Kinematic analysis of dynamic lumbar motion in patients with lumbar segmental instability using digital videofluoroscopy

Dynamic segmental kinematics of the lumbar spine during diagnostic movements

Background: In vivo measurements of segmental-level kinematics are a promising avenue for better understanding the relationship between pain and its underlying, multi-factorial basis. To date, the bulk of the reported segmental-level motion has been restricted to single plane motions. Methods: The present work implemented a novel marker set used with an optical motion capture system to non-invasively measure dynamic, 3D in vivo segmental kinematics of the lower spine in a laboratory setting. Lumbar spinal kinematics were measured for 28 subjects during 17 diagnostic movements. Results: Overall regional range of motion data and lumbar angular velocity measurement were consistent with previously published studies. Key findings from the work included measurement of differences in ascending versus descending segmental velocities during functional movements and observations of motion coupling paradigms in the lumbar spinal segments. Conclusion: The work contributes to the task of establishing a baseline of segmental lumbar movement patterns in an asymptomatic cohort, which serves as a necessary pre-requisite for identifying pathological and symptomatic deviations from the baseline.

Myofascial Treatment for Microcirculation in Patients with Postural Neck and Shoulder Pain

Vascular impairment is a crucial factor associated with chronic muscle pain, but relevant research from the microcirculatory aspect is lacking. Here, we investigated the differences in neck muscle microcirculation detected through laser-doppler flowmetry (LDF) and cervical biomechanics by a videofluoroscopic image in asymptomatic participants and patients with postural neck and shoulder pain. To understand the mechanism behind the effect of myofascial treatment, transverse friction massage (TFM) was applied and the immediate effects of muscular intervention on microcirculation were monitored. In total, 16 asymptomatic participants and 22 patients (mean age = 26.3 ± 2.4 and 25.4 ± 3.2 years, respectively) were recruited. Their neck muscle microcirculation and spinal image sequence were assessed. The differences in the baseline blood flow between the asymptomatic and patient groups were nonsignificant. However, the standard deviations in the measurements of the upper trapezius muscle in the patients were significantly larger (p < 0.05). Regarding the TFM-induced responses of skin microcirculation, the blood flow ratio was significantly higher in the patients than in the asymptomatic participants (p < 0.05). In conclusion, postintervention hyperemia determined through noninvasive LDF may be an indicator for the understanding of the mechanism underlying massage therapies and the design of interventions for postural pain.

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.

Calibration and validation of a novel hybrid model of the lumbosacral spine in ArtiSynth-The passive structures

In computational biomechanics, two separate types of models have been used predominantly to enhance the understanding of the mechanisms of action of the lumbosacral spine (LSS): Finite element (FE) and musculoskeletal multibody (MB) models. To combine advantages of both models, hybrid FE-MB models are an increasingly used alternative. The aim of this paper is to develop, calibrate, and validate a novel passive hybrid FE-MB open-access simulation model of a ligamentous LSS using ArtiSynth. Based on anatomical data from the Male Visible Human Project, the LSS model is constructed from the L1-S1 rigid vertebrae interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, and facet joints. A mesh convergence study, sensitivity analyses, and systematic calibration were conducted with the hybrid functional spinal unit (FSU) L4/5. The predicted mechanical responses of the FSU L4/5, the lumbar spine (L1-L5), and the LSS were validated against literature data from in vivo and in vitro measurements and in silico models. Spinal mechanical responses considered when loaded with pure moments and combined loading modes were total and intervertebral range of motions, instantaneous axes and centers of rotation, facet joint contact forces, intradiscal pressures, disc bulges, and stiffnesses. Undesirable correlations with the FE mesh were minimized, the number of crisscrossed collagen fiber rings was reduced to five, and the individual influences of specific anatomical structures were adjusted to in vitro range of motions. Including intervertebral motion couplings for axial rotation and nonlinear stiffening under increasing axial compression, the predicted kinematic and structural mechanics responses were consistent with the comparative data. The results demonstrate that the hybrid simulation model is robust and efficient in reproducing valid mechanical responses to provide a starting point for upcoming optimizations and extensions, such as with active skeletal muscles.

Prospective surgical solutions in degenerative spine: spinal simulation for optimal choice of implant and targeted device development

Objectives

The most important goal of surgical treatment for spinal degeneration, in addition to eliminating the underlying pathology, is to preserve the biomechanically relevant structures. If degeneration destroys biomechanics, the single segment must either be surgically stabilized or functionally replaced by prosthetic restoration. This study examines how software-based presurgical simulation affects device selection and device development.

Methods

Based on videofluoroscopic motion recordings and pixel-precise processing of the segmental motion patterns, a software-based surrogate functional model was validated. It characterizes the individual movement of spinal segments relative to corresponding cervical or lumbar spine sections. The single segment-based motion of cervical or lumbar spine of individual patients can be simulated, if size-calibrated functional X-rays of the relevant spine section are available. The software plug-in “biokinemetric triangle” has been then integrated into this software to perform comparative segmental motion analyses before and after treatment in two cervical device studies: the correlation of implant-induced changes in the movement geometry and patient-related outcome was examined to investigate, whether this surrogate model could provide a guideline for implant selection and future implant development.

Results

For its validation in 253 randomly selected patients requiring single-level cervical (n=122) or lumbar (n=131) implant-supported restoration, the biokinemetric triangle provided significant pattern recognition in comparable investigations (p<0.05) and the software detected device-specific changes after implant-treatment (p<0.01). Subsequently, 104 patients, who underwent cervical discectomy, showed a correlation of the neck disability index with implant-specific changes in their segmental movement geometry: the preoperative simulation supported the best choice of surgical implants, since the best outcome resulted from restricting the extent of the movement of adjacent segments influenced by the technical mechanism of the respective device (p<0.05).

Conclusions

The implant restoration resulted in best outcome which modified intersegmental communication in a way that the segments adjacent to the implanted segment undergo less change in their own movement geometry. Based on our software-surrogate, individualized devices could be created that slow down further degeneration of adjacent segments by influencing the intersegmental communication of the motion segments.

Intersegmental kinematic analysis of lumbar spine by functional radiography between two subgroups of patients with chronic low back pain

INTRODUCTION

Kinematic deficits such as fault in joint accessory motion is one of the most important contributing factors for developing the movement impairment in the lumbar spine. Functional radiography is accessible method for detecting the artherokinematic disorders. The aim of this study was to compare lumbar spine intersegmental motion between low back pain (LBP) subgroups of movement system impairment (MSI) model by functional radiography.

MATERIALS AND METHODS

20 subjects with chronic LBP in two subgroups of the MSI model (Rotation with Flexion and Rotation with Extension) participated in this study. Five x-rays were taken in different positions. Intersegmental linear translation and angular rotation of the lumbar segments were calculated.

