Forces measured during spinal manipulative procedures in two age groups

Spinal mobilization force-time characteristics: A scoping literature review

BACKGROUND

Spinal mobilization (SMob) is often included in the conservative management of spinal pain conditions as a recommended and effective treatment. While some studies quantify the biomechanical (kinetic) parameters of SMob, interpretation of findings is difficult due to poor reporting of methodological details. The aim of this study was to synthesise the literature describing force-time characteristics of manually applied SMob.

METHODS

This study is reported in accordance with the Preferred Reporting Items for Scoping Reviews (PRISMA-ScR) statement. Databases were searched from inception to October 2022: MEDLINE (Ovid), Embase, CINAHL, ICL, PEDro and Cochrane Library. Data were extracted and reported descriptively for the following domains: general study characteristics, number of and characteristics of individuals who delivered/received SMob, region treated, equipment used and force-time characteristics of SMob.

RESULTS

There were 7,607 records identified and of these, 36 (0.5%) were included in the analysis. SMob was delivered to the cervical spine in 13 (36.1%), the thoracic spine in 3 (8.3%) and the lumbopelvic spine in 18 (50.0%) studies. In 2 (5.6%) studies, spinal region was not specified. For SMob applied to all spinal regions, force-time characteristics were: peak force (0-128N); duration (10-120s); frequency (0.1-4.5Hz); and force amplitude (1-102N).

CONCLUSIONS

This study reports considerable variability of the force-time characteristics of SMob. In studies reporting force-time characteristics, SMob was most frequently delivered to the lumbar and cervical spine of humans and most commonly peak force was reported. Future studies should focus on the detailed reporting of force-time characteristics to facilitate the investigation of clinical dose-response effects.

A Case Report of U-Type Sacral Fracture After Chiropractic Adjustment

CASE

A U-type sacral fracture, or spinopelvic dissociation, resulting from chiropractic manipulation has not been described in the medical literature. This report presents the case of a 74-year-old male patient who sustained a U-type sacral fracture after drop-table chiropractic manipulation.

CONCLUSION

Our case demonstrates that chiropractic manipulative therapy involving the commonly used drop-table can cause severe injury. The patient's course was complicated by a delay in diagnosis and a prolonged hospital stay. Orthopaedic surgeons should have a high degree of suspicion for spinopelvic dissociation in the setting of bilateral sacral fractures. One year after injury, with conservative management, the patient returned to baseline function with mild residual neuropathy.

Devices Used to Measure Force-Time Characteristics of Spinal Manipulations and Mobilizations: A Mixed-Methods Scoping Review on Metrologic Properties and Factors Influencing Use

Background: Spinal manipulations (SMT) and mobilizations (MOB) are interventions commonly performed by many health care providers to manage musculoskeletal conditions. The clinical effects of these interventions are believed to be, at least in part, associated with their force-time characteristics. Numerous devices have been developed to measure the force-time characteristics of these modalities. The use of a device may be facilitated or limited by different factors such as its metrologic properties.

Objectives: This mixed-method scoping review aimed to characterize the metrologic properties of devices used to measure SMT/MOB force-time characteristics and to determine which factors may facilitate or limit the use of such devices within the context of research, education and clinical practice.

Methods: This study followed the Joanna Briggs Institute's framework. The literature search strategy included four concepts: (1) devices, (2) measurement of SMT or MOB force-time characteristics on humans, (3) factors facilitating or limiting the use of devices, and (4) metrologic properties. Two reviewers independently reviewed titles, abstracts and full articles to determine inclusion. To be included, studies had to report on a device metrologic property (e.g., reliability, accuracy) and/or discuss factors that may facilitate or limit the use of the device within the context of research, education or clinical practice. Metrologic properties were extracted per device. Limiting and facilitating factors were extracted and themes were identified.

Results: From the 8,998 studies initially retrieved, 46 studies were finally included. Ten devices measuring SMT/MOB force-time characteristics at the clinician-patient interface and six measuring them at patient-table interfaces were identified. Between zero and eight metrologic properties were reported per device: measurement error (defined as validity, accuracy, fidelity, or calibration), reliability/repeatability, coupling/crosstalk effect, linearity/correlation, sensitivity, variability, drift, and calibration. From the results, five themes related to the facilitating and limiting factors were developed: user-friendliness and versatility, metrologic/intrinsic properties, cost and durability, technique application, and feedback.

Conclusion: Various devices are available to measure SMT/MOB force-time characteristics. Metrologic properties were reported for most devices, but terminology standardization is lacking. The usefulness of a device in a particular context should be determined considering the metrologic properties as well as other potential facilitating and limiting factors.

Characterization of thoracic spinal manipulation and mobilization forces in older adults

BACKGROUND

Spinal mobilization and spinal manipulation are common interventions used by manual therapists to treat musculoskeletal conditions in older adults. Their force-time characteristics applied to older adults' thoracic spine are important considerations for effectiveness and safety but remain unknown. This study aimed to describe the force-time characteristics of posterior-to-anterior spinal mobilization and manipulation delivered to older adults' thoracic spine.

