Relationships between lumbar inter-vertebral motion and lordosis in healthy adult males: a cross sectional cohort study

Concurrent validity of skin-based motion capture systems in measuring dynamic lumbar intervertebral angles

Spine kinematics are commonly measured by external sensors such as motion capture and accelerometers. However, these skin-based measures cannot directly capture intervertebral motion of the lumbar spine. To date, research in this area has focused on the estimation of intervertebral kinematics using static trials but no study has analyzed agreement throughout the dynamic range of motion. This study investigated the agreement between skin-based sensors (accelerometers and motion capture) and quantitative fluoroscopy (QF) in measuring lumbar spine kinematics for the duration of complete flexion and extension motion in a healthy female population. Twenty female participants (age 30-57, BMI < 30) were guided through a standing flexion and extension bending protocol while spine kinematics were concurrently measured by QF (L2, L3, L4, L5, and S1) and motion capture sensors and accelerometers positioned over the spinous processes of L2, L4, and S1. Intervertebral angles (L2-L4, L4-S1, L2-S1) and individual vertebrae levels were compared between measures. Non-parametric limits of agreement between QF and skin-based markers were greatest at the end-range of motion for both flexion and extension, but differences increased variably between participants, sometimes over-and sometimes underestimating angles, thus, disproving the common assumption that it increases linearly. The two skin-based marker systems showed good agreement with one another showing that they can be used interchangeably but they can only be used to estimate lumbar spine kinematics. Normalizing angles to a change in angle and considering the posture of instrumentation would be beneficial to reduce potential sources of errors.

Reliability of the Biomechanical Assessment of the Sagittal Lumbar Spine and Pelvis on Radiographs Used in Clinical Practice: A Systematic Review of the Literature

Background: Biomechanical analysis of the sagittal alignment of the lumbar spine and pelvis on radiographs is common in clinical practices including chiropractic, physical therapy, scoliosis-related thoraco-lumbo-sacral orthosis (TLSO) management, orthopedics, and neurosurgery. Of specific interest is the assessment of pelvic morphology and the relationship between angle of pelvic incidence, sacral slope, and lumbar lordosis to pain, disability, and clinical treatment of spine conditions. The current state of the literature on the reliability of common methods quantifying these parameters on radiographs is limited. Methods: The objective of this systematic review is to identify and review the available studies on the reliability of different methods of biomechanical analysis of sagittal lumbo-pelvic parameters used in clinical practice. Our review followed the recommendations of the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The design of this systematic review was registered with PROSPERO (CRD42023379873). Results: The search strategy yielded a total of 2387 articles. A total of 1539 articles were screened after deduplication and exclusion by automation tools, leaving 473 full-text articles that were retrieved. After exclusion, 64 articles met the inclusion criteria. The preponderance of the evidence showed good to excellent reliability for biomechanical assessment of sagittal lumbo-pelvic spine alignment. Conclusions: The results of this systematic review of the literature show that sagittal radiographic analysis of spinal biomechanics and alignment of the human lumbo-pelvic spine is a reliable tool for aiding diagnosis and management in clinical settings.

Passive intervertebral restraint is different in patients with treatment-resistant chronic nonspecific low back pain: a retrospective cohort study and control comparison

PURPOSE

In vivo studies of continuous lumbar sagittal plane motion have found passive intervertebral motion to be more uneven in patients with chronic nonspecific low back pain (CNSLBP) than healthy controls, but the mechanisms are unclear. This study aimed to compare patients with CNSLBP with a matched group of pain-free controls for intervertebral restraint during passive recumbent bending.

METHODS

Seventeen patients with CNSLBP and minimal disc degeneration who had quantitative fluoroscopy investigations were matched to 17 healthy controls from a database acquired using the same imaging protocol. The entire database (n = 136) was examined for clustering of peaking times, magnitudes and ROM of the first derivatives of the intervertebral angle/motion curves (PTFD, PMFD and ROM) during flexion and return that might introduce confounding. The groups were then compared for differences in these variables.