RESULTS

In the Rotation with Extension subgroup, the translation and rotation values of the L3-4 segment from full to full position were significantly more than their values in the Rotation with Flexion subgroup ((mean difference = -1.69 (mm) P = 0.01), (mean difference = -3.80 (mm) P = 0.02) respectively). The translation of L2-3 segment from the neutral to the mid-flexion position was significantly greater in the Rotation with Flexion subgroup compared to the Rotation with Extension subgroup (mean difference = 1.12 (mm) P = 0.04). cumulative intersegmental angular rotation of all lumbar segments from mid to mid position was greater in the Rotation with Flexion subgroup compared to the Rotation with Extension subgroup (P = 0.03).

CONCLUSION

Changes in intersegmental translation and angular rotation of lumbar segments in subgroups of patients with LBP may be important contributing factors that induce direction specific lumbar spine loads and contribute to the development or persistence of LBP problems.

Center of rotation locations during lumbar spine movements: a scoping review protocol

OBJECTIVE

The objective of this review is to identify and map current literature describing the center of rotation locations and migration paths during lumbar spine movements.

INTRODUCTION

Altered lumber spine kinematics has been associated with pain and injury. Intervertebral segments' center of rotations, the point around which spinal segments rotate, are important for determining the features of lumbar spine kinematics and the potential for increased injury risk during movements. Although many studies have investigated the center of rotations of humans' lumbar spine, no review has summarized and organized the state of the science related to center of rotation locations and migration paths of the lumbar spine during lumbar spine movements.

INCLUSION CRITERIA

This review will consider studies that include human lumbar spines of any age and condition (e.g. heathy, pathological) during lumbar spine movements. Quantitative study designs, including clinical, observational, laboratory biomechanical experimental studies, mathematical and computer modeling studies will be considered. Only studies published in English will be included, and there will be no limit on dates of publication.

METHODS

PubMed, MEDLINE, Embase, the Cochrane Library Controlled Register of Trials, CINAHL, ACM Digital Library, Compendex, Inspec, Web of Science, Scopus, Google Scholar, and dissertation and theses repositories will be searched. After title and abstract screening of identified references, two independent reviewers will screen the full-text of identified studies and extract data. Data will be summarized and categorized, and a comprehensive narrative summary will be presented with the respective results.

ICR in human cadaveric specimens: An essential parameter to consider in a new lumbar disc prosthesis design

STUDY DESIGN

Biomechanical study in cadaveric specimens.

BACKGROUND

The commercially available lumbar disc prostheses do not reproduce the intact disc's Instantaneous centre of Rotation (ICR), thus inducing an overload on adjacent anatomical structures, promoting secondary degeneration.

AIM

To examine biomechanical testing of cadaveric lumbar spine specimens in order to evaluate and define the ICR of intact lumbar discs.

MATERIAL AND METHODS

Twelve cold preserved fresh human cadaveric lumbosacral spine specimens were subjected to computerized tomography (CT), magnetic resonance imaging (MRI) and biomechanical testing. Kinematic studies were performed to analyse range of movements in order to determine ICR.

RESULTS

Flexoextension and lateral bending tests showed a positive linear correlation between the angle rotated and the displacement of the ICR in different axes.

DISCUSSION

ICR has not been taken into account in any of the available literature regarding lumbar disc prosthesis. Considering our results, neither the actual ball-and-socket nor the withdrawn elastomeric nucleus models fit the biomechanics of the lumbar spine, which could at least in part explain the failure rates of the implants in terms of postoperative failed back syndrome (low back pain). It is reasonable to consider then that an implant should also adapt the equations of the movement of the intact ICR of the joint to the post-surgical ICR.

CONCLUSIONS

This is the first cadaveric study on the ICR of the human lumbar spine. We have shown that it is feasible to calculate and consider this parameter in order to design future prosthesis with improved clinical and biomechanical characteristics.

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.

A novel method for prediction of postoperative global sagittal alignment based on full-body musculoskeletal modeling and posture optimization

Associations between spinal sagittal balance and pain and disability are well documented. Reciprocal changes after spinal surgery might be critical for the outcomes, but assessing their extent remains a challenge. This paper proposes a method for predicting full-body sagittal alignment including reciprocal changes in response to spinal fusion, based on musculoskeletal modeling and inverse-inverse dynamics approach. An established body model (AnyBody) was used, with fused segments modeled as rigid. Posture was optimized based on muscle expenditure minimization, following the concept of the cone of economy. The data of adult spinal fusion patients were obtained retrospectively from an ongoing clinical study. Patient spino-pelvic alignment, body weight and height, age- and pathology-related muscle deterioration, and underwent treatment details were represented in the model. Predicted postural changes were compared to follow-up radiographs to evaluate method validity. Twenty-one cases were analyzed in this preliminary study (age range = 48-74; number of fused segments 1-14). The model predictions correlated well with the radiographic measures at follow-up: TPA, r = 0.83; ΔPILL, r = 0.90; LL, r = 0.90; TK, r = 0.77. The model demonstrated high accuracy in predicting sagittal imbalance (positive predictive value = 1.00, negative predictive value = 0.75). The presented method for patient- and treatment-specific postoperative posture prediction can be used to guide preoperative planning of spinal fusion, but more extensive validation is needed.

Dynamic interactions between lumbar intervertebral motion segments during forward bending and return

Continuous dynamic multi-segmental studies of lumbar motion have added depth to our understanding of the biomechanics of back pain, but few have attempted to continuously measure the proportions of motion accepted by individual levels. This study attempted to compare the motion contributions of adjacent lumbar levels during an active weight bearing flexion and return protocol in chronic, non-specific low back pain (CNSLBP) patients and controls using quantitative fluoroscopy (QF). Eight CNSLBP patients received QF during guided standing lumbar flexion. Dynamic motion sharing of segments from L2 to S1 were calculated and analysed for interactions between levels. Eight asymptomatic controls were then matched to the 8 patients for age and sex and their motion sharing patterns compared. Share of intersegmental motion was found to be consistently highest at L2-L3 and L3-L4 and lowest at L5-S1 throughout the motion in both groups, with the exception of maximum flexion where L4-L5 received the greatest share. Change in motion sharing occurred throughout the flexion and return motion paths in both participant groups but tended to vary more at L4-L5 in patients (p < 0.05). In patients, L5-S1 provided less angular range (p < 0.05) and contributed less at maximum bend (p < 0.05), while L3-L4, on average over the bending sequence, provided a greater share of motion (p < 0.05). Intervertebral motion sharing inequality is therefore a normal feature during lumbar flexion. However, in patients, inequality was more pronounced, and variability of motion share at some levels increased. These effects may result from differences in muscular contraction or in the mechanical properties of the disc.

