Biomechanics of the spine. Part II: Spinal instability

The influence of different stress loading on the biomechanics of motion segments in isolated rabbit spines

Intervertebral disc degeneration greatly affects daily life. Suitable mechanical stress is important for intervertebral disc health as it affects disc cells. Research shows it helps disc cell proliferation and collagen synthesis. However, the influences of forces in diverse directions on the intervertebral disc remain ambiguous. Our study aimed to investigate the impact of stress in various directions on intervertebral discs in New Zealand rabbits. The rabbit model was used because our team previously had established and validated it,which providing an effective platform for researching disc degeneration and treatment methods. We resected the spinal L3/4 and L5/6 motion segments and categorized them into 5 groups. Apart from the control group, distinct mechanical loads (pressure, traction, rotation, rotational traction) were applied to the remaining groups. After mechanical intervention, in contrast to the other groups except for the control group, it was found that the creep displacement in the rotational traction force group was the lowest (0.90 ± 0.06), the fatigue resistance was enhanced, and the tensile strength was increased, showing advantages over the other groups (p < 0.05). Histological examination revealed that the rotational traction force group had a protective effect on the intervertebral disc structure, while the cell damage in the rotational force group was the most severe. This study will help understand the unique effects of stresses in different directions on the intervertebral disc. The general public should avoid direct rotational movements in daily life. Physicians can explore the therapeutic effect of rotational movements under traction on lumbar degenerative changes.

Effect of Vertebral Morphology on Radiographic and Symptomatic Lumbar Spinal Stenosis in Patients Undergoing Microendoscopic Decompression Surgery: A Retrospective Cohort Study

Purpose Lumbar spinal stenosis (LSS) is a degenerative condition characterized by spinal canal narrowing, often leading to nerve compression and significantly impairing quality of life, particularly in older adults. Magnetic resonance imaging (MRI) is the gold standard for diagnosing LSS; however, radiographic evidence of stenosis often does not align with clinical symptoms, complicating management. We explored the relationship between vertebral morphology and both radiographic and symptomatic stenosis, hypothesizing that specific vertebral shapes, particularly oval (O) morphology, increase the risk of symptomatic stenosis. Methods This retrospective cohort study included patients who underwent microendoscopic decompression surgery between 2010 and 2022. Vertebral morphology was classified as bean (B), plane (P), or oval (O) based on MRI assessments of the posterior vertebral wall. Radiographic stenosis was identified based on MRI findings using the Schizas classification, whereas symptomatic stenosis required a correlation with clinical symptoms, such as neurogenic claudication or radicular pain confirmed through physical examination and functional diagnostics. Levels with radiographic stenosis that lacked clinical correlation were categorized as asymptomatic stenosis. The primary outcome was the prevalence of radiographic and symptomatic stenoses across different vertebral morphology groups. Secondary outcomes included the influence of patient demographics and morphology on stenosis at various lumbar levels. Statistical analyses included Chi-square tests and multivariate logistic regression, with p-values <0.05 considered significant. Results A total of 234 patients (105 females and 129 males; mean age: 72.2 years) were included. Radiographic stenosis prevalence increased progressively from L1/2 to L4/5, with the highest rate at L4/5 (167/234, 71.4%). Among these cases, symptomatic stenosis was observed in 86.2% (144/167), with O morphology showing the strongest association (79/86, 91.2%), followed by P morphology (65/81, 80.2%). By contrast, B morphology had the lowest prevalence of radiographic stenosis (10/103, 9.7%) and the weakest correlation with symptomatic outcomes (2/38, 5.3%). Overall, 265/337 (78.6%) of radiographic stenosis cases were symptomatic, whereas 72/337 (21.4%) remained asymptomatic despite MRI findings, highlighting the gap between imaging findings and clinical symptoms. Multivariate analysis confirmed that O morphology was significantly associated with symptomatic stenosis (odds ratio: 3.45; 95% CI: 2.10-5.67; p<0.001), underscoring the influence of vertebral morphology on symptomatic presentation. Conclusions Vertebral morphology was observed to influence the prevalence and severity of both radiographic and symptomatic stenosis. The O morphology demonstrated a higher prevalence of symptomatic stenosis, particularly at the L4/5 level, whereas the B morphology was associated with the lowest prevalence. These findings suggest that incorporating vertebral morphology into diagnostic evaluations and treatment planning for patients with LSS may enhance alignment between imaging findings and clinical presentations, facilitating more accurate prognostic assessments and tailored strategies.

The Development of New Scoring System to Define the Presence of Instability and the Need of Fusion in Degenerative Lumbar Spinal Stenosis - Jakarta Instability Score

STUDY DESIGN

Systematic review, expert opinion and Delphi technique, and validity and reliability studies.

OBJECTIVE

We developed Jakarta Instability Score (JIS) to identify spinal instability and the need of fusion in degenerative lumbar spinal stenosis (LSS).

METHODS

This study consisted of systematic review to find predictors of spinal instability, expert opinion and modified Delphi technique to develop JIS, and validity and reliability studies of the newly developed JIS.

RESULTS

A total of 54 studies were included in the systematic reviews to obtain predictors of spinal instability. Through expert opinion and modified Delphi technique, JIS was developed and consisted of the clinical component (back pain), dynamic radiograph component (dynamic translation and angulation), and MRI component (facet joint effusion), each of the component would be scored, and the total scoring would be from 0 to 14. The final scoring would classify patients into three groups: stable group (score of 0 to 4) in which the fusion is not needed, potentially unstable group (score of 5 to 8) in which the decision of fusion is based on surgeon's clinical judgment, and unstable group (score of 9 to 14) in which the fusion is needed. Final step of study concluded that this JIS had a high validity and reliability.

CONCLUSION

The newly developed JIS was a valid and reliable scoring system that could help to identify the presence of instability in LSS and can be used as a guideline to decide whether spinal fusion will be needed.

Spinopelvic malalignment correlates to lumbar instability and lumbar musculature in chronic low back pain-an exploratory study

As PI-LL mismatch is an effective index for spinal surgery and PI-LL less than 10 probably indicates better quality of life, this study aimed to assess spinopelvic parameters, lumbar instability, and lumbar muscle morphology in patients with chronic low back pain (CLBP) with different PI-LL mismatches. This cross-sectional study included 158 CLBP patients. The association between lumbar extensor muscle morphology (measured from magnetic resonance imaging) and spinopelvic parameters (measured from standing lateral radiographs) and lumbar instability (measured from lumbar flexion/extension radiographs) was compared between two groups of patients with different PI-LL mismatch. PI-LL mismatch showed a significant medium association with lumbar spine stability (χ2 = 8.06, p-value = 0.005, OR = 0.26, 95% CI = 0.10 to 0.69). Total cross-sectional area (TCSA) (OR = < 0.001, 95% CI = < 0.001 to < 0.001), functional cross-sectional area (FCSA) (OR = < 0.001, 95% CI = < 0.001 to < 0. 001) of the multifidus, psoas major TCSA (OR = < 0.001, 95% CI = < 0.001 to < 0.001) and its FCSA (OR = < 0.001, 95% CI = < 0.001 to 0.009) showed a strong negative association with PI-LL mismatch. Patients with lower PI-LL mismatch are younger and have less spinopelvic deviation. They have more local spinal compensatory mechanisms such as increased lumbar lordosis. They have better lumbar musculature and less disability but more lumbar instability.

