A morphological study of lumbar vertebral endplates: radiographic, visual and digital measurements

Comparison of predictive performance for cage subsidence between CT-based Hounsfield units and MRI-based vertebral bone quality score following oblique lumbar interbody fusion

OBJECTIVE

To compare the predictive performance between CT-based Hounsfield units (HU) and MRI-based vertebral bone quality (VBQ) for cage subsidence (CS) following oblique lumbar interbody fusion combined with anterolateral single-rod screw fixation (OLIF-AF).

METHODS

A retrospective study was performed on consecutive patients who underwent OLIF-AF at our institution from 2018 to 2020. CS was determined by CT according to the change in the midpoint intervertebral space height. The VBQ score and HU value were measured from preoperative MRI and CT, respectively. Then, we evaluated the predictive performance of those two parameters by comparing the receiver operating characteristic (ROC) curves.

RESULTS

The mean global and segmental VBQ scores were significantly higher in the CS group, and the mean global and segmental HU values were significantly lower in the CS group. The area under the curve (AUC) of CS prediction was higher in the operative segments' VBQ score and HU value than the measurement in the global lumbar spine. Finally, the combined segmental VBQ score and segmental HU value demonstrated the highest AUC.

CONCLUSION

Both MRI-based VBQ score and CT-based HU value can achieve accurate CS prediction. Moreover, the combination of those two measurements indicated the best predictive performance.

CLINICAL RELEVANCE STATEMENT

Both MRI-based VBQ score and CT-based HU value can be used for cage subsidence prediction, in order to take preventive measures early enough.

KEY POINTS

• Osteoporosis is a risk factor for CS, both MRI-based VBQ score and CT-based HU value are important predictors during vertebral bone quality evaluation. • The VBQ score and HU value measured in the operative segments are better predictors of CS than the measurement in the global lumbar spine. • Combined segmental VBQ score and segmental HU value achieved the best predictive performance for CS.

Cage Obliquity and Radiological Outcomes in Oblique Lateral Interbody Fusion

STUDY DESIGN

Retrospective radiological study.

OBJECTIVE

This study aimed to examine whether cage obliquity affects radiological outcomes in oblique lateral interbody fusion (OLIF).

SUMMARY OF BACKGROUND DATA

The OLIF cage enters the disk space in the oblique direction and is then turned to the true orthogonal orientation. However, orthogonal cage placement is often hindered by cage rotation limitations. Few studies have examined the degree of cage obliquity and its effects in OLIF.

MATERIALS AND METHODS

This study involved 171 levels in 118 consecutive patients who underwent OLIF between L2-L3 and L4-L5 with a minimum two-year follow-up. Cage obliquity was divided into three groups on postoperative axial computed tomography images; cage obliquity <10° (group 1), cage obliquity ≥10° and <20° (group 2), and cage obliquity ≥20° (group 3). The radiological outcomes included anterior/posterior disk height, intervertebral disk angle, foraminal height, fusion, and cage subsidence. Postoperative complications related to cage obliquity were examined.

RESULTS

The mean cage obliquity of the 171 cages was 11.3±6.9°. Cage obliquity was greater at the L4-L5 level (13.4±6.4°) than at other levels (L2-L3 and L3-L4: 6.5±7.0° and 10.1±6.2°, respectively) ( P <0.05). There were no significant differences in radiological outcomes among the groups. There were two cases of postoperative contralateral neurological symptoms in group 3.

CONCLUSIONS

Our study showed that the orthogonal cage rotation in OLIF achieved adequate lateral cage placement. Although accurate cage rotation can be limited at the lower lumbar segments, radiological outcomes were not affected by cage obliquity.

Advances in Hounsfield units value for predicting cage subsidence on spinal interbody fusion surgery

PURPOSE

A growing number of studies have demonstrated that Hounsfield units (HU) value can effectively assess bone quality and predict cage subsidence (CS) after spinal surgery. The purpose of this review is to provide an overview of the utility of the HU value for predicting CS after spinal surgery and to raise some of the unresolved questions in this field.

METHODS

We searched on PubMed, EMBASE, MEDLINE, and Cochrane Library for studies correlating HU value to CS.

RESULTS

Thirty-seven studies were included in this review. We found that HU value can predicted the risk of CS effectively after spinal surgery. Moreover, the HU value of the cancellous vertebral body and the cortical endplate were used for predicting CS, in comparison, the measurement method of HU value in the cancellous vertebral body was more standardized, but which region is more important to CS remains unknown. Different cutoff thresholds of HU value have been established in different surgical procedures for predicting CS. The HU value may be superior to dual-energy X-ray absorptiometry (DEXA) for CS prediction; however, the usage standard of HU value has not been well established.

CONCLUSIONS

The HU value shows great potential for predicting CS and constitutes an advantage over DEXA. However, general consensuses about how CS is defined and HU is measured, which part of HU value is more important, and the appropriate cutoff threshold of the HU value for osteoporosis and CS still require exploration.

Minimally invasive LLIF surgery to decrease the occurrence of adjacent-segment disease compared to conventional open TLIF

PURPOSE

Lateral lumbar interbody fusion with percutaneous pedicle screw fixation (Mis-LLIF) can establish indirect decompression by lifting the vertebra with a large intervertebral cage, which causes less damage to the posterior elements. Thus, Mis-LLIF is expected to reduce the incidence of adjacent segment disease (ASD). The aim of the study was to compare the occurrence of ASD between Mis-LLIF and conventional open transforaminal interbody fusion (TLIF).

METHODS

A total of 156 patients (TLIF group = 88, Mis-LLIF group = 68) who underwent single-level lumbar interbody fusion (L2/3, L3/4, or L4/5) at a single institution between 2003 and 2018 with minimum 2-year follow-up were retrospectively reviewed. The incidence of symptomatic ASD requiring reoperation (S-ASD) and radiological adjacent segment degeneration (R-ASD) 2 years postoperatively were investigated between 51 paired patients from both groups who were propensity score (PS) matched by demographic and baseline clinical data. The effect of characteristics arising from differences in surgical methods between Mis-LLIF and TLIF, such as the amount of distraction of the index fused level (∆H), on S-ASD and R-ASD was also examined.

RESULTS

There were no significant differences in the incidence of S-ASD between the Mis-LLIF and TLIF groups (adjusted OR 1.3; 95% CI 0.41-3.9). There was no significant difference in the incidence of R-ASD between the Mis-LLIF and TLIF groups both at the cranial (adjusted OR 1.0; 95% CI 0.22-4.5) and caudal level (adjusted OR 1.5; 95% CI 0.44-5.3). On the other hand, ∆H was significantly higher in the Mis-LLIF group than in the TLIF group (3.6 mm vs. 1.7 mm, respectively, P < 0.0001), and was extracted as a significant independent risk factor for S-ASD (adjusted HR 2.7; 95% CI 1.1-6.3) and R-ASD at the cranial side (adjusted HR 6.4; 95% CI 1.7-24) in multivariable analysis with PS adjustment.

CONCLUSIONS

The incidence of R-ASD or S-ASD was not significantly reduced in the Mis-LLIF group compared to the TLIF group, with greater ∆H potentially being a contributing factor. Using a thin cage in both TLIF and Mis-LLIF may decrease the occurrence of ASD.

Combined flexion and compression negatively impact the mechanical integrity of the annulus fibrosus

PURPOSE

To observe the effect of static flexion, in combination with compression, on the intralamellar and interlamellar matrix properties of the annulus fibrosus.

METHODS

C3/C4 cervical functional spinal units of porcine specimens were selected. Following preloading, all specimens were loaded under 1200 N axial compression in either a neutral or static end range flexion posture (15º) for 2 h. Following loading, six annulus samples were dissected from each disc: four single-layer and two multi-layer samples. The multi-layer samples underwent peel tests to quantify the mechanical properties of the interlamellar matrix while the single-layer samples underwent tensile tests to quantify the mechanical properties of the intralamellar matrix. Statistical comparisons between properties were performed to determine differences between postural condition, extraction location, and extraction depth.

RESULTS

Flexion elicited a decrease in lamellar adhesive strength (p = 0.045) and in single-layer failure strain (p = 0.03) when compared to a neutral posture. Flexion also had extraction depth-specific effects namely increased intralamellar matrix stiffness in the inner annulus when compared to neutral (p = 0019). Flexion also resulted in a significant decrease in toe region strain for the inner region of the annulus (p = 0.035). The inner region of the annulus was shown to have a significant increase in stress at 30% strain when compared to the outer region after flexion (p = 0.041).