RESULTS

There were significant segmental ROM differences among clusters in the database when PMFD and ROM were used as clustering variables, indicating heterogeneity. However, in the patient-control study, it was PTFD (velocity) that differentiated the groups. At L5-S1, this was at 10.82% of the motion path compared with 25.06% in the controls (p = 0.0002). For L4-5, PTFD was at 23.42% of the motion path in patients and 16.33% in controls (p = 0.0694) suggesting a reduced initial bending moment there. There were no significant differences for PMFD or ROM.

CONCLUSION

Peaking time of passive intervertebral velocity occurs early at L5-S1 in patients with CNSLBP; however, these findings should be treated with caution pending their replication. Future studies should explore relationships with altered disc pressures and biochemistry. Usefulness for monitoring regenerative disc therapies should be considered.

Spatio-temporal clustering of lumbar intervertebral flexion interactions in 127 asymptomatic individuals

The purpose of this study was to categorize asymptomatic participants based on the clustering of spatial and temporal intervertebral kinematic variables during lumbar flexion. Lumbar segmental interactions (L2-S1) were evaluated in 127 asymptomatic participants during flexion using fluoroscopy. First, four variables were identified consisting of: 1. Range of motion (ROMC), 2. Peaking time of the first derivative for separate segmentation (PTFDs), 3. Peaking magnitude of the first derivative (PMFD), and 4. Peaking time of the first derivative for stepwise (grouped) segmentation (PTFDss). These variables were used to cluster and order the lumbar levels. The number of participants required to constitute a cluster was chosen as 7. Participants formed eight (ROMC), four (PTFDs), eight (PMFD), and four (PTFDss) clusters, which included 85%, 80%, 77%, and 60% of them, respectively, according to the above features. For all clustering variables, angle time series of some lumbar levels showed significant differences between clusters. However, in general, all clusters could be categorized based on the segmental mobility contexts into three main groups as incidental macro clusters: the upper (L2-L4 > L4-S1), middle (L2-L3 < L3-L5 > L5-S1) and lower (L2-L4 < L4-S1) domains. There are spatial and temporal segmental interactions and between-subject variability in asymptomatic participants. In addition, the differences in angle time series among the clusters have provided evidence of feedback control strategies, while the stepwise segmentation facilitates consideration of the lumbar spine as a system and provides supplementary information about segmental interactions. Clinically, these facts could be taken into account when considering any intervention, but especially fusion surgery.

Effects of a microgravity SkinSuit on lumbar geometry and kinematics

PURPOSE

Astronauts returning from long ISS missions have demonstrated an increased incidence of lumbar disc herniation accompanied by biomechanical and morphological changes associated with spine elongation. This research describes a ground-based study of the effects of an axial compression countermeasure Mk VI SkinSuit designed to reload the spine and reduce these changes before return to terrestrial gravity.

METHODS

Twenty healthy male volunteers aged 21-36 without back pain participated. Each lay overnight on a Hyper Buoyancy Flotation (HBF) bed for 12 h on two occasions 6 weeks apart. On the second occasion participants donned a Mk VI SkinSuit designed to axially load the spine at 0.2 Gz during the last 4 h of flotation. Immediately after each exposure, participants received recumbent MRI and flexion-extension quantitative fluoroscopy scans of their lumbar spines, measuring differences between spine geometry and intervertebral kinematics with and without the SkinSuit. This was followed by the same procedure whilst weight bearing. Paired comparisons were performed for all measurements.

RESULTS

Following Mk VI SkinSuit use, participants evidenced more flexion RoM at L3-4 (p = 0.01) and L4-5 (p = 0.003), more translation at L3-4 (p = 0.02), lower dynamic disc height at L5-S1 (p = 0.002), lower lumbar spine length (p = 0.01) and greater lordosis (p = 0.0001) than without the Mk VI SkinSuit. Disc cross-sectional area and volume were not significantly affected.

CONCLUSION

The MkVI SkinSuit restores lumbar mobility and lordosis following 4 h of wearing during hyper buoyancy flotation in a healthy control population and may be an effective countermeasure for post space flight lumbar disc herniation.

The reliability of video fluoroscopy, ultrasound imaging, magnetic resonance imaging and radiography for measurements of lumbar spine segmental range of motion in-vivo: A review

BACKGROUND

Lower back pain (LBP) is a principal cause of disability worldwide and is associated with a variety of spinal conditions. Individuals presenting with LBP may display changes in spinal motion. Despite this, the ability to measure lumbar segmental range of motion (ROM) non-invasively remains a challenge.

