Pilot Study of The Effectiveness of Multiple Impulse

Therapy for Musculoskeletal Complaints

 

Joseph M. Evans, Ph.D., Daniel L. Collins, D.C., Reed H Grundy, B.S.E.E.

 

ABSTRACT

 

Study Design: This study presents the results of treatment of 50 patients using

multiple impulse therapy provided by the PulStarFRAS™. The study consisted of

a randomized retrospective analysis of patient files to determine symptomatic

improvement over the course of treatment for a variety of musculoskeletal complaints

that were encountered in clinical practice. The multiple impulse therapy was

supplemented, at the discretion of the practitioner, with manual adjustments. The manual

adjustments consisted of HVLA (high velocity low amplitude) and drop table and were administered to fewer than 5% of the patients. Objective: The objective of this study was to document the effectiveness of the multiple impulse therapy provided by the PulStarFRAS for a variety of musculoskeletal symptoms encountered in clinical practice. Setting: The therapy was provided by a single practitioner in a private clinic setting. Results: Important findings of the study include: 1) All patients expressed improvement in symptoms immediately after the first visit (average improvement in subjective pain rating scale of 41%). 2) Patient symptoms improved between the first and second visits for 70% of patients (average improvement in subjective pain scale for all patients was 58%). 3) No patients expressed a negative result to therapy. 4) The majority of patients achieved complete resolution of symptoms between the 3rd and 4th visits. 5) Maximum benefit for all patients across all symptoms required an average of 4.2 visits. 6) The half-life for response to multiple impulse therapy using the PulStarFRAS for all symptoms was 17 to 26 days. 7) The half-life for response to multiple impulse therapy using the PulStarFRAS for low back pain was 9 to 16 days. Conclusion: The results of this study support the use of multiple impulse therapy provided by the PulStarFRAS as a means of resolving musculoskeletal symptoms. These results compare favorably with published studies of techniques of musculoskeletal therapy.

 

 

Differential Compliance Instrument in the Treatment of Infantile Colic: A Report of Two Cases

 

Robert A. Leach, D.C., Journal of Manipulative and Physiological Therapeutics, Vol. 25, No. 1, January 2002

 

ABSTRACT

 

Objective: To report on a novel use for a computer assisted adjusting device as a potentially safe method for treatment of infantile colic. Clinical Features: Two pediatrician-diagnosed cases of infantile colic, characterized by signs of distress, uncontrolled crying, with brief episodes of screaming, were otherwise associated with normal growth (despite low birth weight in the second case) and no other abnormalities. Intervention and Outcome: A PulStar Function Recording and Analysis System (PulStarFRASTM) device was used to administer light impulses (viz. @1.7 joules

which produced a 3 to 4 lb. Force) at each segmental level throughout the dorsal spine using probe tips spaced 2 cm apart, straddling the spinous processes. Crying was reduced by 50% after a single session of instrumented adjusting in a 6-week old female and after four sessions in a 9-week old male, according to colic diaries kept prospectively by the mothers. Uninterrupted daily sleep increased from 3.5 to 6.5 average hours after a single session. Within 10 days (5 and 8 sessions respectively) colicky behavior disappeared and total daily sleep improved to 14.5 average hours (up from 4.5 average previously); results continued over a 30-day follow-up. The treatment was well tolerated, with only mild temporary observed discomfort. These initial findings using a low force instrumented procedure mirror results from controlled trials of manual adjustments for colic. Conclusion: The PulStar mechanical adjusting device appears to have been well tolerated and beneficial in two cases of infantile colic. Further research will be necessary to determine if this device can enhance the safety and/or effectiveness of chiropractic treatment in infants with colic.

 

 

PulStar Differential Spinal Compliance Instrument: A Blinded Randomized Inter- and Intra-Examiner Reliability Study

 

Robert A. Leach, D.C., Patrick L. Parker, M.S., Joseph M. Evans, Ph.D. and Paul S. Veal, D.C.

 

ABSTRACT

 

Objective: To provide an entry-level, new-technology reliability assessment of the PulStar computer assisted, differential spinal compliance instrument. Subjects: Eighteen college students (9 males and 9 females) were recruited by announcements and personal contacts. Methods: Inclusion criteria included subjects aged only in the 18 to 25 range, of normal weight (obesity defined by World Health Organization criteria), and who denied any prior history of significant spinal problems or treatment. Following approval of the consent process by the institutional review board of Mississippi State University, a PulStar Function Recording and Analysis System (PulStarFRAS™) device was evaluated for clinical reliability. Two blinded examiners used the instrument in random order on individual subjects lying prone with their backs exposed, to administer light impulses (vis. ul. 7 joules which produced a 3 to 4 lb. force) at each segmental level throughout the cervical, dorsal, and lumbar spine using probe tips spaced 3 cm apart, straddling the spinous processes, while a computer recorded the findings (resistance to thrust on a scale of 0 to 255 joules). Results: Data were analyzed by Exploratory Data Analysis (EDA) with ANOVA testing, and by use of the Intraclass Correlation Coefficient (ICC). In addition, a means test (ANOVA) was conducted to determine if a trend in variation occurred as a result of repeated light thrusts to the spine, independent of variance explained by different examiners. Using EDA analysis and ANOVA intra-examiner reliability for the two practitioners was very high but not perfect. This was confirmed by ICC statistics demonstrating good to excellent reliability for both practitioners (0.89 for the experienced practitioner, 0.78 for the newly trained practitioner). Inter-examiner reliability of PulStar was similarly very high but not perfect based upon EDA/ANOVA analysis, and good to excellent (ICC = 0.87). Means testing with ANOVA did not explain variance between examinations which might have been expected due to any biological effect of repeated measurements with the device set to analysis mode. A fatigue effect was observed with the newly trained practitioner’s reliability decreasing over time during the trial. Conclusion: the PulStar mechanical adjusting device set to analysis mode appears to have good to excellent reliability when used by either an experienced or a novice (but trained) examiner. In addition, as a measure for spinal resistance to a light thrust, or spinal compliance, reliability was similarly good to excellent between the two doctors using the PulStar instrument. This initial study does not address the validity or clinical significant of the measurement method. Further research will be necessary using greater numbers and a wider variety of subjects, and more diverse examiners, to verify these findings and fully understand the generalizability of these results.