METHODS

Twenty-one older adults (≥65 years) with no thoracic pain received posterior-to-anterior thoracic spinal mobilization and/or manipulation with the force characteristics a chiropractor deemed appropriate. Six-degree-of-freedom load cells and an instrumented treatment table recorded the force characteristics of both interventions at the clinician-participant and participant-table interfaces, respectively. Preload force, total peak force, time to peak and loading rate were analyzed descriptively.

FINDINGS

Based on data from 18 adults (56% female; average: 70 years old), mean resultant spinal mobilization forces at the clinician-participant interface were: 220 ± 51 N during preload, 323 ± 67 N total peak force, and 312 ± 38 ms time to peak. At the participant-table interface, mobilization forces were 201 ± 50 N during preload, 296 ± 63 N total peak force, and 308 ± 44 ms time to peak. Mean resultant spinal manipulation forces at the clinician-participant interface were: 260 ± 41 N during preload, 470 ± 46 N total peak force, and 165 ± 28 ms time to peak. At the participant table interface, spinal manipulation forces were 236 ± 47 N during preload, 463 ± 57 N total peak force, and 169 ± 28 ms time to peak.

INTERPRETATION

Results suggest older adults experience unique, but comparable force-time characteristics during spinal mobilization and manipulation delivered to their thoracic spine compared to the ones delivered to younger adults described in the literature.

Quantitative study of PIMT technique aiming its validation as physical therapy procedure

BACKGROUND

Valgus hindfoot is a very common postural deviation, and the associated foot pronation can be a triggering factor for diseases such as tarsal tunnel syndrome.

RESEARCH QUESTION

This work compares two techniques for hindfoot valgus correction: GPR (Global Postural Reeducation) and PIMT (Postural Integration by Manual Therapy).

METHODS

Sixty young adult subjects from the Brazilian Army with unilateral hindfoot valgus were selected and divided into two groups of 30 subjects, one treated with GPR and the other treated with PIMT. Differences between normal and valgus hindfeet (plantar surface and body weight load) for each subject were measured and analysed, using a baropodometer with subjects in static standing position for 5s. Measurements were performed before and after each treatment session (4 weeks, once a week), and 4 weeks after the end of treatment.

RESULTS

Data shows that both treatments were equally effective for improving symmetry in body weight load between feet and plantar surface. After 4 weeks from the end of treatment, both treatments were equally effective for body weight load symmetry, but plantar surface symmetry was better in PIMT treated subjects.

SIGNIFICANCE

This study shows that PIMT technique can be validated as a physical therapy procedure, at least for valgus hindfoot.

Design and Evaluation of a Percutaneous Fragment Manipulation Device for Minimally Invasive Fracture Surgery

Reduction of fractures in the minimally invasive (MI) manner can avoid risks associated with open fracture surgery. The MI approach requires specialized tools called percutaneous fragment manipulation devices (PFMD) to enable surgeons to safely grasp and manipulate fragments. PFMDs developed for long-bone manipulation are not suitable for intra-articular fractures where small bone fragments are involved. With this study, we offer a solution to potentially move the current fracture management practice closer to the use of a MI approach. We investigate the design and testing of a new PFMD design for manual as well as robot-assisted manipulation of small bone fragments. This new PFMD design is simulated using FEA in three loading scenarios (force/torque: 0 N/2.6 Nm, 75.7 N/3.5 N, 147 N/6.8 Nm) assessing structural properties, breaking points, and maximum bending deformations. The PFMD is tested in a laboratory setting on Sawbones models (0 N/2.6 Nm), and on ex-vivo swine samples (F = 80 N ± 8 N, F = 150 ± 15 N). A commercial optical tracking system was used for measuring PFMD deformations under external loading and the results were verified with an electromagnetic tracking system. The average error difference between the tracking systems was 0.5 mm, being within their accuracy limits. Final results from reduction maneuvers performed both manually and with the robot assistance are obtained from 7 human cadavers with reduction forces in the range of (F = 80 N ± 8 N, F = 150 ± 15 N, respectively). The results show that structurally, the system performs as predicted by the simulation results. The PFMD did not break during ex-vivo and cadaveric trials. Simulation, laboratory, and cadaveric tests produced similar results regarding the PFMD bending. Specifically, for forces applied perpendicularly to the axis of the PFMD of 80 N ± 8 N deformations of 2.8, 2.97, and 3.06 mm are measured on the PFMD, while forces of 150 ± 15 N produced deformations of 5.8, 4.44, and 5.19 mm. This study has demonstrated that the proposed PFMD undergoes predictable deformations under typical bone manipulation loads. Testing of the device on human cadavers proved that these deformations do not affect the anatomic reduction quality. The PFMD is, therefore, suitable to reliably achieve and maintain fracture reductions, and to, consequently, allow external fracture fixation.