Comparison of intra subject repeatability of quantitative fluoroscopy and static radiography in the measurement of lumbar intervertebral flexion translation

Low back pain patients are sometimes offered fusion surgery if intervertebral translation, measured from static, end of range radiographs exceeds 3 mm. However, it is essential to know the measurement error of such methods, if selection for back surgery is going to be informed by them. Fifty-five healthy male (34) and female (21) pain free participants aged 21–80 years received quantitative fluoroscopic (QF) imaging both actively during standing and passively in the lateral decubitus position. The following five imaging protocols were extracted from 2 motion examinations, which were repeated 6 weeks apart: 1. Static during upright free bending. 2. Maximum during controlled upright bending, 3. At the end of controlled upright bending, 4. Maximum during controlled recumbent bending, 5. At the end of controlled recumbent bending. Intervertebral flexion translations from L2-S1 were determined for each protocol and their measurement errors (intra subject repeatability) calculated. Estimations using static, free bending radiographic images gave measurement errors of up to 4 mm, which was approximately twice that of the QF protocols. Significantly higher ranges at L4-5 and L5-S1 were obtained from the static protocol compared with the QF protocols. Weight bearing ranges at these levels were also significantly higher in males regardless of the protocol. Clinical decisions based on sagittal translations of less than 4 mm would therefore require QF imaging.

Repeatability of Cervical Joint Flexion and Extension Within and Between Days

OBJECTIVE

The purpose of this study was to investigate within- and between-day repeatability of free and unrestricted healthy cervical flexion and extension motion when assessing dynamic cervical spine motion.

METHODS

Fluoroscopy videos of 2 repeated cervical flexion and 2 repeated extension motions were examined for within-day repeatability (20-second interval) for 18 participants (6 females) and between-day repeatability (1-week interval) for 15 participants (6 females). The dynamic cervical motions were free and unrestricted from neutral to end range. The flexion videos and extension videos were evenly divided into 10% epochs of the C0-to-C7 range of motion. Within-day and between-day repeatability of joint motion angles (all 7 joints and epochs, respectively) was tested in a repeated-measures analysis of variance. Joint motion angle differences between repetitions were calculated for each epoch and joint (7 joints), and these joint motion angle differences between within-day and between-day repetitions were tested in mixed-model analysis of variance.

RESULTS

For all joints and epochs, respectively, no significant differences were found in joint motion angle between within-day or between-day repetitions. There were no significant effects of joint motion angle differences between within-day and between-day repetitions. The average within-day joint motion angle differences across all joints and epochs were 0.00° ± 2.98° and 0.00° ± 3.05° for flexion and extension, respectively. The average between-day joint motion angle differences were 0.02° ± 2.56° and 0.05° ± 2.40° for flexion and extension, respectively.

CONCLUSIONS

This is the first study to report the within-day and between-day joint motion angle differences of repeated cervical flexion and extension. This study supports the idea that cervical joints repeat their motion accurately.

Influence of Deviated Centers of Rotation on Kinematics and Kinetics of a Lumbar Functional Spinal Unit: An In Vitro Study

Background

Center of rotation (COR) has been used for assessing spinal motion quality. However, the biomechanical influence of COR deviation towards different directions during flexion-extension (FE) remains largely unknown. This study aimed to investigate the alteration in the range of motion (ROM), compressive force, shear force, and neutral zone size (NZ) in a lumbar functional spinal unit (FSU), caused by the deviated COR in different directions during FE.

Material/Methods

Twelve human cadaveric lumbar FSUs (6 for L2–L3, 6 for L4–L5) were tested in a 6-degree-of-freedom servo-hydraulic load frame. These FSUs were firstly applied a 7.5 Nm pure moment to perform FE to obtain their natural COR during FE. Subsequently, they were subjected to FE around 9 established deviated CORs with 6 Nm cyclical loading.

Results

It was found that the ROM and NZ increased significantly when the COR moved from the superior plane to the inferior plane for the L2–L3 unit and when the COR located in the superior plane compared with the inferior plane for the L4–L5 unit. The compressive forces for both FSUs demonstrated significant changes caused by COR shift in the same horizontal plane, while the shear forces demonstrated significant changes caused by COR shift in the same vertical plane.

Conclusions

The ROM, NZ, and shear force of FSU are sensitive to the vertical COR shift, while the compressive force of FSU is highly sensitive to the horizontal COR shift. Additionally, the kinematics and kinetics of the L2–L3 unit are more sensitive to COR location than those of the L4–L5 unit.

Visual and instrumental diagnostics using chromokinegraphics: Reliability and validity for low back pain stratification

BACKGROUND

Low back pain patients have been suggested to exhibit dysfunctional spinal movement patterns. However, there is a lack of clinically applicable but valid and reliable assessment tools, helping to discriminate normal and pathologically altered movement.

OBJECTIVE

We aimed to examine whether kinematic parameters determined with an ultrasound-based motion analysis and thereof derived chromokinegraphical angle-time matrices (CATMAs) are able to discriminate between non-symptomatic and symptomatic movement behaviour in individuals with non-specific chronic (CLBP), specific low back pain (SLBP), and controls.

METHODS

Thoracic and lumbar spine range of motion (ROM [∘]); angular velocity (V [∘/sec]) and side-to-side differences [%] during a lateral flexion movement were assessed in 17 healthy participants, 16 individuals with CLBP and 11 SLBP patients. CATMAs ratings of two investigators (6-item Likert scale) were dichotomised, classifying the observed movement as physiological or non-physiological. Intrarater and interrater reliability were estimated using kappa statistics and Cronbach's Alpha. T-tests and a ROC analysis to determine optimal cut-offs for the separation of the collectives as well as contingency tables for selectivity of the cut-offs (motor outcomes) were calculated.

RESULTS

CATMA ratings displayed partly moderate to good (rater B; i.e. CLBP vs. controls) and partly insufficient discriminant validity (rater A). Due to this, inter-rater reliability was poor (k= 0.061 to 0.135), while intra-rater-reliability was moderate to good for both raters (k= 0.329 to 0.625) except for SLBP vs. controls (rater A; k=-0.18). Regarding kinematics, group differences occurred neither in ROM nor in V (p> 0.05), but in terms of the relative side comparison between CLBP and controls (p<0.05). ROC analysis (CLBP vs. controls) revealed an optimal cut-off at side asymmetries of 16.9% (ROM) and 28.9% (V). Between SLBP patients and controls, no significant differences were observed neither in terms of the absolute values nor the relative side differences of both kinematic variables.

CONCLUSIONS

Side asymmetries of V and ROM may be used to differentiate between controls and individuals with CLBP. CATMAs appear to be of limited diagnostic value for the identification of pathological spine movement.

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.

Motion analysis of the cervical spine during extension and flexion: Reliability of the vertebral marking procedure

Cervical spine motion analysis using videofluoroscopy is currently a technique without a gold standard. We demonstrate the reliability of a rigid and reliable analysis methodology for cervical motion using videofluoroscopic images, representing the entire range of motion during flexion and extension, from the neutral position to the end-range in the sagittal plane. Two researchers with radiography and vertebral marking expertise, and two inexperienced researchers with 10 hours of training manually marked anatomical structures on fluoroscopic images in a procedure designed to control for vertebral rotation around the mid-plane axis. The average marking error across examiners and images was -0.12^∘ (standard deviation: 0.88°), and the intraexaminer error ranged from -1.00^∘ to 1.61° (standard deviation range: 0.27°-1.19°). Our method demonstrated lower errors compared to the higher resolution X-ray studies, and proved that vertebral marking can be performed by persons with no experience in radiographic image analysis.

