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ORIGINAL CONTRIBUTION |
From the Biomechanical Design Research Laboratory and the Department of Mechanical Engineering (Dr Bush) and from the Department of Family Medicine at the College of Osteopathic Medicine (Dr Vorro) at Michigan State University in East Lansing.
Address correspondence to Tamara Reid Bush, PhD, Michigan State University, 2555 Engineering Building, East Lansing, MI 48824-1226.E-mail: reidtama{at}msu.edu
Context: Physicians typically combine the use of palpation and objective measures, as evidence-based medicine dictates, to improve patient diagnosis and care. Practitioners also use palpatory examination in manual medicine to diagnose musculoskeletal impairment; however, there are no commonly accepted objective measures to complement palpatory findings.
Objective: To evaluate coupled vertebral motion as a parameter to complement palpatory findings from a standard clinical diagnostic test of cervical function.
Methods: Two examiners performed a blind screening of volunteer subjects for the presence of palpable symmetry or asymmetry in motions of the head and neck. In cases of interexaminer agreement, subjects then participated in kinematic assessment of cervical motion patterns. Neck angles were recorded, plotted, and evaluated for amounts of vertebral coupling.
Results: Interexaminer agreement was reached with 18 of the 34 subjects screened. Seven subjects with symmetric responses constituted the control group. Experimental subjects consisted of an asymmetric-asymptomatic (pain-free) group (n=6) and an asymmetric-symptomatic (pain) group (n=5). Control subjects exhibited the smallest average linear slope (–0.32) for the least amount of coupled motion. The average linear slopes for asymmetric subjects was –0.42 (asymptomatic) and –0.50 (symptomatic). Data analysis revealed that statistically significant differences among groups will be detected with a larger sample size.
Conclusions: Objective, kinematic parameters can be generated, measured, and evaluated relative to palpatory findings of musculoskeletal impairment by identifying trends in ratios of cervical lateral flexion and axial rotation.
Musculoskeletal dysfunction—such as neck impairment—can be evaluated using palpatory examination. However, even though such diagnostic tests are standard, palpatory findings may differ depending on practitioners' skill levels and experience.5 In addition, most practitioners' orientation toward the application of knowledge rather than the creation of it has contributed to a shortage of scientific research that confirms the validity of palpatory techniques.6 This lack of an evidence base no doubt affects students' understanding and desire to learn these diagnostic methods.
In evaluating the musculoskeletal system, much attention is given to vertebral flexion and rotation. Although these movements are typically described as occurring separately because of the complexity of their motions, they are naturally coupled. Vertebral coupling, along with range of motion, is well documented experimentally.7-14 However, little attention has been given to the clinical relationship between this coupled motion and palpable signs of cervical dysfunction. Currently, there are no published, scientifically accepted objective measures to complement the subjective palpatory findings of cervical function.15-19
The current pilot study evaluates the kinematic parameter of coupled motion. We sought to determine if it is possible to relate this parameter to the palpatory findings of a standard clinical diagnostic test of cervical function (ie, lateral flexion). We believe the current study, in addition to establishing objective correlates of palpatory diagnosis, will also help broaden the understanding of spinal biomechanics, expand practitioners' knowledge base on the role of palpation in the diagnosis of musculoskeletal impairment, and permit new insight into teaching and training venues for manipulation techniques, particularly those specific to osteopathic medicine.
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Methods |
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 Top Methods ResultsDiscussionConclusionsReferences |
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Examiner Training
Before initiating the screening sessions, two osteopathic
physicians—the examiners in the current pilot study—trained
together to develop consensus on diagnostic criteria. The lead examiner
(William L. Johnston, DO) was an instructor and trainer in osteopathic
manipulative medicine (OMM) who had 60 years of experience in osteopathic
clinical manual medicine. The second examiner (M. Shannon Arnsberger, DO) had
5 years of experience as an osteopathic physician and regularly used manual
medicine in her private practice.
