Facet tropism in lumbar motion segments and its significance in disc herniation

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.

Does facet tropism negatively affect the response to transforaminal epidural steroid injections? A prospective clinical study

OBJECTIVE

To examine the impact of the presence of facet tropism on the results of transforaminal epidural steroid injection for unilateral radicular pain induced by lumbar disc herniation.

MATERIALS AND METHODS

We included 112 patients diagnosed with unilateral, single-level lumbar disc herniation-induced radicular pain. Injection was planned at relevant levels. The patients were assessed using the Numerical Rating Scale, the Modified Oswestry Disability Index, and the Beck Depression Inventory before the injection and at hour 1, week 3, and month 3 after the injection. Presence of facet tropism was assessed by measuring the facet angles in the L3-4, L4-5, and L5-S1 segments of lumbar MRI T2 sequence axial section.

RESULTS

A significant decrease in the Numerical Rating Scale and an increase in the Modified Oswestry Disability Index scores were detected at all follow-ups in groups comprising 39 patients with and 61 without facet tropism (p < 0.05). On comparison, improvement in clinical parameters at week 3 and month 3 in the group without facet tropism was greater (p < 0.05). As treatment success is considered to be a ≥ 50% reduction in the Numerical Rating Scale scores, 55.2% of the patients attained treatment success at month 3. Further, although the treatment success rate in the group with facet tropism was 34.2%, it was 69% in that without facet tropism (p < 0.05).

CONCLUSION

Facet tropism correlates with less success of transforaminal epidural steroid injection; therefore, facet tropism may be a worthwhile measurement in a discussion with patients of the benefits of the procedure.

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

STUDY DESIGN

Retrospective study.

PURPOSE

This study aimed to clarify the relationship of both facet tropism (FT) and the sagittally aligned facet (SAF) joint with lumbar disc herniation (LDH) and degenerative spondylolisthesis (DS).

OVERVIEW OF LITERATURE

Despite several studies conducted, there is no consensus on the association of the SAF joint and FT with DH and DS.

METHODS

Between June 2015 and December 2017, magnetic resonance imaging scans of 250 consecutive patients who underwent surgery for LDH and DS were analyzed. The facet angles at all the lower lumbar levels were calculated, and SAF and FT were noted. The relationship between the side of disc herniation and that of the SAF joint were also determined. Statistical analysis was performed, and the relation of SAF and FT to LDH and DS was noted.

RESULTS

We observed a positive relationship between SAF and LDH at L4-5 and L5-S1 with a p-value of 0.02 (<0.05). FT demonstrated a positive association with LDH at L4-5 (p=0.047) but not at L3-4 or L5-S1. SAF demonstrated a positive relationship with DS at L3-4 (p<0.001) but not at L3-4 or L5-S1. FT demonstrated a significant relation with DS at L4-5 (p<0.001), whereas no positive association was observed at L3-4 and L5-S1.

CONCLUSIONS

The L4-5 level demonstrated a significant association with SAF and FT in LDH and DS. Moreover, SAF at L5-S1 demonstrated a positive association with LDH. These findings provide useful information for future longitudinal studies to elucidate the possible causes for such phenomena.

Clinical Characteristics and Risk Factors of Recurrent Lumbar Disk Herniation: A Retrospective Analysis of Three Hundred Twenty-One Cases

STUDY DESIGN

Retrospective clinical series.

OBJECTIVE

To investigate the clinical features and the risk factors for recurrent lumbar disc herniation (rLDH) in China.

SUMMARY OF BACKGROUND DATA

rLDH is a common cause of poor outcomes after lumbar microdiscectomy surgery. Risk factors for rLDH are increasingly being investigated. However, results in these previous studies were not always consistent.

METHODS

Between June 2005 and July 2012, 321 consecutive patients with single-level LDH, who underwent surgery, were enrolled in this study. We divided the patients into the recurrent group (R group) and the nonrecurrent group (N group) and compared their clinical parameters and preoperative radiologic parameters. The relationships between the variables and rLDH were evaluated by univariate analysis and multiple logistic regression analysis.

RESULTS

There was significant difference between groups in sex (P = 0.003), age (P = 0.003), current smoking (P = 0.004), body mass index (BMI) (P = 0.04), occupational lifting (P < 0.001), trauma history (P = 0.04), procedures (P = 0.04), herniation type (P = 0.006), disc height index (DUI) (P = 0.04), facet orientation (FO) (P = 0.04), facet tropism (FT) (P = 0.04), and sagittal range of motion (from) (P = 0.04). By putting these differences in logistic regression analysis, it showed that being male, young age, current smoking, higher BMI, herniation type (transligamentous extrusion), surgical procedures (bilateral laminectomy or total laminectomy), heavy works, undergoing a traumatic event, a large from, a high DUI, a large FT, and a small FO significantly related with rLDH.