CONCLUSION

The current findings suggest that the mechanical properties of the interlamellar and intralamellar matrices are sensitive to flexion, creating an environment that promotes an increased potential for damage to occur.

Lumbar plexus safe working zones with lateral lumbar interbody fusion: a systematic review and meta-analysis

PURPOSE

Significant risk of injury to the lumbar plexus and its departing motor and sensory nerves exists with lateral lumbar interbody fusion (LLIF). Several cadaveric and imaging studies have investigated the lumbar plexus position with respect to the vertebral body anteroposterior plane. To date, no systematic review and meta-analysis of the lumbar plexus safe working zones for LLIF has been performed.

METHODS

This systematic review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Relevant studies reporting on the position of the lumbar plexus with relation to the vertebral body in the anteroposterior plane were identified from a PubMed database query. Quantitative analysis was performed using Welch's t test.

RESULTS

Eighteen studies were included, encompassing 1005 subjects and 2472 intervertebral levels. Eleven studies used supine magnetic resonance imaging (MRI) with in vivo subjects. Seven studies used cadavers, five of which performed dissection in the left lateral decubitus position. A significant correlation (p < 0.001) existed between anterior lumbar plexus displacement and evaluation with in vivo MRI at all levels between L1-L5 compared with cadaveric measurement. Supine position was also associated with significant (p < 0.001) anterior shift of the lumbar plexus at all levels between L1-L5.

CONCLUSIONS

This is the first comprehensive systematic review and meta-analysis of the lumbar neural components and safe working zones for LLIF. Our analysis suggests that the lumbar plexus is significantly displaced ventrally with the supine compared to lateral decubitus position, and that MRI may overestimate ventral encroachment of lumbar plexus.

Influence of the geometric and material properties of lumbar endplate on lumbar interbody fusion failure: a systematic review

Background

Lumbar interbody fusion (LIF) is an established surgical intervention for patients with leg and back pain secondary to disc herniation or degeneration. Interbody fusion involves removal of the herniated or degenerated disc and insertion of interbody devices with bone grafts into the remaining cavity. Extensive research has been conducted on operative complications such as a failure of fusion or non-union of the vertebral bodies. Multiple factors including surgical, implant, and patient factors influencing the rate of complications have been identified. Patient factors include age, sex, osteoporosis, and patient anatomy. Complications can also be influenced by the interbody cage design. The geometry of the bony endplates as well as their corresponding material properties guides the design of interbody cages, which vary considerably across patients with spinal disorders. However, studies on the effects of such variations on the rate of complications are limited. Therefore, this study aimed to perform a systematic review of lumbar endplate geometry and material property factors in LIF failure.

Methods

Search keywords included ‘factor/cause for spinal fusion failure/cage subsidence/cage migration/non-union’, ‘lumbar’, and ‘interbody’ in electronic databases PubMed and Scopus with no limits on year of publication.

Results

In total, 1341 articles were reviewed, and 29 articles were deemed suitable for inclusion. Adverse events after LIF, such as cage subsidence, cage migration, and non-union, resulted in fusion failure; hence, risk factors for adverse events after LIF, notably those associated with lumbar endplate geometry and material properties, were also associated with fusion failure. Those risk factors were associated with shape, concavity, bone mineral density and stiffness of endplate, segmental disc angle, and intervertebral disc height.

Conclusions

This review demonstrated that decreased contact areas between the cage and endplate, thin and weak bony endplate as well as spinal diseases such as spondylolisthesis and osteoporosis are important causes of adverse events after LIF. These findings will facilitate the selection and design of LIF cages, including customised implants based on patient endplate properties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03091-8.

Does cage position affect the risk of cage subsidence after oblique lumbar interbody fusion in the osteoporotic lumbar spine: a finite element analysis

OBJECTIVE

This study aimed to evaluate the biomechanical effects of different cage positions with stand-alone (SA) methods and bilateral pedicle screw fixation (BPSF) in the osteoporotic lumbar spine after OLIF.

METHODS

A finite element (FE) model of an intact L3-L5 lumbar spine was constructed. After validation, an osteoporosis model (OP) was constructed by assigning osteoporotic material properties. SA models (SA1, SA2, SA3) and BPSF models (BPSF1, BPSF2, BPSF3) in which a cage was placed in the anterior, middle and posterior third of the L5 superior endplate (SEP) were constructed at the L4-L5 segment of the OP. The L4-L5 range of motion (ROM), the stress of the L5 SEP, the stress of the cage and the stress of fixation were compared among the different models.

RESULTS

According to the degree of ROM of L4-L5, the stress of the L5 SEP and the stress of the cage for most physiological motions, the SA and BPSF models were ranked as follows: SA2＜SA1＜SA3, BPSF2＜BPSF1＜BPSF3. In BPSF2, the stress of fixation was minimal in most motions. At the same cage position, the ROM of L4-L5, the stress of the L5 SEP and the stress of the cage in the BPSF models were significantly reduced compared with those in SA models; compared with SA2, BPSF2 had a maximum reduction of 83.24%, 70.71% and 73.52% in these parameters, respectively.results CONCLUSIONS: Placing the cage in the middle third of the L5 SEP for OLIF could reduce the maximum stresses of the L5 SEP, the cage and the fixation, which may reduce the risk of postoperative cage subsidence, endplate collapse and fixation fracture in the osteoporotic lumbar spine. Compared with SA OLIF, BPSF could provide sufficient stability for the surgical segment and may reduce the incidence of the aforementioned complications.

An automatic method for feature segmentation of human thoracic and lumbar vertebrae

BACKGROUND AND OBJECTIVE

Because of the three-dimensional distribution of morphological features of human vertebrae and the whole spine, in recent years, to make more precise diagnoses and to design optimized surgical procedures, new protocols have been proposed based on analysing their three-dimensional (3D) models. In the related literature, processes of segmentation and morphological features recognition are essentially performed by a skilled operator that selects the interesting areas. So, being affected by the preparation and experience of the operator, this produces an evaluation that is poorly reproducible and repeatable for the uncertainties of a typical manual measurement process.

METHODS

To overcome this limitation, in this paper a new automatic method is proposed for feature segmentation and recognition of human vertebrae. The proposed computer-based method, starting from 3D high density discretized models of thoracic and lumbar vertebrae, automatically performs both the semantic and geometric segmentation of their morphological features. The segmentation and recognition rules codify some important definitions used in the traditional manual method, considering all the vertebra morphology information that is invariant inter-subject.

RESULTS

The automatic method proposed here is verified by analysing many real vertebrae, both acquired using a 3D scanner and coming from Computerized Tomography (CT) scans. The obtained results are critically discussed and compared with the traditional manual methods for vertebra analysis. The method has proven to be robust and reliable in the segmentation and recognition of morphological features of vertebrae. Furthermore, the proposed automatic method avoids the blurring of quantitative parameters get from vertebrae, resulting from poor repeatability and reproducibility of manual methods used in the state-of-the-art.

CONCLUSIONS

Starting from the automatic segmentation and recognition here proposed, it is possible to automatically calculate the parameters of thoracic or lumbar vertebrae used in archaeology, medicine, or biomechanics or define their new ones.

Ex vivo Evaluation of the Dynamic Morphometry of the Caudal Cervical Intervertebral Disc Spaces of Small Dogs and Cats

The objective of this study was to provide a morphometric description of the caudal cervical intervertebral disc (IVD) spaces of small-breed dogs and cats. Specimens consisting of C4 through C7 from five small-breed dogs and six cats were positioned in neutral, flexion, extension, and lateral bending positions; and CT images were acquired. Height and width of the cranial and caudal vertebral endplates (VEPs), angle between the VEPs (IVD wedge angle), and craniocaudal distance (IVD width) between VEPs for the four loading positions were measured and compared for three segments (C4-C5, C5-C6, and C6-C7). VEP size normalized to body weight from medium-sized dogs was retrieved from a previous study and compared with data from small dogs and cats. A linear mixed model was used to compare outcome measures. Significance was set to p < 0.05. VEP size normalized to body weight was the largest in small dogs compared with cats (p = 0.0422) and medium-sized dogs (p = 0.0064). Cats and medium-sized dogs were similar (p = 0.2763) in this regard. Flexion and extension induced a reduction of IVD width in the ventral portion of the IVD and the area of the nucleus. The dorsal part of the IVD remained unchanged throughout loading conditions. Unique morphometric characteristics of the caudal cervical IVD space of small dogs and cats were detected that are different from those described in sizes of dogs (medium-sized) typically affected by caudal cervical spondylomyelopathy (CSM). These findings may help to understand the different pathomechanisms in cervical spinal disease between small- and medium-sized dogs, including caudal CSM.