Lumbar Stability in Healthy Individuals and Low Back Pain Patients Quantified by Wall Plank-and-Roll Test

BACKGROUND

Low back pain (LBP) has been linked to the degree of lumbar stability, but evaluating lumbar stability has remained a challenge. Previous research has shown that inertial sensors could be used to quantify motor patterns during the wall plank-and-roll (WPR) test, and that LBP may cause deviations in movement from the general motor patterns observed in healthy individuals.

OBJECTIVE

To generalize the lumbar motor patterns during the WPR test in healthy individuals, and to analyze the effect of aging and LBP on the motor patterns during the WPR test.

DESIGN

A descriptive, exploratory research with a convenience sample. This study is registered at the Clinical Research Information Service (Korea) under public trial registration numbers KCT0002481 and KCT0002533.

SETTING

A biomechanics laboratory of a tertiary university hospital.

PARTICIPANTS

57 healthy individuals (23 men 36.7 ± 15.4 years old and 34 women 42.4 ± 17.7 years old) and 17 patients (5 men 48.4 ± 10.9 years old and 12 women 33.7 ± 9.9 years old) with axial LBP.

METHODS

Participants performed the WPR test with 2 inertial sensors placed on the thoracic spine and sacrum. Relative angles between the sensors were calculated to quantify and examine lumbar motion in 3 anatomical planes: axial twist, kyphosis-lordosis, and lateral bending.

MAIN OUTCOME MEASURES

General motor patterns during the WPR test in healthy participants were examined, stratified based on age, and changes based on age were analyzed. Motor patterns of LBP patients were compared with those from the healthy group.

RESULTS

Movement in the kyphosis-lordosis and lateral bending axes showed little variation in healthy participants, whereas in the axial twist axis there were 2 dominant patterns. A χ ² test revealed that the distributions of 2 motor patterns in the axial twist axis between the younger group and the older group were significantly different (P < .05). Furthermore, the older group had decreased lordosis at the static position (P = .02) and at the maximal rotating position (P = .03). Compared with the healthy group, LBP patients showed increasing lateral bending at the maximal rotating position (P = .007) and increased lateral bending excursion angle (P = .04) during the WPR test.

CONCLUSIONS

A general lumbar motor pattern was observed during the WPR test in the healthy participants, but age contributed to variations in this general pattern. Comparison of motor patterns between healthy individuals and LBP patients revealed a different type of variation in the LBP patients. The results presented should be scrutinized with further research, characterizing specific variations in different subgroups of LBP patients.

LEVEL OF EVIDENCE

III.

Continuous lumbar spine rhythms during level walking, stair climbing and trunk flexion in people with and without lumbar disc herniation

Low back pain(LBP) is one of the most prevalent diseases afflicting people today. Abnormal musculoskeletal loadings during activities of daily living (ADLs) have been deemed to be associated with spine rhythm. But no studies have reported abnormal continuous spine rhythms during ADLs in LBP patients. Therefore, the objective of this study was to investigate the continuous lumbar spine rhythms and their difference between people with and without lumbar disc herniation (LDH). Twenty-six healthy people and seven patients with LDH were recruited in this study. They performed level walking, stair climbing, and trunk flexion. Active optical markers placed on the landmark of the spinous process and pelvis were captured using motion analysis system to drive a musculoskeletal model to calculate the continuous lumbar spine rhythms. It was found that the lumbar spine rhythm was roughly constant throughout the analyzed cycle in both healthy people and LDH patients during trunk flexion. LDH patients displayed fluctuant lumbar spine rhythms during level walking and stair climbing and significantly higher segmental contributions of the lumbar segments in the lower lumbar region during stair climbing and trunk flexion. In conclusion, there were different compensatory responses to LDH in the continuous lumbar spine rhythms during different ADLs. This study provides a new insight into the abnormal spinal motion in LDH patients.

Cervical flexion and extension includes anti-directional cervical joint motion in healthy adults

BACKGROUND CONTEXT

Anti-directional cervical joint motion has previously been demonstrated. However, quantitative studies of anti-directional and pro-directional cervical flexion and extension motions have not been published.

PURPOSE

This study aimed for a quantitative assessment of directional and anti-directional cervical joint motion in healthy subjects.

STUDY DESIGN

An observational study was carried out.

PATIENTS SAMPLE

Eighteen healthy subjects comprised the study sample.

OUTCOME MEASURES

Anti-directional and pro-directional cervical flexion and extension motion from each cervical joint in degrees were the outcome measures.

METHODS

Fluoroscopy videos of cervical flexion and extension motions (from neutral to end-range) were acquired from 18 healthy subjects. The videos were divided into 10% epochs of C0/C7 range of motion (ROM). The pro-directional and anti-directional motions in each 10% epoch were extracted, and the ratios of anti-directional motions with respect to the pro-directional motions (0%=no anti-directional movement) were calculated for joints and 10% epochs.

RESULTS

The flexion and extension ROM for C0/C7 were 51.9°±9.3° and 57.2°±12.2°. The anti-directional motions of flexion and extension ROM constituted 42.8%±9.7% and 41.2%±8.2% of the respective pro-directional movements. For flexion, the first three joints (C0/C1, C1/C2, C2/C3) demonstrated larger ratios compared with the last three joints (C4/C5, C5/C6, C6/C7) (p<.03). For extension, C1/C2 and C2/C3 ratios were larger compared with C0/C1, C4/C5, and C5/C6 (p<.03). Comparisons between flexion and extension motions showed larger C0/C1 ratio but smaller C5/C6 and C6/C7 ratios in extension (p<.05).

CONCLUSIONS

This is the first report of quantified anti-directional cervical flexion and extension motion. The anti-directional motion is approximately 40% of the pro-directional motion. The results document that large proportions of anti-directional cervical flexion and extension motions were normal.