The effect of real-time feedback on learning lumbar spine joint mobilization by entry-level doctor of physical therapy students: a randomized, controlled, crossover trial

OBJECTIVE

To examine the effects of real-time, objective feedback on learning lumbar spine joint mobilization techniques by entry-level Doctor of Physical Therapy (DPT) students.

METHODS

A randomized, controlled, crossover design was used. Twenty-four 1st Year DPT students were randomized into two groups. Group 1 (n = 12) practiced with the real-time feedback device first and then without it, while Group 2 (n = 12) practiced without the device first and then with it. Both practice periods with and without the device were 4 weeks long. Data were collected at Baseline, 5 weeks, 11 weeks, and 16 weeks. The crossover period was 5 weeks long, during which neither group practiced with or without the device. Eight force parameters were measured: R1 force; R2 force; Grade III and Grade IV mean peak force, frequency, and amplitude.

RESULTS

When students practiced with the real-time feedback device, they more closely matched the reference standard for two outcomes: 1) the mean difference in R2 force between student and reference standard was better with device (38.0 ± 26.7 N) than without it (51.0 ± 38.5 N); P = .013; and 2) the mean difference in Grade III peak to peak amplitude force was also better with device (8.9 ± 9.3 N) than without it (11.8 ± 11.0); P = .026. All other force parameters improved when students practiced with the real-time feedback device, however, the differences between when they practiced without the device were not statistically significant.

DISCUSSION

Real-time, objective feedback using a direct force measurement device improved learning for some aspects of lumbar spine joint mobilization by entry-level physical therapy students.

LEVEL OF EVIDENCE

2b.

The intra-rater reliability of a revised 3-point grading system for accessory joint mobilizations

OBJECTIVES

Joint mobilizations are often quantified using a 4-point grading system based on the physiotherapist's detection of resistance. It is suggested that the initial resistance to joint mobilizations is imperceptible to physiotherapists, but that at some point through range becomes perceptible, a point termed R1. Grades of mobilization traditionally hinge around this concept and are performed either before or after R1. Physiotherapists, however, show poor reliability in applying grades of mobilization. The definition of R1 is ambiguous and dependent on the skills of the individual physiotherapist. The aim of this study is to test a revised grading system where R1 is considered at the beginning of range, and the entire range, as perceived by the physiotherapists maximum force application, is divided into three, creating 3 grades of mobilization.

METHOD

Thirty-two post-registration physiotherapists and nineteen pre-registration students assessed end of range (point R2) and then applied 3 grades of AP mobilizations, over the talus, in an asymptomatic models ankle. Vertical forces were recorded through a force platform. Intra-class Correlation Coefficients, Standard Error of Measurement, and Minimal Detectable Change were calculated to explore intra-rater reliability on intra-day and inter-day testing. T-tests determined group differences.

RESULTS

Intra-rater reliability was excellent for intra-day testing (ICC 0.96-0.97), and inter-day testing (ICC 0.85-0.93). No statistical difference was found between pre- and post-registration groups.

DISCUSSION

Standardizing the definition of grades of mobilization, by moving R1 to the beginning of range and separating grades into thirds, results in excellent intra-rater reliability on intra-day and inter-day tests.

LEVEL OF EVIDENCE

3b.

Joint mobilization forces and therapist reliability in subjects with knee osteoarthritis

Objectives:

This study determined biomechanical force parameters and reliability among clinicians performing knee joint mobilizations.

Methods:

Sixteen subjects with knee osteoarthritis and six therapists participated in the study. Forces were recorded using a capacitive-based pressure mat for three techniques at two grades of mobilization, each with two trials of 15 seconds. Dosage (force–time integral), amplitude, and frequency were also calculated. Analysis of variance was used to analyze grade differences, intraclass correlation coefficients determined reliability, and correlations assessed force associations with subject and rater variables.

Results:

Grade IV mobilizations produced higher mean forces (P<0.001) and higher dosage (P<0.001), while grade III produced higher maximum forces (P = 0.001). Grade III forces (Newtons) by technique (mean, maximum) were: extension 48, 81; flexion 41, 68; and medial glide 21, 34. Grade IV forces (Newtons) by technique (mean, maximum) were: extension 58, 78; flexion 44, 60; and medial glide 22, 30. Frequency (Hertz) ranged between 0.9–1.1 (grade III) and 1.4–1.6 (grade IV). Intra-clinician reliability was excellent (>0.90). Inter-clinician reliability was moderate for force and dosage, and poor for amplitude and frequency.

Discussion:

Force measurements were consistent with previously reported ranges and clinical constructs. Grade III and grade IV mobilizations can be distinguished from each other with differences for force and frequency being small, and dosage and amplitude being large. Intra-clinician reliability was excellent for all biomechanical parameters and inter-clinician reliability for dosage, the main variable of clinical interest, was moderate. This study quantified the applied forces among multiple clinicians, which may help determine optimal dosage and standardize care.