Management of Cervical Spine Fractures and Injuries: A Literature Review

Cervical spine injuries are one of the most common injuries of the spine that are encountered in the emergency department (ED). More than half of all spinal injuries presenting to the ED involve the cervical spine, with nearly half of them resulting from road traffic accidents. The majority of spinal cord injuries are found to occur in males of younger age groups, with almost half of them resulting in incomplete spinal cord injuries. The initial assessment of a patient with a suspected cervical spine fracture would include an Advanced Trauma Life Support (ATLS)-guided documented assessment of the patient involving a detailed, meticulous primary survey followed by a documented assessment of the patient through a secondary survey. Initial management of the cervical spine fracture begins at the scene of injury with prehospital care, which involves immobilisation of the cervical spine with "triple immobilisation" followed by initial airway management in the ED while maintaining in-line neck stabilisation, thereby minimising the neck movements. Neurological assessment according to the impairment scale and imaging in alert and stable patients is done based on established guidelines. However, a CT scan is the gold standard modality of imaging for suspected cervical spine fractures. All patients with a significant mechanism of injury must be assumed to have an unstable injury to their spine until proven otherwise according to British Orthopaedic Association Standard for Trauma (BOAST) guidelines.

Segmental vertebral three-dimensional motion in patients with L4 isthmic spondylolisthesis under weight-bearing conditions

OBJECTIVE

To investigate in vivo 6-degree-of-freedom (DOF) vertebral motion in patients with isthmic spondylolisthesis (IS) during various functional weight-bearing activities.

METHODS

Fifteen asymptomatic volunteers (mean age 54.8 years) and fourteen patients with IS at L4-5 (mean age 53.4 years) were recruited. The positions of the vertebrae (L4-L5) in the supine, standing, flexion-extension, left-right twisting and left-right bending positions were determined using previously described CT-based models and dual fluoroscopic imaging techniques. Local coordinate systems were established at the center of the anterior vertebra of L4 isthmic spondylolisthesis (AIS), the posterior lamina of L4 isthmic spondylolisthesis (PIS) and the center of the L5 vertebra to obtain the 6DOF range of motion (ROM) at L4-L5 and the range of motion (ROM) between the AIS and the PIS.

RESULTS

The translation along the anteroposterior axis at L4-L5 during flexion-extension, left-right bending and left-right twisting was significantly greater than that of the healthy participants. However, the translation along the mediolateral axis at L4-L5 presented paradoxical motion under different positions: the ROM increased in the supine-standing and flexion-extension positions but decreased in the left-right bending and left-right twisting positions. The separation along the anteroposterior axis during flexion was significantly greater than that during standing, on average, reaching more than 1 mm. The separation along the mediolateral axis during standing, flexion and extension was significantly greater than that in the supine position.

CONCLUSIONS

This study revealed the occurrence of displacement between the AIS and PIS, primarily in the form of separation during flexion. Symptomatic patients with isthmic spondylolisthesis exhibit intervertebral instability, which might be underestimated by flexion-extension radiographs.

Traction Spurs in the Lumbar Spine: A Historical Overview and Future Perspectives

Numerous studies have explored the connection between lumbar osteophytes, their pathophysiology, and instability since Macnab's 1971 report on traction spurs as an indicator of lumbar instability. This study provides a narrative historical overview of traction spurs, a classic finding that suggests lumbar instability. It summarizes the causes of anterior lumbar vertebral osteophytes, the relationship between traction spurs and lumbar spinal instability, and the clinical significance of traction spurs. Vertebral osteophytes are grouped into two categories, namely, traction spurs or claw spurs, which represent different stages of the same pathological process. Traction spurs are indicative of instability and occur in the early stage of disc degeneration, characterized by temporary dysfunction or instability. Traction spur formation following fusion surgery can predict union or nonunion, and it serves as an indicator of preoperative and postoperative segmental instability. The relationship between traction spurs and radiographic instability, as well as their association with imaging findings such as CT and MRI, has been clarified. Additionally, finite element analysis and mechanical testing have been used to investigate the significance of traction spurs. However, further research is needed to verify that traction spurs are an accurate indicator of pre- and postoperative lumbar instability.

Cervical intervertebral disc disease in 307 small-breed dogs (2000-2021): Breed-characteristic features and disc-associated vertebral instability

OBJECTIVE

To evaluate the breed-characteristic features of cervical intervertebral disc disease (C-IVDD) and associated vertebral instability in small-breed dogs and to present the concept of intervertebral disc degeneration and associated instability stage, method of diagnosis, treatment and outcomes.

ANIMALS

In total, 307 client-owned dogs with C-IVDD treated with spinal cord decompression with or without vertebral stabilization (2000-2021).

METHODS

Information on age, sex, affected sites, stabilized sites, diagnostic methods for vertebral instability and outcomes were retrieved. The patient's age, affected sites (cranial vs caudal discs), and frequency of vertebral stabilization were compared in six CD and five NCD breed. Multivariable analyses of the chondrodystrophic (CD) vs non-CD (NCD) groups, and vertebral stabilization (dogs stabilized vs dogs not stabilized) were performed.

RESULTS

In total, 222 (72.3%) and 77 (25.1%) were CD and NCD breeds, respectively. Vertebral instabilities were diagnosed based on the survey radiographs with computed tomography/magnetic resonance imaging (n = 2), dynamic myelography (n = 29), intraoperative spinal manipulation (n = 11) or second surgery in dogs with persistent postoperative paraspinal pain (n = 3). Of these dogs, 295 (96.1%) recovered (median follow-up: 8.5 [range, 1-119] months). Significant differences in age, affected sites and frequency of stabilization were noted among the breeds. Older age and frequent vertebral stabilization were the associated factors for the NCD breed dogs. Male dogs, caudal discs affected (C5-T1) and the NCD breed dogs were risk factors for the dogs with vertebral stabilization.

CONCLUSION

Vertebral stabilization is indicated for small-breed dogs with cervical disc-associated vertebral instability.

The immediate effect of cervical rotation-traction manipulation on cervical paravertebral soft tissue: a study using soft tissue tension cloud chart technology

BACKGROUND

To evaluate the reliability of the Soft Tissue Tension Cloud Chart (STTCC) technology, an original method combining multi-point Cervical Paravertebral Soft Tissue Test (CPSTT) with MATLAB software, we conducted a preliminary analysis on the immediate effects of Orthopaedic Manual Therapy (OMT) on cervical paravertebral soft tissue.

METHODS

30 patients with Cervical Spondylotic Radiculopathy (CSR) were included in this study. We analyzed the differences in CPSTT before and after treatment with Cervical Rotation-Traction Manipulation (CRTM), a representative OMT technique in Traditional Chinese Medicine, using the STTCC technology.

RESULTS

The STTCC results demonstrated that post-treatment CPSTT levels in CSR patients were significantly lower than pre-treatment levels after application of CRTM, with a statistically significant difference (P < 0.001). Additionally, pre-treatment CPSTT levels on the symptomatic side (with radicular pain or numbness) were higher across the C5 to C7 vertebrae compared to the asymptomatic side (without symptoms) (P < 0.001). However, this difference disappeared after CRTM treatment (P = 0.231).

CONCLUSIONS

The STTCC technology represents a reliable method for analyzing the immediate effects of OMT. CSR patients display uneven distribution of CPSTT characterized by higher tension on the symptomatic side. CRTM not only reduces overall cervical soft tissue tension in CSR patients, but can also balance the asymmetrical tension between the symptomatic and asymptomatic sides.

TRIAL REGISTRATION

This study was approved by the Chinese Clinical Trials Registry (Website: . https://www.chictr.org.cn .) on 20/04/2021 and the Registration Number is ChiCTR2100045648.

The Effect of Indirect Decompression Through Extraforaminal Interbody Fusion for Degenerative Lumbar Disease

Purpose

Extraforaminal lumbar interbody fusion as with other methods that involve the mechanism of indirect decompression, the discussion not only focuses on the benefit of minimizing the risk of thecal sac injury and postoperative scarring, but also on the risk of insufficient decompression in the affected neural structures during the reduction of the affected segment.