INTERSEGMENTAL COORDINATION IN LOWER EXTREMITIES AND MULTI-SEGMENTAL SPINE DURING DIFFERENT ACTIVITIES OF DAILY LIVING

Background: Human movement consists of numerous degrees of freedom (DOF). How the nervous system (NS) computes the appropriate command to coordinate these DOFs to finish specific tasks is still hotly debated. One common way to simplify the redundant DOFs is to coordinate multiple DOFs by combining them into units or synergies. The present study aimed to investigate the kinematic complexity of five activities of daily living (ADLs) and to detect the amount of kinematic synergy during every ADL and the relationship of the motion pattern between these ADLs. Method: Twenty-six able-bodied male individuals performed level walking, stair climbing, trunk bending, ipsilateral pick-up and contralateral pick-up in sequence. The segmental excursion of the thorax, upper lumbar, lower lumbar, pelvis, thigh and shank was calculated. Principal component analysis (PCA) was applied to determine the motion pattern of every ADL. Result: In the sagittal plane, trunk bending, ipsilateral pick-up and contralateral pick-up could be simplified by using one principal component (PC) with more than 95% variance accounted for (VAF). In addition, the motion pattern of every PC was similar among the three ADLs. Moreover, the angles between the vectors representing the first PC of the three ADLs were all less than 10[Formula: see text]. Level walking and stair climbing needed at least two PCs to reach 95% VAF. In addition, the motion pattern was different between the two ADLs. Moreover, the angle between the first PC of the two ADLs was around 90[Formula: see text]. In the coronal plane, the five ADLs except contralateral pick-up arrived at 90% VAF with two PCs. The motion pattern and the angle between the first PC both demonstrated larger differences among the five ADLs. Conclusion: Two PCs were essential to represent level walking and stair climbing, indicating a complex control strategy used by the NS. Trunk bending, ipsilateral pick-up and contralateral pick-up could be described with one PC in the sagittal plane, showing a strong coupling and simple motion pattern. In addition, the motion pattern varied considerably among these ADLs. The outcomes of this study can help clinicians to select suitable ADLs for the patients with various joint or disc diseases and to conduct corresponding functional test and rehabilitation.

Trajectory of instantaneous axis of rotation in fixed lumbar spine with instrumentation

Background

Several studies showed instantaneous axis of rotation (IAR) in the intact spine. However, there has been no report on the trajectory of the IAR of a damaged spine or that of a fixed spine with instrumentation. It is the aim of this study to investigate the trajectory of the IAR of the lumbar spine using the vertebra of deer.

Methods

Functional spinal units (L5–6) from five deer were evaluated with six-axis material testing machine. As specimen models, we prepared a normal model, a damaged model, and a pedicle screw (PS) model. We measured the IAR during bending in the coronal and sagittal planes and axial rotation. In the bending test, four directions were measured: anterior, posterior, right, and left. In the rotation test, two directions were measured: right and left.

Results

The IAR of the normal model during bending moved in the bending direction. The IAR of the damaged model during bending moved in the bending direction, but the magnitude of displacement was bigger compared to that of the normal model. In the PS model, the IAR during bending test hardly moved. During rotation test, the IAR of the normal model and PS model located in the spinal canal, but the IAR of the damaged model located in the posterior part of the vertebral body.

Conclusions

In this study, the IAR of damaged model was scattering and that of PS model was concentrating. This suggests that higher mechanical load applied to the dura tube and nerve roots in the damaged model and less mechanical load applied to that in the PS model.

Effects of Preoperative Simulation on Minimally Invasive Hybrid Lumbar Interbody Fusion

OBJECTIVE

The main focus of this study was to evaluate how preoperative simulation affects the surgical work flow, radiation exposure, and outcome of minimally invasive hybrid lumbar interbody fusion (MIS-HLIF).

METHODS

A total of 132 patients who underwent single-level MIS-HLIF were enrolled in a cohort study design. Dose area product was analyzed in addition to surgical data. Once preoperative simulation was established, 66 cases (SIM cohort) were compared with 66 patients who had previously undergone MIS-HLIF without preoperative simulation (NO-SIM cohort).

RESULTS

Dose area product was reduced considerably in the SIM cohort (320 cGy·cm² NO-SIM cohort: 470 cGy·cm²; P < 0.01). Surgical time was shorter for the SIM cohort (155 minutes; NO-SIM cohort, 182 minutes; P < 0.05). SIM cohort had a better outcome in Numeric Rating Scale back at 6 months follow-up compared with the NO-SIM cohort (P < 0.05).

CONCLUSIONS

Preoperative simulation reduced radiation exposure and resulted in less back pain at the 6 months follow-up time point. Preoperative simulation provided guidance in determining the correct cage height. Outcome controls enabled the surgeon to improve the procedure and the software algorithm.

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.

Influences of lumbar disc herniation on the kinematics in multi-segmental spine, pelvis, and lower extremities during five activities of daily living

Background

Low back pain (LBP) is a common problem that can contribute to motor dysfunction. Previous studies reporting the changes in kinematic characteristics caused by LBP present conflicting results. This study aimed to apply the multisegmental spinal model to investigate the kinematic changes in patients with lumbar disc herniation (LDH) during five activities of daily living (ADLs).

Methods

Twenty-six healthy subjects and 7 LDH patients participated in this study and performed level walking, stair climbing, trunk flexion, and ipsilateral and contralateral pickups. The angular displacement of the thorax, upper lumbar (ULx), lower lumbar (LLx), pelvis, hip, and knee was calculated using a modified full-gait-model in the AnyBody modeling system.

Results

In the patient group, the ULx almost showed no sagittal angular displacement while the LLx remained part of the sagittal angular displacement during trunk flexion and the two pickups. In the two pickups, pelvic tilt and lower extremities’ flexion increased to compensate for the deficiency in lumbar motion. LDH patients exhibited significantly less pelvic rotation during stair climbing and greater pelvic rotation in other ADLs, except in contralateral pickup. In addition, LDH patients demonstrated more antiphase movement in the transverse plane between ULx and LLx, during level walking and stair climbing, between thorax and pelvis in the two pickups.

Conclusions

LDH patients mainly restrict the motion of LLx and ULx in the spinal region during the five ADLs. Pelvic rotation is an important method to compensate for the limited lumbar motion. Furthermore, pelvic tilt and lower extremities’ flexion increased when ADLs were quite difficult for LDH patients.

Multi-segmental thoracic spine kinematics measured dynamically in the young and elderly during flexion

In contrast to the cervical and lumbar region, the normal kinematics of the thoracic spine have not been thoroughly investigated. The aim of this study was to characterize normal multi-segmental continuous motion of the whole thoracolumbar spine, during a flexion maneuver, in young and elderly subjects. Forty-two healthy volunteers were analyzed: 21 young (age=27.00±3.96) and 21 elderly (age=70.1±3.85). Spinal motion was recorded with a motion-capture system and analyzed using a 3rd order polynomial function to approximate spinal curvature throughout the motion sequence. The average motion profiles of the two age groups were characterized. Flexion timing of the thoracic region of the spine, as compared to the lumbar spine and hips, was found to be different in the two age groups (p=0.011): a delayed/sequential motion type was observed in most of the young, whereas mostly a simultaneous motion pattern was observed in the elderly subjects. A similar trend was observed in flexion of the lower thoracic segments (p=0.017). Differences between age groups were also found for regional and segmental displacements and velocities. The reported characterization of the thoracic spine kinematics may in the future support identification of abnormal movement or be used to improve biomechanical models of the spine.

