The Relationship of Facet Joint Orientation and Tropism with Lumbar Disc Herniation and Degenerative Spondylolisthesis in the Lower Lumbar Spine

Exploring the Influence of Facet Orientation and Tropism on Neutral Zone Properties

Lumbar spine pathologies have been linked independently to both neutral zone (NZ) properties and facet joint anatomical characteristics; however, the effect of facet joint orientation (FO) and tropism (FT) on NZ properties remains unclear. The aim of the present study was to investigate how axial plane FO and FT relate to NZ range and stiffness in the human lumbar spine and porcine cervical spine. Seven human lumbar functional spine units (FSUs) and 94 porcine cervical FSUs were examined. FO and FT were measured, and in vitro mechanical testing was used to determine anterior-posterior (AP) and flexion-extension (FE) NZ range and stiffness. FO and FT were found to have no significant relationship with AP and FE NZ range. Increases in FT were associated with greater FE and AP NZ stiffness in human FSUs, with no FT-NZ stiffness relationship observed in porcine specimens. A significant relationship (p < 0.001) between FO and FE NZ stiffness was observed for both porcine and human FSUs, with a more sagittal orientation of the facet joints being associated with decreased FE NZ stiffness. Given the link between NZ stiffness and pathological states of the lumbar spine, further research is warranted to determine the practical significance of the observed facet joint anatomical characteristic-NZ property relationship.

Facet Joint Morphology and Tropism in Adolescents: Association With Lumbar Disk Herniation and Spondylolysis

STUDY DESIGN

A cross-sectional and observational study.

OBJECTIVE

To investigate the incidence of bidirectional lumbar facet tropism and its relationship with lumbar spine disease in adolescents.

SUMMARY OF BACKGROUND DATA

There is limited information on facet joint asymmetry in the sagittal plane in adolescents.

MATERIALS AND METHODS

The orientation of all lumbar facet joints was measured in the bidirectional planes on computed tomographic images for 191 patients with low back pain. The patients were divided into 4 groups according to age (<15 or ≥15 yr) and sex. The facet joint angle and tropism rate were compared among the groups. Facet tropism was defined as a difference in bilateral angle of >10° in the axial plane and >5° in the sagittal plane. Facet joint orientation was compared among groups using a one-way analysis of variance and Tukey honestly significant difference test or Games-Howell post hoc test and the incidence of facet tropism using the Kruskal-Wallis test with Bonferroni correction. The association of facet tropism with disease was investigated further by analyzing facet joint orientation and the incidence of facet tropism in 116 patients with single-level lumbar disease.

RESULTS

Facet tropism was observed in 8.7% of axial views and 7.5% of sagittal views. The incidence of axial facet tropism was significantly higher in male patients aged ≥15 years, especially at L4/5. Facet joint morphology in the axial plane was more coronal at L3/4 and L4/5 in male patients ≥15 years than in those <15 years. Facet joint morphology in the sagittal plane was unchanged at around 15 years of age in both sexes. Axial facet tropism was found at L4/5 in 55.6% of patients with herniated nucleus pulposus. There was a significant difference in sagittal facet orientation in patients with spondylolysis at L5. The facet angle was significantly larger in patients with L5 spondylolysis at L3/4 and L4/5.

CONCLUSIONS

Facet tropism in adolescents is similar in the axial and sagittal planes. Facet tropism and specific morphology may be related to lumbar disk herniation and spondylolysis in this age group.

Three Stages on Magnetic Resonance Imaging of Lumbar Degenerative Spine

PURPOSES

To propose a new lumbar degenerative staging system using the current radiological classification system.

METHODS

A cross-sectional analysis of retrospective databases between January 2018 and December 2022 was performed. Total of 410 patients for Modic changes, paravertebral muscle fat infiltration, disc degeneration, articular process degeneration, vertebral endplate degeneration and other structures, and disc displacement, Spondylolisthesis, and stenosis, and grouped patients according to stage were assessed. Visual analog scale, Japanese Orthopaedic Association, and Oswestry Disability Index scores were used to assess low back pain strength, neurological function, and quality of life, respectively.

RESULTS

The lumbar degeneration staging system consists of 8 variables, which can be divided into 3 steps: early, middle and late, and the correlation between each variable is strong (P < 0.05). The later the staging, the worse the Japanese Orthopaedic Association, visual analog scale, and Oswestry Disability Index scores.