Examiner training consisted of evaluating approximately 15 individuals—who did not participate in the present study—in lateral flexion of the head and neck region, specifically to determine whether motions were symmetric or asymmetric. Diagnoses were determined by integrating the following three critical assessments,12,20-22 which were the accepted diagnostic criteria in the current study:
Diagnostic Screening
Subjects were volunteers who responded to advertisements posted around the
MSU campus and at the MSU OMM clinic between January 2003 and June 2003. The
examiners performed a blind screening of subjects for the presence of palpable
symmetry or asymmetry in response to a lateral flexion motion test. The
examiners gave subjects a thorough description of the procedures that were
going to be performed for the screening. Subjects sat on a stool with their
arms crossed in front of their chests while the examiner stood behind the
subject to initiate and guide the motions.
For right lateral flexion, the examiner's right hand was lightly formed to the vertex of the subject's head, fingers to the left and palm to the right, while his left hand rested lightly on the posterior upper-thoracic region (Figure 1). Lateral flexions started with the subject's head in a neutral position (ie, head and eyes facing forward). The examiner asked the subject to close his or her eyes and permit the introduction and guidance of the movements. The examiner moved the head and neck by guiding the ear toward the ipsilateral shoulder until a palpable sense of end-of-range was achieved. Motions were performed at a speed relative to the subject's own motion behavior to acquire palpatory information from the responding tissue.21,22 The head and neck were then guided back to a neutral position, the left and right hand placement was switched, and motion to the opposite side followed.
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Head and neck motion is complex, consisting of combined physiologic behaviors (ie, coupled motions) that occur as a result of vertebral geometry, connecting soft tissues, and the curvatures of the region.21,23 Because of this coupling, the response of the entire cervical region during this diagnostic motion was evaluated—not merely the responses of individual vertebrae.22 The passive lateral flexion diagnostic test, which elicits both lateral and axial rotations, was also chosen for the current study because it is a regularly practiced procedure, common to osteopathic medicine, chiropractic, physical therapy, and other manipulative and body-based disciplines.20-22 Also, previous studies24,25 indicate that this movement produces the most dependable within-subject diagnostic uniformity.
Each examiner documented subject assessments relative to the specific assessment criteria. The examiners then made final overall categorizations of either "symmetric" or "asymmetric" for each subject. Subjects who reported pain in the head or neck region were also classified as "symptomatic." When the examiners concluded their diagnoses, a third person (T.R.B.) collected and reviewed the written records to determine whether there was interexaminer agreement. Subject classification was based on the concurrence of the examiners' findings. In cases where the examiners' findings were not in agreement, subjects were not included in the remainder of the study.
Kinematic Testing Methods
When interexaminer agreement occurred during the screening, subjects were
asked to return for the kinematic test, which occurred within 4 days of the
initial screening. On the day of the kinematic test, an examiner (W.L.J.)
performed an additional palpatory assessment of lateral flexion to confirm
screening results. In the event that the screening and confirmation palpatory
assessments differed, subjects still participated in the kinematic test, but
this change was noted in our records. Data analysis was performed both with
and without those subjects' results.
The same examiner then directed and performed the kinematic test motions. The protocol was identical to the diagnostic screening protocol with the exception that subject motions were video-recorded, as described below under "Data Collection and Analysis." Each cycle consisted of movement first directed to the right, then to the left, and finally back to the neutral position. Examiners paused slightly to adjust hand placement for movement to the opposite direction when the subjects head was back in the neutral position. Two trials, consisting of three cycles each, were performed for each patient. Both sets of data were used in the development of summary data. Trials were separated by 1 to 3 minutes and lasted approximately 35 seconds each.
Data Collection and Analysis
Head and neck kinematic data were collected by a five-camera Qualisys
3-dimensional video-based measurement system (Qualisys; Gothenburg, Sweden).
The five cameras were positioned to record movements of retro-reflective
targets affixed to the subjects. To reduce any motion of the targets relative
to the head, subjects wore a custom-fitted headband, which had three
reflective targets positioned on the temples: one frontal and two lateral
(Figure 1). This
headband was developed and tested in preliminary investigations. Anterior
reflective targets were also applied at the sternal notch and the midsternum.