Analysis of the Curvature and Morphologic Features of the Lumbar Vertebral Endplates Through the Transverse Section: A Radioanatomical Study

BACKGROUND

Knowledge concerning the curvature of the vertebrae through the transverse section is of clinical significance. However, relevant reports are scarce. This study investigated the features based on the cross-sections of lumbar vertebral endplates to provide information for clinical practice.

METHODS

Computed tomography images of 78 subjects were retrospectively reviewed. The geometric morphometrics was performed, and the curvature of the vertebral endplates was calculated by the self-written MATLAB algorithm. The principal component analysis, the canonical variate analysis, the discriminant function analysis, and the Mann-Whitney U test were performed. Statistical significance was set at P < 0.05.

RESULTS

No gender difference was found. In contrast, a morphologic difference was found between the superior and inferior lumbar vertebral endplates and between different segments. More specifically, the shape of the endplates gradually changes from the renal shape at superior L1 to the shell-like shape at inferior L5. The mean curvature values of the lateral anterior border were all around 0.60 cm^-1, whereas the mean curvature values of the lateral posterior borders range from 0.66 to 1.09 cm^-1 from L1 to L5. From L1 to L3, the mean and maximum curvature of the lateral posterior superior vertebral endplates decrease. The trend could also be found on the lateral posterior border of the inferior endplates from L1 to L3.

CONCLUSIONS

The current study described morphologic variations and curvature of the lumbar vertebral endplates, which have not been reported previously. The different curvature distribution could provide important information for surgeons and manufacturers.

Long-term outcome of targeted therapy for low back pain in elderly degenerative lumbar scoliosis

PURPOSE

Treatment of low back pain (LBP) associated with elderly degenerative lumbar scoliosis (DLS) remains controversial. We have developed percutaneous intervertebral-vacuum polymethylmethacrylate injection (PIPI) targeting to the intervertebral vacuum as a minimally invasive surgery. The present study compared the long-term clinical outcomes of PIPI to that of nonoperative treatment.

METHODS

Patients with de novo DLS, aged ≥ 65 years, who had LBP with visual analog scale (VAS) of ≥ 50 for ≥ 6 months with intervertebral vacuum on computed tomography and bone marrow edema (BME) on magnetic resonance imaging were included. The clinical outcomes were evaluated using VAS and the Oswestry Disability Index (ODI) at baseline, 1, 6, 12, 24 months, and at the final follow-up. The course of BME was also evaluated.

RESULTS

One hundred and one patients underwent PIPI and 61 received nonoperative treatment. The mean follow-up duration after PIPI and nonoperative treatment was 63.7 ± 32.4 and 43.9 ± 20.9 months, respectively. VAS and ODI after PIPI were significantly improved compared to post-nonoperative treatment. BME decreased substantially in the PIPI group and it was significantly correlated with VAS and ODI improvement. Following PIPI, LBP recurred in 28 patients (35%). LBP recurrence was identified at the same level of PIPI in 10 patients, at the adjacent level of PIPI in 11 patients, and at the non-adjacent level of PIPI in seven patients. Eighteen patients underwent additional PIPIs, and both VAS and ODI were significantly improved after additional PIPIs.

CONCLUSION

Bone marrow lesions of the endplate are strongly associated with the presence of LBP. PIPI can be considered as an effective, safe and repeatable treatment for LBP in elderly DLS patients.

Morphologic analysis of Chinese lumbar endplate by three-dimensional computed tomography reconstructions for helping design lumbar disc prosthesis

Lumbar disc prostheses have been used increasingly in recent years. The successful design of lumbar disc prostheses depends on accurate morphometric parameters. However, the morphologic dimensions of lumbar endplate area have not been investigated in Chinese population.A total of 1800 lumbar endplates were retrospectively accessed in 150 Chinese adults. Eighteen parameters of each lumbar segment were measured by three-dimensional computed tomography reconstructions from T12/L1 to L5/S1. These obtained parameters were compared between genders, bilateral sides, vertebral segments, and different populations.Endplate length and width increased in general, and there was a significant decrease for length/width ratio from T12 to S1 (P = .03). The average concavity depth of the lower lumbar endplate (2.09 ± 0.93 mm) was usually larger than that of the upper lumbar endplate (1.61 ± 0.74 mm) (P = .02). The percentage of the most concave point of the upper and lower lumbar endplate was 50.01 ± 10.76% and 56.41 ± 9.93%, respectively. Anterior, medium, or posterior intervertebral endplate height was severally 10.01 ± 1.98 mm, 10.46 ± 2.03 mm, and 6.41 ± 1.74 mm, and increased among vertebral segments (P = .01).The intervertebral endplate angle significantly increased from T12-L1 to L5-S1 (P = .01). Parameters displayed significant difference between genders. The morphometric parameters of different populations also showed differences.In conclusion, there is a morphologic discrepancy in dimensions of lumbar endplate regarding genders, vertebral segments, and different populations. It is essential to design the lumbar disc prosthesis suited for Chinese patients specially, for which the morphometric parameters in our study can be utilized.

Endplate injury as a risk factor for cage retropulsion following transforaminal lumbar interbody fusion: An analysis of 1052 cases

Although transforaminal lumbar interbody fusion (TLIF) is a widely accepted procedure, major complications such as cage retropulsion (CR) can cause poor clinical outcomes. Endplate injury (EI) was recently identified as a risk factor for CR, present in most levels developing CR. However, most EIs occurred in non-CR levels, and the features of EIs in CR levels remain unknown.The aim of this study was to identify risk factors for CR following TLIF; in particular, to investigate the relationship between EIs and CR, and to explore the features of EIs in CR.Between October 2010 and December 2016, 1052 patients with various degenerative lumbar spinal diseases underwent bilateral instrumented TLIF. Their medical records, radiological factors, and surgical factors were reviewed and factors affecting the incidence of CR were analyzed.Twenty-one patients developed CR. Nine had back pain or leg pain, of which six required revision surgery. A pear-shaped disc, posterior cage positioning and EI were significantly correlated with CR (P < .001, P = .001, and P < .001, respectively). Computed tomography (CT) scans revealed the characteristics of EIs in levels with and without CR. The majority of CR levels with EIs exhibited apparent compression damage in the posterior part of cranial endplate on the decompressed side (17/18), accompanied by caudal EIs isolated in the central portion. However, in the control group, the cranial EIs involving the posterior part was only found in four of the total 148 levels (P < .001). Most of the injuries were confined to the central portion of the cranial or caudal endplate or both endplates (35 in 148 levels, 23.6%). Additionally, beyond cage breaching into the cortical endplate on lateral radiographs, a characteristic appearance of coronal cage misalignment was found on AP radiographs in CR levels with EIs.A pear-shaped disc, posterior cage positioning and EI were identified as risk factors for CR. EI involving the posterior epiphyseal rim had influence on the development of CR. Targeted protection of the posterior margin of adjacent endplates, careful evaluation of intraoperative radiographs, and timely remedial measures may help to reduce the risks of CR.

Three-Dimensional Morphometric Analysis of Lumbar Vertebral End Plate Anatomy

BACKGROUND

Information on the three-dimensional (3D) shape of vertebral end plates is lacking. Previous studies have analyzed two-dimensional shape; however, 3D data are important because they may help improve our understanding of how differences in shape are related to age, gender, race, size, and other parameters, which may subsequently help improve device design for interbody prosthesis.

OBJECTIVE

To study the 3D shape of lumbar vertebral end plates from normal adult lumbar spines and correlate them with age, gender, spinal/end plate level, end plate surface area, concave depth, and size.

METHODS

An in vivo analysis was undertaken of lumbar vertebral end plate 3D shape. A total of 136 patients' computed tomography scans were used to create 3D models of the lumbar spine for each patient, which were subsequently analyzed.

RESULTS

The shape of the superior end plates is different compared with inferior end plates. Across the lumbar spine (L1-S1), the shape of inferior end plates is similar; however, the shape of the superior end plate varies between spinal levels significantly. There was no clear relationship between age and principal component (PC) shapes but there was a strong correlation between end plate concave depth and end plate PC shape scores.

CONCLUSIONS

Future interbody (disc replacement and fusion) device designs could use the findings that inferior end plate shape is similar throughout the length of the lumbar spine, whereas superior end plate shape changes. Further, future implants could be level-specific because the present study shows that end plate shape varies through the length of the lumbar spine.