Biomechanical measures of knee joint mobilization

BACKGROUND AND PURPOSE

The purpose of this study was to quantify the biomechanical properties of specific manual therapy techniques in patients with symptomatic knee osteoarthritis.

METHODS

Twenty subjects (7 female/13 male, age 54±8 years, ht 1·7±0·1 m, wt 94·2±21·8 kg) participated in this study. One physical therapist delivered joint mobilizations (tibiofemoral extension and flexion; patellofemoral medial-lateral and inferior glide) at two grades (Maitland's grade III and grade IV). A capacitance-based pressure mat was used to capture biomechanical characteristics of force and frequency during 2 trials of 15 second mobilizations. Statistical analysis included intraclass correlation coefficient (ICC(3,1)) for intrarater reliability and 2×4 repeated measures analyses of variance and post-hoc comparison tests.

RESULTS

Force (Newtons) measurements (mean, max.) for grade III were: extension 45, 74; flexion 39, 61; medial-lateral glide 20, 34; inferior glide 16, 27. Force (Newtons) measurements (mean, max.) for grade IV were: extension 57, 76; flexion 47, 68; medial-lateral glide 23, 36; inferior glide 18, 35. Frequency (Hz) measurements were between 0·9 and 1·2 for grade III, and between 2·1 and 2·4 for grade IV. ICCs were above 0·90 for almost all measures.

DISCUSSION AND CONCLUSION

Maximum force measures were between the ranges reported for cervical and lumbar mobilization at similar grades. Mean force measures were greater at grade IV than III. Oscillation frequency and peak-to-peak amplitude measures were consistent with the grade performed (i.e. greater frequency at grade IV, greater peak-to-peak amplitude at grade III). Intrarater reliability for force, peak-to-peak amplitude and oscillation frequency for knee joint mobilizations was excellent.

Computer assisted learning in manipulative therapy education

Teaching manipulative therapy is one of the most relevant issues in a physiotherapy course. However, for an effective instruction of this topic practical experience is considered fundamental. To achieve this purpose, this paper presents a computer assisted environment for the practical learning of manipulative therapy. The implementation of such a laboratory includes standard Personal Computers (PCs), the popular software package Matlab, a digital camera and gloves with embedded strength sensors located in the thumb and near the wrist. The students wear a glove that measures the applied force in the patient. These signals are acquired and stored in a computer providing the teachers with the necessary information to analyze the applied force and verify if the manual therapy was successful. A digital camera is also used to record the images of the student's movements during the manual therapy application. The developed system has an autonomy of 15h allowing the application of thirty therapies and the corresponding data analysis.

A comparison of cervical spine mobilization forces applied by experienced and novice physiotherapists

STUDY DESIGN

Clinical measurement, cross-sectional.

OBJECTIVES

To compare cervical mobilization forces applied by physiotherapists and students, and the factors associated with forces for each group.

BACKGROUND

Cervical spine joint mobilization is a common manual technique for treating patients with mechanical neck pain. But little is known about the forces applied during this technique. Potential variability between therapists may result from clinical experience or may be due to factors present in individuals prior to clinical practice exposure.

METHODS

One hundred sixteen practicing physiotherapists and 120 physiotherapy students without clinical experience applied grades I through IV posteroanterior mobilization to the premarked C2 and C7 spinous and articular processes of 1 of 67 asymptomatic subjects. An instrumented table recorded applied forces (N), force amplitudes (N), and oscillation frequencies (Hz), and a custom device measured subjects' spinal stiffness (N/mm). Independent t tests were used to compare the forces applied by therapists and students, intraclass correlation coefficients were used to determine variability, and linear regression was used to establish factors associated with applied forces.

RESULTS

Students' forces were generally lower (mean difference, 15.7 N for grades III and IV; P<.001) and applied with slower oscillation frequencies (0.12 Hz; P<.001) than therapists' forces. Similar factors were associated with applied forces for both groups: male gender and greater subject body weight were associated with higher applied forces, and greater C2 stiffness with lower forces. Having thumb pain was associated with lower applied forces for therapists but higher ones for students.

CONCLUSIONS

Students apply lower forces than therapists. Similar factors appear to affect applied forces regardless of clinical experience.

Muscle repositioning: combining subjective and objective feedbacks in the teaching and practice of a reflex-based myofascial release technique

Muscle Repositioning (MR) is a new style of myofascial release that elicits involuntary motor reactions detectable by electromyography. This article* describes the principal theoretical and practical concepts of MR, and summarizes a workshop presented October 31, 2009, after the Second International Fascia Research Congress, held at Vrije Universitiet, Amsterdam.

The manual mechanical input of MR integrates the client’s body segments into a block, which is evident as a result of the diagnostic manual oscillations the practitioner imparts to the client’s body. Segmental integration is achieved when the client’s body responds as a unit to the oscillatory assessment. It appears that manually sustaining the condition of segmental integration evokes involuntary muscle reactions, which reactions might correspond to mechanisms that maintain homeostasis, such as pandiculation. It might be that these reactions are part of the MR mechanism of action and underlie its clinically observed efficacy in the treatment of musculoskeletal disorders.

