Purpose and background

Recent research has identified possible functional biomarkers in chronic, nonspecific back pain (CNSLBP) based on intervertebral kinematics. Although excessive IV-RoM is no longer regarded as a clear motion abnormality, some studies have found subtle kinematic measures such as mid-range laxity and motion sharing inequality to be greater in CNSLBP patients. We studied a group of such patients who were investigated following failed interventions in terms of these subtle measures.

Background

Dynamic measurement of continuous intervertebral motion in low back pain (LBP) research in-vivo is developing. Lumbar motion parameters with the features of biomarkers are emerging and show promise for advancing understanding of personalised biometrics of LBP. However, measurement of changes over time inevitably involve error, due to subjects' natural variation and/or variation in the measurement process. Thus, intra-subject repeatability of parameters to measure changes over time should be established.

Purpose and background

Identifying features in nonspecific low back pain (NSLBP) subjects that distinguish them from controls, or for elucidating subgroups, has proved elusive. Yet these would be helpful to monitor progress, improve management, and understand the nature of the condition. Previous work using quantitative videofluoroscopy (QF) has indicated that the distribution of motion between lumbar intervertebral joints is more uneven in those with a history of NSLBP. However, there maybe other features of these complex motion patterns yet to be revealed. A multivariate analysis was therefore carried out to explore other possible differences.

Purpose and Background:

Despite the rise of back pain disability, objective mechanical assessment is generally lacking. Quantification of intervertebral kinematics using fluoroscopy provides objective measurement, but its use in clinical practice has not been assessed. This study reviewed cases referred to one UK site for lumbar spine quantitative fluoroscopic (QF) examinations and compared the reasons for referral with the findings reported.

Purpose and Background:

To compare static and dynamic lumbar intervertebral ranges of motion (IV-RoM) in patients with chronic, nonspecific low back pain with upper and lower cut off values derived from healthy controls when variability and measurement errors were reduced.

Measurements from functional radiographs suffer from high variability and measurement errors, making cut off values for excessive or insufficient motion problematical. This study compared maximum lumbar IV-RoM and maximum IV-RoM at any point in continuous motion sequences in patients with chronic, non-specific back pain with upper and lower cut off values for L2 to L5 from matched controls using quantitative fluoroscopy, where variation and measurement errors were reduced.

Background and purpose

Investigating inter-vertebral biomechanics in vivo using end-of-range imaging is difficult due to high intra subject variation, measurement errors and insufficient data. Quantitative fluoroscopy (QF) can reliably measure continuous motion but may suffer from contamination from uncontrolled loading and muscle contraction which compromises comparisons between studies and limits interpretation of results. This study presents the methods used to overcome these limitations.

Study Purpose

A preliminary study to compare continuous sagittal plane lumbar inter-vertebral kinematics in 10 healthy volunteers in recumbent and weight bearing configurations using quantitative fluoroscopy.

Background and Purpose: The majority of non-specific low back pain is presumed to be mechanical in origin. Many interventions, including manipulation, mobilisation, core strengthening and rigid/motion preserving surgery rely on the premise that intervertebral motion is related to pain in some patients, however, there is no reliable in vivo experimental evidence for this. We compared continuous intervertebral motion from quantitative digital fluoroscopic sequences in asymptomatic controls and patients with chronic non-specific low back pain to investigate associations between pain and intervertebral motion.

Methods: Thirty asymptomatic volunteers and 21 patients with chronic non-specific low back pain underwent passive, controlled, recumbent lateral bending motion during video-fluoroscopic screening. These provided 90 and 44 intervertebral levels from L2-L5 respectively for analysis. Vertebrae were registered digitally and automatically tracked throughout the motion. Inter-vertebral rotation phenotypes for each left-right sequence were obtained and analysed for stiffness (inter-vertebral motion of less than 3o), lax appearance and paradoxical motion. A similar population underwent sEMG studies to determine if muscle activity was present during controlled passive recumbent motion. Associations between pain and stiffness, lax appearance and paradoxical motion were calculated from chi-squared distributions. A subset of patients also had MR scans to assess disc degeneration.