CONCLUSION

Based on our data, sex, age, current smoking, BMI, occupational lifting, trauma, surgical procedures, herniation type, DUI, FO, FT, and from showed a significant correlation with the incidence of rLDH. Patients with these risk factors should be paid more attention for prevention of recurrence after primary surgery.

LEVEL OF EVIDENCE

3.

Is Facet Tropism Associated with Increased Risk of Disc Herniation in the Lumbar Spine?

STUDY DESIGN

Retrospective case control study.

PURPOSE

In current study, we compared the incidence of facet tropism (FT) in patients with lumbar disc herniation and normal controls.

OVERVIEW OF LITERATURE

It has been suggested that FT can be associated with increased risk of lumbar disc herniation.

METHODS

A total of 66 and 63 patients with L4/L5 and L5/S1 disc herniation, respectively, were evaluated in the present study. The control group comprised 61 normal subjects. Facet joint angle was measured using axial magnetic resonance images. The FT was defined as a difference of >10° between the right and left facet joints. The incidence of FT was compared between patients and controls. We also investigated the relationship between facet orientation (sagittal or coronal) and side of disc herniation.

RESULTS

The incidence of FT at the L4/L5 level was significantly higher in patients with disc herniation (48.5% vs. 26.2%, p =0.01), while it was found to be the same at the L5/S1 level in patients and controls (50.8% vs. 36%, p =0.098). Among the 64 patients with FT, intervertebral disc herniation occurred significantly toward the more sagittally oriented facet joint in 41 patients (p <0.05).

CONCLUSIONS

FT is associated with increased risk of L4/L5 intervertebral disc herniation, but not at the L5/S1 level. In addition, disc herniation occurred toward the more sagittally oriented facet joint.

Facet orientation and tropism: Associations with asymmetric lumbar paraspinal and psoas muscle parameters in patients with chronic low back pain

BACKGROUND

Many studies have explored the relationship between facet tropism and facet joint osteoarthritis, disc degeneration and degenerative spondylolisthesis. However, the associations between facet orientation and tropism, and paraspinal muscles have not been studied.

OBJECTIVE

To analyze the associations between facet orientation and tropism, and parameters of paraspinal muscles in patients with chronic low back pain.

METHODS

Ninety-five patients with chronic low back pain were consecutively enrolled. Their facet joint angles were measured on computed tomography (CT) while gross cross-sectional area (GCSA), functional cross-sectional area (FCSA) and T2 signal intensity of lumbar paraspinal and psoas muscle were evaluated on magnetic resonance imaging (MRI).

RESULTS

The GCSA and FCSA were significantly smaller for multifidus muscle (P< 0.001), but significantly larger for erector spinae and psoas muscles (P< 0.001), in coronally-orientated group than those in sagittally-orientated group. The differences of bilateral GCSA and FCSA of multifidus muscle were significantly larger in facet tropism group than those in no facet tropism group (P= 0.009 and P= 0.019).

CONCLUSIONS

Muscular asymmetries may develop in the lumbar region of the spine, which are associated with facet asymmetry in patients with chronic low back pain. Longitudinal studies are needed to understand the causal relationship between facet orientation and tropism and muscular asymmetry in future.

Facet tropism: possible role in the pathology of lumbar disc herniation in adolescents

OBJECTIVE The role of facet tropism (FT) in lumbar disc herniation (LDH) is ambiguous. The present study aimed to investigate the association between FT and LDH in adolescents. METHODS This study included 65 adolescents with LDH with 1- or 2-level LDH, or both. Facet angles were measured with MRI. FT was defined as asymmetry of 10° between the left and right side. The same levels of 30 healthy persons who had no lumbar lesions were used as controls. Statistical analysis was performed using the chi-square test. RESULTS FT was identified in 16 of 39 patients with LDH in L4-5 and in 3 of 30 controls (p = 0.006, OR 6.261, 95% CI 1.619-24.217). It was also identified in 12 of 27 patients with LDH in L5-S1 and in 4 of 30 controls (p = 0.017, OR 5.200, 95% CI 1.420-19.039). One patient had LDH in both L4-5 and L5-S1. CONCLUSIONS FT is associated with LDH in both L4-5 and L5-S1 levels in adolescents.

Irregular Alteration of Facet Orientation in Lumbar Segments: Possible Role in Pathology of Lumbar Disc Herniation in Adolescents

BACKGROUND

The role of the overall structural feature of facet joint in the development of lumbar disc herniation (LDH) is unclear. The present study aimed to investigate the role of irregular alteration of facet orientation (IAFO) in low lumbar segments in the pathology of LDH in adolescents.