A Dynamic Radiographic Imaging Study of Lumbar Intervertebral Disc Morphometry and Deformation In Vivo

Intervertebral discs are important structural components of the spine but also are significant sources of morbidity, especially for the “low back” lumbar region. Mechanical damage to, or degeneration of, the lumbar discs can diminish their structural integrity and elicit debilitating low back pain. Advancement of reparative or regenerative means to treat damaged or degenerated discs is hindered by a lack of basic understanding of the disc load-deformation characteristics in vivo. The current study presents an in vivo analysis of the morphometry and deformation of lumbar (L2-S1) intervertebral discs in 10 healthy participants while performing a common lifting act, using novel dynamic radiographic imaging of the lumbar vertebral body motion. Data analyses show uniquely different (p < 0.05) characteristics in morphometry, normal and shear strain patterns of the L5S1 discs, while the rest of lumbar discs exhibit great similarity. In particular shear strains in L2-L5 discs exhibited stronger linear correlations (R² ≥ 0.80) between strain changes and amount of lumbar flexion-extension motion compared to L5S1 (R² ≤ 0.5). The study therefore advances the state of knowledge on in vivo mechanical responses of the lumbar intervertebral discs during functional tasks.

Distribution of Modic changes in patients with low back pain and its related factors

BACKGROUND

To summarize the clinical distribution of Modic changes in patients with low back pain and explore the related factors.

METHODS

A total of 153 patients were enrolled. Gender, age, disk degeneration, herniation, involved segments, lumbar lordosis angle, and endplate concave angle were recorded, respectively. Patients were divided into two or more groups according to a different classification. The relevant factors were studied with a multivariate logistic regression analysis to analyze their correlation.

RESULTS

A total of 35 patients with type I changes, 110 patients with type II changes, and 8 patients with type III changes. In total, 204 disks were found with Modic changes, L1/2 (10 disks), L2/3 (18 disks), L3/4 (17 disks), L4/5 (76 disks), and L5/S1 (81 disks). Type I changes were distributed mainly under the age of 50. Multivariate regression showed that gender, age, disk degeneration, lumbar lordosis, L4/5 segment lordosis angle, and L5 lower endplate concave angle were related with different types of Modic changes. The regression equation Y = 2.410 - 1.361S - 0.633A - 0.654P + 1.106L - 0.990D (Y means type I changes, S means gender, A means age, P means disk degeneration, L means L4/5 segment lordosis angle, and D means L5 upper endplate concave angle). The OR values were S = 0.256, A = 0.531, P = 0.520, L = 3.022, D = 0.372, respectively.

CONCLUSIONS

Type II changes are the most common, followed by type I. Modic changes mostly occur in L4/5 and L5/S1; young, male, lower-grade disk degeneration, normal physiological curvature of the lumbar spine, and normal endplate concave angle were associated with type I changes; gender and lumbar curvature were the most relevant factors for different types.

Differences in Trabecular Bone, Cortical Shell, and Endplate Microstructure Across the Lumbar Spine

Background

The quality of the vertebral body structures such as endplate, cortex, and trabecular bone is important for understanding the performance of implants, particularly at the bone-implant interface. Although vertebral body structures have been analyzed separately in the literature, there is no comprehensive study to assess these anatomical measurements along with their interrelationships in the lumbar spine. Therefore, the purpose of this study was to assess variations in trabecular microstructure, vertebral endplate thickness and concavity, and vertebral body cortex thickness within the lumbar spine.

Methods

A total of 80 lumbar vertebrae (L1-L5) were dissected from 16 human cadaver specimens and imaged with microcomputed tomography to determine trabecular microstructure, vertebral cortex thickness, endplate thickness, and maximum endplate concavity depth. A paired t test and regression analysis were used to determine significant differences (P < .05) between different vertebral levels and correlations between the analyzed anatomical parameters.

Results

L1 vertebra had significantly better (P < .02) trabecular bone microstructure (eg, trabecular bone volume fraction) than all other lumbar vertebrae. However, L1 vertebra also had significantly thinner (P ≤ .02) anterior, left, and right cortices compared to all other vertebral levels. Within L3-L5 intervertebral disc spaces, cranial endplates had significantly greater (P ≤ .03) thickness and maximum concavity depth compared to their respective caudal endplates. No strong correlations were observed between trabecular bone microstructure, maximum endplate concavity depth, vertebral cortex, and endplate thickness parameters.

Conclusions

Detailed reference data of these anatomical parameters for each lumbar vertebral body can aid in improved understanding of bone quality, particularly when assessing different implant designs and fixation approaches. Moreover, such anatomical knowledge may help clinicians with optimal implant design selection and surgical placement of these devices into their respective locations.

Multidimensional vertebral endplate defects are associated with disc degeneration, modic changes, facet joint abnormalities, and pain

The aim of the current study was to investigate the multi-dimensional characteristics of lumbar endplate defects in humans in relation to disc degeneration and other MRI phenotypes as well as their role with pain and disability. A total of 108 subjects were recruited and underwent 3T MRI of the lumbar spine. Structural endplate defects were identified and their dimensions were measured in terms of maximum width and depth, and were then standardized to the actual width of the endplate and depth of the vertebral body, respectively. Both width and depth of all endplate defects in each subject were added separately and scores were assigned on the basis of size from 1 to 3. Combining both scores provided "cumulative endplate defect scores." Disc degeneration scores, Modic changes, disc displacement, HIZ, and facet joint changes were assessed. Subject demographics, pain profile, and Oswestry Disability Index (ODI) were also obtained. Endplate defects were observed in 67.5% of the subjects and in 13.5% of the endplates. All dimensions of endplate defects showed significance with disc degenerative scores, Modic changes, and posterior disc displacement (p < 0.05). Maximum width (p = 0.009) and its standardized value (p = 0.02), and cumulative endplate defect scores (p = 0.004) increased with narrow facet joints. Cumulative endplate defect scores showed a strong positive association with ODI (p < 0.05) compared to disc degenerative scores. Large size endplate defects were strongly associated with degenerative spine changes and more back-related disability. Findings from this study stress the need to assess endplate findings from a multi-dimensional perspective, whose role may have clinical utility. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Ex vivo computed tomography evaluation of loading position on morphometry of the caudal cervical intervertebral disk spaces of dogs

OBJECTIVE To provide an objective, quantitative morphometric description of the caudal cervical intervertebral disk (IVD) spaces of dogs. SAMPLE Vertebral specimens consisting of C4 through C7 from 5 medium-sized dogs. PROCEDURES CT images were obtained with the specimens positioned in neutral, flexion, extension, and lateral bending positions. Size and shape of the cranial and caudal end plates, angle between the end plates (IVD wedge angle), and craniocaudal distance (IVD width) between end plates for the 4 loading positions were measured and compared for the 3 segments (C4-5, C5-6, and C6-7). RESULTS End plate size and shape, IVD wedge angle, and IVD width were not significantly different among the 3 segments. Caudal cervical end plates were consistently larger than cranial cervical end plates. The IVD wedge angle ranged from -4.8° to 15.2°. Flexion induced a reduction in IVD width in the ventral portion of the IVD, whereas extension induced a decrease in width in the dorsal portion of the IVD. Central IVD width remained unchanged among the loading positions. CONCLUSIONS AND CLINICAL RELEVANCE Unique morphometric and dynamic characteristics of the caudal cervical IVD space of dogs were detected. These findings may help investigators when designing IVD prostheses for dogs with cervical spondylomyelopathy.

Comparison of Transforaminal Lumbar Interbody Fusion Using the Boomerang-Shaped Cage with Traditional Posterior Lumbar Interbody Fusion for Lumbar Spondylolisthesis

INTRODUCTION

This study aimed to compare the clinical and radiological results of transforaminal lumbar interbody fusion (TLIF) with a boomerang-shaped cage and traditional posterior lumbar interbody fusion (PLIF) according to fused level and elucidate whether TLIF could replace PLIF at all lumbar levels.

METHODS

The study investigated 128 patients with lumbar spondylolisthesis who underwent a single-level TLIF or traditional PLIF. Intraoperative blood loss, operative time, and recovery rate were analyzed. Percent slip, disc height, and local lordosis at the fused level were measured using X-ray images from preoperation to the final follow-up.

RESULTS

No significant differences in recovery rate were observed at any level. The operative time and intraoperative blood loss were significantly less in the TLIF group at the L4/5 and L5/S1 levels. There were no significant differences in disc height or local lordosis at the L3/4 and L4/5 levels, and a satisfactory level of maintenance after the operation was achieved in both groups. However, at the L5/S1 level, postoperative maintenance after TLIF could not be achieved, and the obtained disc height and local lordosis in TLIF significantly decreased.