 

 

The Minimum Energy Hypothesis: A Unified Model Of Fixation Resolution

 

Joseph M. Evans, Ph.D., C. Ray Hill, Ph.D., Robert A. Leach, D.C., Daniel L. Collins, D.C., Journal of Manipulative and Physiological Therapeutics, Vol. 25, No. 2, February 2002

 

ABSTRACT

Objective: To present a new theoretical construct, the Minimum Energy hypothesis, which explains structural changes observed in the spine concomitant to spinal joint fixation resolution in initial investigations. Design: Theoretical analysis. Hypothesis: A unified theory of manipulative effectiveness is proposed which integrates the fixation and sensory tonus models of manipulation. The theory is based on the fact that the spine will assume a position of minimum internal energy when mechanical equilibrium is achieved. Using a simple mathematical model, it is shown that the fixation model and the sensory tonus models are two different aspects of the same theoretical construct. The Minimum Energy hypothesis predicts that the spine will seek an optimal minimum energy configuration, if the constraints preventing it from doing so are removed. Constraints are hypothesized to be joint fixations caused by inflammation in and about the spine and its sequella, muscle spasm, fibroadipose and scar tissue, and ultimately degeneration. It is further hypothesized that use of a computerized mechanical manipulative device may resolve such fixations, an example of which is radiographically demonstrable cervical hypolordosis. Conclusion: A unified theory of manipulative effectiveness based on the concept of minimum energy to attain mechanical equilibrium is brought forward to explain the results of initial investigations.

 

 

Similarities and Differences Between X-ray Analysis And Computerized Fixation Imaging of the Cervical Spine

 

Joseph M. Evans Ph.D., Daniel L. Collins D.C. Presented at the Seventh Annual National Subluxation Conference Sponsored by Sherman College of Straight Chiropractic Spartanburg South Carolina October 1999

 

ABSTRACT

 

This paper presents a comparative study of the results of x-ray analysis and Computerized Fixation Imaging (CFI) analysis of the cervical spine. Twenty-five patients seeking chiropractic care at a private clinic were randomly selected to participate in the study.

 

This study was undertaken to answer questions from clinicians using the Sense Technology PulStarFRAS (Function Recording and Analysis System). These questions arise regarding the findings of a mature and widely used method of spinal analysis (x-ray) and this new and rapidly evolving method of objective instrumented palpation (CFI).

 

Significant major findings were:

 

·      A Kendall coefficient of concordance of .74 was obtained between the results of x-ray analysis and the results of CFI analysis.

·      A Kendall coefficient of concordance of .74 was obtained between x-ray findings of arthritic joint involvement and CFI analysis and

·      A Kendall coefficient of concordance of .76 was obtained between x-ray findings of discontinuities of cervical spine curvature and CFI analysis.

 

These results show that there is a high degree of correlation between x-ray analysis and CFI in findings of discontinuities of spinal structure and in observation of evidence of osteo-arthritis.

 

 

The Clinical Application of Differential Compliance Methodology to Joint Fixation Identification and Resolution Using the PulStarFRAS™

 

Joseph M. Evans Ph.D., Daniel Collins, D.C., Journal of Vertebral Subluxation Research, Vol. 2, No. 3, 1998

 

ABSTRACT

 

This Paper describes a single subject case study designed to evaluate the clinical usefulness of Differential Compliance Methodology employing the PulStarFRAS instrumentation. The results of the study illustrate the effectiveness of multiple impulse percussive force application in the release of fixations of spinal joints, where the fixations were identified by compliance readings obtained with the PulStarFRAS. Over a progression of three weeks, the patient experienced a change in cervical curvature from a radius of 150 cm to 15 cm, as well as resolution of presenting symptoms. Moreover, a restoration of normal cervical hard tissue compliance was recorded. Based on the results of the study, Differential Compliance Methodology including multiple impulse force application using the PulStarFRAS can be considered to have been an effective intervention in the care of the patient studied, who exhibited signs of spinal fixation with accompanying musculoskeletal dysfunction and other symptoms.

 

 

Differential Compliance Measured by the Function Recording and Analysis System in the Assessment of Vertebral Subluxation

 

Joseph M. Evans Ph.D., Journal of Vertebral Subluxation Research, Vol. 2, No. 1, 1998

 

ABSTRACT

 

This study presents the theory of differential compliance and the clinical application of instrumentation designed for its detection in the clinical setting. The engineering principle of using a mechanical impulse to excite a structure coupled to sensors to measure the response, has been employed in the design of the Function Recording and Analysis System (FRAS). This system, linked to software which analyzes input data, is further designed to graphically display relative differences in vertebral compliance. The present study employed assessment of a region of the spine encompassing the occiput to the third thoracic vertebra as a model to demonstrate how compliance measurements can be obtained, graphically displayed, and interpreted. The reliability of the instrumentation to accurately and consistently measure different levels of compliance was tested on three artificial substrates of varying “stiffness” and three human tissue locations exhibiting different “Stiffness’ including the heel, palm, and finger tip. Moreover, intra- and inter-examiner reliability in the use of the system has also been reported. Statistical evaluation of repeated measures for each of these categories included analysis by chi-square, Pearson product moment correlation, and intraclass correlation coefficients (ICC). Results indicated a high level of consistency of the instrument in measuring substrates of varying compliance. Moreover, strong intra-examiner reliability (ICC ³ 0.90), and inter-examiner reliability (ICC = 0.65) suggest a consistent use of the instrument among and between practitioners. These findings indicate a useful role for the FRAS in the characterization of vertebral subluxation, as well as serving as one means of assessing changes in flexibility of the spine following the chiropractic adjustment.