METHODS

Sixty-five adolescents with LDH were included in the study. Facet angles were measured in magnetic resonance imaging. The IAFO was defined as the irregular orientation of the included facet joints angle, which was regularly increased from L3 to S1 in the normal group, including small-large-small (SLS) type, large-small-large (LSL) type, and large-small-smaller (LSS) type. Thirty normal adolescents without lumbar lesions were selected into the control group. Statistical analysis was performed using χ(2) test.

RESULTS

IAFO was observed in 20 of 65 subjects in LDH group compared with 3 of 30 in the control group [P = 0.038; OR=4 (1.086, 14.735)]. The SLS type was observed in 14 patients, and the LSL type was found in 6 patients, compared with 2 and 1, respectively, in the control group, no LSS type was found in the two groups. There were 8 subjects with IAFO of SLS style herniated in L5/S1 level compared with 6 subjects in L4/5. There was 1subject with IAFO of LSL style herniated in L5/S1 level compared with 5 subjects in L4/5.

CONCLUSIONS

The findings of this study suggest that the IAFO in the lumbar spine was associated with lumbar disc herniation in adolescents.

Migration patterns of herniated disc fragments: a study on 1,020 patients with extruded lumbar disc herniation

BACKGROUND CONTEXT

Herniated disc fragments are known to migrate in various directions within the spinal canal. To date, no comprehensive studies have been undertaken to examine the migration patterns of herniated disc material using a standard nomenclature and classification system.

PURPOSE

To report migration patterns of extruded lumbar disc fragments.

STUDY DESIGN

A review of magnetic resonance (MR) images.

PATIENT SAMPLE

A total of 1,020 consecutive Azeri patients with symptomatic extruded lumbar intervertebral disc herniation.

OUTCOME MEASURES

Migration patterns of extruded lumbar disc fragments in vertical and horizontal planes and their association with age, gender, body mass index (BMI), and the level of herniation.

METHODS

High-quality axial and sagittal MR images of the lumbar spine were used. Disc material that was displaced away from the site of extrusion, regardless of continuity, was considered "migrated." The migration patterns observed were rostral or caudal in the vertical plane and central, paracentral, subarticular, foraminal, or extraforaminal in the horizontal plane.

RESULTS

In the vertical plane, rostral and caudal migrations were observed in 27.8% and 72.2% of the patients, respectively. The number of rostral migrations increased significantly with increasing age and in higher levels in the lumbar spine (p<.001 for both). Radiculopathy was significantly more frequent in caudal migrations than in rostral migrations (78.9% vs. 65.1%, p<.001). There was no significant association between gender or BMI and migration patterns in the vertical plane. In the horizontal plane, central, paracentral, subarticular, foraminal, and extraforaminal migrations were reported in 17.3%, 74.2%, 4.3%, 2.5%, and 1.8% of the patients, respectively. The youngest (median age 39 years, interquartile range [IQR] 13 years) and the oldest (median age 55 years, IQR 15 years) groups of patients (p<.001) had the most formainal and extraforaminal migrations, respectively. Radiculopathy was present in 66.5%, 76.8%, 88.6%, 96%, and 27.8% of the patients with central, paracentral, subarticular, foraminal, and extraforaminal migrations, respectively (p<.001). No significant association was found between gender, BMI, or the level of herniation and migration pattern in the horizontal plane.

CONCLUSIONS

Caudal and paracentral migrations are the most common patterns of migration in patients with extruded lumbar disc herniation in the vertical and horizontal planes, respectively. Age and the level of herniation may affect the migration patterns of herniated lumbar disc material.

End plate disproportion and degenerative disc disease: a case-control study

Study Design

Case-control.

Purpose

To determine whether a disproportion between two neighboring vertebral end plates is associated with degenerative disc disease.

Overview of Literature

Recently, it has been suggested that disproportion of the end plates of two adjacent vertebrae may increase the risk of disc herniation.

Methods

Magnetic resonance (MR) images (n=160) with evidence of grades I-II lumbar degenerative disc disease (modified Pfirrmann's classification) and normal MR images of the lumbar region (n=160) were reviewed. On midsagittal sections, the difference of anteroposterior diameter of upper and lower end plates neighboring a degenerated (in the case group) or normal (in the control group) intervertebral disc was calculated (difference of end plates [DEP]).

