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Biomedical subjects

S A Gracovetsky

Publications and source records attributed to S A Gracovetsky.

12 recordsLinked to original sources
PubMed2000

Relationship between functional evaluation measures and self-assessment in nonacute low back pain.

STUDY DESIGN: The correlations between objective biomechanical indicators of function and self-assessment scores were examined retrospectively for 91 subjects with nonacute low back pain. OBJECTIVES: To examine the correlation between self-assessment, trunk range of motion (ROM), velocity, and complex mechanical coordination patterns of the spine in nonacute low back pain. SUMMARY OF BACKGROUND DATA: In low back pain, there is often little concordance between pain, physical impairment, and disability. Use of range of motion and velocity to enhance objectivity in impairment evaluations has been ineffectual. In this study, two hypotheses were examined: range of motion and velocity are controllable and inherently correlated with self-assessment; complex spinal coordination patterns such as range of lordosis cannot be controlled and are independent of self-assessment. METHODS: Self-assessment questionnaires were administered, and indexes of spinal motion and coordination were measured through skin marker kinematics. The correlation between self-assessments and biomechanical measures was determined. RESULTS: Self-assessments of function were significantly correlated with parameters prone to regulation: range of motion, velocity, and load lifted. In contrast, little correlation was found with measures of complex spinal coordination less susceptible to conscious or affective regulation, namely, range of lordosis and estimated segmental mobility. This effect was magnified with increased load. Self-assessment scores were significantly poorer among insurance referrals, regardless of functional status. CONCLUSIONS: Simple parameters of the functional examination, such as range of motion and velocity, are strongly correlated with cognitive state, and thus the information they supply is less than ideal. Complex spinal coordination is a better indicator of the degree of spinal dysfunction and enhances the process of differentiating between pain, disability, and functional impairment.

Adult↗
PubMed1999

Improving the evaluation of benign low back pain.

STUDY DESIGN: A prospective, blind study was conducted to investigate the factors underlying the decisions of expert clinicians in diagnosis of acute, benign low back pain, compared with results obtained with an automated physical examination by machine. From the results, a strategy to significantly improve clinical diagnosis in cases of discordance was determined. OBJECTIVES: To identify factors in the clinical assessment of low back pain that indicate when independent diagnostic testing would be useful. SUMMARY OF BACKGROUND DATA: The clinical evaluation of low back pain is often dominated by subjective reports of pain. Published medical literature has underscored several inherent weaknesses of the clinical examination, and concerns have been raised about its effectiveness for assessing patients with low back pain. Thus, it has been proposed that objective measures to complement the clinician's examination would be beneficial in the formulation of dependable diagnoses. METHODS: Randomly designated subjects, who in describing their conditions were objective or role playing, were assessed by clinicians and a machine for diagnosis of low back pain assessment versus normal backs. Each subject's pain assessment was compared with a gold standard that was established by experts in low back pain. Components of the clinical examination were analyzed to assess which were the most informative in making a reliable diagnosis. The information content of the machine assessment was also analyzed and a strategy to complement the clinical diagnosis with the machine diagnosis determined. RESULTS: Discordance among the various components of the clinical examination was a strong indicator of when the efficacy of the clinical examination dropped below a random level of decision making. When there was discordance, incorporating the functional evaluation by machine into the clinical diagnosis improved the performance of the clinician. Notably, in nonobjective subjects, the accuracy of diagnosis was enhanced by as much as 69%. CONCLUSIONS: It is possible to improve the accuracy of clinical diagnosis by incorporating a functional evaluation by machine when there is discordance between physical examination findings and reported pain.

Acute Disease↗
PubMed1998

Evaluation of clinician and machine performance in the assessment of low back pain.

