Using cineradiography for continuous dynamic-motion analysis of the lumbar spine

Continuous dynamic spinal motion analysis

STUDY DESIGN

Continuous dynamic lumbar intervertebral flexion-extension is assessed by a videofluoroscopy with a new auto-tracking system.

OBJECTIVES

To develop and validate a new method for the continuous assessment of lumbar kinematics.

SUMMARY OF BACKGROUND DATA

Instability of the lumbar spine is thought to be associated with low back pain, but the diagnosis remains difficult. Functional radiographs have been used for diagnosis of spinal instability but error and limitation exist, whereas videofluoroscopy provides a cost-effective way for such analysis. However, common approaches of image analysis of videofluoroscopic video are tedious and time-consuming because of the low quality of the images. Physicians have to extract the vertebrae manually in most cases; thus, continuous motion analysis is hardly achieved.

METHODS

A new system that can perform automatic vertebrae segmentation and tracking is developed. In vitro and in vivo validity were evaluated. Intervertebral flexion and extension was assessed in 30 healthy volunteers.

RESULTS

In vitro and in vivo validity tests have been conducted with good results. A linear-liked pattern of the intervertebral flexion-extension (IVFE) curves in different levels was found, and the IVFE decreased in descending order from L1-L5 at different points of range of motion in flexion. Conversely, extension is evenly contributed at different levels, and the concavity of lumbar lordosis increases steadily in backward movement.

CONCLUSIONS

The newly developed technique in assessing the dynamic lumbar motion is reliable and able to analyze the lumbar intervertebral movement from videofluoroscopic images automatically and accurately. The proposed system requires less human intervention than common approaches. It may have a potential value in the evaluation of spinal "instability" in clinical practice.

Subjective and objective descriptors of clinical lumbar spine instability: A Delphi study

Accurate ability to diagnose lumbar spine clinical instability is controversial for numerous reasons, including inaccuracy and limitations in capabilities of radiographic findings, poor reliability and validity of clinical special tests, and poor correlation between spinal motion and severity of symptoms. It has been suggested that common subjective and objective identifiers are specific to lumbar spine clinical instability. The purpose of this study was to determine if consensual, specific identifiers for subjective and objective lumbar spine clinical instability exist as determined by a Delphi survey instrument. One hundred and sixty eight physical therapists identified as Orthopaedic Clinical Specialists (OCS) or Fellows of the American Academy of Orthopaedic Manual Physical Therapists participated in three Delphi rounds designed to select specific identifiers for lumbar spine clinical instability. Round I consisted of open-ended questions designed to provide any relevant issues. Round II allowed the participants to rank the organized findings of Round I. Round III provided an opportunity to rescore the ranked variables after viewing other participant's results. The results suggest that those identifiers selected by the Delphi experts are synonymous with those represented in related spine instability literature and may be beneficial for use during clinical differential diagnosis.

Spondylolisthesis with postural slip reduction shows different motion patterns with video-fluoroscopic analysis

To compare the motion of lumbar spondylolisthesis between the standing and decubitus positions and to identify the radiological parameters concerning segmental instability, the lumbar sagittal motion of 5 volunteers and 14 patients was recorded using video-fluoroscopy in both positions. Still images at three frames per second were captured, and the motion pattern was compared between the two positions. Patients were classified into two subgroups according to the degree of postural slip reduction. In the volunteer group, the motion patterns were not particularly different between the two positions. In the small postural reduction group, the motion patterns were not particularly different between the two positions, except in one patient for whom the range of motion (ROM) at the upper adjacent level increased in the decubitus position. In the large postural reduction group, a motion pattern change was observed. The ROM at the slip level in three patients increased, and in the remaining four patients the angle at the midpoint in ROM at the slip level shifted to the extension side in the decubitus position. This condition (anterior slip being reduced in the supine position, with disc angle and average disc height increased) is thought to result from anterior column deficiency and the vertical laxity of the surrounding soft tissues. A biomechanically stable fusion technique is recommended for surgical management.