Methods

Eighty-two patients presenting with degenerative lumbar disease with segmental instability underwent ELIF combined with transpedicular fixation and circumferential fusion. Clinical and radiographic evaluations were performed.

Results

The mean ODI significantly improved from 63.4 preoperatively to 32.3 1 year postoperatively. The mean VAS back pain significantly improved from 5.95 to 2.63 postoperatively and VAS (leg pain) improved from 6.04 to 2.44. The mean CSA increased from 103  mm2 preoperatively to 169  mm2 postoperatively. The median extension ratio of CSA was 33%. Disc height, segmental disc angle, and lumbar lordosis also improved significantly. Only three (3.7%) patients were revised using direct central decompression due to neurologic deterioration.

Conclusion

Spinal stenosis was resolved successfully by indirect decompression through extraforaminal interbody fusion via a transmuscular limited approach.

Cervical facet capsular ligament mechanics: Estimations based on subject-specific anatomy and kinematics

Background

To understand the facet capsular ligament's (FCL) role in cervical spine mechanics, the interactions between the FCL and other spinal components must be examined. One approach is to develop a subject-specific finite element (FE) model of the lower cervical spine, simulating the motion segments and their components' behaviors under physiological loading conditions. This approach can be particularly attractive when a patient's anatomical and kinematic data are available.

Methods

We developed and demonstrated methodology to create 3D subject-specific models of the lower cervical spine, with a focus on facet capsular ligament biomechanics. Displacement-controlled boundary conditions were applied to the vertebrae using kinematics extracted from biplane videoradiography during planar head motions, including axial rotation, lateral bending, and flexion-extension. The FCL geometries were generated by fitting a surface over the estimated ligament-bone attachment regions. The fiber structure and material characteristics of the ligament tissue were extracted from available human cervical FCL data. The method was demonstrated by application to the cervical geometry and kinematics of a healthy 23-year-old female subject.

Results

FCL strain within the resulting subject-specific model were subsequently compared to models with generic: (1) geometry, (2) kinematics, and (3) material properties to assess the effect of model specificity. Asymmetry in both the kinematics and the anatomy led to asymmetry in strain fields, highlighting the importance of patient-specific models. We also found that the calculated strain field was largely independent of constitutive model and driven by vertebrae morphology and motion, but the stress field showed more constitutive-equation-dependence, as would be expected given the highly constrained motion of cervical FCLs.

Conclusions

The current study provides a methodology to create a subject-specific model of the cervical spine that can be used to investigate various clinical questions by coupling experimental kinematics with multiscale computational models.

The Effect of Two Types of Back Pillow Support on Transversus Abdominis and Internal Oblique Muscle Fatigue, Patient Satisfaction, and Discomfort Score during Prolonged Sitting

Natural rubber is considered an economic plant in Thailand and is used to manufacture many products. Foam back pillows have proven to have various benefits for the lower back. However, no study has compared the effects of foam and rubber pillows. Therefore, the current study aimed to compare the efficacy of foam and rubber pillows on transversus abdominis and internal oblique muscle fatigue, patient satisfaction, and discomfort scores during 60 min of prolonged sitting. Thirty healthy participants were invited to the study and randomized into three sitting conditions over three consecutive days. The three groups were as follows: control, foam pillow, and rubber pillow. Our results revealed that the discomfort score increased with the sitting time in all three groups (p < 0.05). The control group had the highest discomfort when compared to the rubber pillow group at 30 min (T4; p = 0.007) and 60 min (T7; p = 0.0001), as well as the foam pillow group at 60 min (T7; p = 0.0001). Participants were more satisfied sitting with the two types of back pillows at the initial time (T1; p = 0.0001) and at 60 min (T7; p = 0.0001) when compared with the control group. Furthermore, the participants were more satisfied with using rubber pillows rather than foam pillows throughout the sitting period (p = 0.0001). The control group experienced more transversus abdominis and internal oblique muscle fatigue at 60 min (T7) of sitting compared to the initial time (T1) (p = 0.038). Thus, sitting with pillow support can decrease deep trunk muscle fatigue, and using a pillow made from natural rubber may ensure greater satisfaction and less discomfort for the user.

Reliability and repeatability of a modified thoracolumbar spine injury classification scoring system

Purpose

On the basis of the Thoracolumbar Injury Classification and Severity Score (TLICS), an modified TLICS classification system was presented, its reliability and repeatability were assessed, and the factors influencing classification consistency were examined.

Methods

Five spinal surgeons were chosen at random. The clinical data of 120 patients with thoracolumbar fractures admitted to the Department of Spine Surgery, Ningbo Sixth Hospital from December 2019 to June 2021 were categorized using the modified TLICS system. After 6 weeks, disrupt the order of data again. Using unweighted Cohen's kappa coefficients, the consistency of the modified TLICS system was assessed in five aspects: neurofunctional status, disc injury status, fracture morphology, posterior ligament complex (PLC) integrity, and treatment plan.

Results

In terms of reliability, the average kappa values for the subclasses of the modified TLICS system (neurofunctional status and disc injury status) were 0.920 and 0.815, respectively, reaching the category of complete confidence. Fracture morphology and treatment plan had average kappa values of 0.670 and 0.660, respectively, which were basically reliable. The average kappa value of PLC integrity was 0.453, which belonged to the category of moderate confidence. The average kappa coefficients of each subcategory (neurological status, disc injury status) had excellent consistency, and the kappa values were 0.936 and 0.879, respectively, which belonged to the completely credible category. The kappa values of fracture morphology and treatment plan repeatability were 0.772 and 0.749, respectively, reaching the basic credibility category. PLC integrity repeatability kappa value is low, 0.561, to moderate credibility category.

Conclusion

The modified TLICS system is intuitive and straightforward to understand. The examination of thoracolumbar fracture injuries is more exhaustive and precise, with excellent reliability and repeatability. The examination of neurological status and disc injury status is quite reliable and consistent. The consistency of fracture morphology is slightly poor, which is basically credible; the PLC integrity consistency is poor, reaching a reliability level of moderate, which may be associated with the subjectivity of clinical evaluation of PLC.

Factors associated with spinal instability in low back lumbar diseases with leg pain: Analysis of sagittal translation and segmental angulation

BACKGROUND

Determining the association between radiographic spinal instability assessment and lower back lumbar diseases with lower limb symptoms can contribute to evidence-based assessment and treatment in clinical practice and rehabilitation. Therefore, radiological evidence of lumbar spine instability assessment, such as sagittal translation (ST) and segmental angulation (SA), is clinically important.

OBJECTIVE

To identify factors associated with the assessment of spinal instability in lumbar disc herniation with leg pain and discogenic low back pain using ST and SA.

METHODS

We examined 112 patients with lumbar disc herniation with leg pain and 116 with discogenic low back pain at our clinic from 2016 to 2021. Data on age, gender, sports activities, and occupation were collected from medical records. Additionally, ST and SA of L4 and L5 during maximum trunk flexion and extension were measured using radiography. Simple and multiple logistic regression analyses were used for statistical analysis.

RESULTS

Simple logistic regression analysis showed that ST and SA (odds ratio [OR]: 1.11; 95% confidence interval [CI]: 1.03-1.19) were associated with lumbar disc herniation. Multiple logistic regression analysis showed that only ST was associated with lumbar disc herniation (OR: 2.29; 95% CI: 1.78-3.00).

CONCLUSION

Multiple logistic regression analysis showed that ST was associated with lumbar disc herniation with leg pain and had a stronger association than SA.