For the practitioner and the client alike, segmental integration provides unique sensations. In teaching MR, these paired sensations can be used as kinesthetic feedback resources, because quality of touch can be guided by the client’s reported sensations, which should match the practitioner’s sensations. Another form of feedback with respect to quality of touch is the visually discernable degree of segmental integration. Finally, because the involuntary motor activity elicited by the MR touch can be objectively monitored through electromyography and possibly other instrumented measurements, the MR approach might yield objectivity, precision, and reproducibility—features seldom found in manual therapies.

Cervical spine mobilisation forces applied by physiotherapy students

OBJECTIVES

Postero-anterior (PA) mobilisation is commonly used in cervical spine treatment and included in physiotherapy curricula. The manual forces that students apply while learning cervical mobilisation are not known. Quantifying these forces informs the development of strategies for learning to apply cervical mobilisation effectively and safely. This study describes the mechanical properties of cervical PA mobilisation techniques applied by students, and investigates factors associated with force application.

PARTICIPANTS

Physiotherapy students (n=120) mobilised one of 32 asymptomatic subjects.

METHODS

Students applied Grades I to IV central and unilateral PA mobilisation to C2 and C7 of one asymptomatic subject. Manual forces were measured in three directions using an instrumented treatment table. Spinal stiffness of mobilised subjects was measured at C2 and C7 using a device that applied a standard oscillating force while measuring this force and its concurrent displacement. Analysis of variance was used to determine differences between techniques and grades, intraclass correlation coefficients (ICC) were used to calculate the inter- and intrastudent repeatability of forces, and linear regression was used to determine the associations between applied forces and characteristics of students and mobilised subjects.

RESULTS

Mobilisation forces increased from Grades I to IV (highest mean peak force, Grade IV C7 central PA technique: 63.7N). Interstudent reliability was poor [ICC(2,1)=0.23, 95% confidence interval (CI) 0.14 to 0.43], but intrastudent repeatability of forces was somewhat better (0.83, 95% CI 0.81 to 0.86). Higher applied force was associated with greater C7 stiffness, increased frequency of thumb pain, male gender of the student or mobilised subject, and a student being earlier in their learning process. Lower forces were associated with greater C2 stiffness.

CONCLUSION

This study describes the cervical mobilisation forces applied by students, and the characteristics of the student and mobilised subject associated with these forces. These results form a basis for the development of strategies to provide objective feedback to students learning to apply cervical mobilisation.

Muscle Repositioning: a new verifiable approach to neuro-myofascial release?

The clinical observation of involuntary motor activity during application of a particular style of myofascial release (Muscle Repositioning-MR) has led to the hypothesis that this technique might evoke neurological reactions. Preliminary EMG recordings presented here show involuntary tonic cervical erector action during MR. Involuntary eye movements were also observed. This article presents these experimental data, along with clinical observations during the application of MR in the treatment of musculoskeletal conditions. The author hypothesizes that MR might constitute a novel manual technique: it produces unique palpatory sensations for the practitioner (e.g., a sense of firmness to the touch and the integration of bodily segments into a single block) that correspond to unique sensory experiences for the client. The article raises the possibility that MR's specific sensory input might activate the central nervous system, thus eliciting neural reactions. These reactions, in turn, might be related to the technique's efficacy. As the EMG objectively measures reactions contemporaneous with subjective palpatory phenomena, MR potentially brings the objective and subjective into congruence. EMG monitoring of touch could serve as an objective criterion in the development of treatment protocols, as well as a feedback tool for teaching. Greater objectivity, precision and reproducibility are all possible outcomes of such an approach. The author believes that MR can be used in various therapeutic settings--either as the principal approach, or as an adjunct to a variety of other approaches.

Study of the force applied during anteroposterior articular mobilization of the talus and its effect on the dorsiflexion range of motion

OBJECTIVE

The aim of this study was to investigate the behavior of the force applied during the Maitland grade III anteroposterior joint mobilization of the talus and its effect on dorsiflexion range of motion (ROM).

METHODS

Two examiners performed measurements of dorsiflexion ROM on both ankles of healthy volunteers using a universal goniometer. The anteroposterior talus mobilization was first applied by examiner A for 30 seconds. Examiner B then repeated the same procedure. A platform was placed under the volunteer's leg to register the forces obtained during mobilization. After the procedure, examiner A assessed the ankle dorsiflexion.

RESULTS

The results showed consistency regarding maximal forces applied throughout the 30 seconds of mobilization as well as low consistency upon the minimal forces. A significant increase in dorsiflexion ROM of the ankle was found immediately after joint mobilization.

CONCLUSIONS

The results of the present study have shown consistent maximal forces applied by one examiner and inconsistent minimal forces during an ankle mobilization in healthy volunteers when the same examiner was compared. Moreover, the applied force was able to increase dorsiflexion ROM after the Maitland grade III anteroposterior mobilization of the talus.