OBJECTIVE

To review the reliability of four non-invasive modalities: Video Fluoroscopy (VF), Ultrasound imaging (US), Magnetic Resonance Imaging (MRI) and Radiography used for measuring segmental ROM in the lumbar spine in-vivo.

METHODS

The methodological quality of seventeen eligible studies, identified through a systematic literature search, were appraised.

RESULTS

The intra-rater reliability for VF is excellent in recumbent and upright positions but errors are larger for intra-rater repeated movements and inter-rater reliability shows larger variation. Excellent results for intra- and inter-rater reliability are seen in US studies and there is good reliability within- and between-day. There is a large degree of heterogeneity in MRI and radiography methodologies but reliable results are seen.

CONCLUSIONS

Excellent reliability is seen across all modalities. However, VF and radiography are limited by radiation exposure and MRI is expensive. US offers a non-invasive, risk free method but further research must determine whether it yields truly consistent measurements.

A Reference Database of Standardised Continuous Lumbar Intervertebral Motion Analysis for Conducting Patient-Specific Comparisons

Lumbar instability has long been thought of as the failure of lumbar vertebrae to maintain their normal patterns of displacement. However, it is unknown what these patterns consist of. Research using quantitative fluoroscopy (QF) has shown that continuous lumbar intervertebral patterns of rotational displacement can be reliably measured during standing flexion and return motion using standardised protocols and can be used to assess patients with suspected lumbar spine motion disorders. However, normative values are needed to make individualised comparisons. One hundred and thirty-one healthy asymptomatic participants were recruited and performed guided flexion and return motion by following the rotating arm of an upright motion frame. Fluoroscopic image acquisition at 15fps was performed and individual intervertebral levels from L2-3 to L5-S1 were tracked and analysed during separate outward flexion and return phases. Results were presented as proportional intervertebral motion representing these phases using continuous means and 95%CIs, followed by verification of the differences between levels using Statistical Parametric Mapping (SPM). A secondary analysis of 8 control participants matched to 8 patients with chronic, non-specific low back pain (CNSLBP) was performed for comparison. One hundred and twenty-seven asymptomatic participants’ data were analysed. Their ages ranged from 18 to 70 years (mean 38.6) with mean body mass index 23.8 kg/m² 48.8% were female. Both the flexion and return phases for each level evidenced continuous change in mean proportional motion share, with narrow confidence intervals, highly significant differences and discrete motion paths between levels as confirmed by SPM. Patients in the secondary analysis evidenced significantly less L5-S1 motion than controls (p < 0.05). A reference database of spinal displacement patterns during lumbar (L2-S1) intersegmental flexion and return motion using a standardised motion protocol using fluoroscopy is presented. Spinal displacement patterns in asymptomatic individuals were found to be distinctive and consistent for each intervertebral level, and to continuously change during bending and return. This database may be used to allow continuous intervertebral kinematics to drive dynamic models of joint and muscular forces as well as reference values against which to make patient-specific comparisons in suspected cases of lumbar spine motion disorders.

Novel assessment of the variation in cervical inter-vertebral motor control in a healthy pain-free population

Spinal control at intervertebral levels is dependent on interactions between the active, passive and neural control elements. However, this has never been quantifiable, and has therefore been outside the reach of clinical assessments and research. This study used fluoroscopy during repeated unconstrained flexion and return neck movements to calculate intersegmental motor control (MC), defined as the difference and variation in repeated continuous angular motion from its average path. The study aimed to determine control values for MC at individual levels and its variability. Twenty male volunteers aged 19–29 received fluoroscopic screening of their cervical spines during 4 repetitions of neutral to full flexion and return motion. Moving vertebral images from C0–C1 to C6–C7 were tracked using cross-correlation codes written in Matlab. MC for each level was defined as the mean of the absolute differences between each repetition’s angular path and their mean and its variability as represented by the SD. 1-way ANOVA and Tukey multiple comparisons were used to identify significant contrasts between levels. The mean MC differences and SDs were highest at C1-2, suggesting that this level has the least control and the most variability. Results at this level alone were highly significant (F-ratio 10.88 and 9.79 P < 0.0001). Significant contrasts were only found between C1-C2 and all other levels. The mean MC difference for summed C1-6 levels was 3.4° (0.7–6.1). This study is the first to quantify intervertebral MC in the cervical spine in asymptomatic people. Studies of neck pain patients are now merited.