CONCLUSIONS

Compared with traditional PLIF, TLIF was a less invasive procedure with a shorter operative time and lesser blood loss. TLIF could obtain similar local lordosis and disc height as PLIF at the L3/4 and L4/5 levels. At the L5/S1 level, the postoperative maintenance of local lordosis and disc height after TLIF was inferior to that after PLIF. On the basis of our results, we do not recommend performing TLIF at only the L5/S1 level.

A Novel Height-Adjustable Nano-Hydroxyapatite/Polyamide-66 Vertebral Body for Reconstruction of Thoracolumbar Structural Stability After Spinal Tumor Resection

BACKGROUND

Reconstruction of thoracolumbar structural stability is a formidable challenge for spine surgeons after vertebral body tumor resection. Various disadvantages of the currently used expandable or nonexpandable cages have limited their clinical applications. We sought to develop a novel prosthesis for clinical use and assess its preliminary clinical outcome in reconstruction of thoracolumbar structural stability after spinal tumor resection.

METHODS

Using data obtained from a retrospective analysis of the morphological characteristics of the thoracolumbar vertebrae and endplates in previously reported studies, we modified the nano-hydroxyapatite/polyamide-66 (n-HA/PA66) strut into a novel height-adjustable vertebral body. A retrospective study was performed of 7 patients who had undergone reconstruction of thoracolumbar structural stability with this novel prosthesis from August 2016 to January 2017.

RESULTS

A novel height-adjustable vertebral body (AHVB) composed of n-HA/PA66 with 2 separate components with a 163° contact surface at each end was manufactured. The height-adjustable range was 28-37 mm. No significant implant-related complications were observed in the process of operation. All patients experienced a significant reduction in pain, with the visual analog scale score decreasing from 7.9 to 4.0. Neurological improvement was assessed using the Frankel grading system after surgery. Postoperative radiographic and computed tomography/magnetic resonance imaging findings indicated that the operated segment was stable, the outcome of kyphosis correction was good, and no prosthesis subsidence or dislocation was observed.

CONCLUSION

This novel prosthesis has many advantages in the reconstruction of height, lordosis, and alignment after thoracolumbar spinal tumor resection and has a favorable prospect for clinical application.

Asymmetry between the superior and inferior endplates is a risk factor for lumbar disc degeneration

Endplate pathology plays an important role in the development of lumbar disc degeneration. Previous research paid little attention to differences between the superior and inferior endplates as a possible risk factor for disc degeneration. The purpose of this study was to test the hypothesis that asymmetry between the superior and inferior endplates is a risk factor for the development of lumbar disc degeneration. A total of 134 patients with lumbar disc herniation (LDH) and 100 healthy adults ("Controls") underwent magnetic resonance imaging scans. Each disc was categorized as non-degenerated (Pfirrmann grades I-II) or degenerated (Pfirrmann grades III-V) and get the following three groups: "Degenerated LDH" discs (n = 145), "Non-degenerated LDH" discs (n = 525) and "Non-degenerated Control" discs (n = 500). On mid-sagittal image, the lumbar endplate morphology could be categorized into three types: Flat, concave, and irregular. Superior and inferior endplates of a given disc were "symmetric" if both were of the same type, and "asymmetric" if they were of different types. The proportion of asymmetric endplates at L4-5 was higher in the "Degenerated LDH" discs group (47%) than in the "Non-degenerated LDH" discs group (21%) or "Non-degenerated Control" discs group (7%) (p < 0.05). At L5-S1 the proportions were 73%, 55%, and 38% (p < 0.05). Asymmetry of superior and inferior endplates in the mid-sagittal plane is a risk factor for lumbar disc degeneration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2469-2475, 2018.

Methodology and cohort profile for the Hangzhou Lumbar Spine Study: a study focusing on back health in a Chinese population

Back pain is a worldwide health problem, adding a tremendous burden to modern societies. However, little information on back health is available in China, even though a quarter of the world's population is Chinese. To enhance knowledge in this area, we designed and initiated the Hangzhou Lumbar Spine Study, which is a cross-sectional study of a general sample of mainland Chinese with focusing on disc degeneration, Modic changes, endplate lesions, and back pain. The study consists of a structured questionnaire to measure back pain history and lifetime exposure to suspected risk factors, magnetic resonance imaging of the lumbar spine, bone mineral density study of the spine and hip, and DNA sample analysis. Here we briefly introduce the study methodology, report the test-retest reliability of the questionnaire, and describe the cohort profile to date. Since May 2014, 301 randomly selected subjects (male/female, 122/179; mean age, 51.0 years; range, 20-87 years) have been recruited. Tests-retests of the questionnaire, completed by 40 participants, revealed good reliability. To our knowledge, the Hangzhou Lumbar Spine Study is the first population-based epidemiological study conducted to characterize lumbar spinal phenotypes and back pain, their interaction, and their associations with lifetime environmental exposure, in mainland Chinese. Epidemiological information obtained from a reliable questionnaire, magnetic resonance (MR) imaging data, dual energy X-ray absorptiometry (DXA) measurements, and DNA analysis may serve as a valuable reference for future studies on back health, particularly for mainland Chinese.

Lumbar Vertebral Endplate Defects on Magnetic Resonance Images: Classification, Distribution Patterns, and Associations with Modic Changes and Disc Degeneration

STUDY DESIGN

A cross-sectional magnetic resonance (MR) imaging study.

OBJECTIVE

To classify and characterize endplate defects using routine lumbar MR images and to determine associations of endplate defects with Modic changes (MCs) and disc degeneration.

SUMMARY OF BACKGROUND DATA

Previously, a cadaveric study revealed that endplate lesions were common and associated with back pain history. New in vivo approaches appropriate for clinical studies are needed to further this potentially important line of research on the clinical significance of endplate lesions, including their relation with MCs, disc degeneration, and back pain.

METHODS

Using a MRI archive, 1564 endplates of 133 subjects (59 men and 74 women, mean age 58.9 ± 11.9 years) with the presence of MCs were retrospectively collected from April of 2014 to June of 2015. On the basis of morphological characteristics, a protocol was proposed to identify three distinct types of endplate defects, including focal, corner, and erosive defects. The location, size, and distribution patterns of various endplate lesions were characterized. MCs and disc degeneration were measured to examine their associations with endplate defects.

RESULTS

Endplate defects were observed in 27.8% of endplates studied. Greater age was associated with the presence of endplate defects. Focal defects were the most common (13.5%), followed by erosive defects (11.1%) and corner defects (3.2%). Defect types also differed in size and distribution patterns. Endplate defects and MCs had similar distribution patterns in the lumbar spine. The presence of endplate defects were associated with the presence of MCs (odds ratio = 4.29, P < 0.001), and associated with less disc signal intensity and disc height, and greater disc bulging (P < 0.05).

CONCLUSION

The three endplate defects identified on routine MR images appear to represent different pathologies and may play a key role in the pathogenesis of MCs. This classification system may facilitate clinical studies on endplate defects.

LEVEL OF EVIDENCE

4.

A review of techniques for visualising soft tissue microstructure deformation and quantifying strain Ex Vivo

Many biological tissues have a complex hierarchical structure allowing them to function under demanding physiological loading conditions. Structural changes caused by ageing or disease can lead to loss of mechanical function. Therefore, it is necessary to characterise tissue structure to understand normal tissue function and the progression of disease. Ideally intact native tissues should be imaged in 3D and under physiological loading conditions. The current published in situ imaging methodologies demonstrate a compromise between imaging limitations and maintaining the samples native mechanical function. This review gives an overview of in situ imaging techniques used to visualise microstructural deformation of soft tissue, including three case studies of different tissues (tendon, intervertebral disc and artery). Some of the imaging techniques restricted analysis to observational mechanics or discrete strain measurement from invasive markers. Full-field local surface strain measurement has been achieved using digital image correlation. Volumetric strain fields have successfully been quantified from in situ X-ray microtomography (micro-CT) studies of bone using digital volume correlation but not in soft tissue due to low X-ray transmission contrast. With the latest developments in micro-CT showing in-line phase contrast capability to resolve native soft tissue microstructure, there is potential for future soft tissue mechanics research where 3D local strain can be quantified. These methods will provide information on the local 3D micromechanical environment experienced by cells in healthy, aged and diseased tissues. It is hoped that future applications of in situ imaging techniques will impact positively on the design and testing of potential tissue replacements or regenerative therapies. LAY DESCRIPTION: The soft tissues in our bodies, such as tendons, intervertebral discs and arteries, have evolved to have complicated structures which deform and bear load during normal function. Small changes in these structures can occur with age and disease which then leads to loss of function. Therefore, it is important to image tissue microstructure in 3D and under functional conditions. This paper gives an overview of imaging techniques used to record the deformation of soft tissue microstructures. Commonly there are compromises between obtaining the best imaging result and retaining the samples native structure and function. For example, invasive markers and dissecting samples damages the tissues natural structure, and staining or clearing (making the tissue more transparent) can distort tissue structure. Structural deformation has been quantified from 2D imaging techniques (digital image correlation) to create surface strain maps which help identify local tissue mechanics. When extended to 3D (digital volume correlation), deformation measurement has been limited to bone samples using X-ray micro-CT. Recently it has been possible to image the 3D structure of soft tissue using X-ray micro-CT meaning that there is potential for internal soft tissue mechanics to be mapped in 3D. Future application of micro-CT and digital volume correlation will be important for soft tissue mechanics studies particularly to understand normal function, progression of disease and in the design of tissue replacements.

