Precision measurement of segmental motion from flexion—extension radiographs of the lumbar spine

doi:10.1016/S0268-0033(96)00039-3

Clinical Biomechanics

Volume 11, Issue 8, December 1996, Pages 457-465

https://doi.org/10.1016/S0268-0033(96)00039-3 Get rights and content

Abstract

Objective. To measure sagittal plane motion of lumbar vertebrae from lateral radiographic views. Previously identified factors of imprecision such as distortion in central projection, off-centre position, axial rotation, and lateral tilt of the spine were compensated.

Study design. This study presents a new protocol to measure sagittal plane rotational and translational motion from lateral flexion-extension radiographs of the lumbar spine.

Background. Conventional methods to determine sagittal plane rotation and translation are prone to error from the distortional effects of the divergence of the radiographic beam and the measurement error inherent in constructing tangents to the contours of the vertebral body. High precision is attained by roentgen-stereophotogrammetric methods, but because of their invasive nature they can be applied only in exceptional cases. Agreement has been reached only in that measurement of sagittal plane motion from lumbar spine flexion-extension radiographs is inaccurate. Normal patterns of sagittal plane motion and the definition of what is an abnormal flexion-extension radiograph have not been settled.

Method. Starting from an analysis of vertebral contours in the lateral view, geometric measures are identified which are virtually independent of distortion, axial rotation or lateral tilt. Applying a new protocol based on those geometric measures, the pattern of translational and rotational motion was determined from flexion—extension radiographs of 61 symptom-free, adult subjects. Measurement errors were quantified in a specimen experiment; a reproducibility study quantified inter- and intraobserver errors.

Results. Magnitude and sign of ‘translation per degree of rotation’ determined from a cohort of 61 adult subjects were very uniform for all levels of the lumbar spine. An auxiliary study evaluating a cohort of 10 healthy subjects where flexion—extension radiographs had been taken standing and side-lying showed no dependence of the rotation/translation pattern on posture. The error study demonstrated errors in angle ranging between 0.7 and 1.6 degrees and errors in displacement ranging between 1.2% and 2.4% of vertebral depth (the largest errors occurring at the $L_{5} S_{1}$ segment). Intra- and interobserver tests showed no or only negligibly small bias and an sd virtually equal to the measurement error multiplied by √2. The relation of displacement to angle observed in the normal cohort can be used in individual cases to predict translational motion depending on the rotation actually performed. A comparison of the predicted translation (determined from normal controls) and the value actually measured allows translational hypo-, normal, or hypermobility to be quantified. Examples illustrate application of the new method in cases of normal, hypo-, and hypermobility and in the case of an instrumented spine.

Conclusions. The results of this study show that precision of the measurement of rotational and translational motion can be considerably enhanced by making allowance for radiographic distortional effects and by minimizing subjective influence in the measurement procedure.

References (29)

FP Morgan et al.
Primary instability of lumbar vertebrae as a common cause of low back pain
J Bone Joint Surg
(1957)
TH Olsson et al.
Vertebral motion in spondylolisthesis
Acta Radiol (Diagn) (Stockh)
(1976)
TH Olsson et al.
Mobility in the lumbosacral spine after fusion studies with the aid of Roentgen stereophotogrammetry
Clin Orthop
(1977)
IAF Stokes et al.
Measurement of movement in painful intervertebral joints
Med Biol Eng Comput
(1980)
IAF Stokes et al.
Assessment of patients with low back pain by biplanar radiographic measurement of intervertebral motion
Spine
(1981)
I Posner et al.
A biomechanical analysis of the clinical stability of the lumbar and lumbosacral spine
Spine
(1982)
TR Lehmann et al.
Instability of the lower lumbar spine
Orthop Transact
(1983)
RC Quinell et al.
Flexion and extension radiography of the lumbar spine. A comparison with lumbar discography
Clin Radiol
(1983)
M Pearcy et al.
Three-dimensional X-ray analysis of normal movement in the lumbar spine
Spine
(1984)
W Keessen et al.
Recordings of the movement at the intervertebral segment L₅−S₁. A technique for the determination of the movement in the L₅−S₁ spinal segment by using three specified postural positions
Spine
(1984)

PR Dupuis et al.

Radiologic diagnosis of degenerative lumbar spinal instability

Spine

(1985)

IAF Stokes et al.

Segmental motion and instability

Spine

(1987)

SD Boden et al.

Lumbosacral segmental motion in normal individuals. Have we been measuring instability properly?

Spine

(1990)

J Dvorak et al.

