Archive for category Research


Patients often present themselves for  chiropractic treatment with conditions that may include  contraindications for manipulative therapy. This report describes  successful chiropractic treatment of acute shoulder pain involving a  patient who presented with mixed metastatic carcinoma affecting the  humerus, scapula, and clavicle using an Activator Adjusting Instrument.

The successful outcome of the case demonstrates the possible value of  instrumental chiropractic adjustment in treating neuromusculoskeletal  cases where a forceful, high-velocity adjustment or manipulation would  be contraindicated because of the underlying osseous pathology involved.  Further study into this possibility should be provided to help train  those physicians who are called upon to treat these cases and to help  further define risk management protocols for the chiropractic  profession.

Chiropr Tech 1995; 7(3):98-102.

Author information: Polkinghorn BS. Private practice of chiropractic. Santa Monica, CA, USA.

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To describe treatment of frozen shoulder syndrome (adhesive capsulitis) via conservative chiropractic treatment to the shoulder joint, utilizing specific contact, low force, instrumental adjusting procedures. A case report, providing an illustrative example of the same, is presented along with a review of the relevant literature.


A 53-yr-old woman suffered severe shoulder pain of over 6 months’ duration. The patient had been diagnosed as having adhesive capsulitis and had undergone a variety of different treatment regimens without obtaining relief, including various NSAIDs, analgesics and physical therapy. At the time of her presentation, her condition had progressed to the point of near total immobility of the shoulder joint, accompanied by severe pain with resulting marked restriction in her normal activities of daily living.


The patient’s shoulder was conservatively managed with chiropractic adjustments to the affected shoulder joint, as well as to the cervicothoracic spine. Treatment consisted of mechanical force, manually assisted short lever chiropractic adjustments, delivered via an Activator Adjusting Instrument. Successful resolution of the presenting symptomatology was achieved.


Chiropractic care may be able to provide an effective mode of therapeutic treatment for certain types of these difficult cases. Low force instrumental adjustments, in particular, may present certain benefits in these cases that the more forceful manipulations and/or mobilizations cannot. As such, further formal investigation of this type of therapeutic intervention for treatment of frozen shoulder may be warranted on a larger scale.

J Manipulative Physiol Ther. 1995 Feb;18(2):105-15. [PMID:7790781]

Author information: Polkinghorn BS. Private practice of chiropractic. Santa Monica, CA, USA.

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From the Publisher

The distinguished editorial board chooses topics that are most critical and clinically relevant to improving patient care. Invited experts write original, comprehensive articles, summarizing the vital changes and critical issues, and give both the practitioner and student fresh, thorough viewpoints on the topics significance.


Perhaps no other technique has been the focus of as much overwhelming scrutiny and controversy as the Activator Methods Chiropractic Technique (AMCT). Until recently, the main question of whether a specific treatment is effective for a particular patient with a given condition has been neglected. However, developments in health care reform have put the process of technology assessment and dissemination on the fast track. This chapter serves  as a follow-up to an appraisal published in 1990. It reviews recent research efforts of Activator Methods, Inc. (AMI) and speculates about the future of what has become know as mechanical force manually-assisted (MFMA) chiropractic adjusting procedures.

Reference: Osterbauer PJ, Fuhr AW, Keller TS. Description and Analysis of Activator Methods Chiropractic Technique. In: Lawrence DJ, Cassidy JD, McGregor M, Meeker WC, and Vernon HT (Eds.): Advances in Chiropractic. Volume 2. St. Louis: Mosby, 1995, pp. 471-520.


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Objective: The objective of this paper is to investigate if there is a relationship between the side of leg length inequality (LLI) and the side of low back pain (LBP).

Design: Carefully standardised radiographic technique as described by Giles (1,2) and reviewed by Rock (3) was utilised to evaluate LLI in individuals who presented for assessment of LBP. Age, sex and the side of LBP were extracted from patient records. The side of LBP was determined by marking a pain diagram, taking the form of a body outline, included in the patient questionnaires. These findings were examined to reveal any relationship between the side of LLI and the side of LBP.