Prevalence of Lumbar Segmental Instability in Young Individuals with the Different Types of Lumbar Disc Herniation-Preliminary Report

Lumbar segmental instability (LSI) can cause pain and disability, and its background can be related to lumbar disc herniation (LDH). This retrospective study was conducted to analyze the prevalence of lumbar segmental instability (LSI) in young patients with different types of lumbar disc herniation (LDH). The study evaluated 133 individuals (18−25 years old) who suffered from LDH and underwent MRI and flexion-extension X-rays. Two groups were created: protrusion (PRO) and extrusion (EXT). LSI was scored positive when translatory motion was greater than 4 mm anteriorly or 2 mm posteriorly at the level of herniation. Statistica 13 was used to perform statistics. The LSI overall prevalence was 18.33% in PRO and 21.92% in EXT (p > 0.05). Out of all LSI positives, higher LSI incidence was observed in females compared to males; in PRO: 63.64%; in EXT: 68.75% (p > 0.05). LSI correlated positively with the passive lumbar extension test (PLE) (R = 0.32; p = 0.01) in the PRO group only. In summary, the results showed that the overall incidence of LSI was higher with severer disc damage. In addition, females were more prone to this pathology. However, the different types of LDH do not significantly affect the prevalence of LSI in young individuals.

Combining clinical exams can better predict lumbar spine radiographic instability

BACKGROUND/OBJECTIVES

Several clinical tests have been proposed to diagnose lumbar instability, but their accuracy is still in question. The primary purpose of this study was to evaluate the diagnostic accuracy of the clinical lumbar instability tests. The secondary goal was to design a model to detect lumbar instability.

DESIGN

A prospective diagnostic cross-sectional study.

METHOD

A sample of 202 patients with chronic low back pain were participated in the study. Five lumbar instability tests including Aberrant movement, Passive lumbar extension, Prone segmental instability, H and I and pheasant tests were compared to flexion/extension radiography as the gold standard for diagnosing lumbar instability using two by two tables. Multiple Logistic Regression analysis was applied to develop a model using demographic information as well as the patients' pain intensity, disability level, lumbar lordosis and the clinical tests.

RESULTS

Among the five examined tests, Prone segmental instability, H and I and pheasant tests showed very small likelihood ratios and diagnostic odd's ratio. The largest values were for H and I test with the positive likelihood ratio of 1.28 (95% CI: 0.72 to 2.29) and diagnostic odd's ratio of 1.37 (95% CI: 0.66 to 2.83); the diagnostic accuracy measures were smaller for the other studied clinical tests. The model was developed using weight (t = 1.15, p = 0.03) and lumbar lordosis (t = 3.04, p = 0.00) (which showed a significant relationship with lumbar instability) and prone segmental instability test. The final model has the positive likelihood ratio of 2.07 (95% CI: 1.41 to 3.05) and diagnostic odd's ratio of 3.77 (95% CI: 2.03 to 7.01).

CONCLUSION

Each individual test had very small to no power in discriminating patients with lumbar instability. The developed model just slightly improved the accuracy of radiological instability detection.

Comparison of Oblique Lateral Interbody Fusion (OLIF) and Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF) for Treatment of Lumbar Degeneration Disease: A Prospective Cohort Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To assess the differences in the clinical and radiological outcomes between oblique lateral interbody fusion (OLIF) and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

SUMMARY OF BACKGROUND DATA

Nowadays, there is still a controversy regarding whether OLIF is superior to MI-TLIF in the management of degenerative lumbar disease.

METHODS

Between August 3, 2019 and February 3, 2020, 137 patients were assigned to OLIF or MI-TLIF at their request and the surgeon's discretion: 71 in the OLIF group and 66 in the MI-TLIF group. The perioperative data, patient-reported outcomes, radiographic outcomes, and complications were compared between the two groups.

RESULTS

The OLIF group showed shorter operation time (110.5 vs.183.8 minutes, P < 0.001), lesser estimated blood loss (123.1 vs. 232.0 mL, P < 0.001), shorter length of hospital stay (5.5 vs. 6.7 days, P < 0.001), and lower serum creatine kinase (CK) (1 day postoperatively) (376.0 vs. 541.8 IU/L, P < 0.01) than that of MI-TLIF group. Both groups showed no significant differences in the visual analog scale (VAS) scores of lower back and leg pain and the Oswestry Disability Index (ODI) scores preoperatively and at 1, 3, and 12 months postoperatively, respectively (P > 0.05). Compared with the MI-TLIF group, the OLIF group showed better restoration of disc height (DH) (4.7/4.6/4.7 vs. 3.7/3.7/3.7 mm, P < 0.01) and lumbar lordosis angle (LLA) (10.5°/10.8°/11.1° vs. 5.8°/5.7°/5.3°, P < 0.001), but not the value of segmental lordosis angle (SLA) (P > 0.05) at 1 day, 1 month, and 1 year postoperatively, respectively. The complication rate of OLIF was higher than that of MI-TLIF (29.4% vs. 9.7%, P < 0.01).

CONCLUSION

Compared with MI-TLIF, OLIF showed similar results in terms of patient-reported outcomes, restoration of SLA and fusion rate, and superior results with respect to restoration of DH and LLA, operation time, estimated blood loss, length of hospital stay, and serum CK levels (1 day postoperatively). Even though the complication rate of OLIF is higher than that of MI-TLIF, it does not bring persistent and substantial damage to the patients.Level of Evidence: 3.

Which traumatic spinal injury creates which degree of instability? A systematic quantitative review

BACKGROUND CONTEXT

Traumatic spinal injuries often require surgical fixation. Specific three-dimensional degrees of instability after spinal injury, which represent criteria for optimum treatment concepts, however, are still not well investigated.

PURPOSE

The aim of this review therefore was to summarize and quantify multiplanar instability increases due to spinal injury from experimental studies.

STUDY DESIGN/SETTING

Systematic review.

METHODS

A systematic review of the literature was performed using keyword-based search on PubMed and Web of Science databases in order to detect all in vitro studies investigating the destabilizing effect of simulated and provoked traumatic injury in human spine specimens. Together with the experimental designs, the instability parameters range of motion, neutral zone and translation were extracted from the studies and evaluated regarding type and level of injury.

RESULTS

A total of 59 studies was included in this review, of which 43 studies investigated the effect of cervical spine injury. Range of motion increase, which was reported in 58 studies, was generally lower compared to the neutral zone increase, given in 37 studies, despite of injury type and level. Instability increases were highest in flexion/extension for most injury types, while axial rotation was predominantly affected after cervical unilateral dislocation injury and lateral bending solely after odontoid fracture. Whiplash injuries and wedge fractures were found to increase instability equally in all motion planes.

CONCLUSIONS

Specific traumatic spinal injuries produce characteristic but complex three-dimensional degrees of instability, which depend on the type, level, and morphology of the injury. Future studies should expand research on the cervicothoracic, thoracic, and lumbosacral spine and should additionally investigate the destabilizing effects of the injury morphology as well as concomitant rib cage injuries in case of thoracic spinal injuries. Moreover, neutral zone and translation should be measured in addition to the range of motion, while mechanical injury simulation should be preferred to resection or transection of structures to ensure high comparability with the clinical situation.

A diagnostic tool for people with lumbar instability: a criterion-related validity study

BACKGROUND

Several clinical tests used to identify patients with lumbar instability have reported diagnostic accuracy in separate studies with conflicting results. To augment the diagnostic process, tests that are better able to identify lumbar instability suitable for use in the clinical setting are required. The aim of this study was to identify the probability to diagnose patients with lumbar instability, using x-ray imaging as the reference standard.