Results

Mean DEP was significantly higher in the case group at the L5-S1 level (2.73±0.23 mm vs. 2.21±0.12 mm, p=0.03). Differences were not statistically significant at L1-L2 (1.31±0.13 mm in the cases vs. 1.28±0.08 mm in the controls, p=0.78), L2-L3 (1.45±0.12 mm in the cases vs. 1.37±0.08 mm in the controls, p=0.58), L3-L4 (1.52±0.13 mm in the cases vs. 1.49±0.10 mm in the controls, p=0.88), and L4-L5 (2.15±0.21 mm in the cases vs. 2.04±0.20 mm in the controls, p=0.31) levels. The difference at the L5-S1 level did not remain significant after adjusting for body mass index (BMI), which was significantly higher in the patients.

Conclusions

End plate disproportion may be a significant, BMI-dependent risk factor for lumbar degenerative disc disease.

Disproportion of end plates and the lumbar intervertebral disc herniation

BACKGROUND CONTEXT

It is suggested that the shape of the vertebral end plates may play a role in the development of abnormalities in the intervertebral disc. On midsagittal magnetic resonance images of the spine in patients with lumbar intervertebral disc herniation, a notable disproportion frequently exists between the end plates of two vertebrae to which the disc is attached. There is apparently no study in the literature examining possible association of this disproportion with development of disc herniation.

PURPOSE

To determine whether a disproportion between two neighboring vertebral end plates is associated with the presence of disc herniation at the same level.

STUDY DESIGN

Case-control study.

PATIENT SAMPLE

Two hundred fifty patients with primary lumbar disc herniation in the case group and 250 age- and sex-matched normal individuals in the control group.

OUTCOME MEASURES

On midsagittal sections, the difference of anteroposterior diameter of upper and lower end plates neighboring a herniated (in the case group) or normal (in the control group) intervertebral disc was calculated and expressed as "difference of end plates" or "DEP."

METHODS

Subjects with previous spinal surgery, spondylolisthesis, or a significant vertebral deformity were excluded. For the main outcome variable, DEP was calculated at the level with herniated intervertebral disc in the case group, and the mean value was compared with mean DEP at the same level in the controls.

RESULTS

Mean DEP was significantly higher in the case group at both L4-L5 (2.45±0.28 vs. 2.08±0.27 mm, p=.02) and L5-S1 (3.32±0.18 vs. 2.51±0.13 mm, p<.001) levels. Similar differences were only marginally insignificant at L2-L3 (1.96±0.14 mm in the cases vs. 1.33±0.15 mm in the controls, p=.07) and L3-L4 (2.17±0.11 mm in the cases vs. 1.55±0.09 mm in the controls, p=.06) levels, with no significant difference at L1-L2 level (1.81±0.10 mm in the cases vs. 1.28±0.09 mm in the controls, p=.12). Each 1 mm increase of DEP at L4-L5 and L5-S1 levels was associated with 53% and 56% elevation in disc herniation risk at the corresponding levels, respectively.

CONCLUSIONS

Difference of end plate is a significant and probably independent risk factor for lumbar disc herniation.

Association of facet tropism and progressive facet arthrosis after lumbar total disc replacement using ProDisc-L

PURPOSE

The purpose of this retrospective study was to examine the association of facet tropism and progressive facet arthrosis (PFA) after lumbar total disc replacement (TDR) surgery using ProDisc-L.

METHODS

A total of 51 segments of 42 patients who had undergone lumbar TDR using ProDisc-L between October 2003 and July 2007 and completed minimum 36-month follow-up period were retrospectively reviewed. The changes of facet arthrosis were categorized as non-PFA and PFA group. Comparison between non-PFA and PFA group was made according to age, sex, mean follow-up duration, grade of preoperative facet arthrosis, coronal and sagittal prosthetic position and degree of facet tropism. Multiple logistic regression analysis was also performed to analyze the effect of facet tropism on the progression of facet arthrosis.

RESULTS

The mean age at the surgery was 44.43 ± 11.09 years and there were 16 males and 26 females. The mean follow-up period was 53.18 ± 15.79 months. Non-PFA group was composed of 19 levels and PFA group was composed of 32 levels. Age at surgery, sex proportion, mean follow-up period, level of implant, grade of preoperative facet arthrosis and coronal and sagittal prosthetic position were not significantly different between two groups (p = 0.264, 0.433, 0.527, 0.232, 0.926, 0.849 and 0.369, respectively). However, PFA group showed significantly higher degree of facet tropism (7.37 ± 6.46°) than that of non-PFA group (3.51 ± 3.53°) and p value was 0.008. After adjustment for age, sex and coronal and sagittal prosthetic position, multiple logistic regression analysis revealed that facet tropism of more than 5° was the only significant independent predictor of progression of facet arthrosis (odds ratio 5.39, 95 % confidence interval 1.251-19.343, p = 0.023).