 

 

Pilot Study of the Repeatability of the PulStarFRASTM

 

Joseph M. Evans, Ph.D., Daniel L. Collins, D.C., Reed H. Grundy, B.S.E.E.

Submitted to Journal of the Neuromusculoskeletal System

 

ABSTRACT

 

Objective: The objective of this study was to document the repeatability of computerized method of instrumented palpation of the spinal musculoskeletal system in three positions of analysis: prone, sitting and standing. Clinical Setting: Private chiropractic office. Results: The spines of ten patients (7,200 observations) were analyzed by four investigators following a repeated measures design. Each subject’s spinal structure was analyzed in the prone, sitting and standing positions. The measured compliance of the spine was observed to vary smoothly along the spine with the exception of T2 where a discontinuity was observed. Four clinical users of the PulStarFRAS with different levels of experience with the PulStarFRAS were able to reproduce their findings on ten chiropractic patients with remarkable consistency (R+.83 for experienced users; .73-.75 for less experienced users). Inter-examiner results were also high. The positional analysis showed that the prone position produced the highest repeatability. Conclusion: this study contributes to the understanding of the musculoskeletal system’s response to low energy dynamic impulses, but more research is needed before the results can be extended to the general patient population. The study results indicate that instrumented palpation with the PulStarFRAS has the potential of exceeding the repeatability of any other method of clinical assessment of the musculoskeletal system in general use.

 

 

The Use of Kaplan-Meier Survival Analysis for the Evaluation of Musculoskeletal Therapy

Joseph M. Evans, Ph.D.

 

ABSTRACT

 

Introduction: Survival analysis is seldom used in studies of the effectiveness of musculoskeletal therapy. The reasons for this are unclear given the simplicity and power of the procedure and its use for a wide variety of problems in other fields of medical research. Under the assumption that the neglect of this method of analysis is due at least in part to unfamiliarity on the part of researchers, this work describes the analysis and discusses examples of its use in musculoskeletal research. Discussion: Survival analysis is the calculation of the probability of the occurrence of an event (becoming pain free) in the patient population under study. The mathematical underpinning of the method is described and the use of the results is illustrated with two case studies drawn from the current literature. Conclusion: Survival analysis is a powerful analysis technique that offers the researcher a clear and unambiguous method of presenting the results of studies of the effectiveness of musculoskeletal therapy and comparing the results to other studies.

 

 

Estimating the Efficiency and Effectiveness of Techniques of Musculoskeletal Therapy

 

Joseph M. Evans, Ph.D.

 

ABSTRACT

Introduction: Assessing the relative effectiveness of musculoskeletal manipulation techniques is difficult and controversial. This study proposes a numerical method for comparing the results of trials of musculoskeletal therapy as an alternative to ranking literature by experts in the field. The method is based on the observation that, in general, the course of recovery of patients with musculoskeletal complaints can be approximated by an exponential function. Methods: Using data from published studies, a simple exponential model was used as the basis for estimating the

half-life (the time necessary for half of the patients in a study to express relief of pain) of various techniques of musculoskeletal therapy. Results: The half-life of the techniques used in the study varied from 6 to 195 days. The majority of studies had estimated half-lives of 22 to 83 days. Conclusion: The results suggest that studies of most techniques of chiropractic and osteopathic therapy exhibit similar half-lives and in that sense similar efficiency. One possible explanation for this result is that, especially in the early course of patient treatment, the natural healing process dominates the results and therefore differences in treatment techniques and protocols are unlikely to be discerned until the majority of patients have finished the course of treatment. In other words, differences in treatment efficiency and effectiveness are unlikely to be observed using relatively short treatment times and/or small subject sizes.

DOCUMENTATION OF COMPLIANCE MEASUREMENT USED IN THE FORCE RECORDING AND ANALYSIS SYSTEM

J. M. Evans, C. L. Evans

Sense Technology, Inc.

BACKGROUND

Shortly after the introduction of the Model SHLCP-5 Precision Adjustor, reports were received from clinicians that the sound of the impulse changed during use. Some clinicians began using the change in sound as an indicator that the adjustment phase should be terminated.4 Another group of clinicians5 began to use the instrument as a percussor to help locate points on the spine as candidates for adjustment.

The use of percussive techniques as an aid to diagnosis is well known in the medical arts. The image of the physician tapping our body with a small hammer is a vivid childhood memory for most.

As commonly practiced, this technique is subject to wide variability in both the application of the percussive force (was the last impulse the same as the current impulse?) and the interpretation of the results (you can hear the difference, can't you?). This variability and the total subjectivity of the interpretation of the results require a certain minimum training and individual aptitude to make the technique useful and the results transferable across patients and examiners.

The development of the Force Recording and Analysis System presents an opportunity to improve the percussive technique since:

•Each impulse on a given force setting is delivered with essentially the same energy content.