A posterior reflective target was applied to the spinous process of thoracic
segment 6 (T6) to account for any possible thoracic motion occurring during
the test. To reduce target motion relative to the body, subjects wore
snug-fitting clothing and, when possible, targets were attached directly to
the skin. Data were recorded at a rate of 12 Hz.
Data analysis was performed in 2006. Dynamic target data were identified and tracked using Qualisys Track Manager software (Qualisys; Gothenburg, Sweden). Computations were then made to determine head motion relative to the thorax. Richards26 showed the Qualisys system to be accurate within 1 mm and 1.5 degrees of target position. Whittle and Walker27 reported various computation sequences and corresponding errors specific to the head and neck. Therefore, to reduce error in the current pilot study, we followed Whittle and Walker's recommendations27 and computed data in the following sequence: (1) lateral flexion, (2) axial rotation, and (3) forward flexion/extension.
Each subject's angular head and neck data were plotted on individual graphs with lateral flexions on the x-axis and rotations along the y-axis. Plotting these angles on individual graphs and determining the slope values of the data sets quantified specific relationships between the two angles. These slopes represented ratios of rotation to lateral flexion, thus establishing the target parameter used to quantify the amounts of cervical vertebral coupling. Finally, these slopes were averaged across subjects and inspected for trends related to clinical diagnoses.
An initial assessment of the data demonstrated lack of homogeneity of
variances and departure from normality. Thus, the standard analysis of
variance (ANOVA) was not applicable, and nonparametric testing was used. The
Kruskal-Wallis nonparametric one-way ANOVA was performed and a 95% confidence
interval (
=.05) was established.
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Results |
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TopMethodsResultsDiscussionConclusionsReferences |
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=.05.
Figure 3 provides plots of the primary and secondary motions for a single subject and single trial. Figure 4 presents graphic comparisons between a symmetric-asymptomatic subject and an asymmetric-asymptomatic subject. These graphs typify results from each subject group and indicate that symmetric subjects demonstrated less rotation with greater ranges of lateral flexion (ie, flatter slopes) than asymmetric subjects.
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Discussion |
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TopMethodsResultsDiscussionConclusionsReferences |
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The research presented in the current study is a foundational activity, as the kinematic factor of coupled motion has not been previously reported in association with cervical impairment. With the increased global call for evidence-based medicine,28 it is clear that additional research is necessary before a "gold standard" for objective evaluation can be associated with cervical dysfunction. However, the current pilot study demonstrates the potential for the kinematic profile of coupled motion to serve as an objective measure.
The asymmetric-symptomatic group had the smallest sample size and also the largest variation in slope values. However, this variation is not surprising because many things may alter a motion profile, including the pain and restriction that can accompany somatic dysfunction. A larger group of symptomatic subjects is recommended for future investigations. For research in which an unprecedented attempt to link a palpatory diagnosis to a biomechanical measure is made, special attention is required to determine appropriate sample size.
Interexaminer Reliability
Our diagnostic screening protocol incorporated tests by two examiners in
order to address concerns associated with interexaminer reliability. However,
for the purposes of the current pilot study, we also attempted to limit the
amount of repetitive diagnostic palpation to avoid any risk of unintentional
therapeutic effects from our study protocol. Thus, the number of examiners and
trials was kept to a minimum.
Few interexaminer studies provide reliable conclusions,29 while others provide less positive or questionable outcomes.30 What is apparent, however, is that studies in manual medicine that address interexaminer reliability would benefit from the use of objective markers.5,16-19,31-36
Objective markers—such as values for coupled vertebral motion—may improve consistency across examiners, particularly those just learning the skill. Palpatory diagnosis is taught by direct, shared experience between instructors and students. This training process allows students to develop diagnostic psychomotor skills and clinical rationales to accurately assess palpable findings. However, motion and tissue texture cues used in palpatory diagnoses relate to complex motor behaviors that are typically evaluated in a subjective manner. Therefore, objective information, coupled with other advances in palpatory training,37 can provide students with additional information to aid in skill development. Students can be exposed to didactic sessions of palpatory diagnosis and can confirm diagnoses with the kinematic test. Over time, the consistent use of such didactic sessions may help improve consistency among clinicians who practice the various forms of manual medicine.28,38
Diagnostic Assessment
In our study protocol, the interval between diagnostic screening and
kinematic testing provided an opportunity for changes to occur in some
subjects' movement patterns. Originally, the reason for this interval was
logistic, related to the amount of time needed to compare the results of the
diagnostic screening and perform the kinematic procedures. Based on the
results of the current pilot study, interexaminer reliability studies should
include same-day diagnoses and kinematic testing.