Association between Measures of Vertebral Endplate Morphology and Lumbar Intervertebral Disc Degeneration

Purpose

The aim of this study was to evaluate the association between vertebral endplate morphology and the degree of lumbar intervertebral disc degeneration via magnetic resonance imaging (MRI).

Methods

In total, 150 patients who met the inclusion criteria and were 20–60 years of age were retrospectively evaluated. Patients were evaluated for the presence of intervertebral disc degeneration or herniation, and the degree of degeneration was assessed at all lumbar levels. Vertebral endplate morphology was evaluated based on the endplate sagittal diameter, endplate sagittal concave angle (ECA), and endplate sagittal concave depth (ECD) on sagittal MRI. The association between intervertebral disc degeneration or herniation and endplate morphological measurements was analysed.

Results

In MRI, superior endplates ( ie, inferior endplates of the superior vertebra) were concave and inferior endplates ( ie, superior endplates of the inferior vertebra) were flat at all disc levels. A decrease in ECD and an increase in ECA were detected at all lumbar levels as disc degeneration increased ( P < .05). At the L4-L5 and L5-S1 levels, a decrease in ECD and an increase in ECA were detected in the group with herniated lumbar discs ( P < .05). There was no association between lumbar disc degeneration or herniation and endplate sagittal diameter at lumbar intervertebral levels ( P > .05). At all levels, ECD of women was significantly lesser than that of men and ECA of women was significantly greater than that of men ( P < .05).

Conclusions

There is an association between vertebral endplate morphology and lumbar intervertebral disc degeneration. Vertebral endplates at the degenerated disc level become flat; the severity of this flattening is correlated with the degree of disc degeneration.

Defects of the vertebral end plate: implications for disc degeneration depend on size

BACKGROUND CONTEXT

Bony vertebral end plates must be porous to allow metabolite transport into the disc, and yet strong to resist high intradiscal pressure (IDP). End plate defects may therefore have nutritional and mechanical consequences for the disc, depending on their size and type. We hypothesize that broad, diffuse defects are more closely associated with disc decompression and degeneration than are focal Schmorl's node-type defects.

PURPOSE

This study aimed to determine how the size and type of end plate defects are related to decompression and degeneration in the adjacent intervertebral disc.

STUDY DESIGN

Mechanical, histologic, and micro-computed tomographic investigations were carried out in cadaver spines.

METHODS

The study involved 40 motion segments (T8-T9 to L4-L5) dissected from 23 cadavers aged 48-98 years. Intradiscal stresses were measured, under 1 kN compression, by pulling a pressure transducer along the disc's midsagittal diameter. The resulting "stress profiles" revealed nucleus pressure (IDP) and maximum stresses in the anterior and posterior annulus. Micro-computed tomography was then used to examine all 40 discs, with 5 mm of adjacent bone on either side, so that end plate defects could be characterized at a resolution of 35 µm. Cross-sectional area (in the transverse plane), volume, location, and morphologic type were determined for all bony defects in the 80 end plates. Finally, discs from each motion segment (with hyaline cartilage and bone attached) were sectioned (undecalcified) at 7 µm for histology to allow degeneration to be assessed.

RESULTS

Substantial defects were identified in 24 of 40 specimens (35 of 80 end plates). Of these, 83% was centrally located, and 17% was laterally located. Defects occurred more frequently in male than female specimens (p=.043), and were more common in thoracic than lumbar end plates (p=.002), although lumbar defects were greater in volume (p=.05). Defect area and volume increased with decreasing IDP, with decreasing peak stress in the annulus, and with increasing tissue degeneration. Stepwise multiple regression showed that average defect area depended most strongly on IDP, whereas maximum defect area and volume depended most strongly on peak stress in the anterior annulus. Multiple end plate defects were associated with lower values of IDP and higher degeneration scores when compared with erosions and Schmorl's nodes.

CONCLUSIONS

Disc degeneration has a stronger association with large or multiple end plate defects than with small or single defects (of any type). Large end plate defects probably allow greater volume changes within the disc, leading to greater nucleus decompression.

A computational measurement of cartilaginous endplate structure using ultrashort time-to-echo MRI scanning

BACKGROUND AND OBJECTIVE

Ultrashort time-to-echo (UTE) MRI scanning has been applied to observe the cartilaginous endplate (CEP) in intervertebral disc. CEP plays a critical role in IVD health and disease. Nevertheless, current measurements of CEP based on UTE MRI technique are still by manual segmentation, and observation of signal abnormality was usually time-consuming and often disturbed by subjective bias. This study hence proposed an efficient way to harvest the global parameters of CEP after UTE MRI scanning.

METHODS

Ex-vivo UTE-MRI scanning was performed using 12 goat lumbar spine specimens. After the UTE-MRI data were collected, the computational method for CEP segmentation and assessment was developed. Global view of CEP, e.g., surface morphology as well as distributions of thickness and signal intensity, were measured. Histological staining of the CEP as well as manual CEP segmentation was then conducted to validate the accuracy.

RESULTS

Segmentation of CEP by the proposed method presented a good agreement with manual measurement, with mean Jaccard index of 0.7296 and mean Cohen's Kappa coefficient of 0.8286. The processing time for CEP segmentation and property measurements was 59.2s which was much shorter than the manual measurement.

CONCLUSIONS

This newly-developed technique is able to qualitatively and quantitatively assess the CEP structure, which is very valuable for the clinicians and researchers to accurately evaluate the endplate health after UTE MRI scanning.

A morphometric study of the middle and lower cervical vertebral endplates and their components

Cervical disc arthroplasty is a common method of treating cervical degenerative disease. However, the footprints of most prosthesis dimensions are obtained from data of Caucasian individuals. Besides, there is a large discrepancy between footprints of currently available cervical disc prostheses and anatomic dimensions of cervical endplates. We aimed to detail the three-dimensional (3D) anatomic morphology of the subaxial cervical vertebral endplate, utilizing high-precision, high-resolution scanning equipment, and provide a theoretical basis for designing appropriate disc prostheses for Chinese patients.A total of 138 cervical vertebral endplates were studied. Each endplate was digitized using a non-contact optical 3D range scanning system and then reconstructed to quantify diameters and surface area for the whole endplate and its components (central endplate and epiphyseal rim). The whole endplate and mid-plane concavity depth were measured.There is marked morphologic asymmetry, in that the cranial endplate is more concave than the corresponding caudal endplate, with endplate concavity depths of 2.04 and 0.69 mm, respectively. For the caudal endplates, the endplate concavity apex locations were always located in the posterior portion (81.42%), while in cranial endplates relatively even. The central endplate was approximately 60% of the area of the whole endplate and the anterior section of the ring was the widest. From C3/4 down to C6/7 discs, the vertebral endplate gradually became more elliptical. Chinese cervical endplate anatomic sizes are generally smaller than that of Caucasians. Although Korean and Chinese individuals both belong to the Asian population subgroup, the majority of anatomic dimensions differ. Singaporean cervical endplate morphology is very similar to that of Chinese patients.We performed a comprehensive and accurate quantitative description of the cervical endplate, which provide references to shape and profile an artificial cervical disc without sacrificing valuable bone stock. To design a device with footprint as large as possible to distribute the axial load, we suggest that additional attention should be paid to the marginal rim. It is essential to specifically design appropriate disc prosthesis for Chinese patients. To fit the morphologic and biomechanical variations, we also propose that the disc prostheses for different vertebral segments should be separately designed.