CONCLUSIONS

The data demonstrate that significant higher degree of facet tropism was seen in PFA group compared with non-PFA group and facet tropism of more than 5° had a significant association with PFA after TDR using ProDisc-L.

Association of facet tropism with lumbar disc herniation

PURPOSE

Facet tropism is defined as asymmetry between left and right facet joints and is postulated as a possible cause of disc herniation. In the present study, the authors used a 3-T MRI to investigate the association between facet tropism and lumbar disc herniation at a particular motion segment. They also examined whether the disc herniated towards the side of the more coronally oriented facet joint.

METHODS

Sixty patients (18-40 years) with single level disc herniation (L3-L4, L4-L5, or L5-S1) were included in the study. Facet angles were measured using MRI of 3-T using the method described by Karacan et al. Facet tropism was defined as difference of 10° in facet joint angles between right and left sides. Normal disc adjacent to the herniated level was used as control. We also examined if disc herniated towards the side of more coronally oriented facet.

RESULTS

Twenty-five herniations were at L4-L5 level and 35 at L5-S1. Statistical analysis was performed using the Fischer Exact Test. At L4-L5 level, 6/25 cases had tropism compared to 3/35 controls (p = 0.145). At L5-S1 level, 13/35 cases had tropism as compared to 1/21 controls (p = 0.0094). Of 19 cases having tropism, the disc had herniated towards the coronally oriented facet in six (p = 0.11).

CONCLUSION

The findings of the study suggest that facet tropism is associated with lumbar disc herniation at the L5-S1 motion segment but not at the L4-L5 level.

Laterality of cervical disc herniation

PURPOSE

Cervical disc herniation (CDH) is found more frequently at the lower cervical spine than at the upper or middle level. However, there is scarcity of data about the laterality of CDH. The aim of this study is to detect the laterality of CDH.

METHODS

We retrospectively evaluated preoperative computed tomography myelograms and magnetic resonance images of 75 cases of CDH who underwent single level anterior cervical discectomy and fusion at C4-5, C5-6, or C6-7 levels from 2008 to 2010 in our institute. Statistical analyses were performed using the Chi-square test.

RESULTS

Eleven cases were found at C4-5 level, 42 cases at C5-6 level, and 22 cases at C6-7 level. At C4-5 level, CDH was recognized at the right side in 2 cases, at the left side in 2 cases, and at the center in 7 cases. At C5-6 level, CDH was found at the right side in 20 cases and at the left side in 22 cases. At C6-7 level, CDH was found at the right side in 3 cases and at the left side in 19 cases with significantly high frequency of left-sided CDH (p < 0.025).

CONCLUSIONS

In this study, it was revealed that the left-sided CDH was more frequent than the right-sided CDH at C6-7 level.

Effect of age and lordotic angle on the level of lumbar disc herniation

It has been previously suggested in the literature that with aging, degenerative changes as well as disc herniation start at the lower lumbar segments, with higher disc involvement observed in an ascending fashion in older age groups. We conducted a study to investigate this correlation between age and level of disc herniation, and to associate it with the magnitude of the Lumbar Lordotic Angle (LLA), as measured by Cobb's method. We followed retrospectively lumbosacral spine MRI's of 1419 patients with symptomatic disc herniation. Pearson's correlation was used in order to investigate the relationship between LLA, age, and level of disc herniation. Student's t-test was applied to assess gender differences. Young patients were found to have higher LLA (R = 0.44, P < 0.0001) and lower levels of disc herniation (R = 0.302, P < 0.0001), whereas older patients had higher level herniation in lower LLA group (mean LLA 28.6° and 25.4°) and lower level herniation in high LLA group (mean LLA 33.2°). We concluded that Lumbar lordotic Cobb's angle and age can be predictors of the level of lumbar disc herniation. This did not differ among men and women (R = 0.341, P < 0.0001).

Unilateral spondylolysis and the presence of facet joint tropism

STUDY DESIGN

Retrospective review of the CT scans performed in a group of patients examined for a possible spondylolysis.

OBJECTIVE

To investigate whether there is an association between unilateral spondylolysis and facet joint tropism.

SUMMARY OF BACKGROUND DATA

Spondylolysis is a fatigue fracture of the pars interarticularis of great importance in sports injury. The demonstration of a unilateral spondylolysis is important because there is a potential for full healing if the athletic activity is modified, whereas bilateral spondylolysis frequently leads to established nonunion. Coronally orientated facet joints are known to predispose to spondylolysis by increasing the point loading of the pars interarticularis. The importance of this finding has not been investigated in unilateral spondylolysis.

METHODS

A review of patients with low back pain and a possible diagnosis of spondylolysis who were investigated with multislice CT was performed. The coronal orientation of the facet joints at L4/5 and L5/S1 was measured and comparison was done between those with and without a spondylolysis.