•The peak force of the impulse is objectively measured and highly repeatable when the impulse is delivered to a given substrate.

•Changes in the peak force of the impulse due to differences in the substrate to which the impulse is applied are easily measured and objective.

With these potential benefits in mind, it was decided to investigate the potential for improving the use of the Model SHLCP-5 Precision Adjustor by incorporating an objective method of measuring substrate compliance in the Force Recording and Analysis System Model 01.

PURPOSE

Development of a reliable objective method of assessing differences in the response of the body to the application of a light impulse loading.

THEORETICAL ANALYSIS

Impulse techniques are commonly used in engineering analysis to examine the response characteristics of structures or electrical circuits.6 7 These techniques employ the use of instrumented impulse hammers to excite a structure and appropriate sensors to measure the response of the structure. Of particular interest is the single point vibration analysis in which the excitation and response of the structure occur at the same point.

The adjusting head of the Force Recording and Analysis System may be used in a manner consistent with single point impulse-response testing. In this case the excitation of the "structure" is achieved by the armature within the solenoid body being brought into contact with the anvil of the adjusting head. To achieve this excitation, the adjusting head must first be pressed against the patient until a pre-defined preload is achieved. This assures that the initial conditions for the impulse are the same each time.

At a given force level the energy imparted to the solenoid armature is the same each time the head is activated. Since the mass of the armature is also constant, the velocity of impact of the armature with the anvil is essentially constant. The energy of excitation imparted to the anvil by the armature will thus be constant each time the head is activated at a given force level.

After the anvil has been excited by the armature, it is free to move with respect to the adjusting head. The movement of the anvil against the resistance of the substrate (patient simulator or patient body) determines the force between the anvil and the patient's body as measured by the force transducer attached to the front of the anvil. Under these conditions, "the stiffness of the contacting surfaces affects the shape of the force pulse..."8

Illustration of Pulse Shapes Obtained From Different Substrates

Illustration Using a Simple Discrete Parameter Model

The patient's body is represented by the spring with spring constant K and the damper C. In the equation of motion for this system, the mass used would include the mass of the anvil as well as a virtual mass of tissue. Assuming that the damping and virtual mass are essentially constant, the frequency response of the system and, therefore, the shape of the impulse would be determined primarily by the spring constant or stiffness of the substrate.

If this simple analysis is fundamentally sound, the peak force of each impulse would be expected to vary with the stiffness (or inversely with the compliance) of the substrate and would be expected to be constant at a point on a substrate.

OBJECTIVE

Document rationale and performance of assessment techniques.

MATERIALS

Sense Technology Force Recording and Analysis System Model 01.

Patient simulators of various density and elasticity.

Patient volunteer.

METHOD

The adjusting head of the Force Recording and Analysis System was placed on a substrate simulating a point on the body of a patient and activated twenty times. The peak force for each impulse was recorded. The mean peak force and standard deviation of the observation was calculated. This test was repeated twenty times and the standard deviation of the total data set was calculated. This is a measure of the variability in the peak force measurements. Two peak force measurements many standard deviations apart indicate a change in the physical system.

This test was repeated on simulator materials of different compliance.

After the tests were concluded on substrates of constant but different compliance, the test was repeated on a volunteer. The first test point was chosen to be the heel of the subject's hand, the second test point was the palm of the subject's hand and the third was the tip of the index finger.

All tests were run at a force setting of fifteen pounds and the peak force was recorded with the Force Recording and Analysis System.

Results of the patient simulator tests are summarized in Table 1.

ANALYSIS

The results of the tests indicate that the peak force of the impulse produced by the adjusting head of the Force Recording and Analysis System can be reliably reproduced when the impulse is applied to a single point on a unchanging substrate such as a patient simulator. The results also indicate that the peak force of the impulse is repeatable when applied on one point of the body. An estimation of the measurement error at each force level is shown in the graph.

In addition, the mean force varies in a predictable and expected manner when the impulse is applied to surfaces of differing compliance; that is, low compliance substrates (high resistance) result in a higher peak impulse with higher compliance substrates (lower resistance) substrates resulting in lower peak forces. Furthermore, the variability of the data indicate that differences in peak force of greater than ten percent (fifteen pounds at full scale) have a ninety-five percent chance of representing valid differences in the underlying substrate.

CONCLUSIONS

The results of the testing and analysis indicate that fundamental engineering analysis methodologies may be productively applied to the problem of quantifying the analysis of the compliance of the human body. In particular, single point vibration analysis techniques utilizing impulse loading are useful in explaining and analyzing the force output of the adjusting head of the Sense Technology Force Recording and Analysis System. The peak force has been shown to be related to the compliance of the substrate to which the adjusting head is applied. The peak force has been shown to be essentially constant for a single substrate. Variations of greater than ten percent in the peak force indicate a high probability that the output was derived from two different substrates.
APPENDIX II Intra- and Inter-Examiner Reliability Studies

DOCUMENTATION OF INTRA- AND INTER-EXAMINER RELIABILITY OF

DIFFERENTIAL COMPLIANCE METHODOLOGY

(a pilot study)

K. Allen D.C., R. Crisman, D.C., R. Keeler, D.C.,

J. Pesce, D.C. S. Saleeby, D.C., J. M. Evans, Ph.D.

The compliance of the human spine may be thought of as the ease of movement of each individual vertebra. For the purposes of this paper, compliance is defined as the displacement response of a structure when subjected to a unit force. It is the inverse of stiffness and intuitively can be thought of as the flexibility of a structure. This paper describes reliability studies on an instrument which measures the compliance of the human spine, before, during and after adjustment.