Factors associated with physiotherapists' confidence during assessment of clinical cervical and lumbar spine instability

BACKGROUND AND PURPOSE

Physiotherapists commonly encounter patients with complaints of vague, indistinguishable neck and back pain, such as clinical spine instability. Since confidence is a component of expert clinical practice, we were interested in measuring expert clinicians' confidence in diagnosing and assessing clinical spine instability. The aims of the present study were to factor out the common 'identifiers' associated with physiotherapists' objective, physical diagnosis and assessment of clinical spine instability, and to determine the association of reported diagnostic confidence to these identifiers.

METHOD

The study used data from a Delphi instrument for the factor analysis and a survey of APTA Board-certified orthopaedic specialists for report of confidence. Using an ologit regression analysis, the identifier themes and clinical background characteristics were associated with confidence in diagnosis of clinical spine instability.

RESULTS

Only clinical cervical spine instability obtained significant findings. The identifier 'observable or palpable abnormalities of motion during movement assessment in clinical practice' was positively associated with reported confidence in diagnosis, as was the influence of manual therapy background models: Cyriax, Maitland, McKenzie, NAIOMPT, Osteopathic, Paris and other. Male gender yielded negative association with reported confidence. No factors were associated with reported lumbar confidence.

CONCLUSIONS

Multiple backgrounds of physiotherapists demonstrate confidence in detecting clinical spine instability using observable or palpable methods to detect abnormal movements.

Lumbar spine intersegmental motion analysis during lifting

There are a lot of in vitro and also in vivo studies under strictly restricted and subject-demanding laboratory conditions using X-ray or MRI recordings, but very few studies give information about the lumbar spine intersegmental behavior in daily life activities. Aims of this study were to measure the intersegmental lumbar spine motions during lifting trials and to determine the different motion patterns of different subjects performing comparable lifting tasks. First, 11 healthy volunteers had to perform lifting tasks (box weight 4-15 kg) using their favorite lifting technique (no instructions by the researcher). The coordinates of skin-markers attached on lumbar spines of the subjects were measured using 3D-motion capturing and then transformed to Cardan-angles. Second, 23 volunteers performed lifting tasks (box weight 4-15 kg) with the instruction to bend their knees during lifting. Coordinates of this smaller set of markers on lumbar spines of the subjects were transformed to intersegmental angles using a spline-method. From the first experiment three groups of motion patterns are distinguishable: subjects who used only small intersegmental range of motion within their upper lumbar spine and bended their knees during lifting were in contrast to subjects who used 3.25 times wider range of motion in the upper lumbar spine and did not bend the knees (cluster analysis, c = 0.76). The third group was not assignable to these other two groups. Within all lifting trials of the second experiment different groups were detectable also: in spite of all subjects bended their knees, there were subjects with wide range of motion of lumbar spine motion segments. Other subjects were able to reduce intersegmental range of motion (k-means clustering, msv > 0.47). From this it follows that the intersegmental motion of lumbar spine is individually different and not equal for all lumbar levels. Furthermore, lifting technique influenced the motion of the lumbar spine. But not for all subjects, the advice to bend the knees during the lifting effectively reduced the lumbar motion ranges.

IN CONCLUSION

special instructions to reduce lumbar spinal motion are recommended. Due to different lumbar spine motion patterns, different loading situations are anticipated because of changing lever arms and angular accelerations. This understanding is important in reducing spinal loading and to prevent spinal disorders in manual material handling tasks.