Manual Forces Applied During Cervical Mobilization

OBJECTIVE

Manual therapists routinely use passive accessory mobilization techniques to treat patients with mechanical neck disorders, but little is known about the manual forces applied. The aim of this study was to quantify the manual forces applied to the cervical spine during joint mobilization.

METHODS

Ten physiotherapists performed posterior-to-anterior mobilizations to C2 and C7 (both centrally and unilaterally, 1 right and 1 left, grades I-IV) on a single asymptomatic male subject. Manual forces were measured in 3 planes using an instrumented treatment table.

RESULTS

The instrumented table showed excellent reliability (intraclass correlation coefficient [2,1], 0.99; 95% confidence interval, 0.97-1.00) and accuracy (mean absolute error; vertical force, 1.1 N; SD, 1.5). There were considerable differences between therapists for mean peak force, force amplitude, and oscillation frequency for each technique and grade. Mean peak forces (grade I, 21.8 N; SD, 15.0; grade II, 34.9 N; SD, 20.9; grade III, 58.2 N; SD, 27.5; grade IV, 61.0 N; SD, 29.9) were considerably lower than previously reported lumbar mobilization forces. Intratherapist repeatability for all mobilization parameters was high. Force amplitude and oscillation frequency measures indicated that therapists generally adhered to the published definitions of the grades of mobilization when applying force, but when asked, provided quite different definitions of the grades.

CONCLUSIONS

This study provides preliminary evidence that cervical mobilization forces vary considerably between therapists, but intratherapist repeatability is high.

Basic Science Research Related to Chiropractic Spinal Adjusting: The State of the Art and Recommendations Revisited

OBJECTIVE

The objectives of this white paper are to review and summarize the basic science literature relevant to spinal fixation (subluxation) and spinal adjusting procedures and to make specific recommendations for future research.

METHODS

PubMed, CINAHL, ICL, OSTMED, and MANTIS databases were searched by a multidisciplinary team for reports of basic science research (since 1995) related to spinal fixation (subluxation) and spinal adjusting (spinal manipulation). In addition, hand searches of the reference sections of studies judged to be important by the authors were also obtained. Each author used key words they determined to be most important to their field in designing their individual search strategy. Both animal and human studies were included in the literature searches, summaries, and recommendations for future research produced in this project.

DISCUSSION

The following topic areas were identified: anatomy, biomechanics, somatic nervous system, animal models, immune system, and human studies related to the autonomic nervous system. A relevant summary of each topic area and specific recommendations for future research in each area were the primary objectives of this project.

CONCLUSIONS

The summaries of the literature for the 6 topic sections (anatomy, biomechanics, somatic nervous system, animal models, immune system, and human studies related to the autonomic nervous system) indicated that a significant body of basic science research evaluating chiropractic spinal adjusting has been completed and published since the 1997 basic science white paper. Much more basic science research in these fields needs to be accomplished, and the recommendations at the end of each topic section should help researchers, funding agencies, and other decision makers develop specific research priorities.

Manual Forces Applied During Posterior-to-Anterior Spinal Mobilization: A Review of the Evidence

OBJECTIVE

The objective of this review was to evaluate the evidence for the consistency of force application by manual therapists when carrying out posterior-to-anterior (PA) mobilization techniques, including the factors that influence the application and measurement of mobilization forces.

METHODS

Studies were identified by searching 6 electronic databases up to April 2005, screening the reference lists of retrieved articles, and contacting experts by e-mail. Relevant articles were defined as those that described the measurement of forces applied during spinal mobilization or discussed the reliability of measurement of manual forces.

RESULTS

Twenty studies described the quantitative measurement of applied force during a PA mobilization technique, with most focusing on the lumbar spine. When defined by magnitude, frequency, amplitude, and displacement, PA mobilization forces are extremely variable among clinicians applying the same manual technique. Variability may be attributed to differences in techniques, measurement or reporting procedures, or variations between therapists or between patients.

CONCLUSIONS

The inconsistency in manual force application during PA spinal mobilization in existing studies suggests that further studies are needed to improve the clinical standardization of manual force application. Future research on mobilization should include forces applied to the cervical and thoracic spines in addition to the lumbar spine while thoroughly describing force parameters and measurement methods to facilitate comparison between studies.

Development of a Hand Dynamometer for the Control of Manually Applied Forces

OBJECTIVE

The aim of the study was to develop a prototype tool capable of providing instantaneous feedback about manually applied forces, and to use it to determine (1) whether force constancy can be maintained during different application postures and (2) whether sensitivity to stiffness using the tool is different from sensitivity when assessing stiffness with the hands.

METHODS

Subjects were students and staff in a health sciences faculty. A series of grade II and IV mobilizing forces were delivered using a mobilizing tool, a modified JAMAR dynamometer fitted with a molded handle. Forces were executed without feedback at application points on a plinth that were near, midway, and far from the body. Thereafter, discrimination between elastic stiffness was determined with hands alone or using the tool.