CONCLUSIONS

Patients with later stages have worse clinical scores. This staging system recommends a uniform classification to assess lumbar degeneration.

Facet Joint Orientation/Tropism Could Be Associated with Fatty Infiltration in the Lumbar Paraspinal Muscles

BACKGROUND

Facet joint orientation (FJO) and facet joint tropism (FJT) are associated with intervertebral disc degeneration and paraspinal muscle atrophy. However, none of the previous studies has evaluated the association of FJO/FJT with fatty infiltration in the multifidus, erector spinae, and psoas muscles at all lumbar levels. In the present study, we aimed to analyze whether FJO and FJT were associated with fatty infiltration in the paraspinal muscles at any lumbar level.

METHODS

Paraspinal muscles and FJO/FJT were evaluated from L1-L2 to L5-S1 intervertebral disc levels on T2-weighted axial lumbar spine magnetic resonance imaging.

RESULTS

Facet joints were more sagittally and coronally oriented at the upper and lower lumbar levels, respectively. FJT was more obvious at lower lumbar levels. The FJT/FJO ratio was higher at upper lumbar levels. Patients with sagittally oriented facet joints at the L3-L4 and L4-L5 levels had fattier erector spinae and psoas muscles at the L4-L5 level. Patients with increased FJT at upper lumbar levels had fattier erector spinae and multifidus at lower lumbar levels. Patients with increased FJT at the L4-L5 level had less fatty infiltration in the erector spinae and psoas at the L2-L3 and L5-S1 levels, respectively.

CONCLUSIONS

Sagittally oriented facet joints at lower lumbar levels could be associated with fattier erector spinae and psoas muscles at lower lumbar levels. The erector spinae at upper lumbar levels and psoas at lower lumbar levels might have become more active to compensate the FJT-induced instability at lower lumbar levels.

Are there correlations between facet joint parameters and lumbar disk herniation laterality in young adults?

OBJECTIVE

We aimed to determine whether there is an association, in young adults, between the occurrence of lumbar disk herniation (LDH) at a given segment and the segment's facet joint parameters [facet orientation (FO) and tropism (FT)]. In addition, associations between facet joint parameters in the corresponding segment and LDH laterality were also investigated.

METHODS

We retrospectively analyzed data from 529 patients who were between 18 and 35 years old, who had experienced single-level LDH (L4-5 or L5-S1) between June 2017 and December 2019, and with<2 years of clinical history. We included an additional 122 patients with no history of LDH as an age-matched control group. LDH were classified by laterality (left-sided, right-sided, or central herniation). At each level, we investigated the relationship between facet joint parameters and herniation laterality.

RESULTS

FO_A values at the L4-L5 level and the L5-S1 level were significantly lower and FT was higher for the LDH group compared with those for the control group. The level at which LDH occurred, FO_L, FO_R, and FT differed significantly among the three groups. There was a significant association between herniationlaterality and FO at the L4-L5 level but not at the L5-S1 level.

CONCLUSIONS

Abnormal facet joint parameters are significantly associated with LDH. Young adults with higher FT should be paid more attention, to prevent the occurrence of LDH. Compared with L5-S1 level, intervertebral disk herniation at the L4-L5 level tended to occur ipsilateral to the side with a lower facet joint angle when FT was present.

Facet Joint Syndrome: Pathophysiology, Diagnosis, and Treatment

Facet joint osteoarthritis (OA) is the most frequent form of facet joint syndrome. Medical history, referred pain patterns, physical examination, and diagnostic imaging studies (standard radiographs, magnetic resonance imaging, computed tomography and single-photon emission computed tomography) may suggest but not confirm lumbar facet joint (LFJ) syndrome as a source of low back pain (LBP). However, the diagnosis and treatment of facet joint syndrome is still controversial and needs further study. It is widely acknowledged that block with local anesthetic is perhaps the most effective method to establish a diagnosis of pain from LFJ. Particularly, there are different rates of success among different populations selected for diagnostic block with various positive criteria. Currently, in addition to conservative treatments for pain such as painkillers, functional exercises, and massage, there are many other methods, including block, denervation of the nerves that innervate the joints by radiofrequency, freezing or endoscopy, and injections. Due to the limited duration of pain relief from neurolysis of medial branch, many scholars have recently turned their targets to dorsal roots and LFJ capsules. Therefore, we reviewed the latest research progress of facet joint syndrome from diagnosis to treatment.