RESULTS

The coronal angle of 140 facet joints in 35 patients was recorded. Of 35 patients, 23 had a spondylolysis which was unilateral in 12 patients. The facet joint angle was significantly more coronally orientated in the presence of a spondylolysis when compared with an intact pars (means, 53° and 43°, respectively; P < 0.01). In the presence of a unilateral spondylolysis, the facet joint was significantly more coronally orientated on the side of the spondylolysis (means, 52° and 45°, respectively; P < 0.01). CONCLUSION.: This study is the first investigation of facet joint anatomy in unilateral spondylolysis. Asymmetric facet joints do increase the force through one side of the spine, with a unilateral spondylolysis occurring on the side of the more coronally orientated facet joint.

Analysis of the relationship between facet joint angle orientation and lumbar spine canal diameter with respect to the kinematics of the lumbar spinal unit

STUDY DESIGN

Retrospective cross-sectional study.

OBJECTIVE

This study aimed to elucidate the relationship among facet orientation, kinematics of a spinal unit, and change in lumbar spine canal diameter by using kinetic magnetic resonance imaging.

SUMMARY OF BACKGROUND DATA

Some studies have suggested an association between increased sagittally oriented facet angles and degenerative lumbar spondylolisthesis. However, no study has specifically addressed the association of facet orientation with the kinematics of a spinal unit and change in canal diameter.

METHODS

Kinetic magnetic resonance imagings were performed with patients in flexion, neutral, and extension positions. Study subjects were classified into 6 groups-AA, BB, CC, AB (BA), BC (CB), and AC (CA)-on the basis of bilateral facet angles (A, narrow; B, normal; and C, wide) and disc and facet joint degeneration. A magnetic resonance imaging analyzer was used for anatomic measurements and for calculating changes in canal diameters and disc bulging as well as the lumbar spine kinematics.

RESULTS

Osseous canal diameters were significantly smaller in the group AA than in the group BB, whereas they were significantly larger in the group CC than in the group BB. Canal diameter at the disc level was significantly smaller in the group AA than in the group BB in all 3 positions, whereas it was significantly larger in the group CC than in the group BB. Translational motion was significantly more in the group AA than in the group BB, whereas it was significantly lesser in the group CC than in the group BB.

CONCLUSIONS

We demonstrated the relationship among facet orientation, osseous canal diameter, kinematics of a spinal unit, and change in lumbar spine canal diameter. Patients with sagittally oriented facets had narrow osseous canals with mobility, whereas those with coronally oriented facets had stable and wider osseous canals. This finding is helpful in understanding the mechanism underlying lumbar spinal canal stenosis and degenerative spondylolisthesis.

The relationship between degree of facet tropism and amount of dynamic disc bulge in lumbar spine of patients symptomatic for low back pain

Facet tropism has been investigated as a predisposing factor for degenerative changes in the lumbar spine; however, no prior study has evaluated the relationship between disc bulge and facet tropism. In this study, we used kinetic magnetic resonance imaging (kMRI) to investigate the association between degree of facet tropism and amount of disc bulge in the lumbar spine in relation to age. kMRIs in the flexion, neutral, and extension positions were performed on 410 consecutive patients with low back pain. T2-weighted midsagittal and axial mid-disc cuts were analyzed to measure disc bulge and facet angle. Facet asymmetry was calculated and classified as: no facet tropism, <6°; mild facet tropism, 6–11°; or severe facet tropism, ≥11°. Maximal static bulge (MSB), maximal dynamic bulge (MDB), and age in the facet tropism groups were compared by age subpopulations and MDB categories, defined by the positions between which the largest change in disc bulge occurs. We found the severe facet tropism group to be associated with a nearly significant increase in MSB and MDB over the no facet tropism group in the older subpopulation at the L4–L5 level only, and a larger MDB in the L4–L5 MDB category [E–N], where the greatest change in disc bulge occurs between neutral and extension positions (p = 0.013). Our findings suggest that severe facet tropism is associated with increased disc bulge at L4–L5 in only a subset of older age patients, but may in large part be due to biomechanical factors that define the [E–N] category.

Mri-Based Morphological Predictorsof Spect Positive Facet Arthropathyin Patients With Axial Back Pain

OBJECTIVE

A major barrier to understanding facetogenic low back pain has been the lack of radiographic diagnostic criteria. This study investigates the correlation between radiographic findings on magnetic resonance imaging (MRI) scans and single photon emission computed tomographic (SPECT) scans in patients clinically found to have facetogenic axial back pain.