RESULTS

Force was maintained at grade II when the point of application was moved away from the body, but attempts to replicate grade IV mobilization forces in similar postures showed a decrease despite increased effort. Variation in force produced was substantial both within and between subjects. Stiffness discrimination was not significantly different whether hands or the tool was used.

CONCLUSION

There is substantial variation in manually applied forces that could be controlled if instantaneous force readout was available. Reports of hand injury in manual therapists motivate further development of devices that maintain sensitivity and allow for control of applied force and spread the load over a greater surface area on the hands.

Comparison of human lumbar facet joint capsule strains during simulated high-velocity, low-amplitude spinal manipulation versus physiological motions

BACKGROUND CONTEXT

Spinal manipulation (SM) is an effective treatment for low back pain (LBP), and it has been theorized that SM induces a beneficial neurophysiological effect by stimulating mechanically sensitive neurons in the lumbar facet joint capsule (FJC).

PURPOSE

The purpose of this study was to determine whether human lumbar FJC strains during simulated SM were different from those that occur during physiological motions.

STUDY DESIGN/SETTING

Lumbar FJC strains were measured in human cadaveric spine specimens during physiological motions and simulated SM in a laboratory setting.

METHODS

Specimens were tested during displacement-controlled physiological motions of flexion, extension, lateral bending, and axial rotations. SM was simulated using combinations of manipulation site (L3, L4, and L5), impulse speed (5, 20, and 50 mm/s), and pre-torque magnitude (applied at T12 to simulate patient position; 0, 5, 10 Nm). FJC strains and vertebral motions (using six degrees of freedom) were measured during both loading protocols.

RESULTS

During SM, the applied loads were within the range measured during SM in vivo. Vertebral translations occurred primarily in the direction of the applied load, and were similar in magnitude regardless of manipulation site. Vertebral rotations and FJC strain magnitudes during SM were within the range that occurred during physiological motions. At a given FJC, manipulations delivered distally induced capsule strains similar in magnitude to those that occurred when the manipulation was applied proximally.

CONCLUSIONS

FJC strain magnitudes during SM were within the physiological range, suggesting that SM is biomechanically safe. Successful treatment of patients with LBP using SM may not require precise segmental specificity, because the strain magnitudes at a given FJC during SM do not depend upon manipulation site.

Failure characteristics of the thoracic spine with a posteroanterior load: investigating the safety of spinal mobilization

STUDY DESIGN

In vitro biomechanical study of human cadaveric thoracic spine segments and one intact cadaver and applied load measurements in human volunteers.

OBJECTIVES

To quantify failure load and pattern of midthoracic vertebrae under a posteroanterior load and to compare failure load in vitro with applied load in vivo.

SUMMARY OF BACKGROUND DATA

Osteoporosis and back pain are common alone and in combination among older adults. Spinal mobilization techniques have been shown to relieve back pain and improve function in various clinical settings. However, whether controlled spinal mobilization can cause vertebral fracture in individuals with osteoporosis is not known.

METHODS

Twelve T5-T8 cadaveric specimens (mean age, 77 years) were scanned using bone densitometry, radiographed, and measured for bone size. The authors measured failure load, failure site, and intervertebral motion (using a precision optoelectronic camera system) when a posteroanterior load was applied at the spinous process of T6 using a servohydraulic material testing machine. Post-test radiography and CT scan were used to verify failure site. These tests were repeated in an intact cadaver using a Tekscan I-Scan sensor to measure applied loads. The authors also quantified in vivo applied loads during posteroanterior mobilization during seven trials by two experienced physiotherapists.

RESULTS

Mean (SD) in vitro failure load of 479 N (162 N) was significantly higher than the mean (SD) in vivo applied load of 145 N (38 N) (P = 0.0004). Macroscopic observation revealed a fracture at the T6 spinous process in 11 specimens and one at the T7 spinous process. These fractures were detected by plain radiography in three of 12 cases and by CT scan in six of 12 cases.

CONCLUSIONS

The results suggest a reasonable margin between failure load in vitro and applied mobilization load in vivo.

Influence of standardized mobilization on the posteroanterior stiffness of the lumbar spine in asymptomatic subjects

BACKGROUND AND PURPOSE

Spinal mobilization is commonly used to relieve pain and assist recovery of mobility in individuals with low back pain. Fundamental to this concept is the belief that spinal mobilization will influence the mechanical properties of the symptomatic motion segment. The objective of the present study was to examine the segmental effects of a standardized mobilization procedure on the posteroanterior (PA) stiffness of the lumbar spine.

METHOD

Audio and visual feedback was used to train a physiotherapist to perform PA mobilization at a consistent load and frequency. After training, twenty-four subjects without low back pain were recruited for the intervention phase of the study. The spinal posteroanterior mobilization (SPAM) apparatus was used to measure the PA stiffness of the lumbar spine at three measurement sites (L1, L3 and L5). The trained physiotherapist then applied the standardized PA mobilization technique via the L3 spinous process for two minutes. Following mobilization, PA stiffness was measured three times at the three locations.