However, the fact that several subjects' diagnostic grouping changed between the initial and the confirmatory palpatory screenings is not as surprising as it is revealing about the difficulty related to generating reliable analytic techniques involving palpatory protocols. These changes may have resulted from a variety of factors. For example, subjects in pain on the day of the initial screening may have taken medication or other steps to reduce or relieve the pain before the confirmation assessment. Also, any injury or strenuous or unusual physical activity between the initial screening and the kinematic test day could have prompted changes in screening status.
Without objective tools to corroborate a clinical diagnosis based on palpatory findings, it will never be known whether such changes represent adaptive differences in subjects' movement behaviors or differences in examiners' judgements. For more accurate assessments of subjects' self-reported pain, studies should use a standardized pain rating scale as well as details regarding the etiology of their pain (eg, congenital abnormality, injury, surgery, bone pathology).
Clinical Utility
Reference data such as blood pressure values, respiratory rates, blood cell
counts, urinalysis, chemical panels, and lipid profiles are common in medicine
and provide objective information to assist clinicians in making diagnoses.
For example, physicians will subjectively assess patients' heart sounds.
However, before arriving at a diagnosis, physicians will also establish
objective parameters of heart health (eg, blood pressure, heart rate). The
subjective assessment will then be combined with the objective data to arrive
at a diagnosis.
The results of the current pilot investigation attempt to establish objective correlates for the subjective assessments of palpatory diagnosis, just as heart sounds and blood pressure are correlated. Once objective palpatory markers are established (in this case, parameters for coupled vertebral motions), they can be used in various areas of medicine.38 Figure 5 denotes several areas where an objective measure can be incorporated.
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Conclusions |
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TopMethodsResultsDiscussionConclusionsReferences |
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The preliminary data presented here indicate that objective, kinematic parameters can be generated, measured, and evaluated relative to palpatory findings of musculoskeletal impairment by identifying trends for coupled cervical vertebral motion—specifically differences in ratios of cervical lateral flexion and axial rotation. Findings from the current pilot investigation are being incorporated into the study protocols of upcoming research projects. We predict that larger sample sizes will statistically link objective measures to palpatory clinical diagnoses. Once the parameter of coupled motion has been statistically linked to palpatory evaluation, future studies can address matters of interexaminer reliability, subject sample size, and the effects of repeated palpatory examinations on subjects.
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Footnotes |
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We thank all of our collaborators, particularly the students and clinicians who helped with data collection and analysis.
We also thank William L. Johnston, DO, for his participation in this study and for his enduring inspiration. This experiment was Bill's final scientific effort—he died shortly after the completion of the data collection.
Throughout his career, Bill endeavored to understand and report relationships between clinical experiences and a theoretical basis for osteopathic manual medicine. In doing so, he attracted a variety of collaborators to the truest spirit of the scientific method. Together, Bill and his co-researchers sought to acquire new knowledge, amend and integrate existing knowledge, embrace objectivity, and work to assess differences between fact and belief.
For the current pilot study, Bill collaborated with an engineer (T.R.B.) and an anatomist (J.V.) to better understand physiologic correlates of palpable clinical signs of musculoskeletal function and dysfunction detected during clinical motion tests. His enthusiasm for this research was contagious, especially for those who shared his love of human-movement phenomena and biomechanics.
We are most fortunate to have worked with Bill. Our efforts, which were always a challenge, ended with great reward, but, for us, their most enduring significance will always be the pleasure of Bill's company, the opportunity to share our search for an objective basis for manual medicine, and Bill's inspiration to continue our work.
Submitted April 24, 2007; revision received August 8, 2007; accepted August 20, 2007.
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References |
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The largest
negative number is the endpoint of left lateral flexion, while the largest
positive number is the endpoint of right lateral flexion.