Conclusion: Stiffness was observed significantly more frequently in patients with pain, as was paradoxical motion and lax appearance. sEMG activity was very small throughout motion in both groups. MR degeneration was not associated with stiffness in patients. Results must, however, be regarded as preliminary as greater normative referencing, group matching, more extensive kinematic analysis, flexion-extension, weight-bearing, and clinical outcomes studies are needed.

Background: Intervertebral motion is often assumed to be altered with back pain, however, the patterns are inaccessible to measurement in live subjects. A method for digitally tracking and analysing fluoroscopic images of the vertebrae of subjects who are undergoing standardised passive motion has recently been brought into clinical use for the assessment of surgical fusions. We have studied the differences between the behaviour of spinal linkages in subjects who are asymptomatic, and those who have had fusion operations. This paper describes the reliability, ranges and qualitative features of intervertebral motion patterns in 27 asymptomatic subjects and 3 fusion patients.

Methods and results: Thirty asymptomatic male volunteer subjects aged 19–40, underwent 2 –20 second sessions of fluoroscopic screening during 80 degrees of lumbar spine bending within 20 minutes of each other. Intervertebral sidebending motion from L2–5 was measured in 27 subjects whose images were judged suitable for tracking. Approximately 120 digitised images throughout each motion sequence were analysed 5 times by 2 blinded observers for intervertebral range and each result averaged. The intra-subject biological error (RMS), for range of intervertebral motion was 2.75° for Observer1 and 2.91° for Observer 2. The interobserver error for tracking the same screenings was 1.86° (RMS). At almost all levels, these motion patterns were remarkably regular.

Four male patients aged 33, 44, 45 and 52 years, who had undergone different spinal stabilisation procedures consisting of flexible stabilisation (DNESYS), posterior instrumented fusion, and anterior interbody fusion with facet fixation were investigated. Images were acquired and analysed in the same way except that a larger number of images (500 per screening) was utilised in each case. Four operated levels and 2 adjacent levels were analysed. All motion patterns were easily distinguishable from those of the normal subjects. The PLIF and DYNESYS stabilisations demonstrated no motion at the instrumented levels. The anterior inter-body fusion-transfacet fixation patient was shown to have developed a pseudarthrosis.

Conclusions: Detailed lumbar intervertebral bending patterns in asymptomatic subjects were distinguishable from the fused and adjacent-to fused segments in operated patients. Results suggest that there is sufficient reliability in the method to evaluate lumbar intersegmental ranges and motion patterns for fusion assessment.

Background: The prospect of a second operative procedure following an apparently unsuccessful spinal fusion is an unwelcome one. Since 1987, we have worked to develop an objective method of measuring the motion between vertebrae from fluoroscopic images. Successive versions have been evaluated for their reliability and validity. However, only the current one combines sufficiently reduced operator interaction with acceptable error limitation to be operationally useful as a tool for reporting findings about graft integrity for spinal surgeons. The current work brings this to an advanced prototype stage.

Methods and results: The measurement of lumbar intervertebral coronal and saggital plane motion in vivo using this technique is in 3 stages: Fluoroscopic screening of patients lying on a passive motion table Co-ordinated real-time digital acquisition of the intensifier images.

Registration of the images of each vertebra by templates which are automatically tracked and whose output is converted to inter-vertebral kinematic parameters and averaged for display and reporting.

Results are currently displayed as inter-vertebral angles throughout the motion that indicate whether or not solid fusion has been achieved. The Instrument Measurement Error is quantifiable and will vary with image quality, but can be improved by averaging. The technology is applicable to any imaging system of sufficient speed and resolution and may, for example, be used with MR in the future.

Conclusions: An advanced prototype version of this device is now approaching readiness for service as a routine procedure for use by specially trained radiographers. Its limitations will be determined mainly by the quality of the intensifier images. This can be expected, in the future, to benefit from yet further advances in the technology.