STUDY DESIGN: A prospective blind study to test and compare the performance of clinicians (evaluators) with that of an automated machine (the Spinoscope) in conducting an examination on randomly designated simulators/dissimulators and honest subjects to assess acute benign low back pain. OBJECTIVES: To test the impact of reported pain and history on the clinical examination and to compare the ability of clinicians and the machine to recognize normal findings in a controlled group of subjects with and without benign low back pain. BACKGROUND: The literature raises serious questions regarding the efficacy of the clinical examination for patients with low back pain. METHODS: A "gold standard" (clinical examination by experts in low back pain) was established against which the clinical examination by the evaluators and the machine assessment (incorporating weight-lifting ability) of honest subjects and simulators/dissimulators were compared using the receiver operating characteristic technique. The selection of subjects was performed according to strict inclusion and exclusion criteria. RESULTS: The evaluators were more accurate with the honest subjects, the machine more accurate with the simulators/dissimulators, and, for the entire population tested, the they were equivalent in accuracy (71% vs. 72% concordance). Results from the machine's expert system and from clinician readers of the machine data compared favorably. The machine's concordance with the gold standard increased with increasing loads lifted by the subject. CONCLUSION: By relying primarily on the subject's self-presentation, often to the exclusion of objective findings, the clinician may err in evaluating low back function when the patient does not report his or her true condition. The additional functional analysis provided by the machine offers the clinician objective, pertinent information to complement the findings from the clinical examination.

Biomechanical Phenomena↗
PubMed1997

The impact of inefficient clinical diagnosis on the cost of managing low back pain.

The clinical examination remains the pivotal factor in evaluating low back pain (LBP) for decisions concerning compensation and rehabilitation. Many practitioners believe it to be highly reliable, even though existing literature does not support this belief. Not only are there no data supporting the efficacy of clinical diagnosis for LBP, but also published data underscore its many inherent weaknesses. Healthcare risk managers need accurate clinical information to make decisions. If current clinical information is unreliable, then healthcare risk management strategies for LBP must be revised. This article reviews the work of many researchers in their attempts to unravel the problem of diagnosing LBP. The following conclusions were reached: The problem is significant and continues to increase. The problem is rooted in the clinician's strong dependency on reported pain, which may not always be a reliable source of objective information. Quantification of the impact of the objectivity of reported pain on clinical performance demonstrates the need for a independent source of functional data that can improve the diagnosis. Technology exists to complement the clinical examination, improve clinical performance, and thus reduce the cost associated with LBP management. The research results presented in this article unveil disturbing findings for healthcare risk managers. The strong bias clinicians reserve for reported pain may lead them to overrate pathology, treat patients inappropriately, prescribe unnecessary imaging tests, and generate unfounded medical opinions that are responsible for many disputes. Data are presented to demonstrate the financial benefits that result from the introduction of systematic objective controls via technology. These sound management principles allow the risk manager to determine the validity of claims and treatment proposals. Risk managers can then make informed decisions on contentious claims and regulate the large number of clinician-supported disability cases--decisions that represent significant savings.

Canada↗
PubMed1993

Examining motion in the cervical spine. I: Imaging systems and measurement techniques.

Instruments for measuring mobility in the cervical spine range from plumb-lines and inclinometers to sophisticated optoelectronic systems. In order to investigate the need and possible uses for an enhancement to a new diagnostic instrument, we examine some of the available diagnostic systems suitable for cervical motion analysis. These should be of practical use in a clinical setting for the diagnosis of soft tissue injuries. We begin by evaluating the respective roles of plain radiographs, cineradiography, computer tomography, and magnetic resonance imaging in examining the cervical spine. Then we consider Moiré photography, inclinometers, and some opto-electronic scanners, as well as the mathematical techniques needed to correlate skin and spine motion with these devices. We find that there does not appear to be an effective non-invasive tool for comprehensive clinical cervical motion analysis; in particular, coupled joint motion is inadequately quantified. Improperly diagnosed cervical spine injuries, such as hyperextension and hyperflexion, may result in chronic long-term effects. Therefore, instrumentation that would permit objective, routine clinical evaluation of patients could help to avoid such situations.