Sense Technology, Inc. has developed a unique chiropractic adjusting system which incorporates a percussive adjusting head. This percussor is instrumented with a force transducer that supplies data to a computer system. The computer stores and displays the force data for clinical evaluation. This system, referred to as the Force Recording and Analysis System (FRAS), is an extension of previous adjustors which are marketed without the force instrumentation.9 The clinician uses the Force Recording and Analysis System to challenge each vertebra with a low energy impulse. The system records and displays the peak force measured at each vertebra. The compliance of the vertebra is inversely proportional to the peak force. The results of the compliance assessment are used by the clinician, in conjunction with other diagnostic techniques (such as palpation, X-ray examination, thermal analysis, and analysis of patient complaint and history) to determine appropriate adjustment locations.

BACKGROUND

Sigler and Howe [20] and Jackson et al. [10] have pointed out that when measurement systems are used as the basis for diagnostic techniques, the reliability of the measurement system directly influences the reliability of the diagnostic system. Sigler and Howe found that the errors involved in measuring very small changes in atlas position on X-ray films were of such magnitude that the validity of the entire diagnostic and therapeutic regime was open to question. Jackson et. al. found using a somewhat different measurement system that changes in angles between vertebrae could be reliably obtained from X-ray films. A series of studies has been conducted examining the reliability of palpation and motion palpation for the detection of "somatic dysfunction" with mixed results [4,14,15,17,25,27]. Where statistical significance has been achieved, the level or strength of the findings has been relatively low. DeBoer et. al. [4] points out that such findings are not surprising since even well-established procedures such as reading X-rays, E K G's or blood pressure give maximum intra-examiner correlation in the range of .40 to .60. Others [19,21-24] have attempted to assess the reliability of simple instrumentation (inclinometers, temperature measurement instruments and penetration devices) as aids to diagnosis, again with mixed results. Several authors [7,8,16] have critiqued the methodology used in intra- and inter- examiner reliability studies. Their critiques may be useful as general guides and to raise questions regarding statistical methodology.

In previous work[6] we have documented the reliability and applicability of force measurement techniques for measuring differences in compliance of various substrates including the human body. That study concluded that the peak force of the impulse of the adjusting head varies directly with the stiffness of the substrate ( inversely with the compliance). The measures obtained showed that the system produced a repeatable result and that differences of greater than ten percent in peak force were significant.

Clinicians are currently using the Model SHLCP-5 Precision Adjustor to percussively test the spine both before and after adjustment [3]. The force levels used are generally higher (twenty-five pounds) than used for the initial assessment of the Force Recording and Analysis System (fifteen pounds). The proposal to apply these techniques to the analysis of compliance along the human spine raises some fundamental questions. This study examined the following:

•Will the measured peak forces resulting from application of very light impulse loads differ significantly vertebra to vertebra?

•How will differences in patient physique (including body fat content, muscle size, muscle tone, etc.) affect the results?

•Will the pattern of force readings be reproducible on a patient?

•Will the pattern of force readings be reproducible by more than one examiner?

In order to provide preliminary answers to these questions, the following trials were conducted:

Trial One- Examine the variability of compliance measurements in the cervical spine

Trial Two- Determine the reproducibility of repeated compliance readings taken by the same examiner.

Trial Three- Determine the reproducibility of repeated compliance measures taken by two different examiners.

TRIAL ONE

Determine the variability of compliance measurements

of the human spine using the Force Recording and Analysis System.

Method: A 30mm dual prong attachment was used to straddle the

spinous of the patient's vertebrae. The examining chiropractor

stabilized the head of the seated patient in flexion, chose the line

of drive and positioned the tips of the attachment on the

appropriate vertebra. Measurements were taken in the cervical

area of the spine of ten patients.

Results: Variations of peak force of up to 55% were found along the cervical

spine of individual patients.

Analysis: Some variation in measured peak force along the spine would be

expected from measurement variability alone. The commonly

observed differences in peak force of over ten percent between

adjacent vertebrae suggest that there is information in the

measurements that cannot be explained by measurement

variability [6]. This is suggestive of clinical significance.

Occasional differences in the mean of the cervical measurements

between patients were observed during the initial testing phase.

These differences were eliminated by normalizing each set of

measurements against the highest reading before display. The

normalized display showed the peak force readings as a percent of

the highest peak force reading for each patient. These normalized

displays allow the clinician to focus on the difference between

peak force readings rather than their absolute value.

Illustration of Normalized Display

TRIAL TWO
Determine the reproducibility of repeated compliance readings
taken by the same examiner.

Method: Using the 30mm dual prong attachment to straddle the
spinous of the patient's cervical vertebrae, the examining
chiropractor stabilized the head and neck of the seated patient
in flexion. The examining chiropractor chose the line of drive
and positioned the tips of the instrument on the occiput, and
vertebrae C1-7 and T1-3. Twenty patients participated in the study.
The examiner obtained a second set of readings on each patient
immediately after the first set. There were no markings on the
patient to serve as position references.

Research
Hypothesis: The patterns of compliance measurements obtained using the
Force Recording and Analysis System in consecutive measure-
ments of the human cervical spine by the same examiner show
no significant differences from one trial to the next.

Statistical
Analysis: Each set of consecutive readings was examined for similarity
using the following statistical techniques. First, the probability that
the two sets of data were different was computed using a c2
statistic. This method was chosen since an estimate of the
measurement error at each force level was available.[6] The c2
statistic was computed using the formula:


where: xi = the first set of data collected from the patient
yi = the second set of data
= the standard deviation at the force level
= the standard deviation at the force level
and are calculated using the empirical relationship
developed in [6]:

where: = .14
= .035


The probability of obtaining a c2 value at least as large as that
observed, assuming the measurements were drawn from the same
distribution, was computed from an incomplete gamma function.10
If this probability is smaller than .05, then the hypothesis that the
data sets are the same may be rejected with a confidence of 95%.