Lumbar Intervertebral Kinematics During an Unstable Sitting Task and Its Association With Standing-Induced Low Back Pain

People developing transient low back pain during standing have altered control of their spine and hips during standing tasks, but the transfer of these responses to other tasks has not been assessed. This study used video fluoroscopy to assess lumbar spine intervertebral kinematics of people who do and do not develop standing-induced low back pain during a seated chair-tilting task. A total of 9 females and 8 males were categorized as pain developers (5 females and 3 males) or nonpain developers (4 females and 5 males) using a 2-hour standing exposure; pain developers reported transient low back pain and nonpain developers did not. Participants were imaged with sagittal plane fluoroscopy at 25 Hz while cyclically tilting their pelvises anteriorly and posteriorly on an unstable chair. Intervertebral angles, relative contributions, and anterior-posterior translations were measured for the L3/L4, L4/L5, and L5/S1 joints and compared between sexes, pain groups, joints, and tilting directions. Female pain developers experienced more extension in their L5/S1 joints in both tilting directions compared with female nonpain developers, a finding not present in males. The specificity in intervertebral kinematics to sex-pain group combinations suggests that these subgroups of pain developers and nonpain developers may implement different control strategies.

Investigator analytic repeatability of two new intervertebral motion biomarkers for chronic, nonspecific low back pain in a cohort of healthy controls

Background

Understanding the mechanisms underlying chronic, nonspecific low back pain (CNSLBP) is essential to advance personalized care and identify the most appropriate intervention. Recently, two intervertebral motion biomarkers termed “Motion Sharing Inequality” (MSI) and “Motion Sharing Variability” (MSV) have been identified for CNSLBP using quantitative fluoroscopy (QF). The aim of this study was to conduct intra- and inter-investigator analytic repeatability studies to determine the extent to which investigator error affects their measurement in clinical studies.

Methods

A cross-sectional cohort study was conducted using the image sequences of 30 healthy controls who received QF screening during passive recumbent flexion motion. Two independent investigators analysed the image sequences for MSI and MSV from October to November 2018. Intra and inter- investigator repeatability studies were performed using intraclass correlations (ICC), standard errors of measurement (SEM) and minimal differences (MD).

Results

Intra-investigator ICCs were 0.90 (0.81,0.95) (SEM 0.029) and 0.78 (0.59,0.89) (SEM 0.020) for MSI and MSV, respectively. Inter-investigator ICCs 0.93 (0.86,0.97) (SEM 0.024) and 0.55 (0.24,0.75) (SEM 0.024). SEMs for MSI and MSV were approximately 10 and 30% of their group means respectively. The MDs for MSI for intra- and inter-investigator repeatability were 0.079 and 0.067, respectively and for MSV 0.055 and 0.067.

Conclusions

MSI demonstrated substantial intra- and inter-investigator repeatability, suggesting that investigator input has a minimal influence on its measurement. MSV demonstrated moderate intra-investigator reliability and fair inter-investigator repeatability. Confirmation in patients with CNSLBP is now required.

An in vivo study exploring correlations between early-to-moderate disc degeneration and flexion mobility in the lumbar spine

PURPOSE

Early disc degeneration (DD) has been thought to be associated with loss of spine stability. However, before this can be understood in relation to back pain, it is necessary to know the relationship between DD and intervertebral motion in people without pain. This study aimed to find out if early-to-moderate DD is associated with intervertebral motion in people without back pain.

METHODS

Ten pain-free adults, aged 51-71, received recumbent and weight bearing MRI scans and quantitative fluoroscopy (QF) screenings during recumbent and upright lumbar flexion. Forty individual level and 10 composite (L2-S1) radiographic and MRI DD gradings were recorded and correlated with intervertebral flexion ROM, translation, laxity and motion sharing inequality and variability for both positions.

RESULTS

Kinematic values were similar to previous control studies. DD was evidenced up to moderate levels by both radiographic and MRI grading. Disc height loss correlated slightly, but negatively with flexion during weight bearing flexion (R =  - 0.356, p = 0.0.025). Composite MRI DD and T2 signal loss evidenced similar relationships (R =  - 0.305, R =  - 0.267) but did not reach statistical significance (p = 0.056, p = 0.096). No significant relationships between any other kinematic variables and DD were found.