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.

Lumbar Facet Tropism on Different Facet Portions and Asymmetry Between Ipsilateral Cephalad and Caudad Portions: Their Correlations With L4/5 and L5/S1 Lumbar Disc Herniation

STUDY DESIGN

A retrospective case-control study.

OBJECTIVE

To investigate the correlation between lumbar disc herniation (LDH) and lumbar facet tropism (FT) on cephalad and caudad facet portions, respectively; to investigate the asymmetry between ipsilateral cephalad and caudad facet portions and its correlation with LDH.

SUMMARY OF BACKGROUND DATA

There are still heavy debates on the exact correlation between lumbar FT and LDH. However, no study ever focused on the FT on different facet portions and asymmetry between ipsilateral cephalad and caudad portions in patients with LDH.

METHODS

One hundred patients with L4/5 LDH, 100 patients with L5/S1 LDH, and 100 participants without LDH (control group) were age and sex matched and included in this study. Participants in each group were further divided into two subgroups based on age (≥ or < 50 yr old). Bilateral facet joint angles on both cephalad and caudad portions were measured. FT and asymmetry between ipsilateral cephalad and caudad portions in each LDH group were compared with those in corresponding control group.

RESULTS

Comparing with control participants, the mean difference of bilateral facet angles in older patients with L4/5 LDH was significantly greater either on cephalad portion and caudad portion, whereas significantly higher frequency of FT was only exhibited on cephalad portion. In older patients with L4/5 LDH, the mean difference of facet angle between ipsilateral cephalad and caudad portions was significantly greater than that of control participants, the frequency of ipsilateral cephalad, and caudad facet asymmetry was also significantly higher.

CONCLUSIONS

Only the FT on cephalad portion but not caudad portion of facet joint is associated with L4/5 LDH of older patients. The measurement on different portions of facet joint may result in discrepancy on FT identification. Asymmetry between ipsilateral cephalad and caudad facet portions is also associated with L4/5 LDH in older patients.

LEVEL OF EVIDENCE

3.

Facet Tropism and Orientation: Risk Factors for Degenerative Lumbar Spinal Stenosis

The aim of this study is to establish whether facet tropism (FT) and orientation (FO) are associated with degenerative lumbar spinal stenosis (DLSS). A retrospective computerized tomography (CT) study including 274 individuals was divided into two groups: control (82 males and 81 females) and stenosis (59 males and 52 females). All participants have undergone high-resolution CT scan of the lumbar spine in the same position. FT and FO were measured at L1-2 to L5-S1. Significant sagittal FO was noted in the stenosis males (L2-3 to L4-5) and females (L2-3 to L5-S1) compared to the controls. The prevalence of FT was remarkably greater in the stenosis males (L4-5, L5-S1) and females (L3-4, L5-S1) compared to their counterparts in the control group. Our results also showed that FT (L3-4 to L5-S1) increases approximately 2.9 times the likelihood for DLSS development. This study indicates that FO and FT in the lower lumbar spine are significantly associated with DLSS.

XLIF interbody cage reduces stress and strain of fixation in spinal reconstructive surgery in comparison with TLIF cage with bilateral or unilateral fixation: a computational analysis

In treating recalcitrant low back pain, extreme lateral lumbar interbody fusion (XLIF) with a large cage is reported to have better stability compared to approach of transforaminal lumbar interbody fusion (TLIF) using a small cage. In addition, bilateral pedicle screw fixation (PSF) in comparison with unilateral fixation achieved no inferior fusion rate, but with a significant reduction in operation time and blood loss. The aim of the study was to understand the mechanism underpinning the stability of lumbar interbody fusion using different cage sizes with unilateral or bilateral PSF. A computer model of human lumbar vertebrae L4 and L5 with implants was reconstructed based on CT scans and simulated in Ansys Workbench. Simulation results demonstrated that for either XLIF or TLIF cages, the maximum values of rod stress were comparable with bilateral and unilateral PSF. However, the stability was considerably reduced with unilateral PSF for TLIF due to significantly increased facet joint strain for TLIF; whereas for XLIF with left unilateral PSF, the max facet joint strain was comparable to bilateral PSF, possibly due to facet tropism of this specific subject.