In addition, the Pearson product moment correlation (r ) was
computed on the data sets using the formula:



where: xi = the first set of data collected from the patient
yi = the second set of data

Finally, the intra-class correlation coefficient (ICC) was computed
by performing a one way analysis of variance and formulating the
ICC according to:



where = the variance within the data
= the variance between the data sets
m = the number of levels of the analysis

The chi square metric computes the square of the difference between each paired observation (the value obtained at level C1 on the first observation is subtracted from the value obtained at C1 on the second observation and the difference squared) and then compares that value to an estimate of the measurement, determined through empirical repetitive testing on known substrates of constant compliance[6].

If the measurements are exactly the same, the chi square returns a value of zero and the probability of obtaining a poorer (larger) result is necessarily equal to one. The larger the chi square the less likely that the two sets of measurements are "the same" or that the measurement is repeatable within an acceptable degree of error.

The chi square is a good measure of the significance of the difference between two sets of measures. Because its numeric values are not subject to direct interpretation, it does not provide a measure of the strength of the association. Some form of correlation coefficient is generally used as a measure of the strength of a significant association. The most widely used is the linear correlation (also referred to as the product-moment correlation or Pearson's r). The use of this statistic has been criticized [7,8,16], primarily because of artifacts such as obtaining a high correlation even though the two sets of measures differed by some constant value (i.e., a correlation equal to one would be obtained from two data sets even though each value in the second data set were twice the value of its mate in the first data set). In our case, where the pattern of data within the set may be more important than the exact values, this limitation may not be important.

The intra-class correlation coefficient (ICC) has been proposed, [7,16] as a more reliable indicator of the strength of a significant association for reliability studies involving continuous measurements. This coefficient can be constructed from the results of a one way analysis of variance. The formulation is:



where = the variance within the data
= the variance between the data sets
m = the number of levels of the analysis

If the data sets are exactly the same then MSB equals zero and the ICC equals one. If the variance between the data sets is greater than the variance within the data set then the ICC will be negative (no agreement between levels). If the variance between the data sets is less than the variance within the data then the ICC will be positive and there is said to be some agreement between levels. The results are summarized in TABLE 1.

Examiner Patient p r
1 1 10.52 .484 .98
1 2 41.23 <.0000 .86
1 3 12.01 .363 .85
1 4 11.94 .368 .80
1 5 12.62 .319 .85
1 6 9.47 .579 .80
1 7 10.89 .452 .82
1 8 12.11 .355 .74
1 9 3.73 .977 .97
1 10 15.56 .158 .82
1 11 14.82 .191 .80
1 12 11.5 .402 .84
1 13 20.61 .038 .91
1 14 15.68 .153 .82
1 15 15.35 .167 .86

Linear Correlation Across Patients for Examiner One =.88
ICC Across Patients for Examiner One =.90

2 1 18.58 .069 .89
2 2 9.21 .602 .95
2 3 14.43 .210 .91
2 4 49.91 <0000 .72
2 5 19.94 .046 .86

Linear Correlation Across Patients for Examiner Two =.85
ICC Across Patients for Examiner Two =.93

Linear Correlation Across Patients for Examiner One and Two =.96
ICC Across Patients for Examiner One and Two =.96

TABLE 1- INTRA-EXAMINER RELIABILITY

Example of results judged to be "different" according to the c2 criterion.

Example of results judged to be "the same" according to the c2 criterion.

Analysis: The two consecutive readings taken in the cervical area
were highly correlated for each chiropractor. In addition,
the c2 probability indicates that the null hypothesis (the
measurements are the same) could be rejected in only three
cases. It appears that the intra-examiner reliability
of the tests is high, by any of the metrics. The chi-squared and
ICC metrics sometimes disagree since chi-squared normalizes the
observed variability against an empirical estimate of the
measurement error, and the ICC normalizes against the variability
in the patient's measurements. If the ICC is calculated for all of the
data, a very high value is returned. This is done in the
overall ICC measurements reported in TABLE 1 above.

Sources of Variability:
There are two obvious sources of variability which may influence
the outcome of this intra-examiner reliability study. The first is
the error introduced due to imperfect placement. By placement,
we mean the position of the dual prong tips used for contacting
the patient during the examination as well as the line of drive
chosen by the examiner. Even with markings on the cervical area
(which were not used in this study), the angle of the instrument
and the positioning of the tips would be impossible to duplicate
exactly from the first examination to the second.

Another source of error is a result of the measurement itself.
In our case, it is not difficult to understand that the second
set of measurements may differ from the first due to the act of
measuring because the energy used in the measurement may
well be sufficient to cause changes in the underlying structure
of the spine. Such changes would be expected to result in
differences in response to the energy of the test impulse. That
these changes are relatively small is attested to by the excellent
agreement found. This agreement may well be improved by
training and/or lowering the energy of the impulse.

Conclusions:
The intra-examiner reliability of compliance measurements
obtained in the cervical spine with the Force Recording and
Analysis System is consistently high.

TRIAL THREE
Determine the reproducibility of repeated compliance readings
taken by two different examiners.

Method: Using the 30mm dual prong attachment to straddle the spinous
of the patient's cervical vertebrae, an examining chiropractor
stabilized the head and neck of the seated patient in flexion.
The first examining chiropractor chose the line of drive and
positioned the tips of the instrument on the occiput and
vertebrae C1-7 and T1-3. Three patients participated in the study.
A second examiner obtained a second set of readings on each patient
immediately after the first set. There were no markings on the
patient to serve as position references.