METHODS

Thirty-one patients with severe axial back pain underwent lumbar MRI and SPECT scans. Two hundred thirty facets were identified and were graded from 1 to 4 using synovial area, size, cartilaginous discontiguity, osteophytic overgrowth, and joint space obliteration. Twenty-nine "hot" joints were identified on SPECT scans. MRI features of 230 lumbar facets were correlated with SPECT results.

RESULTS

Four basic morphological patterns were identified on the basis of synovial appearance on MRI scans, light, mottled, narrowed, and obliterated, and formed the basis for the grading 1 to 4, respectively (sensitivity for "hot facet", 0.93). The mottled group had 0.90 specificity (P = 0.0001). Osteophytic overgrowth demonstrated 0.94 specificity (P = 0.0004). Facet hypertrophy was not associated with increased tracer uptake.

CONCLUSION

We identify four types of synovial architecture on T2-weighted MRI scans with overall high sensitivity for predicting SPECT positivity. These four grades likely represent a continuum of facet degeneration, from a normal to obliterated joint. One particular subtype, Grade 2, demonstrated a high specificity for SPECT and synovial fluid increase suggestive of inflammation. Facet hypertrophy was not predictive of bone scan positivity, perhaps suggesting the protective nature of a hypertrophied facet. Synovial abnormalities correlate with SPECT findings and a grading scale is proposed delineating the degeneration of a lumbar facet over time. A subtype of SPECT(+) inflamed joint is proposed. Further studies will be needed to improve our understanding of the natural history of the lumbar facet.

Facet tropism and interfacet shape in the thoracolumbar vertebrae: characterization and biomechanical interpretation

STUDY DESIGN

Thoracolumbar facet and interfacet linear dimensions were measured and analyzed.

OBJECTIVE

To characterize and analyze the thoracolumbar facet and interfacet size and shape in relation to gender, ethnic group, and age and to detect the extent of normal facet tropism along the thoracolumbar spine.

SUMMARY OF BACKGROUND DATA

Knowledge on facet tropism and interfacet shape is limited in the literature as most data are based on 2-dimensional measurements, small samples, or isolated vertebrae.

METHODS

Facet shape as represented by width, length, width/length ratio and interfacet distances was obtained directly from dry vertebrae of 240 adult human spines. The specimen's osteologic material is part of the Hamann-Todd Osteological Collection housed at the Cleveland Museum of Natural History, Cleveland, OH. A total of 4080 vertebrae (T1-L5) from the vertebral columns of individuals 20 to 80 years of age were measured, using a Microscribe 3-dimensional apparatus (Immersion Co., San Jose, CA). Data were recorded directly on computer software. Statistical analysis included paired t tests and ANOVA.

RESULTS

A significant correlation was found between all thoracolumbar facet dimensions and an individual's height and weight. Facet tropism is a major characteristic of the thoracolumbar spine, the left being longer in the thorax while the right is longer in the lumbar. In general, facet size is age-independent and greater in males compared with females with a significant ethnic component. Facet length is similar for all thoracic vertebrae, whereas it sharply and continuously increases in the lumbar vertebrae. Facet dimension manifests a bipolar distribution along the thoracolumbar vertebrae. Width/length ratio indicates that facets are longer than wider for most verte-brae. The interarticular area manifests a marked inverted trapezoidal shape at T1-T2, a rectangular shape at T3-L3, and an ordinary trapezoidal shape at L4-L5.

CONCLUSIONS

Facet tropism is a normal characteristic in humans, yet it varies along the thoracolumbar spine.

Facet angles in lumbar disc herniation: their relation to anthropometric features

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To investigate the alteration of facet joint angle and its relation to anthropometric features in lumbar disc herniation.

SUMMARY OF BACKGROUND DATA

In the previous studies, the facet tropism and its relation to the level, type, side, and development of lumbar disc herniation were reported. This study was the first to correlate anthropometric feature, facet angle, and asymmetry in patients with lumbar disc herniation. METHODS.: Sixty-one patients with lumbar disc herniation were included in this study. The body height, vertex-to-spina iliaca posterior superior distance, spina iliaca posterior superior-to-floor distance, and net weight were measured and body mass index calculated. The facet angles were measured for each facet joint using computed tomography. The intraobserver error was found to be +/- 1.66 degrees. We defined facet tropism as the bilateral angle difference greater than 2 intraobserver errors. The asymmetry rate was a ratio of degree of angles of the more coronally oriented facet joint to the more sagittally oriented facet joint at the same intervertebral level.