Setting: The study was conducted in a private chiropractic practice.

Participants: From January 1993 to September 1993 all patients presenting for chiropractic assessment of LBP where included. Patients whose history revealed relevant trauma, surgery or whose radiographic examination showed anomaly or pathology, likely to confound results, were excluded from the study.

Results and Conclusion: A relationship has been demonstrated between the LLI side and the side of LBP. The broad age range of subjects may well have been a confounding factor in this study. Re-analysis of the sample of patients aged 34 years or less demonstrated that the LBP side is most commonly opposite the side of LLI.

 COMSIG Rev. 1995 Jul 1; 4(2): 33–36. [PMCID: PMC2050381]

Author information: Anderson RG, Hayek R, Foggerty MP.

Free PMC Article

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To test systematically if spinal manipulative treatments (SMT) and the audible release associated with SMT cause activation of spinal muscles.


Experimental pilot study.


Human Performance Laboratory, The University of Calgary.


One male and one female asymptomatic volunteer.


Slow and fast SMTs to the left transverse process of thoracic vertebrae using a reinforced hypothenar contact. The treatment forces were directed in a posterior-to-anterior direction with the subjects in a prone position.

Main Outcome Measures:

Forces applied by the chiropractor during SMT. Measurements of the audible release using skin-mounted accelerometers. Electromyographical activity of selected spinal muscles.


Electromyographical (EMG) activity was observed consistently 50-100 msec after the onset of each of the fast SMTs, whether the treatment resulted in an audible release or not; for slow SMTs, there was never any visible electromyographical activity of the target muscles, whether the treatment resulted in an audible release or not.


The results of this study suggest that fast treatment thrusts elicit muscle activation, whereas slow force application does not. The timing of the onset of the EMG response suggests that activation may be produced by a reflex response originating in the muscle spindles. It also appears that the audible release does not (by itself) evoke muscle activation or a joint proprioceptive reflex response as has been speculated in the literature.

J Manipulative Physiol Ther. 1995 May;18(4):233-6. [PMID:7636413]

Author information: W. Herzog, PhD.; P.J. Conway, DC; Y.T. Zhang, PhD.; J. Gal, PhD; A.C.S. Guimaraes. Faculty of Physical Education, University of Calgary, Alberta, Canada.

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The objective of this paper is to review the literature on the audible release associated with manipulation.


Bibliographic information in pertinent articles and papers located in the MEDLINE database containing the keywords joint, joints, cartilage, crack, cracking, cavitation, crepitus and noise.


All articles relevant to the objectives were selected.


All available data was used.


The audible release is caused by a cavitation process whereby a sudden decrease in intracapsular pressure causes dissolved gasses in the synovial fluid to be released into the joint cavity. Once a joint undergoes cavitation, the force-displacement curve changes and the range of motion of the joint increases. The gasses released from the synovial fluid make up about 15% of the joint volume and consist of approximately 80% carbon dioxide. Habitual joint cracking does not correlate with arthritic changes, but does correlate with loss of grip strength and soft-tissue swelling. During the “crack” associated with a joint manipulation, there is a sudden joint distraction that occurs in less time than that required to complete the stretch reflexes of periarticular muscles. Theories on the cavitation mechanism were reviewed and new information on the cavitation process is introduced. In this paper, it is proposed that the cavitation process is generated by an elastic recoil of the synovial capsule as it “snaps back” from the capsule/synovial fluid interface.


Because the sudden joint distraction during a manipulation occurs in a shorter time period than that required to complete the stretch reflexes of the periarticular muscles, there is likely to be a high impulse acting on the ligaments and muscles associated with the joint. This is an important conclusion, because others have proposed that reflex actions from high threshold periarticular receptors are associated with the many beneficial results of manipulation. This suggests that the cavitation process provides a simple means for initiating the reflex actions and that without the cavitation process, it would be difficult to generate the forces in the appropriate tissue without causing muscular damage.

