°, thoracic kyphosis was 28.12 ± 12° and lumbar lordosis was 53.48 ± 12.6°. L3-4 FA on the right side was more coronally oriented in 1AR curves compared to 1AL curves (37° vs. 31°, p = 0.04). On comparing FT at each level, 1AR curves had a higher FT at L3-4 (1.5° vs. - 2.3°, p = 0.01) and L4-5 levels (5.8° vs. - 0.28°, p < 0.001) compared to 1AL patients. Similarly, 1AR patients had significantly more patients with severe FT at L3-4 (34.8% vs. 13.7%, p = 0.02) and at L4-5 (17.3% vs. 6.8%, p = 0.01) compared to 1ALcurves.

CONCLUSION

L3-4 joints are more coronally oriented in 1AR curves compared to 1AL curves. 1AR patients displayed higher FT at L3-4 and L4-5 compared to 1AL patients. 1AR curves also reveal a higher percentage of severe FT at L3-4 and L4-5 levels. This may influence the curve behavior and progression in these two curve types.

Facet joint thickness and lumbar instability documented on myelo-computed tomography studies in patients with lumbar degenerative disease

Background

Various indicators of vertebral instability in patients with lumbar degenerative disease can be identified in myelo-computed tomography (CT) studies.

Methods

Of 120 patients, 45 with lumbar degenerative spondylolisthesis (LDS; 53 lumbar lesions) and 75 with lumbar spinal stenosis alone (LSS; 105 lesions) (2015-2019) myelo-CT studies and surgery confirmed the presence of lumbar instability. Myelo-CT findings indicative of instability included facet joint thickness (FJT), fluid in the facet joint, facet tropism, and air in the facet and/or disc.

Results

For the 120 study patients, FJT was significantly elevated in both the LDS and LSS groups.

Conclusion

FJT on myelo-CT is more specific for lumbar instability than other imaging parameters when evaluating LDS. An increase in FJT suggests vertebral instability likely warranting fusion.

Analysis of Chronic Low Back Pain Caused by Lumbar Microinstability After Percutaneous Endoscopic Transforaminal Discectomy: A Retrospective Study

Objective

Chronic low back pain (CLBP) after percutaneous endoscopic transforaminal discectomy (PTED) surgery may be caused by preoperative lumbar microinstability (MI). However, there is a paucity of research on the relationship between lumbar microinstability and chronic low back pain. The purpose of this article is to assess the preoperative radiographic characteristics of patients and evaluate the effects of lumbar microinstability on patient-reported outcomes among single-level lumbar disc herniation (LDH) patients who underwent PTED.

Methods

This study retrospectively reviewed the radiographic characteristics of a consecutive series of 127 patients with low back pain and leg pain caused by single-level LDH underwent PTED from August 2018 to March 2021. They were divided into three groups according to the radiographic parameters: the stable group (Group S), the dysfunctional group (Group D), and the microinstability group (Group M). The visual analogue scale (VAS) scores for leg and low back pain and Oswestry Disability Index (ODI) were evaluated preoperatively and postoperatively. Logistic regression analysis was used to identify independent risk factors for CLBP.

Results

Compared with Group D and Group S, Group M had the highest ODI scores (P < 0.01) and VAS scores (low back pain) (P < 0.01) after 1 year, while there were no significant differences in the VAS scores for leg pain at different time points after surgery (P > 0.05). In addition, the logistic regression analysis results regarding CLBP revealed that muscle fatty degeneration on MRI (95% CI, 1.20-8.51, P = 0.02), and facet tropism (95% CI, 1.39 -11.37, P = 0.01) may be independent risk factors.

Conclusion

Patients with lumbar microinstability may have CLBP after PTED, so patients with lumbar microinstability may need to take internal fixation surgery to solve their symptoms.

Facet Tropism/Inclination and Its Association with Intervertebral Disc Herniation in the Lumbar Spine - A Radiological Evaluation

Objective  To assess the role of facet tropism (FT) in intervertebral disc prolapse. Methods  A total 98 patients with lower back pain were included in the study. Magnetic resonance imaging scans were performed and analyzed. The angles of the right and left facets were measured on the axial section. Patients without disc prolapse at the L3-L4, L4-L5 and L5-S1 levels act as controls for those with disc prolapse at the same levels. A statistical analysis was also performed. Results  The incidence of FT at the L3-L4 level was of 85.2% in patients with disc herniation ( n  = 27), and of 56.3% in the control group, which was statistically significant ( p  = 0.008). Similarly, at the L4-L5 level, incidence of FT among cases and controls was of 71.4% ( n  = 35) and 52.4% respectively ( p  = 0.066). At the L5-S1 the incidence was of 66% and 51% among cases and controls respectively ( p  = 0.13). Conclusion  We found a positive association between FT and disc herniation at the L3-L4 level, but no association at the L4-L5 and L5-S1 levels.

Three-dimensional digital measurement of the facet joint in normal and lumbar intervertebral disc herniation aged 13-18 years

BACKGROUND

Lumbar facet joint is an important element of spinal "three-joint complex". Whether there is a relationship between strange structure of facet joint and adolescent lumbar disc herniation (ALDH) is nonetheless controversial, and the current research is mainly centered on adults.