METHODS

This study was a cross-sectional, diagnostic validity study. One hundred forty participants with chronic low back pain underwent an x-ray assessment and 14 clinical examinations. Data were analysed using multivariate regression methods to determine which clinical tests were most diagnostic for lumbar instability when they were applied together.

RESULTS

Eighteen (12.85%) participants had radiological lumbar instability. Three clinical tests i) interspinous gap change during flexion-extension, ii) passive accessory intervertebral movement tests, iii) posterior shear test demonstrated an ability to diagnose lumbar instability of 67% when they were all positive. At this probability threshold, sensitivity, specificity, positive likelihood ratio (+LR), and negative likelihood ratio (-LR) were 5.56, 99.18%, 6.78, and 0.95.

CONCLUSIONS

These 3 clinical tests could be useful in identifying patients with lumbar instability in the general community. These three tests are simple to perform by physical therapists, reliable to use in a clinical setting, and safe for patients. We recommend physical therapists use these three tests to assess patients who are suspected of having lumbar instability, in the absence of an x-ray assessment, to receive appropriate targeted intervention or referral for further investigation.

TRIAL REGISTRATION

Thai Clinial Trial Registry (TCTR 20180820001; 19th August 2018).

The Management of Cervical Spine Injuries - A Literature Review

Due to the inherent bony instability of the cervical spine, there is an over-reliance on ligamentous structures for stability, making this segment of the vertebral column most prone to traumatic injuries. The frequently occurring mechanisms of injury include axial compression, hyper-flexion, hyper-extension, and rotational type injuries. Good pre-hospital care and a thorough assessment in the emergency department of patients suspected to have a cervical spine injury (CSI) leads to improved clinical outcomes. The objective of the initial evaluation of a patient with a suspected CSI is to identify the presence of injuries through thorough clinical and radiologic assessments as missed injuries are potentially catastrophic. The treatment of cervical spine injuries can be conservative, pharmacological, or surgical, and aims to halt SCI progression, stabilize the spine, and to allow rehabilitation of the patient.

Visualization of the epimysium and fascia thoracolumbalis at the lumbar spine using MRI

BACKGROUND

The fascia thoracolumbalis (FTL) is an important component for stabilization and motion control of the lumbar spine. It coordinates the traction forces of the autochthonous muscles of the back (AM) and connects them to the muscles of the abdominal wall, shoulder, and buttocks.

OBJECTIVES

The aim of our study was to describe the assessment of the normal FTL and epimysium of the AM in MRI and to identify patterns associated with pathological changes in the lumbar spine.

MATERIAL AND METHODS

A total of 33 patients were retrospectively evaluated: 15 patients had no pathology at the lumbar spine; six patients had previous hemilaminectomy, three had spondylodesis, two had ventrolisthesis, and seven had scoliosis. The thickness of the FTL and EM was measured, and the adhesion of both structures was assessed.

RESULTS

The fascial thickness at the levels of the lumbar vertebral bodies LVB 3 was 1.8, of LVB 4 it was 2.0, of LVB 5 it was 2.1, and at the sacral vertebra SVB 1 it was 1.8 mm. Fascial adhesions together with thickening of the EM occurred at the level of LVB 4 in 36% of the cases independently of the underlying disorder. Only thickening of the EM was seen in 48% of cases at the level of SVB 1. By contrast, adhesion of the FTL without epimysial changes occurred in 36% of cases at the level of LVB 3.

CONCLUSION

Thickening and adhesions at the EM and FTL occurred both postoperatively and in the case of scoliosis. Furthermore, lipomatous and muscular herniation could be detected in the FTL postoperatively. Epimysial and fascial alterations may be imaging manifestations of chronic myofascial back pain and should be included in radiological assessments.

Pyogenic spondylodiscitis : The quest towards a clinical-radiological classification

BACKGROUND

Pyogenic spondylodiscitis (PS) is a debilitating condition laden with orthopedic and neurological complications. The choice of the best step in management is often delayed due to the controversy encompassing its multiple facets. Several classification systems were proposed in the literature to define optimal management; however, consensus was not achieved.

OBJECTIVE

The aim of this study was to review the literature and critically appraise the classification systems of PS and the rationale behind the classification criteria.

METHODS

A literature search was conducted in PubMed. Titles and abstracts of articles were searched using different synonyms of spondylodiscitis and its classification. No restrictions regarding language of publication or date of publication were applied.

RESULTS

A total of 43 papers with 5 encompassing 3 main classifications were found in the literature. These classifications were overlapping but different. They encompassed neurologic deficits, abscess formation and segmental instability, laboratory parameters and morphological changes in magnetic resonance imaging (MRI) as the most important factors used to classify PS, assess the severity and guide treatment.

CONCLUSION

The current classification schemes overlap and encompass the most clinically relevant factors; however, some could be too complex for interdisciplinary clinical practice and do not adequately address unique entities, such as PS of the cervical spine, anterolisthesis and retrolisthesis. Most importantly, some criteria must be utilized in concert with recently published guidelines and should be re-assessed for validity and reliability. A uniform orthopedic parlance is required to optimize the management of this debilitating and life-threatening condition.

Human Disc Nucleotomy Alters Annulus Fibrosus Mechanics at Both Reference and Compressed Loads

Nucleotomy is a common surgical procedure and is also performed in ex vivo mechanical testing to model decreased nucleus pulposus (NP) pressurization that occurs with degeneration. Here, we implement novel and noninvasive methods using magnetic resonance imaging (MRI) to study internal 3D annulus fibrosus (AF) deformations after partial nucleotomy and during axial compression by evaluating changes in internal AF deformation at reference loads (50 N) and physiological compressive loads (∼10% strain). One particular advantage of this methodology is that the full 3D disc deformation state, inclusive of both in-plane and out-of-plane deformations, can be quantified through the use of a high-resolution volumetric MR scan sequence and advanced image registration. Intact grade II L3-L4 cadaveric human discs before and after nucleotomy were subjected to identical mechanical testing and imaging protocols. Internal disc deformation fields were calculated by registering MR images captured in each loading state (reference and compressed) and each condition (intact and nucleotomy). Comparisons were drawn between the resulting three deformation states (intact at compressed load, nucleotomy at reference load, nucleotomy at compressed load) with regard to the magnitude of internal strain and direction of internal displacements. Under compressed load, internal AF axial strains averaged -18.5% when intact and -22.5% after nucleotomy. Deformation orientations were significantly altered by nucleotomy and load magnitude. For example, deformations of intact discs oriented in-plane, whereas deformations after nucleotomy oriented axially. For intact discs, in-plane components of displacements under compressive loads oriented radially outward and circumferentially. After nucleotomy, in-plane displacements were oriented radially inward under reference load and were not significantly different from the intact state at compressed loads. Re-establishment of outward displacements after nucleotomy indicates increased axial loading restores the characteristics of internal pressurization. Results may have implications for the recurrence of pain, design of novel therapeutics, or progression of disc degeneration.