CONCLUSION

This study found only small, indefinite associations between early-to-moderate DD and intervertebral motion in healthy controls. Motion sharing in the absence of pain was also not related to early DD, consistent with previous control studies. Further research is needed to investigate these relationships in patients.

New insights into lumbar flexion tests based on inverse and direct kinematic musculoskeletal modeling

Measurement of maximal lumbar flexion is considered to be a crucial element in the assessment of lumbar spine mechanics in situations as diverse as physiotherapy, orthopaedics, ergonomics, sport or aging. However, currently, there is no consensus on a reference test. This study aims to characterise five maximal lumbar flexion tests (four classical tests and a new, specifically-developed test designed to constrain pelvic retroversion) based on a three-dimensional, participant-specific musculoskeletal model. Twenty-six male and female participants performed the five tests. Movements were modelled in OpenSim to estimate change in length in lumbar, hamstring and gluteus muscles, together with lumbar flexion and pelvic tilt. These so-called "inverse" kinematic results were compared using a two-way ANOVA (sex×test). In a second step, lumbar muscle change in length was computed using a direct kinematic method. Lumbar flexion and lumbar muscle change in length were found to be greater when participants were in seated postures, with little pelvic retroversion. Female participants were observed to have less lumbar flexion than male participants (77±14° and 91±12°, respectively). Hip extensor muscles (hamstrings and gluteus) were fully stretched during each of the five tests. Our results highlight the specific roles of hamstrings, gluteus and lumbar muscles into reaching maximal lumbar flexion. Coupling inverse and direct kinematic methods proved to be a useful tool to enhance our knowledge of lumbar tests. Our findings help to characterise the role of the muscles involved in lumbar flexion, and we propose some recommendations for improving and standardising these tests.

Can Biomechanics Research Lead to More Effective Treatment of Low Back Pain? A Point-Counterpoint Debate

SYNOPSIS

Although biomechanics plays a role in the development and perhaps the persistent or recurrent nature of low back pain (LBP), whether biomechanics alone can provide the basis for intervention is debated. Biomechanics, which refers to the mechanics of the body, including its neuromuscular control, has been studied extensively in LBP. But, can gains be made in understanding LBP by research focused on this component of biology in the multifactorial biopsychosocial problem of LBP? This commentary considers whether biomechanics research has the potential to advance treatment of LBP, and how likely it is that this research will lead to better treatment strategies. A point-counterpoint format is taken to present both sides of the argument. First, the challenges faced by an approach that considers biomechanics in isolation are presented. Next, we describe 3 models that place substantial emphasis on biomechanical factors. Finally, reactions to each point are presented as a foundation for further research and clinical practice to progress understanding of the place for biomechanics in guiding treatment of LBP. J Orthop Sports Phys Ther 2019;49(6):425-436. Epub 15 May 2019. doi:10.2519/jospt.2019.8825.

Intrasubject repeatability of in vivo intervertebral motion parameters using quantitative fluoroscopy

PURPOSE

In vivo quantification of intervertebral motion through imaging has progressed to a point where biomarkers for low back pain are emerging. This makes possible deeper study of the condition's biometrics. However, the measurement of change over time involves error. The purpose of this prospective investigation is to determine the intrasubject repeatability of six in vivo intervertebral motion parameters using quantitative fluoroscopy.

METHODS

Intrasubject reliability (ICC) and minimal detectable change (MDC) of baseline to 6-week follow-up measurements were calculated for six lumbar spine intervertebral motion parameters in 109 healthy volunteers. A standardised quantitative fluoroscopy (QF) protocol was used to provide measurements in the coronal and sagittal planes using both passive recumbent and active weight-bearing motion. Parameters were: intervertebral range of motion (IV-RoM), laxity, motion sharing inequality (MSI), motion sharing variability (MSV), flexion translation and anterior disc height change during flexion.