Research
Hypothesis: The patterns of compliance measurements obtained using
the Force Recording and Analysis System in consecutive
measurements of the human cervical spine by two different
examiners show no significant differences from one trial to
the next.

Statistical
Analysis: This analysis was conducted in the same manner as the
previous analysis for the intra-examiner reliability.


Examiner Patient p r
1-3 21 10.95 .447 .80
1-3 22 8.45 .673 .87
1-3 23 11.4 .432 .75


Linear Correlation Across Patients for Examiner One and Three =.89
ICC Across Patients for Examiner One and Three =.65


Analysis: The two consecutive readings taken in the cervical area
were highly correlated for each chiropractor. In addition,
the c2 probability indicates that the null hypothesis (the
measurements are the same) could not be rejected in any
of the cases. It appears that the intra-examiner repeatability
of the tests is high.


Discussion: The purpose of this trial is to determine whether
or not the compliance measurements obtained by two different
clinicians on a single patient are the same. The statistics suggest
that the measurements are quite reproducible across clinicians.


CONCLUSION

This study suggests that the measurements of the FRAS system reflect the actual compliance of the patient's spine. Further, the intra- and inter- examiner reproducibility of these measurements is good. A subsequent study will quantify our observations that these compliance measurements change after chiropractic adjustment with the instrument. Clinicians are just beginning to develop diagnostic and treatment rules to use the information provided by this new instrument.

Sense Technology Inc.
12/15/94

NOTES ON THE VALIDITY OF COMPLIANCE MEASUREMENTS OBTAINED WITH THE FORCE RECORDING AND ANALYSIS SYSTEM

Rob Crisman DC

ABSTRACT

OBJECTIVE

To verify that striated muscle contraction reduces the response of the skeletal structure to a low energy impulse when compared to the relaxed state. In addition, to verify that joints of different mobility will have predictable outcomes, i.e., when tested with a low energy impulse, skeletal joints with low mobility will elicit a higher response than skeletal joints with higher mobility.

DESIGN

Four normal volunteers were recruited to investigate the effects of muscle spasm on the readings obtained with the Force Recording and Analysis System (FRAS). Additionally a series of joints with known and different gross compliance were tested.

SETTING

Private clinical practice.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Differential Compliance readings obtained with the Force Recording and Analysis System.

RESULTS

The results verified that the measurements taken with the FRAS on human subjects confirmed the hypotheses postulated by the investigator that muscle spasm may produce lower readings and that measurements taken on joints of low compliance versus joints of high compliance in human volunteers varied in the manner expected.

CONCLUSION

Both hypotheses were confirmed by the tests. It appears that the compliance measurements obtained using the FRAS vary predictably in the expected manner and may be useful in the clinical setting.

KEY INDEXING TERMS

CFI, Computer, Fixation, Medical Imaging, Compliance.

INTRODUCTION

The Force Recording and Analysis System (FRAS) manufactured by Sense Technology Inc. is used to perform a Computerized Fixation Imaging Scan (CFI Scan) of a patient's skeletal structure. The Differential Compliance Methodology implemented with the FRAS enables the examiner to objectively determine the relative compliance of two or more vertebral segments or to evaluate the mobility of a single spinal segment in any of its degrees of freedom.

The first step in obtaining a CFI Scan is to obtain a measure of the compliance of each vertebra or segment of the spine under evaluation. This measure is obtained by applying a low energy mechanical impulse to each segment of the spine sequentially and recording the response of the segment. After all segments of interest have been challenged in this way, the responses are displayed visually for the examiner as a bar graph. Low bar graph readings indicate a segment with high compliance (low resistance) and high bar graph readings indicate a segment of low compliance (high resistance). The clinical interpretation of these results is that a joint segment with a much lower compliance than its neighbors may be fixated and a candidate for adjustment.

Previous work1 has demonstrated that the FRAS instrument gives reliable and predictable results when applied to surfaces of known and constant compliance and to parts of the body with different compliance. Clinical use of the instrument, while supporting the general conclusions drawn from these tests, raises questions regarding the role of the musculature surrounding and attached to skeletal segments. In particular, striated muscle contraction surrounding a joint segment commonly found in soft tissue injury2.may influence the results of the scan. If the muscle contraction reduces the normal response of the segment, a joint segment that is in fact fixated may be judged normal or of high compliance.

The purpose of this study is to examine the hypothesis that muscle contraction reduces the response of a skeletal segment to the mechanical impulse used to challenge the segment. In addition, a series of joints of different compliance were tested to examine the hypothesis that joints of low compliance produce higher readings when compared to joints of high compliance.

METHODS

SUBJECTS

Four normal, pain free volunteers (two females: the first, 26 years of age, 170 cm in height, 66 kg in weight; the second, 33 years of age, 165 cm in height, 65.8 kg in weight; and two males: the first, 27 years of age, 180 cm in height; 86 kg in weight; the second, 32 years of age, 183 cm in height, 88.4 kg in weight) were recruited for the study. Each subject was required to read an information sheet describing the study and give written informed consent before being included in the study.

PROCEDURE

EFFECT OF MUSCLE SPASMS

In order to test the effect of muscle spasm or tetanus on the compliance readings obtained with the Force Recording and Analysis System, one site on each subject was tested. The site chosen was the anterior midpoint of the diaphysis of the right humerus. The midpoint was visually determined after palpation of both ends of the bone. This point, coincident with the belly of the bicep muscle, is the thickest part of the muscle when in full contraction. Tests were made with the elbow bent at approximately 35 degrees, 90 degrees and 150 degrees with the bicep muscle in full isotonic contraction. The same point was tested three times at 35 degrees, three times at 90 degrees, twice at 150 degrees and three times with no contraction.