OBJECTIVE

To find out the normal lumbar facet joints between 13 and 18 years old to provide anatomical basis for early diagnosis and therapy of lumbar disc herniation.

METHODS

CT imaging information of 32 sufferers with lumbar disc herniation aged from 13 to 18 years old in Inner Mongolia have been collected as the ALDH group, and 62 wholesome subjects in the equal period had been chosen as the normal group. Uncooked records of continuous scanning lumbar tomography pix were imported into MIMICS 21.0 for evaluation and size in DICOM format. The parameters include facet joint height, facet joint width, et al.

RESULTS

1. The left and right transverse angle of L₅S₁ segment in the ALDH group were (52.41 ± 9.2) ° and (55.99 ± 10.91) ° (P < 0.05), and the differences were statistically significant. The right side is larger than the left side. 2. Facet joint thickness in L₃-L₅ segment of the normal group was significantly higher than that of male (1.63 ± 0.32) mm than that of female (1.38 ± 0.25) mm; In 16-18 years old group, comparison of facet joint cross-sectional area was statistically significant (22.1 ± 3.04) mm² in male than (18.92 ± 3.71) mm² in female. 3. In comparison between normal and ALDH group, there was significant difference in L_3-4 transverse angle (P < 0.05), L_4-5 facet joint height and facet joint thickness (P < 0.05), L₅S₁ facet joint thickness and transverse angle (P < 0.05).

CONCLUSION

When ALDH occurs in the L₅S₁ segment, there is a substantial difference between the left and right sides of the transverse angle, and there is a difference in the thickness and the facet joint cross-sectional area between males and females, which is generally larger in males than in females. Facet joint height is larger, transverse angle of left and right is asymmetric, inferior articular process is larger, and facet joint thickness is smaller can indicate that lumbar disc herniation is effortless to occur.

Modifications in lumbar facet joint are associated with spondylolisthesis in the degenerative spine diseases: a comparative analysis

BACKGROUND

Magnetic resonance imaging (MRI) is important in the assessment of degenerative spine disease. However, its role is limited in the identification of spinal instability; therefore, weight-bearing and dynamic studies like X-rays are required. The supine position eliminates the gravitational pull, corrects the vertebral slippage, and opens the facet joints leading to the collection of the synovial fluid into the joint space, which is detected on the MRI and can serve as a marker for instability. We aim to compare the facet fluid, facet hypertrophy, facet angle, and disc degenerative changes among the patients presenting with degenerative spondylolisthesis (DS) and those without.

METHODS

We performed a retrospective review for all the patients treated at our institution from January 2015 to December 2016. Facet Fluid Index (FFI) (ratio of facet fluid width and facet joint width) was calculated to assess the joint fluid. The percentage of spondylolisthesis was measured on X-rays. Each radiological parameter was compared between the two groups, i.e., patients with DS and patients without DS. A p value < 0.05 was considered significant.

RESULTS

In total, 61 patients, 28 with DS and 33 without DS, were enrolled. Baseline characteristics were similar in the two groups (p > 0.05). The average values of FFI, facet fluid width, and the difference between the superior and inferior facet were significantly higher in the group with instability (p < 0.05). Multivariate analysis demonstrated a 4.44 (95% confidence interval [CI] 2.03-5.365) times increase in the odds of instability with a unit increase in FFI, p < 0.0001.

CONCLUSIONS

We report a positive linear correlation between the facet joint effusion and facet hypertrophy on MRI and the percentage of vertebral translation on X-ray. Prospective studies will determine if these markers can play a role in predicting spinal instability.

Facet Tropism in Lumbar Spine and Cervical Spine: A Systematic Review and Meta-Analysis

BACKGROUND

Facet tropism (FT) refers to the difference in the orientation of facet joints with respect to each other in the sagittal plane. FT leads to unequal biomechanical forces on facet joint and intervertebral disc during rotation and other physiologic movements. Most of the studies have reported the incidence of FT in the lumbar spine to vary between 40% and 70%, with L4-5 level being the most commonly afflicted level. The objective of this study was to find the association between FT and various lumbar and cervical degenerative disorders.

METHODS

A systematic search of PubMed was performed with the keywords "facet tropism" and "facet asymmetry." Data for meta-analysis were extracted from the studies to obtain pooled impact of FT on lumbar disc herniation (LDH) and lumbar degenerative spondylolisthesis (LDS).

RESULTS

Eighty-two articles were included in the systematic review and 18 studies had the required data to be included in the meta-analysis. The pooled standard mean difference between FT angles in patients with or without LDH was 0.31 with (P = 0.04). The pooled odds ratio for FT in patients with LDH was 3.27 with (P = 0.02). Subgroup analysis showed that there is no significant difference in the L3/4, L4/5, and L5S1 subgroups. The pooled standard mean difference between FT angles in patients with or without LDS was 0.54 (P = 0.009).

CONCLUSIONS

FT is significantly associated with LDH and LDS along with various other lumbar and cervical degenerative diseases.