MRI has limited agreement with CT in the evaluation of vertebral fractures of the canine trauma patient

Complete assessment of vertebral trauma in dogs currently requires CT and MRI for evaluation of the osseous and soft tissue structures that contribute to vertebral stability. Some studies in people have suggested that MRI may be sensitive and specific at detecting vertebral fractures making this potentially a single modality that could be used in spinal trauma evaluation. This study aimed to assess the ability for observers to evaluate vertebral fractures using MRI when compared to CT, which was used as the reference standard. Twenty-nine dogs with previously diagnosed acute vertebral fractures and four dogs with no vertebral fracture that had undergone sequential CT and MRI were included into the study. One hundred twenty-eight vertebrae were evaluated for the presence of fractures. Imaging studies were read by two observers blinded to the history. While both observers had similarly high sensitivity and specificity for simple detection of any fractured vertebrae, interobserver agreement was only moderate (κ = 0.584). When evaluations were specifically limited to detection of structurally unstable fractured vertebrae both observers showed improved specificity and interobserver agreement became substantial (κ = 0.650). Complete agreement for exact fracture location between MRI and CT results was only achieved in 14.3-32.6% of fractured vertebra with up to 79% of fractures being missed in some vertebral structures. This suggests that although MRI may be able to detect the presence of fractured vertebrae, it is not able to replace CT for the complete evaluation of the traumatized spine and documentation of fracture morphology.

Effect of corporal suspension and pendulum exercises on neuromuscular properties and functionality in patients with medullar thoracic injury

BACKGROUND

Traumatic spinal cord injury (TSCI) is one of the most devastating injuries that has a physical impact on patients. The CHORDATA® method involves suspension and pendulous exercises and has been clinically used to treat patients with TSCI. Although empirically used to treat neurological patients, there is no scientific evidence of the efficacy of this method.

PURPOSE

To evaluate the chronic effects of CHORDATA® method on torque, muscle activation, muscle thickness, and functionality in patients with traumatic spinal cord injury.

METHODS

Twenty-six male patients with medullar thoracic injury were randomly categorised into two groups: intervention group (n = 14) and control group (n = 12). Rehabilitation program comprised of 16 sessions of body suspension and pendulum exercises (twice/week). The maximal voluntary isometric trunk flexion and extension torques, muscle activation and thickness (external and internal oblique, rectus and transversus abdominis, longissimus, and multifidus muscles), and functionality (adapted reach test) were evaluated before and after of rehabilitation program.

FINDINGS

A significant increase was observed in maximal voluntary isometric torque (flexion, 58%; extension, 76%), muscle activation of the rectus abdominis muscle, and muscle thickness of all intervention group muscles, without changes in the control group. Compared to the pre-intervention period, the intervention group also showed improvement in functionality at post-intervention, but no such differences were noted in the control group.

INTERPRETATION

The corporal suspension and pendulum exercises training improved rectus abdominis muscle activation, trunk muscles structure and strength, and reaching capacity in medullar thoracic injury patients.

The role of the facet capsular ligament in providing spinal stability

Low back pain (LBP) is the most common type of pain in America, and spinal instability is a primary cause. The facet capsular ligament (FCL) encloses the articulating joints of the spine and is of particular interest due to its high innervation - as instability ensues, high stretch values likely are a cause of this pain. Therefore, this work investigated the FCL's role in providing stability to the lumbar spine. A previously validated finite element model of the L4-L5 spinal motion segment was used to simulate pure moment bending in multiple planes. FCL failure was simulated and the following outcome measures were calculated: helical axes of motion, range of motion (ROM), bending stiffness, facet joint space, and FCL stretch. ROM increased, bending stiffness decreased, and altered helical axis patterns were observed with the removal of the FCL. Additionally, a large increase in FCL stretch was measured with diminished FCL mechanical competency, providing support that the FCL plays an important role in spinal stability.

Quantifying Range of Motion and Stress Patterns at the Transitional Lumbosacral Junction: Pilot Study Using a Computational Model for Load-Bearing at Accessory L5-S1 Articulation

Background

Symptomatic or asymptomatic transitional anomalies at the lumbosacral junction are common occurrences in the population. Lumbosacral (L5-S1) accessory articulations are the most common presentations of transitional anomalies at this region. Such anatomical alterations are believed to be associated with biomechanical changes of load-bearing and movement restrictions leading to low back pain. This study attempts to use computational models of a normal and a lumbosacral transitional vertebrae (LSTV) accessory articulation to analyze and compare the range of motion and loading patterns at the lumbosacral articulations.

Methods

Three-dimensional Finite Element computational models of normal and accessory L5-S1 articulated sacrum were created. These models were tested for range of motion and stress patterns generated at the lumbosacral articulations using similar loading and motion simulation to elicit different moments/excursions at the lumbosacral junctions.

Results

Compared to the normal variant, the transitional model exhibited different range of motion and divergent patterns of stress generation at the lumbosacral and accessory articulations with equal and physiological magnitudes of loading applied to both the models.

Conclusions

The finite element modeling approach can be used for biomechanical investigations in LSTV variants. However, larger sample studies with different LSTV models may be required to statistically compare movement and loading patterns at LSTV-affected lumbosacral and sacroiliac junctions, and to recommend definitive treatment strategies in these situations.

Injuries to the Rigid Spine: What the Spine Surgeon Wants to Know

The biomechanical stability of the spine is altered in patients with a rigid spine, rendering it vulnerable to fracture even from relatively minor impact. The rigid spine entities are ankylosing spondylitis (AS), diffuse idiopathic skeletal hyperostosis, degenerative spondylosis, and a surgically fused spine. The most common mechanism of injury resulting in fracture is hyperextension, which often leads to unstable injury in patients with a rigid spine per the recent AOSpine classification system. Due to the increased risk of spinal fractures in this population, performing a spine CT is the first step when a patient with a rigid spine presents with new back pain or suspected spinal trauma. In addition, there should be a low threshold for performing a non-contrast-enhanced spine MRI in patients with a rigid spine, especially those with AS who may have an occult fracture, epidural hematoma, or spinal cord injury. Unfortunately, owing to insufficient imaging and an unfamiliarity with fracture patterns in the setting of a rigid spine, fracture diagnosis is often delayed, leading to significant morbidity and even death. The radiologist's role is to recognize the imaging features of a rigid spine, identify any fractures at CT and MRI, and fully characterize the extent of injury. Reasons for surgical intervention include neurologic deficit or concern for deterioration, an unstable fracture, or the presence of an epidural hematoma. By understanding the imaging features of various rigid spine conditions and vigilantly examining images for occult fractures, the radiologist can avoid a missed or delayed diagnosis of an injured rigid spine. ^©RSNA, 2019.

Dynamic MRI in the evaluation of the spine: state of the art

INTRODUCTION

Degenerative disease of the spine is a generic term encompassing a wide range of different disease processes, which leads to spinal instability; traumatic/neoplastic events can accelerate this aging process. Therefore, the dynamic nature of the spine and its mobility across multiple segments is difficult to depict with any single imaging modality.

METHODS

A review of PubMed databases for articles published about kMRI in patients with cervical and lumbar spinal desease was performed. We focused on the physiopathological changes in the transition from supine to upright position in spine instability.

DISCUSSION

Until a few years ago, X-ray was the only imaging modality for the spine in the upright position. Of the imaging techniques currently available, MRI provides the greatest range of information and the most accurate delineation of soft-tissue and osseous structures. Conventional MRI examinations of the spine usually are performed in supine position, in functional rest, but the lumbar spine instability is often shown only by upright standing. This can result in negative findings, even in the presence of symptoms. Regardless, the final result is distorted. To overcome this limitation, Kinetic MRI (kMRI) can image patients in a weight-bearing position and in flexed and extended positions, thus revealing abnormalities that are missed by traditional MRI studies.

CONCLUSION

Despite some limitations, the upright MRI can be a complementary investigation to the traditional methods when there are negative results in conventional MRI in symptomatic patients or when surgical therapy is scheduled.