A videofluoroscopy-based tracking algorithm for quantifying the time course of human intervertebral displacements

The motions of individual intervertebral joints can affect spine motion, injury risk, deterioration, pain, treatment strategies, and clinical outcomes. Since standard kinematic methods do not provide precise time-course details about individual vertebrae and intervertebral motions, information that could be useful for scientific advancement and clinical assessment, we developed an iterative template matching algorithm to obtain this data from videofluoroscopy images. To assess the bias of our approach, vertebrae in an intact porcine spine were tracked and compared to the motions of high-contrast markers. To estimate precision under clinical conditions, motions of three human cervical spines were tracked independently ten times and vertebral and intervertebral motions associated with individual trials were compared to corresponding averages. Both tests produced errors in intervertebral angular and shear displacements no greater than 0.4° and 0.055 mm, respectively. When applied to two patient cases, aberrant intervertebral motions in the cervical spine were typically found to correlate with patient-specific anatomical features such as disc height loss and osteophytes. The case studies suggest that intervertebral kinematic time-course data could have value in clinical assessments, lead to broader understanding of how specific anatomical features influence joint motions, and in due course inform clinical treatments.

Effect of Off-Axis Fluoroscopy Imaging on Two-Dimensional Kinematics in the Lumbar Spine: A Dynamic In Vitro Validation Study

Spine intersegmental motion parameters and the resultant regional patterns may be useful for biomechanical classification of low back pain (LBP) as well as assessing the appropriate intervention strategy. Because of its availability and reasonable cost, two-dimensional (2D) fluoroscopy has great potential as a diagnostic and evaluative tool. However, the technique of quantifying intervertebral motion in the lumbar spine must be validated, and the sensitivity assessed. The purpose of this investigation was to (1) compare synchronous fluoroscopic and optoelectronic measures of intervertebral rotations during dynamic flexion-extension movements in vitro and (2) assess the effect of C-arm rotation to simulate off-axis patient alignment on intervertebral kinematics measures. Six cadaveric lumbar-sacrum specimens were dissected, and active marker optoelectronic sensors were rigidly attached to the bodies of L2-S1. Fluoroscopic sequences and optoelectronic kinematic data (0.15-mm linear, 0.17-0.20 deg rotational, accuracy) were obtained simultaneously. After images were obtained in a true sagittal plane, the image receptor was rotated in 5 deg increments (posterior oblique angulations) from 5 deg to 15 deg. Quantitative motion analysis (qma) software was used to determine the intersegmental rotations from the fluoroscopic images. The mean absolute rotation differences between optoelectronic values and dynamic fluoroscopic values were less than 0.5 deg for all the motion segments at each off-axis fluoroscopic rotation and were not significantly different (P > 0.05) for any of the off-axis rotations of the fluoroscope. Small misalignments of the lumbar spine relative to the fluoroscope did not introduce measurement variation in relative segmental rotations greater than that observed when the spine and fluoroscope were perpendicular to each other, suggesting that fluoroscopic measures of relative segmental rotation during flexion-extension are likely robust, even when patient alignment is not perfect.

Attainment rate as a surrogate indicator of the intervertebral neutral zone length in lateral bending: an in vitro proof of concept study

Background

Lumbar segmental instability is often considered to be a cause of chronic low back pain. However, defining its measurement has been largely limited to laboratory studies. These have characterised segmental stability as the intrinsic resistance of spine specimens to initial bending moments by quantifying the dynamic neutral zone. However these measurements have been impossible to obtain in vivo without invasive procedures, preventing the assessment of intervertebral stability in patients. Quantitative fluoroscopy (QF), measures the initial velocity of the attainment of intervertebral rotational motion in patients, which may to some extent be representative of the dynamic neutral zone. This study sought to explore the possible relationship between the dynamic neutral zone and intervertebral rotational attainment rate as measured with (QF) in an in vitro preparation. The purpose was to find out if further work into this concept is worth pursuing.

Method

This study used passive recumbent QF in a multi-segmental porcine model. This assessed the intrinsic intervertebral responses to a minimal coronal plane bending moment as measured with a digital force guage. Bending moments about each intervertebral joint were calculated and correlated with the rate at which global motion was attained at each intervertebral segment in the first 10° of global motion where the intervertebral joint was rotating.

Results

Unlike previous studies of single segment specimens, a neutral zone was found to exist during lateral bending. The initial attainment rates for left and right lateral flexion were comparable to previously published in vivo values for healthy controls. Substantial and highly significant levels of correlation between initial attainment rate and neutral zone were found for left (Rho = 0.75, P = 0.0002) and combined left-right bending (Rho = 0.72, P = 0.0001) and moderate ones for right alone (Rho = 0.55, P = 0.0012).

Conclusions

This study found good correlation between the initial intervertebral attainment rate and the dynamic neutral zone, thereby opening the possibility to detect segmental instability from clinical studies. However the results must be treated with caution. Further studies with multiple specimens and adding sagittal plane motion are warranted.

Development of a novel radiographic measure of lumbar instability and validation using the facet fluid sign

BACKGROUND

Lumbar spinal instability is frequently referenced in clinical practice and the scientific literature despite the lack of a standard definition or validated radiographic test. The Quantitative Stability Index (QSI) is being developed as a novel objective test for sagittal plane lumbar instability. The QSI is calculated using lumbar flexion-extension radiographs. The goal of the current study was to use the facet fluid sign on MRI as the "gold standard" and determine if the QSI is significantly different in the presence of the fluid sign.

METHODS

Sixty-two paired preoperative MRI and flexion-extension exams were obtained from a large FDA IDE study. The MRI exams were assessed for the presence of a facet fluid sign, and the QSI was calculated from sagittal plane intervertebral rotation and translation measurements. The QSI is based on the translation per degree of rotation (TPDR) and is calculated as a Z-score. A QSI > 2 indicates that the TPDR is > 2 std dev above the mean for an asymptomatic and radiographically normal population. The reproducibility of the QSI was also tested.

RESULTS

The mean difference between trained observers in the measured QSI was between -0.28 and 0.36. The average QSI was significantly (P = 0.047, one-way analysis of variance) higher at levels with a definite fluid sign (2.3±3.2 versus 0.60±2.4).

CONCLUSIONS

Although imperfect, the facet fluid sign observed may be the best currently available test for lumbar spine instability. Using the facet fluid sign as the "gold standard" the current study documents that the QSI can be expected to be significantly higher in the presence of the facet fluid sign. This supports that QSI might be used to test for sagittal plane lumbar instability.

CLINICAL RELEVANCE

A validated, objective and practical test for spinal instability would facilitate research to understand the importance of instability in diagnosis and treatment of low-back related disorders.

Quantification of Lumbar Stability During Wall Plank-and-Roll Activity Using Inertial Sensors

OBJECTIVE

To develop a simple method of quantifying dynamic lumbar stability by evaluating postural changes of the lumbar spine during a wall plank-and-roll (WPR) activity while maintaining maximal trunk rigidity.

DESIGN

A descriptive, exploratory research with a convenience sample.

SETTING

A biomechanics laboratory of a tertiary university hospital.