Cranio-caudal asymmetries in trabecular architecture reflect vertebral fracture patterns

Clinically, vertebral fractures often occur in the upper lumbar spine and involve the superior endplate of a vertebra (which is immediately caudal to a disc). Knowledge that the cranial endplate of a disc is thicker and has greater bone mineral density (BMD) than the corresponding caudal endplate helps to explain this phenomenon. In this study, we investigated structural differences in vertebral trabeculae on either side of a lumbar disc to provide further insight into vertebral fracture risk. As the focus is trabecular difference within a spinal motion segment, we define cranial and caudal vertebral trabeculae relative to the disc. Ninety-two spinal motion segments from 46 cadaveric lumbar spines (males, mean age 50years, range 21-63years) were studied. Disc narrowing on radiography and spread of barium sulfate (BaSO₄) on discography were measured to indicate disc degeneration. Micro-computed tomography (μCT) images were obtained at a resolution of 82μm for each vertebra and processed to include only vertebral trabeculae. Using image processing, the vertebral trabeculae were divided into superior and inferior halves, and then into central and peripheral regions which were approximately opposite to the disc pulposus and annulus, and further into anterior and posterior sub-regions. Microarchitecture measurements for each vertebral region were obtained to determine the differences between the cranial and caudal trabeculae (relative to disc) and their associations with age and disc degeneration within each spinal motion segment. Data from the upper (L1/2-L3/4) and lower (L4/5) lumbar segments were analyzed separately. In the upper lumbar region, the trabeculae cranial to a disc on average had 5.3% greater BMD and trabecular bone volume, 3.6% greater trabecular number, 9.7% greater connectivity density, and 3.7% less trabecular separation than the corresponding caudal trabeculae (P<0.05 for all). Similar trends were observed in peripheral, anterior and posterior regions, but not in central region. No structural difference was observed in the trabeculae of L4/5 segment. Structural asymmetries of vertebral trabeculae were not associated with age, disc degeneration, or disc narrowing. Vertebral trabecular parameters cranial to the disc were greater than caudally in the upper but not in the lower lumbar region. Findings further explain why vertebral fractures are more common in the upper lumbar region and more frequently involve the endplate caudal to a disc.

Quantitative morphometric study of the subaxial cervical vertebrae end plate

BACKGROUND CONTEXT

Cervical disc arthroplasty has been gradually adopted as an alternative for the treatment of cervical degenerative disease. However, there is a large discrepancy between footprints of currently available cervical disc prostheses and anatomic dimensions of cervical end plates.

PURPOSE

This study aimed to accurately and comprehensively quantify the three-dimensional (3D) anatomic morphology of the cervical vertebral end plate and provide a theoretical basis for designing appropriate disc prostheses. Moreover, we introduced a novel geometric and mechanical model for 3D reconstruction techniques of the cervical end plate.

STUDY DESIGN

A descriptive study of the geometry of the middle and lower cervical vertebral end plates in cadaveric spines was carried out.

METHODS

A total of 138 cervical vertebral end plates were digitized using an optical 3D range scanning system, and then each end plate was reconstructed using the digitized image. For each end plate, the morphologic characteristics of six surface curves and the end plate concavity depth were symmetrically chosen and depicted.

RESULTS

The cranial end plates (relative to the disc) were concave and the caudal end plates were relatively flat at all disc levels, with mean concavity depths of 2.04 and 0.69 mm, respectively. For the caudal end plates, the end plate concavity apex was most often (81.42%) located in the posterior portion, whereas in the cranial end plates, the distribution was relatively even. For the sagittal curves, the foremost point and the rearmost point on the middle curve had a more forward position than those in the left curve and the right curve. Regarding the frontal plane curves, the length of the middle curve was longer than that of the anterior curve and posterior curve. For the cranial end plate, the maximal mean depth was the middle curve, whereas for the caudal end plate, the maximum depth was the posterior curve.

CONCLUSIONS

There is marked morphologic asymmetry, in that the cranial end plate is more concave than the corresponding caudal end plate. In the sagittal plane, the caudal end plates are aerofoil-shaped, whereas the cranial end plates are arc-shaped. In the transverse plane, the end plates are kidney-shaped. These morphologic characteristics of cervical vertebral end plates should be taken into consideration when designing cervical devices, such as artificial discs.

In vivo measurement of vertebral endplate surface area along the whole-spine

Accurate determination of vertebral endplate surface area and diameters plays an important role in surgical procedures, spinal implant design and sizing. The objective of this study was to contribute with baseline information on the endplate geometrical parameters using subject-based 3D whole-spine computed tomography (CT) models based on myelogram CT images taken of 49 patients with spinal disorders. Superior and inferior bony endplate mesh-models were created from said 3D CT models and endplate geometrical parameters including total polygon-mesh areas, projected areas and antero posterior and transverse diameters of each endplate were measured. The position of each endplate was determined by the cumulative distance along the spinal column with respect to C2. Endplate area and diameters were analyzed by gender, spinal level, age and correlation with spinal position. Males had larger endplates than females at all levels (p < 0.05) but S1. While endplate areas and transverse diameters increased with age at C3-L5 in females, these increases were not consistent through the whole-spine and even decreases with age were found at T1-T3 in males. There was a strong linear correlation between endplate area and spinal position in males and females with correlation coefficient values of r = 0.938 and r = 0.911, respectively. However, multiple comparisons of the geometrical parameters through the whole-spine revealed localized reduction of the anteroposterior or transverse diameters at T4 and L5-S1 levels. These regional and age-related changes in endplate dimensions should be taken into account for safe interventional treatments at these sites. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1418-1430, 2016.

Bone Marrow Edema and Low Back Pain in Elderly Degenerative Lumbar Scoliosis: A Cross-Sectional Study

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To examine whether bone marrow edema is associated with low back pain in elderly patients with degenerative lumbar scoliosis.

SUMMARY OF BACKGROUND DATA

The cause of low back pain in degenerative lumbar scoliosis is unclear.

METHODS

A total of 120 degenerative lumbar scoliosis patients 65 years of age or older were evaluated. Radiography, computed tomography (CT), magnetic resonance imaging (MRI), and tender point examination in the lumbar spine were performed. On MRI, coronal gadolinium-contrasted T1- or T2-weighed fat-saturated images were used to score the size of bone marrow edema. The prevalence of bone marrow edema in patients with and without low back pain was compared; in patients with low back pain, we tested whether the locations of lumbar tender point were consistent with that of bone marrow edema.

RESULTS

Bone marrow edema was found in 62 of 64 (96.9%) patients with low back pain compared with 21 of 56 (37.5%) patients without it (P < 0.001). Bone marrow edema located more frequently on the concave side than on the convex side of scoliosis (P < 0.001). Among patients with low back pain, bone marrow edema score was associated with low back pain severity (r = 0.724; P < 0.001), and the location of lumbar tender point were consistent with that of bone marrow edema (κ value = 0.745; P < 0.001).

CONCLUSION

Bone marrow edema on MRI was closely associated with the presence of low back pain in elderly degenerative lumbar scoliosis.

LEVEL OF EVIDENCE

4.

Targeted Therapy for Low Back Pain in Elderly Degenerative Lumbar Scoliosis: A Cohort Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To compare the novel treatment procedure with nonoperative treatment for low back pain (LBP) in elderly patients with degenerative lumbar scoliosis (DLS).

SUMMARY OF BACKGROUND DATA

Treatment of LBP associated with elderly DLS is controversial. We developed a novel treatment procedure, termed percutaneous intervertebral-vacuum polymethylmethacrylate injection (PIPI).

METHODS

We included patients with de novo DLS aged ≥65 years who had LBP with a visual analogue scale (VAS) score of >50 for ≥6 months with intervertebral vacuum and vertebral bone marrow edema (BME) defined on fat-saturated T2-weighted or gadolinium-enhanced T1-weighted magnetic resonance imaging. The primary outcomes were evaluated using the VAS score and modified Oswestry Disability Index (ODI). As an objective measurement, we scored BME on magnetic resonance imaging.

RESULTS

Between August 2004 and July 2011, 109 patients underwent PIPI and 53 received nonoperative treatment. At 1 month, mean improvements in VAS scores were -55.3 (95% CI, -60.5 to -50.1) and -1.9 (CI, -7.7 to 3.8) and mean improvements in ODI were -22.7 (CI, -27.3 to -18.2) and -0.6 (CI, -6.6 to 5.4) for the PIPI and nonoperative groups, respectively. At 2 years, mean improvements in VAS scores were -52.2 (CI, -59.9 to -44.4) and -4.0 (CI, -10.9 to 3.0) and mean improvements in ODI were -20.7 (CI, -27.3 to -14.5) and -1.0 (CI, -7.7 to 5.7) for the PIPI and nonoperative groups, respectively. BME substantially decreased in the PIPI group compared with the nonoperative group (P <0.001) and correlated with VAS score and ODI improvements (VAS score: r = 0.502, P <0.001; ODI: r = 0.372, P <0.001).