Spine biomechanics

Current trends in spine research are reviewed in order to suggest future opportunities for biomechanics. Recent studies show that psychosocial factors influence back pain behaviour but are not important causes of pain itself. Severe back pain most often arises from intervertebral discs, apophyseal joints and sacroiliac joints, and physical disruption of these structures is strongly but variably linked to pain. Typical forms of structural disruption can be reproduced by severe mechanical loading in-vitro, with genetic and age-related weakening sometimes leading to injury under moderate loading. Biomechanics can be used to quantify spinal loading and movements, to analyse load distributions and injury mechanisms, and to develop therapeutic interventions. The authors suggest that techniques for quantifying spinal loading should be capable of measurement "in the field" so that they can be used in epidemiological surveys and ergonomic interventions. Great accuracy is not required for this task, because injury risk depends on tissue weakness as much as peak loading. Biomechanical tissue testing and finite-element modelling should complement each other, with experiments establishing proof of concept, and models supplying detail and optimising designs. Suggested priority areas for future research include: understanding interactions between intervertebral discs and adjacent vertebrae; developing prosthetic and tissue-engineered discs; and quantifying spinal function during rehabilitation. "Mechanobiology" has perhaps the greatest future potential, because spinal degeneration and healing are both mediated by the activity of cells which are acutely sensitive to their local mechanical environment. Precise characterisation and manipulation of this environment will be a major challenge for spine biomechanics.

A new technique for digital fluoroscopic video assessment of sagittal plane lumbar spine motion

STUDY DESIGN

Methodological reliability.

OBJECTIVE

Develop a measurement technique to assess dynamic motion of the lumbar spine using enhanced digital fluoroscopic video (DFV) and a distortion compensated roentgen analysis (DCRA).

SUMMARY OF BACKGROUND DATA

Controversy over both the definition and consequences of lumbar segmental instability persists. Information from static imaging has had limited success in providing an understanding of this disorder. DFV has the potential to provide further information about lumbar segmental instability; however, the image quality is poor and clinical application is limited.

METHODS

DFV from 20 male subjects (11 with and nine without low back pain) were obtained during eccentric lumbar flexion (30 Hz). Each DFVs was enhanced with a series of filters to accentuate the vertebral edges. An adapted DCRA algorithm was applied to determine segmental angular and linear displacement. Both intraimage and interimage reliability were assessed using intraclass correlation coefficients (ICC) and standard error of the measurement (SEM). RESULTS.: Intraimage reliability yielded an average ICC of 0.986, and the SEM ranged from 0.4-0.7 degrees and 0.2-0.3 mm. Interimage reliability yielded an average ICC of 0.878, and the SEM ranged from 0.7-1.4 degrees and 0.4-0.7 mm.

CONCLUSIONS

Enhanced DFV combined with a DCRA resulted in reliable assessment of lumbar spine kinematics. The error values associated with this technique were low and were comparable to published error measurements obtained when using a similar algorithm on hand-drawn outlines from static radiographs.

Upright, weight-bearing, dynamic-kinetic MRI of the spine: initial results

The potential relative beneficial aspects of upright, weight-bearing (pMRI), dynamic-kinetic (kMRI) spinal imaging over that of recumbent MRI (rMRI) include the revelation of occult spinal disease dependent on true axial loading, the unmasking of kinetic-dependent spinal disease and the ability to scan the patient in the position of clinically relevant signs and symptoms. This imaging unit under study also demonstrated low claustrophobic potential and yielded comparatively high resolution images with little motion/magnetic susceptibility/chemical shift artifact. Overall, it was found that rMRI underestimated the presence and maximum degree of gravity-dependent spinal pathology and missed altogether pathology of a dynamic nature, factors that are optimally revealed with p/kMRI. Furthermore, p/kMRI enabled optimal linkage of the patient's clinical syndrome with the medical imaging abnormality responsible for the clinical presentation, thereby allowing for the first time an improvement at once in both imaging sensitivity and specificity.

Modelling and simulation of the intervertebral movements of the lumbar spine using an inverse kinematic algorithm

An inverse kinematic model is presented that was employed to determine the optimum intervertebral joint configuration for a given forward-bending posture of the human trunk. The lumbar spine was modelled as an open-end, kinematic chain of five links that represented the five vertebrae (L 1-L5). An optimisation equation with physiological constraints was employed to determine the intervertebral joint configuration. Intervertebral movements were measured from sagittal X-ray films of 22 subjects. The mean difference between the X-ray measurements of intervertebral rotations in the sagittal plane and the values predicted by the kinematic model was less than 1.6 degrees. Pearson product-moment correlation R was used to measure the relationship between the measured and predicted values. The R-values were found to be high, ranging from 0.83 to 0.97, for prediction of intervertebral rotation, but poor for intervertebral translation (R= 0.08-0.67). It is concluded that the inverse kinematic model will be clinically useful for predicting intervertebral rotation when X-ray or invasive measurements are undesirable. It will also be useful to biomechanical modelling, which requires accurate kinematic information as model input data.