J Manipulative Physiol Ther. 1995 Mar-Apr;18(3):155-64.  [PMID:7790795]

Author information: Brodeur R. Department of Biomechanics, Michigan State University, East Lansing 48824, USA.

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Fuhr Optoelectric



a) Establish a precise, standardized method to assess prone leg alignment changes (functional “leg length inequality”), which have, until now, been reported clinically to occur as a result putative chiropractic subluxation isolation tests [neck flexion (C5) and extension (C1)]; and b) describe differences in leg alignment changes in a group of healthy subjects and patients with chronic spinal complaints.


Two group, two isolation tests, descriptive, repeated measure analysis of variance.


Exercise and Sport Research Institute, Arizona State University.


Eight healthy controls, eight patients with a history of chronic spinal complaints and observable leg alignment reactivity.


Active cervical flexion/extension maneuvers.


Optoelectric markers affixed to heels and occiput, as subjects lay prone. Marker locations sampled at 100 Hz for 10 sec during: a) three no movement trials, b) three cervical extension and c) three flexion trials. Data transformed to local reference frame approximately each subject’s longitudinal axis prior to analysis.


Heel position movement occurred during trials and were highly individualistic. Patients exhibited more asymmetrical movements than the controls during the head-up trials. No differences existed between controls and patients for range of heel displacement or net displacement.


The results of this study allow the following to be concluded: 1) small leg displacements (< 1 mm) were recorded by the optoelectric measurement system; 2) heel position changes during isolation tests were identifiable; 3) as a result of head-up maneuvers, patients exhibited more asymmetrical heel movement than controls (t = 8.743, p < .01); 4) The heel range of motion was not different between the groups; and 5) The net change in heel position was not different between the groups. Patients exhibited more asymmetrical heel motion during head-up isolation tests, suggesting that some phenomena may separate these two groups, warranting future study.

J Manipulative Physiol Ther. 1994 Oct;17(8):530-8. [PMID:7836876]

Author information: De Witt JK, Osterbauer PJ, Stelmach GE, Fuhr AW. Exercise and Sport Research Institute, Arizona State University, Tempe 85287-0404.

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To present the first reported case of successful chiropractic intervention in treatment of a torn medial meniscus of the knee, the meniscal tear being documented by magnetic resonance imaging (MRI).


A 54-yr-old woman complaining of right knee pain of several months’ duration with accompanying marked functional impairment was diagnosed as having a tear in the posterior horn of the ipsilateral medial meniscus, verified by MRI studies of the same. Independent consultation with three medical specialists resulted in the unanimous decision that surgical intervention for the purpose of meniscectomy provided the only therapeutic approach indicated for the problem. However, the patient was reticent to undergo said surgical procedure and chose, instead, to utilize chiropractic care and conservative management in an effort to resolve her condition without having to resort to surgery.


The patient received chiropractic treatment to the knee via mechanical force, manually assisted short lever chiropractic adjusting procedures (MFMA) utilizing an Activator Adjusting Instrument. Auxiliary treatment included the use of homeopathic therapy as an adjunct to chiropractic care. Said treatment resulted in a complete resolution of the patient’s disability, the patient recovering full function of the knee joint and achieving an asymptomatic status without having to submit to surgical intervention and its possible adverse sequelae.


Conservative management of meniscal tears via chiropractic treatment may provide a therapeutically effective and financially cost containing alternative to routine meniscectomy in certain cases involving torn medial menisci of the knee.

J Manipulative Physiol Ther. 1994 Sep;17(7):474-84. [PMID:7989881]

Author information: Polkinghorn BS. Private practice of chiropractic. Santa Monica, CA.