RESULTS

The best overall intrasubject reliability (ICC) and agreement (MDC) were for disc height (ICC 0.89, MDC 43%) and IV-RoM (ICC 0.96, MDC 60%), and the worst for MSV (ICC 0.04, MDC 408%). Laxity, MSI and translation had acceptable reliability (most ICCs > 0.60), but not agreement (MDC > 85%).

CONCLUSION

Disc height and IV-RoM measurement using QF could be considered for randomised trials, while laxity, MSI and translation could be considered for moderators, correlates or mediators of patient-reported outcomes. MSV had both poor reliability and agreement over 6 weeks. These slides can be retrieved under Electronic Supplementary Material.

Have Studies that Measure Lumbar Kinematics and Muscle Activity Concurrently during Sagittal Bending Improved Understanding of Spinal Stability and Sub-System Interactions? A Systematic Review

In order to improve understanding of the complex interactions between spinal sub-systems (i.e., the passive (ligaments, discs, fascia and bones), the active (muscles and tendons) and the neural control systems), it is necessary to take a dynamic approach that incorporates the measurement of multiple systems concurrently. There are currently no reviews of studies that have investigated dynamic sagittal bending movements using a combination of electromyography (EMG) and lumbar kinematic measurements. As such it is not clear how understanding of spinal stability concepts has advanced with regards to this functional movement of the spine. The primary aim of this review was therefore to evaluate how such studies have contributed to improved understanding of lumbar spinal stability mechanisms. PubMed and Cochrane databases were searched using combinations of the keywords related to spinal stability and sagittal bending tasks, using strict inclusion and exclusion criteria and adhering to PRISMA guidelines. Whilst examples of the interactions between the passive and active sub-systems were shown, typically small sample sizes meant that results were not generalizable. The majority of studies used regional kinematic measurements, and whilst this was appropriate in terms of individual study aims, the studies could not provide insight into sub-system interaction at the level of the spinal motion segment. In addition, the heterogeneity in methodologies made comparison between studies difficult. The review suggests that since Panjabi’s seminal spinal control papers, only limited advancement in the understanding of these theories has been provided by the studies under review, particularly at an inter-segmental level. This lack of progression indicates a requirement for new research approaches that incorporate multiple system measurements at a motion segment level.

Variation in lifting kinematics related to individual intrinsic lumbar curvature: an investigation in healthy adults

Objective

Lifting postures are frequently implicated in back pain. We previously related responses to a static load with intrinsic spine shape, and here we investigate the role of lumbar spine shape in lifting kinematics.

Methods

Thirty healthy adults (18-65 years) performed freestyle, stoop and squat lifts with a weighted box (6-15 kg, self-selected) while being recorded by Vicon motion capture. Internal spine shape was characterised using statistical shape modelling (SSM) from standing mid-sagittal MRIs. Associations were investigated between spine shapes quantified by SSM and peak flexion angles.

Results

Two SSM modes described variations in overall lumbar curvature (mode 1 (M1), 55% variance) and the evenness of curvature distribution (mode 2 (M2), 12% variance). M1 was associated with greater peak pelvis (r=0.38, p=0.04) and smaller knee flexion (r=-0.40, p=0.03) angles; individuals with greater curviness preferred to lift with a stooped lifting posture. This was confirmed by analysis of those individuals with very curvy or very straight spines (|M1|>1 SD). There were no associations between peak flexion angles and mode scores in stoop or squat trials (p>0.05). Peak flexion angles were positively correlated between freestyle and squat trials but not between freestyle and stoop or squat and stoop, indicating that individuals adjusted knee flexion while maintaining their preferred range of lumbar flexion and that 'squatters' adapted better to different techniques than 'stoopers'.

Conclusion

Spinal curvature affects preferred lifting styles, and individuals with curvier spines adapt more easily to different lifting techniques. Lifting tasks may need to be tailored to an individual's lumbar spine shape.

Aberrant intervertebral motion in patients with treatment-resistant nonspecific low back pain: a retrospective cohort study and control comparison

PURPOSE

Intervertebral kinematic assessments have been used to investigate mechanical causes when back pain is resistant to treatment, and recent studies have identified intervertebral motion markers that discriminate patients from controls. However, such patients are a heterogeneous group, some of whom have structural disruption, but the effects of this on intervertebral kinematics are unknown.