RESULTS

The physiotherapist was able to apply a standardized mobilization with a mean force of 146 N (standard deviation (SD) 8 N) at a frequency of 1.5 Hz. The first trial on each assessment demonstrated a pre-condition effect. Two minutes' PA mobilization resulted in no significant change in the PA stiffness of the lumbar spine at the level to which the mobilization was applied, or at the L1 and L5 segments. The 95% confidence intervals (CI) of the difference in PA stiffness before and after testing included zero at each measurement site.

CONCLUSIONS

Clinicians should pre-condition the spine when assessing PA stiffness both before and after interventions. A standardized mobilization of 150 N at 1.5 Hz for two minutes had no segmental effect on spinal PA stiffness. Subsequent studies need to consider other mechanisms that may contribute to the changes that occur after PA spinal mobilization.

Spinal manipulative therapy for low back pain

Growing interest in complementary and alternative medicine in the United States has been paralleled by increased use of spinal manipulative therapy in an attempt to manage symptoms of low back pain, spinal stenosis, and spondylolisthesis. Chiropractors have been the main practitioners of spinal manipulative therapy, with osteopaths and physical therapists providing a smaller fraction of these services. Theories explaining the mode of action of spinal manipulative therapy are largely preliminary and have focused on the mechanical effects of manipulative forces on the spine and neurologic responses to manipulation. The effects of spinal manipulation on patients with both acute and chronic low back pain have been investigated in randomized clinical trials. Most reviews of these trials indicate that spinal manipulative therapy provides some short-term benefit to patients, especially with acute low back pain.

Forces applied during manual therapy to patients with low back pain

BACKGROUND

To date, there is little information available regarding the forces used during mobilization treatment of patients with low back pain (LBP).

OBJECTIVE

This study measured such forces and investigated whether the force characteristics could be predicted on the basis of physical therapist and patient characteristics.

SUBJECTS

Ten physical therapists applied a central posteroanterior (PA) mobilization treatment to 80 patients with LBP, providing data on treatment of 123 lumbar levels.

METHODS

Physical therapists were required to treat their patients while the patients lay on an instrumented couch. This couch has been shown to be highly accurate in its measurement of force in 3 directions (error <2%) and has demonstrated high test-retest reliability (ICC [2, 1], 99% CI = 0.99-1.00). The forces applied by the physical therapists were recorded over a 10-second period. Data on the characteristics of the physical therapists and patients were collected by means of questionnaires.

RESULTS

The force used by physical therapists related not only to patient characteristics but also to physical therapist characteristics. Interestingly, current pain intensity and nature of symptoms did not affect the forces used. The overall patterns of the force characteristics were generally consistent with previous studies performed in asymptomatic subjects. However, the magnitude of the force applied and the frequency of each grade used in the present study are relatively higher than in earlier studies.

CONCLUSION

These preliminary data provide some useful quantitative information about the forces used during mobilization treatment of patients with LBP. Also, the force characteristics described here may provide useful data for both teaching and research in manual therapy.

The response of posteroanterior lumbar stiffness to repeated loading

Lumbar posteroanterior (PA) responses are determined by manual examination and are used to guide treatment decisions and interpret changes in symptoms within and between treatments. Mechanical devices that simulate manual assessment have been developed to measure lumbar PA responses. The two variables used to describe lumbar PA responses to mechanical loading are stiffness coefficient K and displacement D30. The purpose of this study was to investigate the behaviour of lumbar PA responses with repeated loading over time. Lumbar PA responses at L4 were measured in 18 pain-free subjects using a mechanical device. Measurements were made for five consecutive loading cycles on three test occasions. The responses were compared between the five cycles within a single test occasion and between three test occasions. An identical procedure was also used to test a set of elastic springs for comparison. There was a significant increase in both stiffness coefficient K and displacement D30 between the first cycle and subsequent cycles of a single test occasion on human subjects. This response which demonstrates an increase in stiffness and displacement between the first and subsequent cycles can be considered a normal response to PA loading. PA stiffness remains constant over several tests both within one day and between days.

Development of an instrumented couch to measure forces during manual physiotherapy treatment

This paper reports on an instrumented couch developed to measure the forces applied during posteroanterior (PA) mobilization to the lumbar spine. The couch was evaluated for reliability by applying known weights to the empty couch, while accuracy was investigated by applying weights both to the empty couch and to a human subject lying on the couch. The equipment appears highly reliable when measuring forces in three directions (ICC(2,1); 99% CI=0.99-1.00) and also demonstrates acceptable accuracy; a maximum error of less than 2% being obtained when measuring forces applied to human subjects. The results demonstrate a highly linear relationship (r2=0.99) between the force readings and the known weights. In conclusion, the instrumented couch demonstrates suitable accuracy and reliability for measuring the force applied to a subject during the application of PA mobilization to the lumbar spine.