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To (i) measure lumbar intervertebral motion patterns produced during low force, high frequency posteroanterior (PA) thrusts applied to adjacent thoracolumbar spinal segments; (ii) determine the dependence of PA stiffness and impedance characteristics of the thoracolumbar spine on loading frequency; and (iii) ascertain the feasibility of using PA stiffness or impedance to characterize the in vivo mechanical response of the spine during spinal manipulation.


Hospital in Gothenburg, Sweden.


Three subjects–one normal (male), one patient diagnosed with L4-5 degenerative disk disease (female), and one patient diagnosed with L5 retrospondylolisthesis (male).


Intervertebral motion device (IMD) attached to pins inserted into the L3-4 or L4-5 spinous processes. Four repeated PA impulses were delivered to each of the spinous processes (T11-L3) using an Activator Adjusting Instrument with a force-acceleration measurement system.


Peak-to-peak intervertebral axial displacement, PA shear displacement and flexion-extension (FE) rotation were obtained using the IMD. Thoracolumbar PA impedance (force/velocity) vs. frequency histories and peak PA dynamic stiffness (impedance x frequency) were determined from the force-acceleration measurements. Averages and standard deviations of these measures were calculated from the repeated interventions performed at each level.


For the normal subject, the AAI PA impulses applied to the L2 spinous process (72 +/- 9 N) produced a 1.62 +/- 1.06 mm peak-to-peak intervertebral axial displacement, 0.48 +/- 0.1 mm PA shear displacement, and 0.89 +/- 0.49 degrees FE rotation at the L3-4 spinal segment. The amplitude of the lumbar intervertebral motion in the normal subject’s spine decreased approximately sixfold when the AAI impulses were delivered further from the IMD measurement site. In both patients the axial, PA shear and FE lumbar intervertebral motions were of the same magnitude, but showed less variability than the normal subject as the AAI impulses were delivered closer to the IMD measurement site. The normal thoracolumbar spine exhibited a maximum dynamic PA impedance at a frequency of approximately 100-150 Hz, resulting in a peak PA stiffness ranging from 62 KN/m (L2 segment) to 124 KN/m (T11 segment). Thoracolumbar PA stiffness values tended to be higher for the patient with a severely degenerated disk (85-362 KN/m), whereas the patient with retrospondylolisthesis had a lower PA stiffness (32-96 KN/m).


In vivo kinematic measurements of the normal and pathologic human lumbar spine indicate that low force, PA impulses produce measurable segmental motions and reinforce the notion that mechanical processes play an important role in spinal manipulation and mobilization. Calculations of the peak dynamic stiffness derived from impedance vs. frequency measurements indicate that the dynamic stiffness of the thoracolumbar spine is considerably greater than previously reported stiffness values obtained using static and quasistatic manipulation and mobilization procedures. Computations of spinal input impedance are relatively simple to perform, can provide a noninvasive measure of the dynamic mechanical behavior of the spine, appear to have potential to discriminate pathologic changes to the spine, and warrant further study on a larger sample of normals and patients. Ultimately, chiropractic clinicians may be able to use low force, impact type spinal manipulation, together with dynamic impedance analysis procedures, to quantify the mechanical response of the normal and abnormal spine, to perform spinal diagnosis and subsequently to prescribe therapeutic treatment to patients.

J Manipulative Physiol Ther. 1994 Sep;17(7):431-41. [PMID: 7989876]

Author information: Nathan M, Keller TS. Department of Mechanical Engineering, University of Vermont, Burlington 05405-0156.

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Subject: The Activator Adjusting Instrument – Biomechanical


Reference: Tony S. Keller;  J.B. Lehneman…Musculoskeletal Research Lab, February 1994: pp.1-16


Introduction: The Activator Adjusting Instrument  (AAI) is a devise used for chiropractic manipulations. The device is  intended to produce repeatable impacts (manipulations) at various force  settings. The force is easily adjusted by turning the small knob on the  lower part of the device.


Objective: The purpose of this study is to determine  the effect of the force setting, and preload on the actual force  delivered by the AAi to the impact surface.

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