For convenience, the tests were conducted using an eleven point data collection and analysis algorithm. In general, the first eight readings were obtained with the muscle under examination in a contracted state. Then, without leaving the data collection routine, the last three readings were obtained with the muscle in a relaxed normal state of tetany. After all eleven data points were collected, the algorithm normalized the results and displayed all the data points as a series of eleven bars in graph format.

COMPARISON OF JOINTS OF DIFFERENT COMPLIANCE

In order to compare compliance measurements obtained on joints of known and different compliance, a series of tests were made on sutura, condyloid and ginglymus joints. These tests were conducted on the male subjects The tests were conducted in the presumed order of lowest compliance to the highest compliance, i.e. the sutura was tested first followed by the condyloid and ginglymus joints. The specific joints chosen were:

•Sutura: left temporal/parietal joint

•Condyloid: right trapezoid bone

•Ginglymus: second digit- middle phalangeal

Again, for convenience, an eleven point algorithm was used for data collection and analysis. Each joint with the exception of the last was challenged four times with the low force impulse and the response recorded. The last joint was challenged three times.

DATA ANALYSIS

Each skeletal segment of interest is challenged by a low energy impulse. This impulse contains a wide band of frequencies (from zero to approximately 20,000 Hertz). The segment resists the initial impulse and the amount of resistance is recorded with a force transducer. The peak force recorded is a simple measure of the resistance of the segment to the initial low energy impulse. More complex analysis of the response waveform would reveal the major frequency of the response of the segment. For our purposes, the maximum response was sufficient to characterize the compliance of each of the skeletal segments of interest.

After the segment has been challenged and the maximum response recorded, the analysis routine asks for the next segment. The investigator repeats the test on all segments of interest in turn. In this case the analysis routine was composed of eleven segments. After all eleven segments have been tested, the analysis routine selects the segment with the maximum response and sets its value to one. The values of the remaining segments are transformed to a value proportional to the maximum value by the following relationship:

fn = fi /fmax

where fn = the normalized maximum value for segment i

fi = the maximum value for segment i

fmax = the maximum value recorded for all segments

This yields a set of values for the segments tested that are normalized relative to the maximum value recorded. These values are then displayed for the investigator as a bar graph with eleven elements.

RESULTS

Typical results obtained from the humerus with the elbow bent at 35 degrees, 90 degrees, and 150 degrees and relaxed. First nine measurements with muscle in full isotonic contraction with the elbow at the three respective angles; first three measurements at 35 degrees, second three at 90 degrees, next three at 150 degrees, remaining measurements with muscle relaxed.

Typical results obtained from sequential testing of sutura joint, condyloid joint, and ginglymus joint. First four measurements obtained from the sutura joint; second four measurements from the condyloid; last three measurements from the ginglymus.

DISCUSSION

The results of the tests clearly indicate that contracted versus relaxed striated muscle gives lower readings when the muscle is contracted. The reason for this result appears to be the greater absorption of the energy of the test impulse when the test is conducted on contracted striated muscle. The greater absorption may be due to the actin and myosin filament crossing over each other in the sacromere, causing the muscle to be thicker at the belly of the muscle.3 Also, the tension of the muscle creates a spring board effect which, when combined with the damping properties of tissue, acts to shield the underlying structure much like a spring and shock absorber in an automobile. Conversely, when the muscle was relaxed, the impulse penetrates directly to the underlying bone which produces a higher response to the impulse.

When a low reading is obtained clinically with the FRAS, the clinician must determine whether the reading represents a highly mobile (hypermobile?) segment or whether the reading is due to muscular involvement. This determination is relatively straightforward and is made primarily through palpation of the segment in question to determine evidence of tenderness or muscle tightness.

CONCLUSION

Two hypothesis were postulated by the examiner. The first was that a joint surrounded by muscle in contraction would produce a low response to a low energy mechanical impulse when compared to the response to the same impulse when the muscle is not in contraction. The hypothesis was tested by challenging the skeletal body at one point where the contraction of the overlying muscle was easily controlled. The point was the belly of the bicep muscle over the midpoint of the humerus. The intensity of the contraction was controlled by varying the angle between the humerus and the forearm. Observation of the test results showed that the more intense the contraction at either site correlated with lower readings (higher apparent compliance). These results supported the hypothesis and confirmed instructions in the manufacturer's manuals as well as the clinical protocol co-authored by the author.

The second hypothesis was that joints with different compliance would produce different results when tested and that the results would vary predictably with known joint compliance when compared on the same scale. This hypothesis was also confirmed. The response obtained from the sutura was 40 percent higher than the responses obtained from the condyloid and approximately 500 percent greater than that obtained from the ginglymus.

Both hypotheses were confirmed by the tests. It appears that the compliance measurements obtained using the FRAS vary predictably in the expected manner and may be useful in the clinical setting.

REFERENCES

1. Evans, J M, Evans, C L. Documentation of Compliance Measurement Used in the Force Recording and Analysis System, Sense Technology Inc., 1994

2 Gordon, Huxley and Julian, "The Length-tension Diagram of Single Vertebrate Striate Muscle Fibers, "Journal of Physiology 171:28P, 1964.

3 Lan, N.C. et al., "Mechanisms of Glucocorticoid Hormone Action,"Journal of Steroid Biochemistry, 20:77, 1984.