Biomechanical Phenomena↗
PubMed1993

Examining motion in the cervical spine. II: Characterization of coupled joint motion using an opto-electronic device to track skin markers.

Analysis of coupled motion in the cervical spine may be useful in helping to identify injuries. In order to investigate this possibility, the nature of coupled motion in the spine and previous investigations on this subject are reviewed here. An enhanced set of displays are developed for an existing opto-electronic device employed for the non-invasive measurement of movement in the upper spine. This instrument consists of a high resolution motion analysis system which tracks small infrared emitting diodes (IREDs). Kinematic data for the motion of the markers is processed and absolute coordinates for the location of each IRED at any time are tabulated; coupled motion with respect to a fixed calibration frame, as well as for vertebrae relative to each other, is deduced from these. Overall analysis provided by the original device includes assessment of cervical lordosis, thoracic kyphosis, and inter-segmental mobility. Characterization of coupled motion, in particular, involves a series of plots showing principal versus secondary motion. Principal movements include flexion-extension, lateral bending, and axial rotation, corresponding to motion in the sagittal, transverse, and horizontal planes, respectively. Mobility is represented in terms of the direction angles made by virtual vectors orthogonal to the planes made by markers on the head, neck, and shoulders. Development of the enhanced displays and the required refinements are described. Precision of the deduced angles is found to be approximately 1 degree. This representation of coupled motion is expected to be valuable in improving the accuracy of attempts to identify normal versus pathological motion in the cervical spine.

Algorithms↗
PubMed1987

Relationship between lordosis and the position of the centre of reaction of the spinal disc.

Whenever we stand upright in apparent static equilibrium, we are, in fact, continuously making minor adjustments in order to maintain our balance. For each intervertebral joint, a point must exist at which all moments applied to the joint are continually and dynamically balanced. This point, known as the centre of reaction, is a mathematical invention necessary to perform analyses of spinal motion, but which need not be associated with any real anatomical structure. As the spine flexes and extends, this centre is expected to move; where it moves and the rationale for its motion is worthy of enquiry. In this paper, we propose that the centre of reaction remains confined to the nucleus of the disc, but only if one simple but crucial assumption is made; that the motion of the spine and control of its musculature maintain a minimum and equal stress at each intervertebral joint. This is a simple hypothesis which imposes a very specific relationship between lordosis and the centre of reaction. We investigate this relationship and its consequences on the teaching of lifting. The impossibility of designing experiments adequately to verify this hypothesis prevents in vivo verification, and, therefore, the model's verification must be made through the inferred consequences. For example, the capability of correctly predicting physiological responses of the musculoskeletal system is an indication of the validity of a model; however, this is not universally accepted. In this particular case, additional experimental data are available in the form of the locus of the centre of rotation of a vertebra vis-à-vis its lower neighbour as the spine flexes and extends. It is instructive to compare the predicted locus of the centre of reaction to experimentally determined locus of the centre of rotation; more than just coincidental similarities are found.

Biomechanical Phenomena↗
PubMed1987

Energy transfers in the spinal engine.

Locomotion is generally perceived as being the function of the legs. The trunk is considered to be carried along in a more or less passive way. This popular hypothesis appears to have been accepted with little substantiation. In light of the numerous observations contradicting this view, we have proposed an alternative hypothesis in which the spine and its surrounding tissues comprise the basic engine of locomotion. This theory is consistent with available experimental data which suggest that the motion of the spine precedes that of the legs. Indeed, the variations in the power delivered to the pelvis by the spine are strikingly similar to, but slightly ahead of, the variation in power at the hip.

Biomechanical Phenomena↗
PubMed1987

The resting spine. A conceptual approach to the avoidance of spinal reinjury during rest.

During periods of rest, the human spine assumes many different postures. This article examines the patterns of stress exerted on the lumbar spine by the more commonplace reclining postures. It proposes a rationale for choosing an optimal resting posture. In the event that the spine is injured, this study suggests that a sleeping posture that will minimize the stress at the level of injury should be adopted.

Back Pain↗