RESULTS

The facet asymmetry was observed at the herniation level in 70.5% of the patients. There was a correlation between the degree of the more sagittally oriented facet joint angle and facet asymmetry rate at the herniation level (R = -0.684, P = 0.0001 for L4-L5 lumbar disc herniation; R = -0.509, P = 0.008 for L5-S1 lumbar disc herniation). The body height correlated with the degree of the more sagittally oriented facet joint angle, the degree of more coronally oriented facet joint angle, and asymmetry rate, respectively (R = -0.571, P = 0.0001; R = -0.474, P = 0.002; R = 0.314, P = 0.045, respectively). There was no correlation between the degree of these angles and the vertex-to-spina iliaca posterior superior distance. The spina iliaca posterior superior-to-floor distance was correlated with the degree of the more sagittally oriented facet joint angle (R = -0.457, P = 0.0001) and more coronally oriented facet joint angle (R = -0.435, P = 0.004) but not with the asymmetry rate. The degree of facet angles was not correlated with body weight and body mass index.

CONCLUSION

This study revealed that patients with lumbar disc herniation had the asymmetry and sagittalization of facet joints, and these alterations were more evident in the taller patients.

Facet joint geometry and intervertebral disk degeneration in the L5-S1 region of the vertebral column in German Shepherd Dogs

OBJECTIVE

To evaluate the possible association between facet joint geometry and intervertebral disk degeneration in German Shepherd Dogs.

ANIMALS

25 German Shepherd Dogs and 11 control dogs of similar body weight and condition.

PROCEDURE

Facet joint angles in the caudal portion of the lumbar region of the vertebral column (L5-S1) were measured by use of computed tomography, and the intervertebral discs were evaluated microscopically. The relationship between facet joint geometry and disk degeneration was evaluated by use of statistical methods.

RESULTS

German Shepherd Dogs had significantly more facet joint tropism than control dogs, but an association with disk degeneration was not found. However, German Shepherd Dogs had a different facet joint conformation, with more sagittally oriented facet joints at L5-L6 and L6-L7 and a larger angle difference between the lumbar and lumbosacral facet joints, compared with control dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

A large difference between facet joint angles at L6-L7 and L7-S1 in German Shepherd Dogs may be associated with the frequent occurrence of lumbosacral disk degeneration in this breed.

The relation between vertebral endplate shape and lumbar disc herniations

STUDY DESIGN

Blinded review of selected and un-selected computed tomographic myelograms.

OBJECTIVE

To determine whether shape of the vertebral body endplate margins is a risk factor for the development of symptomatic lumbar disc herniations. The law of LaPlace for a fluid-filled tube suggests that anular tension could be related to endplate shape and a propensity for disc herniation.

SUMMARY OF BACKGROUND DATA

It was hypothesized that the law of Laplace could apply to the lumbar spine because of to the cylindrical shape of the lumbar disc and its high water content in nonelderly individuals. It was further hypothesized that differences in the radius of the curvature could place stresses on the anulus that would make posterior disc herniations more likely with "rounder" endplates.

METHODS

Ninety-seven contrast computed tomography scans were reviewed at transitional L4-L5 and L5-S1 in patients under 60 years of age, without previous spine surgery and without spondylolisthesis. Determinations of disc herniations and measurements of endplates were performed by blinded observers. A ratio of these measurements was used to determine the relative circularity of the endplate. Height, weight, body mass index, and disc endplate size and shape were related to the presence of disc herniation.

RESULTS

By multiple logistic regression, only endplate shape was strongly related to disc herniations. Endplate area was a less significant factor in men.

CONCLUSIONS

The shape of the vertebral body margin at the endplate is an important factor contributing to the development of disc herniations at L4-L5 and L5-S1.

Pain Generators of the Lumbar Spine

Different anatomical structures and pathophysiological functions can be responsible for lumbar pain, each producing a distinctive clinical profile. Pain can arise from the intervertebral disc, either acutely as a primary disc related disorder, or as result of the degradation associated with chronic internal disc disruption. In either case, greatest pain provocation will be associated with movements and functions in the sagittal plane. Lumbar pain can also arise from afflictions within the zygapophyseal joint mechanism, as result of synovitis or chondropathy. Either of these conditions will produce the greatest pain provocation during three-dimensional movements, due to maximal stress to either the synovium or joint cartilage. Finally, patients can experience different symptoms associated with irritation to the dural sleeve, dorsal root ganglion, or chemically irritated lumbar nerve root. Differential diagnosis of these conditions requires a thorough examination and provides information that can assist the clinician in selecting appropriate management strategies.

Influence of age on the development of pathology

Patients of different ages present with different lumbar spine afflictions. These afflications are linked to age-related changes in the intervertebral disc, zygapophyseal joints, and capsuloligamentous structures. Disc degeneration precedes all other changes, resulting in nonspecific low back pain that can potentially advance into specific low back pain conditions.