Scapular fractures: a common diagnostic pitfall

Scapular fractures are one of the most difficult fractures to diagnose on radiographs. Detection can be challenging because of the obscuration by the overlying structures or incomplete imaging due to difficult patient collaboration. Familiarity with imaging characteristics of these abnormalities will allow radiologists to better diagnose and characterize scapular fractures. Three-dimensional computed tomographic scans are considered the gold standard for scapular diagnoses. Treatment strategies differ depending on the type of scapular fractures, but the site and degree of displacement will determine whether surgical intervention should be considered. Complications can occur in fractures that are undiagnosed or improperly evaluated. The purpose of this article is to describe imaging features of traumatic scapular injury, and discuss the role of diagnostic imaging in clinical decision making after shoulder trauma. (www.actabiomedica.it)

Instability in Thoracolumbar Trauma: Is a New Definition Warranted?

STUDY DESIGN

Review of the articles.

OBJECTIVE

The objective of this study was to review all articles related to spinal instability to determine a consensus statement for a contemporary, practical definition applicable to thoracolumbar injuries.

SUMMARY OF BACKGROUND DATA

Traumatic fractures of the thoracolumbar spine are common. These injuries can result in neurological deficits, disability, deformity, pain, and represent a great economic burden to society. The determination of spinal instability is an important task for spine surgeons, as treatment strategies rely heavily on this assessment. However, a clinically applicable definition of spinal stability remains elusive.

MATERIALS AND METHODS

A review of the Medline database between 1930 and 2014 was performed limited to papers in English. Spinal instability, thoracolumbar, and spinal stability were used as search terms. Case reports were excluded. We reviewed listed references from pertinent search results and located relevant manuscripts from these lists as well.

RESULTS

The search produced a total of 694 published articles. Twenty-five articles were eligible after abstract screening and underwent full review. A definition for spinal instability was described in only 4 of them. Definitions were primarily based on biomechanical and classification studies. No definitive parameters were outlined to define stability.

CONCLUSIONS

Thirty-six years after White and Panjabi's original definition of instability, and many classification schemes later, there remains no practical and meaningful definition for spinal instability in thoracolumbar trauma. Surgeon expertise and experience remains an important factor in stability determination. We propose that, at an initial assessment, a distinction should be made between immediate and delayed instability. This designation should better guide surgeons in decision making and patient counseling.

Biomechanical effect of interspinous process distraction height after lumbar fixation surgery: An in vitro model

Pedicle screw fixation may induce abnormal activity at adjacent segment and accelerate the degeneration of lumbar vertebrae. Dynamic stabilizers could provide an intermediate solution between conservative treatment and fusion surgery. Lumbar vertebral segment cephalad to instrumented fixation was the most common localization of adjacent segment degeneration. The aim of this study is to explore the use of interspinous process devices in the lumbar vertebral segment cephalad to fixation segment in changing the mechanical distribution and limiting abnormal activity of the spine. Eight specimens were tested in the following groups: intact group, instability group (bilateral facetectomy at L3-L4), fixation group (bilateral facetectomy and pedicle screw fixation at L3-L4), and hybrid fixation group (fixation at L3-L4 and simulating interspinous device implantation of 6, 8, 10, 12, 14, 16, and 18 mm at L2-L3). Range of motion, motion of vertebral body, and strain distribution change were recorded. The range of motion in extension with 16- and 18-mm hybrid constructs was significantly lower than intact, instability, and fixation groups. In flexion and lateral bending, the strain values of L4 inferior articular process with 18-mm hybrid construct have a significant difference compared with other groups. In axial rotation, under the condition of a contralateral state, the strain values of L2 superior articular process with 18-mm hybrid construct have a significant difference compared with intact and fixation groups. The strain value of the L4 inferior articular process had negative correlation with height distraction in three dimensions, except extension. A negative correlation between the strain value of the L2 superior articular process and distraction height was found in contralateral bending and contralateral axial rotation. Interspinous process devices above the fixation segment can change the mechanical distribution of the spine and limit activity in some of the segments of the spine, which may delay the degeneration of the adjacent segment.

Cervical traction therapy with and without neck support: A finite element analysis

BACKGROUND

Cervical traction is commonly used for treating neck pain. However, few studies have investigated the biomechanical impact such traction has on soft tissues.

OBJECTIVES

To analyze the biomechanics of cervical traction therapy in a supine position with and without neck support (NS and non-NS).

METHODS

A finite element model of the cervical spine was constructed to investigate the mechanism behind cervical traction therapy. An axial traction force of 100-N was loaded on the upper surface of C0 to simulate traction weight. Neck support traction was simulated by additionally constraining anterior-posterior motion of the surface of the C4 vertebral lamina. The average von Mises stress, tensile force and motions of related tissues were calculated and compared between the two conditions. Stress in the posterior annulus fibers under flexion was also recorded for comparison.

RESULTS

At the C4-C5 and C5-C6 levels, NS traction resulted in less of a decrease in the lordotic angle. At these levels, the highest average stress was distributed in the posterior annulus fibers with non-NS traction and both traction therapies produced greater stress on the posterior annulus fibers than physical flexion. The intradiscal pressure in all intervertebral discs between C4-T1 decreased during both traction therapies.

CONCLUSION

Neck support traction therapy produced less tension on the posterior annulus fibers and ligaments posterior to it at the C4-C5 and C5-C6 levels. In order to minimize the potential harm to soft tissue in clinical practice, it may be beneficial to use a neck support according to the targeted level.

Computer simulation of lumbar flexion shows shear of the facet capsular ligament

BACKGROUND CONTEXT

The lumbar facet capsular ligament (FCL) is a posterior spinal ligament with a complex structure and kinematic profile. The FCL has a curved geometry, multiple attachment sites, and preferentially aligned collagen fiber bundles on the posterior surface that are innervated with mechanoreceptive nerve endings. Spinal flexion induces three-dimensional (3D) deformations, requiring the FCL to maintain significant tensile and shear loads. Previous works aimed to study 3D facet joint kinematics during flexion, but to our knowledge none have reported localized FCL surface deformations likely created by this complex structure.

PURPOSE

The purpose of this study was to elucidate local deformations of both the posterior and anterior surfaces of the lumbar FCL to understand the distribution and magnitude of in-plane and through-plane deformations, including the prevalence of shear.

STUDY DESIGN/SETTING

The FCL anterior and posterior surface deformations were quantified through creation of a finite element model simulating facet joint flexion using a realistic geometry, physiological kinematics, and fitted constitutive material.

METHODS

Geometry was obtained from the micro-CT data of a healthy L3-L4 facet joint capsule (n=1); kinematics were extracted from sagittal plane fluoroscopic data of healthy volunteers (n=10) performing flexion; and average material properties were determined from planar biaxial extension tests of L4-L5 FCLs (n=6). All analyses were performed with the non-linear finite element solver, FEBio. A grid of equally spaced 3×3 nodes on the posterior surface identified regional differences within the strain fields and was used to create comparisons against previously published experimental data. This study was funded by the National Institutes of Health and the authors have no disclosures.

RESULTS

Inhomogeneous in-plane and through-plane shear deformations were prominent through the middle body of the FCL on both surfaces. Anterior surface deformations were more pronounced because of the small width of the joint space, whereas posterior surface deformations were more diffuse because the larger area increased deformability. We speculate these areas of large deformation may provide this proprioceptive system with an excellent measure of spinal motion.

CONCLUSIONS

We found that in-plane and through-plane shear deformations are widely present in finite element simulations of a lumbar FCL during flexion. Importantly, we conclude that future studies of the FCL must consider the effects of both shear and tensile deformations.