CONCLUSION

PIPI improved treatment for LBP, with a sustained clinical benefit for at least 2 years.

LEVEL OF EVIDENCE

3.

Digital tomosynthesis and high resolution computed tomography as clinical tools for vertebral endplate topography measurements: Comparison with microcomputed tomography

Endplate morphology is understood to play an important role in the mechanical behavior of vertebral bone as well as degenerative processes in spinal tissues; however, the utility of clinical imaging modalities in assessment of the vertebral endplate has been limited. The objective of this study was to evaluate the ability of two clinical imaging modalities (digital tomosynthesis, DTS; high resolution computed tomography, HRCT) to assess endplate topography by correlating the measurements to a microcomputed tomography (μCT) standard. DTS, HRCT, and μCT images of 117 cadaveric thoracolumbar vertebrae (T10-L1; 23 male, 19 female; ages 36-100 years) were segmented, and inferior and superior endplate surface topographical distribution parameters were calculated. Both DTS and HRCT showed statistically significant correlations with μCT approaching a moderate level of correlation at the superior endplate for all measured parameters (R(2)Adj=0.19-0.57), including averages, variability, and higher order statistical moments. Correlation of average depths at the inferior endplate was comparable to the superior case for both DTS and HRCT (R(2)Adj=0.14-0.51), while correlations became weak or nonsignificant for higher moments of the topography distribution. DTS was able to capture variations in the endplate topography to a slightly better extent than HRCT, and taken together with the higher speed and lower radiation cost of DTS than HRCT, DTS appears preferable for endplate measurements.

Validity and reliability of computerized measurement of lumbar intervertebral disc height and volume from magnetic resonance images

BACKGROUND CONTEXT

Magnetic resonance (MR) examinations of morphologic characteristics of intervertebral discs (IVDs) have been used extensively for biomechanical studies and clinical investigations of the lumbar spine. Traditionally, the morphologic measurements have been performed using time- and expertise-intensive manual segmentation techniques not well suited for analyses of large-scale studies..

PURPOSE

The purpose of this study is to introduce and validate a semiautomated method for measuring IVD height and mean sagittal area (and volume) from MR images to determine if it can replace the manual assessment and enable analyses of large MR cohorts.

STUDY DESIGN/SETTING

This study compares semiautomated and manual measurements and assesses their reliability and agreement using data from repeated MR examinations.

METHODS

Seven healthy asymptomatic males underwent 1.5-T MR examinations of the lumbar spine involving sagittal T2-weighted fast spin-echo images obtained at baseline, pre-exercise, and postexercise conditions. Measures of the mean height and the mean sagittal area of lumbar IVDs (L1-L2 to L4-L5) were compared for two segmentation approaches: a conventional manual method (10-15 minutes to process one IVD) and a specifically developed semiautomated method (requiring only a few mouse clicks to process each subject).

RESULTS

Both methods showed strong test-retest reproducibility evaluated on baseline and pre-exercise examinations with strong intraclass correlations for the semiautomated and manual methods for mean IVD height (intraclass correlation coefficient [ICC]=0.99, 0.98) and mean IVD area (ICC=0.98, 0.99), respectively. A bias (average deviation) of 0.38 mm (4.1%, 95% confidence interval 0.18-0.59 mm) was observed between the manual and semiautomated methods for the IVD height, whereas there was no statistically significant difference for the mean IVD area (0.1%±3.5%). The semiautomated and manual methods both detected significant exercise-induced changes in IVD height (0.20 and 0.28 mm) and mean IVD area (5.7 and 8.3 mm(2)), respectively.

CONCLUSIONS

The presented semiautomated method provides an alternative to time- and expertise-intensive manual procedures for analysis of larger, cross-sectional, interventional, and longitudinal MR studies for morphometric analyses of lumbar IVDs.

Effects of sagittal endplate shape on lumbar segmental mobility as evaluated by kinetic magnetic resonance imaging

STUDY DESIGN

Retrospective analysis using kinetic magnetic resonance imaging.

OBJECTIVE

To investigate relationships between vertebral endplate remodeling, Modic changes, disc degeneration, and lumbar segmental mobility.

SUMMARY OF BACKGROUND DATA

Previous studies have shown that disc degeneration and vertebral endplate Modic changes are associated with differences in spinal motion, however, the effects of vertebral endplate morphology on lumbar segmental motion have not been fully investigated.

METHODS

A total of 420 patients underwent kinetic magnetic resonance imaging of 2100 lumbar motion segments. Sagittal endplate shapes (concave, flat, irregular), Modic changes (types, 0-3), and disc degeneration (grade, I-V) were assessed along with translational and angular motion of vertebral segments in flexion, extension, and neutral positions.

RESULTS

The most common findings were concave endplate shape (63.24%), type 2 Modic change (71.79%), and grade II disc degeneration (40.33%). Flat, irregular endplates were more common at L1-L2, L4-L5, and L5-S1 than L2-L3 and L3-L4. Types 1, 2, and 3 Modic changes increased in frequency according to endplate shape: concave less than flat less than irregular. Type 0 was observed to decrease with the change of endplate shape from flat to concave to irregular. Vertebral levels with irregular endplates had more disc generation than those with flat; levels with flat endplates had significantly more disc degeneration than those with concave. Translational motion of the lumbar segment was greatest at levels with irregular endplates and decreased at those with flat and then concaves endplates. Angular motion was least at levels with irregular endplates and increased at levels with flat, then concave endplates.

CONCLUSION

The degree of pathogenic lumbar segmental motion is associated with remodeling of the sagittal endplate. Endplate remodeling may occur as an adaptation to restrain abnormal movement of the lumbar segment.

LEVEL OF EVIDENCE

N/A.

Disc cell therapies: critical issues

BACKGROUND

Disc cell therapies, in which cells are injected into the degenerate disc in order to regenerate the matrix and restore function, appear to be an attractive, minimally invasive method of treatment. Interest in this area has stimulated research into disc cell biology in particular. However, other important issues, some of which are discussed here, need to be considered if cell-based therapies are to be brought to the clinic.

PURPOSE

Firstly, a question which is barely addressed in the literature, is how to identify patients with 'degenerative disc disease' who would benefit from cell therapy. Pain not disc degeneration is the symptom which drives patients to the clinic. Even though there are associations between back pain and disc degeneration, many people with even severely degenerate discs, with herniated discs or with spinal stenosis, are pain-free. It is not possible using currently available techniques to identify whether disc repair or regeneration would remove symptoms or prevent symptoms from occurring in future. Moreover, the repair process in human discs is very slow (years) because of the low cell density which can be supported nutritionally even in healthy human discs. If repair is necessary for relief of symptoms, questions regarding quality of life and rehabilitation during this long process need consideration. Also, some serious technical issues remain. Finding appropriate cell sources and scaffolds have received most attention, but these are not the only issues determining the feasibility of the procedure. There are questions regarding the safety of implanting cells by injection through the annulus whether the nutrient supply to the disc is sufficient to support implanted cells and whether, if cells are able to survive, conditions in a degenerate human disc will allow them to repair the damaged tissue.

CONCLUSIONS

If cell therapy for treatment of disc-related disorders is to enter the clinic as a routine treatment, investigations must examine the questions related to patient selection and the feasibility of achieving the desired repair in an acceptable time frame. Few diagnostic tests that examine whether cell therapies are likely to succeed are available at present, but definite exclusion criteria would be evidence of major disc fissures, or disturbance of nutrient pathways as measured by post-contrast MRI.

The role of the vertebral end plate in low back pain

End plates serve as the interface between rigid vertebral bodies and pliant intervertebral disks. Because the lumbar spine carries significant forces and disks don't have a dedicated blood supply, end plates must balance conflicting requirements of being strong to prevent vertebral fracture and porous to facilitate transport between disk cells and vertebral capillaries. Consequently, end plates are particularly susceptible to damage, which can increase communication between proinflammatory disk constituents and vascularized vertebral bone marrow. Damaged end plate regions can be sites of reactive bone marrow lesions that include proliferating nerves, which are susceptible to chemical sensitization and mechanical stimulation. Although several lines of evidence indicate that innervated end plate damage can be a source of chronic low back pain, its role in patients is likely underappreciated because innervated damage is poorly visualized with diagnostic imaging. This literature review summarizes end plate biophysical function and aspects of pathologic degeneration that can lead to vertebrogenic pain. Areas of future research are identified in the context of unmet clinical needs for patients with chronic low back pain.