Functional radiographic diagnosis of the lumbar spine. Flexion-extension and lateral bending

Spine

(1991)

Cited by (125)

A novel tool to quantify in vivo lumbar spine kinematics and 3D intervertebral disc strains using clinical MRI
2023, Journal of the Mechanical Behavior of Biomedical Materials
Medical imaging modalities that calculate tissue morphology alone cannot provide direct information regarding the mechanical behaviour of load-bearing musculoskeletal organs. Accurate in vivo measurement of spine kinematics and intervertebral disc (IVD) strains can provide important information regarding the mechanical behaviour of the spine, help to investigate the effects of injuries on the mechanics of the spine, and assess the effectiveness of treatments. Additionally, strains can serve as a functional biomechanical marker for detecting normal and pathologic tissues. We hypothesised that combining digital volume correlation (DVC) with 3T clinical MRI can provide direct information regarding the mechanics of the spine. Here, we have developed a novel non-invasive tool for in vivo displacement and strain measurement within the human lumbar spine and we used this tool to calculate lumbar kinematics and IVD strains in six healthy subjects during lumbar extension. The proposed tool enabled spine kinematics and IVD strains to be measured with errors that did not exceed 0.17 mm and 0.5%, respectively. The findings of the kinematics study identified that during extension the lumbar spine of healthy subjects experiences total 3D translations ranging from 1 mm to 4.5 mm for different vertebral levels. The findings of strain analysis identified that the average of the maximum tensile, compressive, and shear strains for different lumbar levels during extension ranged from 3.5% to 7.2%. This tool can provide base-line data that can be used to describe the mechanical environment of healthy lumbar spine, which can help clinicians manage preventative treatments, define patient-specific treatments, and to monitor the effectiveness of surgical and non-surgical interventions.
Novel force–displacement control passive finite element models of the spine to simulate intact and pathological conditions; comparisons with traditional passive and detailed musculoskeletal models
2022, Journal of Biomechanics
Citation Excerpt :
The trunk weight of ∼344 N (corresponding to a body mass of ∼68 kg) is partitioned among upper arms (∼36 N), forearms/hands (∼29 N), head (46 N) and T1–L5 segments (∼233 N) that are applied via rigid elements at their centers of mass. For each simulated task (in neutral upright standing and flexions as described below), the measured sagittal rotations of thorax and pelvis (Arjmand et al., 2010, 2009) and individual lumbar vertebra (Arjmand et al., 2010; Dvořák et al., 1991; Frobin et al., 1996) are prescribed into the model (Ebrahimkhani et al., 2021). An optimization algorithm minimizing sum of cubed muscle stresses is used to determine unknown muscle forces.
Passive finite element (FE) models of the spine are commonly used to simulate intact and various pre- and postoperative pathological conditions. Being devoid of muscles, these traditional models are driven by simplistic loading scenarios, e.g., a constant moment and compressive follower load (FL) that do not properly mimic the complex in vivo loading condition under muscle exertions. We aim to develop novel passive FE models that are driven by more realistic yet simple loading scenarios, i.e., in vivo vertebral rotations and pathological-condition dependent FLs (estimated based on detailed musculoskeletal finite element (MS-FE) models). In these novel force–displacement control FE models, unlike the traditional passive FE models, FLs vary not only at different spine segments (T12-S1) but between intact, pre- and postoperative conditions. Intact, preoperative degenerated, and postoperative fused conditions at the L4-L5 segment for five static in vivo activities in upright and flexed postures were simulated by the traditional passive FE, novel force–displacement control FE, and gold-standard detailed MS-FE spine models. Our findings indicate that, when compared to the MS-FE models, the force–displacement control passive FE models could accurately predict the magnitude of disc compression force, intradiscal pressure, annulus maximal von Mises stress, and vector sum of all ligament forces at adjacent segments (L3-L4 and L5-S1) but failed to predict disc shear and facet joint forces. In this regard, the force–displacement control passive FE models were much more accurate than the traditional passive FE models. Clinical recommendations made based on traditional passive FE models should, therefore, be interpreted with caution.
Effect of changes in the lumbar posture in lifting on trunk muscle and spinal loads: A combined in vivo, musculoskeletal, and finite element model study
2020, Journal of Biomechanics
Irrespective of the lifting technique (squat or stoop), the lumbar spine posture (more kyphotic versus more lordotic) adopted during lifting activities is an important parameter affecting the active-passive spinal load distribution. The advantages in either posture while lifting remains, however, a matter of debate. To comprehensively investigate the role on the trunk biomechanics of changes in the lumbar posture (lordotic, free or kyphotic) during forward trunk flexion, validated musculoskeletal and finite element models, driven by in vivo kinematics data, were used to estimate detailed internal tissue stresses-forces in and load-sharing among various joint active-passive tissues. Findings indicated that the lordotic posture, as compared to the kyphotic one, resulted in marked increases in back global muscle activities (~14–19%), overall segmental compression (~7.5–46.1%) and shear (~5.4–47.5%) forces, and L5-S1 facet joint forces (by up to 80 N). At the L5-S1 level, the lordotic lumbar posture caused considerable decreases in the moment resisted by passive structures (spine and musculature, ~14–27%), negligible reductions in the maximum disc fiber strains (by ~0.4–4.7%) and small increases in intradiscal pressure (~1.8–3.4%). Collectively and with due consideration of the risk of fatigue and viscoelastic creep especially under repetitive lifts, current results support a free posture (in between the extreme kyphotic and lordotic postures) with moderate contributions from both active and passive structures during lifting activities involving trunk forward flexion.
Hypersensitivity of trunk biomechanical model predictions to errors in image-based kinematics when using fully displacement-control techniques
2019, Journal of Biomechanics
Recent advances in medical imaging techniques have allowed pure displacement-control trunk models to estimate spinal loads with no need to calculate muscle forces. Sensitivity of these models to the errors in post-imaging evaluation of displacements (reported to be ∼0.4–0.9° and 0.2–0.3 mm in vertebral displacements) has not yet been investigated. A Monte Carlo analysis was therefore used to assess the sensitivity of results in both musculoskeletal (MS) and passive finite element (FE) spine models to errors in measured displacements. Six static activities in upright standing, flexed, and extended postures were initially simulated using a force-control hybrid MS-FE model. Computed vertebral displacements were subsequently used to drive two distinct fully displacement-control MS and FE models. Effects of alterations in the reference vertebral displacements (at 3 error levels with SD (standard deviation) = 0.1, 0.2, and 0.3 mm in input translations together with, respectively, 0.2, 0.4, and 0.6° in input rotations) were investigated on the model predictions. Results indicated that outputs of both models had substantial task-dependent sensitivities to errors in the measured vertebral translations. For instance, L5-S1 intradiscal pressures (IDPs) were considerably affected (SD values reaching 1.05 MPa) and axial compression and shear forces even reversed directions as translation errors increased to 0.3 mm. Outputs were however generally much less sensitive to errors in measured vertebral rotations. Accounting for the accuracies in image-based kinematics measurements, therefore, it is concluded that the current measured vertebral translation errors at and beyond 0.1 mm are too large to drive biomechanical models of the spine.
Knowledge extraction from medical imaging for advanced patient-specific musculoskeletal models
2019, Encyclopedia of Biomedical Engineering
The objective of this article is to address the methodology developed to model the musculoskeletal systems with material, geometry, forces knowledge extracted from medical imaging. For hard tissue, from computed tomography personalized bone mechanical properties could be extracted and moreover its follow up could provide data for validation of patient-specific predictions. For soft tissue, mechanical, physical, and biochemical properties can be extracted from magnetic resonance imaging (MRI). Advanced MRI such as dynamic MRI and magnetic resonance elastrography allowed, respectively, to analyze the in vivo forces generated by the muscles in movement but also its mechanical properties in passive and active behavior. Based on these knowledges, patient-specific geometry, mechanical properties, and forces assessed are derived from advanced medical imaging techniques. These data are of importance for developing patient-specific computer modeling for prediction and evaluation of therapeutic, surgical, or functional rehabilitation treatments. Notions of reliability of the numerical models and uncertainty are addressed in order to provide an objective tool for aided decision support system to clinicians. Clinical applications will be given as illustrative examples.
Motion analysis of the cervical spine during extension and flexion: Reliability of the vertebral marking procedure
2018, Medical Engineering and Physics
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 $- 0 . 12^{\circ}$ (standard deviation: 0.88°), and the intraexaminer error ranged from $- 1 . 00^{\circ}$ 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.