Incorporating Six Degree-of-Freedom Intervertebral Joint Stiffness in a Lumbar Spine Musculoskeletal Model-Method and Performance in Flexed Postures

Intervertebral translations and rotations are likely dependent on intervertebral stiffness properties. The objective of this study was to incorporate realistic intervertebral stiffnesses in a musculoskeletal model of the lumbar spine using a novel force-dependent kinematics approach, and examine the effects on vertebral compressive loading and intervertebral motions. Predicted vertebral loading and intervertebral motions were compared to previously reported in vivo measurements. Intervertebral joint reaction forces and motions were strongly affected by flexion stiffness, as well as force-motion coupling of the intervertebral stiffness. Better understanding of intervertebral stiffness and force-motion coupling could improve musculoskeletal modeling, implant design, and surgical planning.

Spine Instability Neoplastic Score: agreement across different medical and surgical specialties

BACKGROUND CONTEXT

Spinal instability is an acknowledged complication of spinal metastases; in spite of recent suggested criteria, it is not clearly defined in the literature.

PURPOSE

This study aimed to assess intra and interobserver agreement when using the Spine Instability Neoplastic Score (SINS) by all physicians involved in its management.

STUDY DESIGN

Independent multicenter reliability study for the recently created SINS, undertaken with a panel of medical oncologists, neurosurgeons, radiologists, orthopedic surgeons, and radiation oncologists, was carried out.

PATIENT SAMPLE

Ninety patients with biopsy-proven spinal metastases and magnetic resonance imaging, reviewed at the multidisciplinary tumor board of our institution, were included.

OUTCOME MEASURES

Intraclass correlation coefficient (ICC) was used for SINS score agreement. Fleiss kappa statistic was used to assess agreement on the location of the most affected vertebral level; agreement on the SINS category ("stable," "potentially stable," or "unstable"); and overall agreement with the classification established by tumor board.

METHODS

Clinical data and imaging were provided to 83 specialists in 44 hospitals across 14 Spanish regions. No assessment criteria were pre-established. Each clinician assessed the SINS score twice, with a minimum 6-week interval. Clinicians were blinded to assessments made by other specialists and to their own previous assessment. Subgroup analyses were performed by clinicians' specialty, experience (≤7, 8-13, ≥14 years), and hospital category (four levels according to size and complexity). This study was supported by Kovacs Foundation.

RESULTS

Intra and interobserver agreement on the location of the most affected levels was "almost perfect" (κ>0.94). Intra-observer agreement on the SINS score was "excellent" (ICC=0.77), whereas interobserver agreement was "moderate" (ICC=0.55). Intra-observer agreement in SINS category was "substantial" (k=0.61), whereas interobserver agreement was "moderate" (k=0.42). Overall agreement with the tumor board classification was "substantial" (κ=0.61). Results were similar across specialties, years of experience, and hospital category.

CONCLUSIONS

Agreement on the assessment of metastatic spine instability is moderate. The SINS can help improve communication among clinicians in oncology care.

Viscoelastic Response of the Human Lower Back to Passive Flexion: The Effects of Age

Low back pain is a leading cause of disability in the elderly. The potential role of spinal instability in increasing risk of low back pain with aging was indirectly investigated via assessment of age-related differences in viscoelastic response of lower back to passive deformation. The passive deformation tests were conducted in upright standing posture to account for the effects of gravity load and corresponding internal tissues responses on the lower back viscoelastic response. Average bending stiffness, viscoelastic relaxation, and dissipated energy were quantified to characterize viscoelastic response of the lower back. Larger average bending stiffness, viscoelastic relaxation and dissipated energy were observed among older vs. younger participants. Furthermore, average bending stiffness of the lower back was found to be the highest around the neutral standing posture and to decrease with increasing the lower back flexion angle. Larger bending stiffness of the lower back at flexion angles where passive contribution of lower back tissues to its bending stiffness was minimal (i.e., around neutral standing posture) highlighted the important role of active vs. passive contribution of tissues to lower back bending stiffness and spinal stability. As a whole our results suggested that a diminishing contribution of passive and volitional active subsystems to spinal stability may not be a reason for higher severity of low back pain in older population. The role of other contributing elements to spinal stability (e.g., active reflexive) as well as equilibrium-based parameters (e.g., compression and shear forces under various activities) in increasing severity of low back pain with aging should be investigated in future.

Degenerative disease of the lumbar spine

In the last 25 years, scientific research has brought about drastic changes in the concept of low back pain and its management. Most imaging findings, including degenerative changes, reflect anatomic peculiarities or the normal aging process and turn out to be clinically irrelevant; imaging tests have proven useful only when systemic disease is suspected or when surgery is indicated for persistent spinal cord or nerve root compression. The radiologic report should indicate the key points of nerve compression, bypassing inconsequential findings. Many treatments have proven inefficacious, and some have proven counterproductive, but they continue to be prescribed because patients want them and there are financial incentives for doing them. Following the guidelines that have proven effective for clinical management improves clinical outcomes, reduces iatrogenic complications, and decreases unjustified and wasteful healthcare expenditures.

Supine spinal magnetic resonance imaging with straightened lower extremities in spondylolisthesis: a comparison with the conventional technique

OBJECTIVES

To compare the degree of slip in spondylolisthesis on supine magnetic resonance (MR) images obtained with flexed and straightened lower extremities.

METHODS

Supine spinal MR studies were performed in 100 cases of symptomatic spondylolisthesis with flexed and then straightened lower extremities. The angle of lumbar lordosis (by Cobb's method) and the degree of slip (by Taillard's method) were compared between the two sets of images.

RESULTS

The mean angle of lumbar lordosis increased from 51.65±8.57° on MR images with flexed lower limbs to 57.39±9.05° on MR images with straightened lower limbs (p<0.001; mean percent increase: 11.51%). Similar change was also observed for the mean degree of slip (from 25.80±7.74% to 28.68±7.93%, p<0.001; mean percent increase: 12.60%). After MR imaging with straightened lower extremities 22 out of 54 initially grade I cases had grade II disease (p<0.001).

CONCLUSIONS

Supine magnetic resonance imaging with straightened lower extremities detects higher degree of slippage in symptomatic patients with spondylolisthesis compared to conventional MRI with flexed lower extremities.

Fractures of the thoracic spine in patients with minor trauma: comparison of diagnostic accuracy and dose of biplane radiography and MDCT

OBJECTIVES

To investigate the accuracy of biplane radiography in the detection of fractures of the thoracic spine in patients with minor trauma using multidetector computed tomography (MDCT) as the reference and to compare the dose of both techniques.

METHODS

107 consecutive trauma patients with suspected fractures of the thoracic spine on physical examination were included. All had undergone biplane radiography first, followed by a MDCT scan between October 2008 and October 2012. A fourfold table was used for the classification of the screening test results. Both the Chi-square test (χ(2)) and the mean dose-length product (DLP) were used to compare the diagnostic methods.

RESULTS

MDCT revealed 77 fractures in 65/107 patients (60.7%). Biplane radiography was true positive in 32/107 patients (29.9%), false positive in 19/107 patients (17.8%), true negative in 23/107 (21.5%) and false negative in 33/107 patients (30.8%), showing a sensitivity of 49.2%, a specificity of 54.7%, a positive predictive value (PPV) of 62.7%, a negative predictive value (NPV) of 41.1%, and an accuracy of 51.4%. The presence of a fracture on biplane radiography was highly statistical significant, if this was simultaneously proven by MDCT (χ(2)=7.6; p=0.01). None of the fractures missed on biplane radiography was unstable. The mean DLP on biplane radiography was 14.5mGycm (range 1.9-97.8) and on MDCT 374.6mGycm (range 80.2-871).

CONCLUSIONS

The sensitivity and the specificity of biplane radiography in the diagnosis of fractures of the thoracic spine in patients with minor trauma are low. Considering the wide availability of MDCT that is usually necessary for taking significant therapeutic steps, the indication for biplane radiography should be very restrictive.