METHODS

Thirty-seven patients with treatment-resistant back pain referred for quantitative fluoroscopy were matched to an equal number of pain-free controls for age and sex. All received passive recumbent flexion assessments for intervertebral motion sharing inequality (MSI), variability (MSV), laxity and translation. Comparisons were made between patient subgroups, between patients and controls and against normative levels from a separate group of controls.

RESULTS

Eleven patients had had surgical or interventional procedures, and ten had spondylolisthesis or pars defects. Sixteen had no disruption. Patients had significantly higher median MSI values (0.30) than controls (0.27, p = 0.010), but not MSV (patients 0.08 vs controls 0.08, p = 0.791). Patients who received invasive procedures had higher median MSI values (0.37) than those with bony defects (0.30, p = 0.018) or no disruption (0.28, p = 0.0007). Laxity and translation above reference limits were not more prevalent in patients.

CONCLUSION

Patients with treatment-resistant nonspecific back pain have greater MSI values than controls, especially if the former have received spinal surgery. However, excessive laxity, translation and MSV are not more prevalent in these patients. Thus, MSI should be investigated as a pain mechanism and for its possible value as a prognostic factor and/or target for treatment in larger patient populations. These slides can be retrieved under Electronic Supplementary Material.

RSA in Spine: A Review

STUDY DESIGN

Systematic review of literature.

OBJECTIVES

This systematic review was conducted to investigate the accuracy of radiostereometric analysis (RSA), its assessment of spinal motion and disorders, and to investigate the limitations of this technique in spine assessment.

METHODS

Systematic review in all current literature to invesigate the role of RSA in spine.

RESULTS

The results of this review concluded that RSA is a very powerful tool to detect small changes between 2 rigid bodies such as a vertebral segment. The technique is described for animal and human studies for cervical and lumbar spine and can be used to analyze range of motion, inducible displacement, and fusion of segments. However, there are a few disadvantages with the technique; RSA percutaneous procedure needs to be performed to implant the markers (and cannot be used preoperatively), one needs a specific knowledge to handle data and interpret the results, and is relatively time consuming and expensive.

CONCLUSIONS

RSA should be looked at as a very powerful research instrument and there are many questions suitable for RSA studies.

Uneven intervertebral motion sharing is related to disc degeneration and is greater in patients with chronic, non-specific low back pain: an in vivo, cross-sectional cohort comparison of intervertebral dynamics using quantitative fluoroscopy

PURPOSE

Evidence of intervertebral mechanical markers in chronic, non-specific low back pain (CNSLBP) is lacking. This research used dynamic fluoroscopic studies to compare intervertebral angular motion sharing inequality and variability (MSI and MSV) during continuous lumbar motion in CNSLBP patients and controls. Passive recumbent and active standing protocols were used and the relationships of these variables to age and disc degeneration were assessed.

METHODS

Twenty patients with CNSLBP and 20 matched controls received quantitative fluoroscopic lumbar spine examinations using a standardised protocol for data collection and image analysis. Composite disc degeneration (CDD) scores comprising the sum of Kellgren and Lawrence grades from L2-S1 were obtained. Indices of intervertebral motion sharing inequality (MSI) and variability (MSV) were derived and expressed in units of proportion of lumbar range of motion from outward and return motion sequences during lying (passive) and standing (active) lumbar bending and compared between patients and controls. Relationships between MSI, MSV, age and CDD were assessed by linear correlation.

RESULTS

MSI was significantly greater in the patients throughout the intervertebral motion sequences of recumbent flexion (0.29 vs. 0.22, p = 0.02) and when flexion, extension, left and right motion were combined to give a composite measure (1.40 vs. 0.92, p = 0.04). MSI correlated substantially with age (R = 0.85, p = 0.004) and CDD (R = 0.70, p = 0.03) in lying passive investigations in patients and not in controls. There were also substantial correlations between MSV and age (R = 0.77, p = 0.01) and CDD (R = 0.85, p = 0.004) in standing flexion in patients and not in controls.

CONCLUSION

Greater inequality and variability of motion sharing was found in patients with CNSLBP than in controls, confirming previous studies and suggesting a biomechanical marker for the disorder at intervertebral level. The relationship between disc degeneration and MSI was augmented in patients, but not in controls during passive motion and similarly for MSV during active motion, suggesting links between in vivo disc mechanics and pain generation.