PARTICIPANTS

Sixteen healthy young subjects (8 men and 8 women; 30.7 ± 6.8 years old) and 3 patients (2 men 46 and 50 years old; 1 woman 54 years old) with low back pain (LBP).

METHODS

The subjects performed the WPR activity with 2 inertial sensors attached on the thoracic spine and sacrum. Relative angles between the sensors were calculated to characterize lumbar posture in 3 anatomical planes: axial twist (AT), kyphosis-lordosis (KL), or lateral bending (LB). Isokinetic truncal flexion and extension power were measured.

MAIN OUTCOME MEASURES

AT, KL, and LB were compared between the initial plank and maximal roll positions. Angular excursions were compared between males and females and between rolling sides, and tested for correlation with isokinetic truncal muscle power. Patterns and consistencies of the lumbar postural changes were determined. Lumbar postural changes of each patient were examined in the aspects of pattern and excursion, considering those from the healthy subjects as reference.

RESULTS

AT, KL, and LB were significantly changed from the initial plank to the maximal roll position (P < .01); that is, the thoracic spine rotated further, lumbar lordosis increased, and the thoracic spine was bent away from the wall by 6.9° ± 12.0°, 9.5° ± 6.5°, and 7.9° ± 4.9°, respectively. The patterns and amounts of lumbar postural changes were not significantly different between the rolling sides or between male and female participants, except that the excursion in AT was larger on the dominant rolling side. The excursions were not related to isokinetic truncal muscle power. The 3 LBP patients showed varied deviations in pattern and excursion from the average of the healthy subjects.

CONCLUSIONS

Certain amounts and patterns of lumbar postural changes were observed in healthy young subjects, with no significant variations based on gender, rolling side, or truncal muscle power. Application of the evaluation on LBP patients revealed prominent deviations from the healthy postural changes, suggesting potential clinical applicability. Therefore, with appropriate development and case stratification, we believe that the quantification of lumbar postural changes during WPR activity can be used to assess dynamic lumbar stability in clinical practice.

Moving back: The radiation dose received from lumbar spine quantitative fluoroscopy compared to lumbar spine radiographs with suggestions for dose reduction

PURPOSE

Quantitative fluoroscopy is an emerging technology for assessing continuous inter-vertebral motion in the lumbar spine, but information on radiation dose is not yet available. The purposes of this study were to compare the radiation dose from quantitative fluoroscopy of the lumbar spine with lumbar spine radiographs, and identify opportunities for dose reduction in quantitative fluoroscopy.

METHODS

Internationally reported dose area product (DAP) and effective dose data for lumbar spine radiographs were compared with the same for quantitative fluoroscopy and with data from a local hospital for functional radiographs (weight bearing AP, lateral, and/or flexion and extension) (n = 27). The effects of procedure time, age, weight, height and body mass index on the fluoroscopy dose were determined by multiple linear regression using SPSS v19 software (IBM Corp., Armonck, NY, USA).

RESULTS AND CONCLUSION

The effective dose (and therefore the estimated risk) for quantitative fluoroscopy is 0.561 mSv which is lower than in most published data for lumbar spine radiography. The dose area product (DAP) for sagittal (flexion + extension) quantitative fluoroscopy is 3.94 Gy cm² which is lower than local data for two view (flexion and extension) functional radiographs (4.25 Gy cm²), and combined coronal and sagittal dose from quantitative fluoroscopy (6.13 Gy cm²) is lower than for four view functional radiography (7.34 Gy cm²). Conversely DAP for coronal and sagittal quantitative fluoroscopy combined (6.13 Gy cm²) is higher than that published for both lumbar AP or lateral radiographs, with the exception of Nordic countries combined data. Weight, procedure time and age were independently positively associated with total dose, and height (after adjusting for weight) was negatively associated, thus as height increased, the DAP decreased.

Dynamic motion characteristics of the lower lumbar spine: implication to lumbar pathology and surgical treatment

PURPOSE

Many studies have reported on the segmental motion range of the lumbar spine using various in vitro and in vivo experimental designs. However, the in vivo weightbearing dynamic motion characteristics of the L4-5 and L5-S1 motion segments are still not clearly described in literature. This study investigated in vivo motion of the lumbar spine during a weight-lifting activity.

METHODS

Ten asymptomatic subjects (M/F: 5/5; age: 40-60 years) were recruited. The lumbar segment of each subject was MRI-scanned to construct 3D models of the L2-S1 vertebrae. The lumbar spine was then imaged using a dual fluoroscopic imaging system as the subject performed a weight-lifting activity from a lumbar flexion position (45°) to maximal extension position. The 3D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral positions along the motion path. The relative translations and rotations of each motion segment were analyzed.

RESULTS

All vertebral motion segments, L2-3, L3-4, L4-5 and L5-S1, rotated similarly during the lifting motion. L4-5 showed the largest anterior-posterior (AP) translation with 2.9 ± 1.5 mm and was significantly larger than L5-S1 (p < 0.05). L5-S1 showed the largest proximal-distal (PD) translation with 2.8 ± 0.9 mm and was significantly larger than all other motion segments (p < 0.05).

CONCLUSIONS

The lower lumbar motion segments L4-5 and L5-S1 showed larger AP and PD translations, respectively, than the higher vertebral motion segments during the weight-lifting motion. The data provide insight into the physiological motion characteristics of the lumbar spine and potential mechanical mechanisms of lumbar disease development.

Proportional lumbar spine inter-vertebral motion patterns: a comparison of patients with chronic, non-specific low back pain and healthy controls

INTRODUCTION

Identifying biomechanical subgroups in chronic, non-specific low back pain (CNSLBP) populations from inter-vertebral displacements has proven elusive. Quantitative fluoroscopy (QF) has excellent repeatability and provides continuous standardised inter-vertebral kinematic data from fluoroscopic sequences allowing assessment of mid-range motion. The aim of this study was to determine whether proportional continuous IV rotational patterns were different in patients and controls. A secondary aim was to update the repeatability of QF measurement of range of motion (RoM) for inter-vertebral (IV) rotation.

METHODS AND MATERIALS

Fluoroscopic sequences were recorded of passive, recumbent coronal and sagittal motion, which was controlled for range and velocity. Segments L2-5 in 40 primary care CNSLBP patients and 40 matched controls were compared. Patients also completed the von Korff Chronic Pain Grade and Roland and Morris Disability Questionnaire. Sequences were processed using automated image tracking algorithms to extract continuous inter-vertebral rotation data. These were converted to continuous proportional ranges of rotation (PR). The continuous proportional range variances were calculated for each direction and combined to produce a single variable representing their fluctuation (CPRV). Inter- and intra-rater repeatability were also calculated for the maximum IV-RoM measurements obtained during controlled trunk motion to provide an updated indication of the reliability and agreement of QF for measuring spine kinematics.