Intervertebral mobility in the progressive degenerative process. A radiostereometric analysis

Three separate stages have previously been defined in the progressive degenerative process. The first stage, characterized as temporary dysfunction with early degenerative findings, transforms into a second period of segmental instability evidenced by a resulting deformity. With the deformity the process has reached a late stage of definitive stabilization induced by osteoligamentary repair mechanisms. To test the validity of this three-stage hypothesis, we assessed the intervertebral mobility for the two most-distal lumbar disc levels in 18 adult patients with low back pain, disc degenerative findings and no prior spinal surgery. Each spinal segment was categorized according to grade of disc degeneration: (IA) normal disc height without dehydration; (IB) normal disc height with dehydration; (II) disc height decreased by less than 50%; (III) disc height decreased by at least 50%; and (IV) disc height obliterated. The intervertebral mobility was measured by radiostereometric analysis (RSA) and compared between the categories. With the patient changing position from supine to sitting, the mean vertical translation across the 11 discs categorized as IA was 2.0 mm. A small increase in mean vertical mobility with progressive loss of disc height through the degenerative stages IB (2.2 mm, seven discs) and II (2.6 mm, ten discs) was not significant. Further degeneration to grade III meant a significant mean reduction in vertical mobility to 0.8 mm for the eight discs in that category. No discs were classified as obliterated, category IV. The corresponding values for sagittal translations were 3.0 mm, 3.1 mm, 3.6 mm and 1.7 mm for the four disc categories found. These alterations were not statistically significant. We conclude that intervertebral mobility changes throughout the degenerative process, and a stage of stabilization begins when disc height is reduced by 50%. The segmental mobility status cannot be deduced from the radiographic, degenerative disc stage, since the inter-individual differences in mobility are pronounced for the same disc status. A fully stable situation cannot be taken for granted, even when the disc is reduced by more than 50%, considering the fact that some persisting mobility was seen for most patients in category III. A preceding stage of instability, in the clinical situation proven by a resulting deformity, was not verified in this study.

The flexion-extension profile of lumbar spine in 100 healthy volunteers

STUDY DESIGN

Dynamic lumbar flexion-extension motions were assessed by an electrogoniometer and a videofluoroscopy unit simultaneously.

OBJECTIVES

The aims of this study were to assess the motion profile of lumbar spine in different genders and age groups and to assess their differences. SUMMARY OF BACKGROUNDS DATA: The dynamic lumbar flexion-extension motions analysis method has been developed and validated. However, data profile of the spinal motions of healthy volunteers has not been established. METHODS.: A total of 100 healthy volunteers, including 50 men and 50 women, were recruited. They were then divided into four equal groups, following their age ranges of 21 to 30 years, 31 to 40 years, 41 to 50 years, and 51 years and older. Lumbar flexion-extension motion was assessed with an electrogoniometer and videofluoroscopy simultaneously. Radiologic images of the lumbar spine were captured during flexion-extension in 10 degrees intervals. Intervertebral flexion-extension (IVFE) of each vertebral level was calculated. The spinal motion of different genders was compared segment by segment with independent t test. The spinal motion of different age groups was compared with one-way analysis of variance.

RESULTS

A linear-liked pattern of the IVFE curves was observed in different genders and age groups. No statistically significant difference in the pattern of motion was found between genders. However, statistically significant difference in the slope of IVFE curves was found at all lumbar levels in subjects whose age was 51 years or older (P < 0.05).

CONCLUSIONS

Assessment of motion profile was found to be helpful for the identification of spinal disorders in clinical practice. Because of the normal variation of spinal motion of subjects in different age ranges, interpretation of spinal motion disorders should be careful. Although the sample size in this study was limited, the database generated might be useful to assist the diagnosis of spinal "instability" in the future.