View all citing articles on Scopus

View full text

PaperPrecision measurement of segmental motion from flexion—extension radiographs of the lumbar spine

Abstract

Primary instability of lumbar vertebrae as a common cause of low back pain

J Bone Joint Surg

Vertebral motion in spondylolisthesis

Acta Radiol (Diagn) (Stockh)

Mobility in the lumbosacral spine after fusion studies with the aid of Roentgen stereophotogrammetry

Clin Orthop

Measurement of movement in painful intervertebral joints

Med Biol Eng Comput

Assessment of patients with low back pain by biplanar radiographic measurement of intervertebral motion

Spine

A biomechanical analysis of the clinical stability of the lumbar and lumbosacral spine

Spine

Instability of the lower lumbar spine

Orthop Transact

Flexion and extension radiography of the lumbar spine. A comparison with lumbar discography

Clin Radiol

Three-dimensional X-ray analysis of normal movement in the lumbar spine

Spine

Recordings of the movement at the intervertebral segment L5−S1. A technique for the determination of the movement in the L5−S1 spinal segment by using three specified postural positions

Spine

Radiologic diagnosis of degenerative lumbar spinal instability

Spine

Segmental motion and instability

Spine

Lumbosacral segmental motion in normal individuals. Have we been measuring instability properly?

Spine

Functional radiographic diagnosis of the lumbar spine. Flexion-extension and lateral bending

Spine

Paper
Precision measurement of segmental motion from flexion—extension radiographs of the lumbar spine

Recordings of the movement at the intervertebral segment L₅−S₁. A technique for the determination of the movement in the L₅−S₁ spinal segment by using three specified postural positions