RESULTS

CPRV was significantly higher in patients (0.011 vs. 0.008, Mann-Whitney two-sided p = 0.008), implying a mechanical subgroup. Receiver operating characteristic curve analysis found its sensitivity and specificity to be 0.78 % (60-90) and 0.55 % (37-73), respectively (area under the curve 0.672). CPRV was not correlated with pain severity or disability. The repeatability of maximum inter-vertebral range was excellent, but range was only significantly greater in patients at L4-5 in right side bending (p = 0.03).

CONCLUSION

The variation in proportional motion between lumbar vertebrae during passive recumbent trunk motion was greater in patients with CNSLBP than in matched healthy controls, indicating that biomechanical factors in passive structures play a part.

Lumbar injuries of the pediatric population

Primary musculoskeletal etiologies, such as stress fractures, strains, facet arthropathy, and sacroiliac joint dysfunction, are more common causes of pediatric pain than systemic diseases, both in the office setting and the emergency room. Systemic features, young age, and atypical pain should clue physicians to causes other than a primary musculoskeletal cause and prompt an intensive search for other conditions.

Assessment of three-dimensional lumbar spine vertebral motion during gait with use of indwelling bone pins

BACKGROUND

This study quantifies the three-dimensional motion of lumbar vertebrae during gait via direct in vivo measurement with the use of indwelling bone pins with retroreflective markers and motion capture. Two previous studies in which bone pins were used were limited to instrumentation of two vertebrae, and neither evaluated motions during gait. While several imaging-based studies of spinal motion have been reported, the restrictions in measurement volume that are inherent to imaging modalities are not conducive to gait applications.

METHODS

Eight healthy volunteers with a mean age of 25.1 years were screened to rule out pathology. Then, after local anesthesia was administered, two 1.6-mm Kirschner wires were inserted into the L1, L2, L3, L4, L5, and S1 spinous processes. The wires were clamped together, and reflective marker triads were attached to the end of each wire couple. Subjects underwent spinal computed tomography to anatomically register each vertebra to the attached triad. Subjects then walked several times in a calibrated measurement field at a self-selected speed while motion data were collected.

RESULTS

Less than 4° of lumbar intersegmental motion was found in all planes. Motions were highly consistent between subjects, resulting in small group standard deviations. The largest motions were in the coronal plane, and the middle lumbar segments exhibited greater motions than the segments cephalad and caudad to them. Intersegmental lumbar flexion and axial rotation motions were both extremely small at all levels.

CONCLUSIONS

The lumbar spine chiefly acts to contribute abduction during stance and adduction during swing to balance the relative motions between the trunk and pelvis. The lumbar spine acts in concert with the thoracic spine. While the lumbar spine chiefly contributes coronal plane motion, the thoracic spine contributes the majority of the transverse plane motion. Both contribute flexion motion in an offset phase pattern.

CLINICAL RELEVANCE

This is a valid model for measuring the three-dimensional motion of the spine. Normative data were obtained to better understand the effects of spine disorders on vertebral motion over the gait cycle.

Capturing Three-Dimensional In Vivo Lumbar Intervertebral Joint Kinematics Using Dynamic Stereo-X-Ray Imaging

Availability of accurate three-dimensional (3D) kinematics of lumbar vertebrae is necessary to understand normal and pathological biomechanics of the lumbar spine. Due to the technical challenges of imaging the lumbar spine motion in vivo, it has been difficult to obtain comprehensive, 3D lumbar kinematics during dynamic functional tasks. The present study demonstrates a recently developed technique to acquire true 3D lumbar vertebral kinematics, in vivo, during a functional load-lifting task. The technique uses a high-speed dynamic stereo-radiography (DSX) system coupled with a volumetric model-based bone tracking procedure. Eight asymptomatic male participants performed weight-lifting tasks, while dynamic X-ray images of their lumbar spines were acquired at 30 fps. A custom-designed radiation attenuator reduced the radiation white-out effect and enhanced the image quality. High resolution CT scans of participants' lumbar spines were obtained to create 3D bone models, which were used to track the X-ray images via a volumetric bone tracking procedure. Continuous 3D intervertebral kinematics from the second lumbar vertebra (L2) to the sacrum (S1) were derived. Results revealed motions occurring simultaneously in all the segments. Differences in contributions to overall lumbar motion from individual segments, particularly L2–L3, L3–L4, and L4–L5, were not statistically significant. However, a reduced contribution from the L5–S1 segment was observed. Segmental extension was nominally linear in the middle range (20%–80%) of motion during the lifting task, but exhibited nonlinear behavior at the beginning and end of the motion. L5–S1 extension exhibited the greatest nonlinearity and variability across participants. Substantial AP translations occurred in all segments (5.0 ± 0.3 mm) and exhibited more scatter and deviation from a nominally linear path compared to segmental extension. Maximum out-of-plane rotations (<1.91 deg) and translations (<0.94 mm) were small compared to the dominant motion in the sagittal plane. The demonstrated success in capturing continuous 3D in vivo lumbar intervertebral kinematics during functional tasks affords the possibility to create a baseline data set for evaluating the lumbar spinal function. The technique can be used to address the gaps in knowledge of lumbar kinematics, to improve the accuracy of the kinematic input into biomechanical models, and to support development of new disk replacement designs more closely replicating the natural lumbar biomechanics.

Plastic optical fibre sensor for spine bending monitoring with power fluctuation compensation

This paper presents the implementation of power fluctuation compensation for an intensity-based optical fibre bending sensor aimed at monitoring human spine bending in a clinical environment. To compensate for the light intensity changes from the sensor light source, a reference signal was provided via the light reflection from an aluminum foil surface fixed at a certain distance from the source fibre end tips. From the results, it was found that the investigated sensor compensation technique was capable of achieving a 2° resolution for a bending angle working range between 0° and 20°. The study also suggested that the output voltage ratio has a 0.55% diversion due to input voltage variation between 2.9 V and 3.4 V and a 0.25% output drift for a 2 h measurement. With the achieved sensor properties, human spine monitoring in a clinical environment can potentially be implemented using this approach with power fluctuation compensation.

Measurement of intervertebral motion using quantitative fluoroscopy: report of an international forum and proposal for use in the assessment of degenerative disc disease in the lumbar spine

Quantitative fluoroscopy (QF) is an emerging technology for measuring intervertebral motion patterns to investigate problem back pain and degenerative disc disease. This International Forum was a networking event of three research groups (UK, US, Hong Kong), over three days in San Francisco in August 2009. Its aim was to reach a consensus on how best to record, analyse, and communicate QF information for research and clinical purposes. The Forum recommended that images should be acquired during regular trunk motion that is controlled for velocity and range, in order to minimise externally imposed variability as well as to correlate intervertebral motion with trunk motion. This should be done in both the recumbent passive and weight bearing active patient configurations. The main recommended outputs from QF were the true ranges of intervertebral rotation and translation, neutral zone laxity and the consistency of shape of the motion patterns. The main clinical research priority should initially be to investigate the possibility of mechanical subgroups of patients with chronic, nonspecific low back pain by comparing their intervertebral motion patterns with those of matched healthy controls.