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PHYS THER
Vol. 84, No. 2, February 2004, pp. 173-190
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Research Reports

Factors Related to the Inability of Individuals With Low Back Pain to Improve With a Spinal Manipulation

Julie M Fritz, Julie M Whitman, Timothy W Flynn, Robert S Wainner and John D Childs

JM Fritz, PT, PhD, ATC, is Assistant Professor, Department of Physical Therapy, University of Pittsburgh, 6035 Forbes Tower, Pittsburgh, PA 15260 (USA) (jfritz{at}pitt.edu)
JM Whitman, PT, DSc, OCS, FAAOMPT, is Element Chief, Physical Therapy Element, Kirtland Air Force Base, Albuquerque, NM
TW Flynn, PT, PhD, OCS, FAAOMPT, is Associate Professor, Department of Physical Therapy, Regis University, Denver, Colo
RS Wainner, PT, PhD, OCS, ECS, FAAOMPT, is Assistant Professor, US Army-Baylor University Graduate Program in Physical Therapy
JD Childs, PT, PhD, MBA, OCS, CSCS, FAAOMPT, is Senior Physical Therapist and Director of Research, Department of Physical Therapy, Wilford Hall Medical Center, San Antonio, Tex
Dr Fritz, Dr Whitman, Dr Flynn, and Dr Wainner provided concept/idea/research design. Dr Fritz, Dr Flynn, Dr Wainner, and Dr Childs provided writing. Dr Whitman, Dr Flynn, and Dr Wainner provided data collection. Dr Fritz, Dr Whitman, and Dr Childs provided data analysis. Dr Flynn provided project management, and Dr Fritz provided fund procurement. Dr Fritz, Dr Flynn, and Dr Wainner provided subjects and facilities/equipment. Special thanks to Jake Magel, PT, DSc, OCS, FAAOMPT, Dan Rendeiro, PT, DSc, OCS, FAAOMPT, Matthew Garber, PT, DSc, OCS, FAAOMPT, and Barb Butler, PT, OCS, for their assistance in data collection. Special thanks to Stephen Allison, PT, PhD, ECS, for his assistance in the study design and statistical support

Address all correspondence to Dr Fritz


Submitted June 17, 2003; Accepted August 18, 2003


   Abstract
 
Background and Purpose. Although spinal manipulation is one of the few interventions for low back pain supported by evidence, it appears to be underutilized by physical therapists, possibly due to therapists' concerns that a patient may not benefit from the intervention. The purpose of this study was to identify factors that are associated with an inability to benefit from manipulation. Subjects. Seventy-five people with nonradicular low back pain (mean age=37.6 years, SD=10.6, range=19–59; mean duration of symptoms=41.7 days, SD=54.7, range=1–252) participated. Methods. Subjects underwent a standardized examination that included history-taking; self-reports of pain, disability, and fear-avoidance beliefs; measurement of lumbar and hip range of motion; and use of various tests. All subjects received a spinal manipulation intervention for a maximum of 2 sessions. Subjects who did not show greater than 5 points of improvement on the modified Oswestry Low Back Pain Disability Questionnaire were considered to have shown no improvement with the manipulation. Baseline variables were tested for univariate relationship with the outcome of the manipulation. Variables showing a univariate relationship were entered into a logistic regression equation, and adjusted odds ratios were calculated. Results. Twenty subjects (28%) did not improve with manipulation. Six variables were identified as being related to inability to improve with manipulation: longer symptom duration, having symptoms in the buttock or leg, absence of lumbar hypomobility, less hip rotation range of motion, less discrepancy in left-to-right hip medial rotation range of motion, and a negative Gaenslen sign. The resulting logistic regression model explained 63% of the variance in manipulation outcome. Discussion and Conclusion. The majority of subjects improved with manipulation. Baseline variables could be identified that were predictive of which subjects would not improve.

Key Words: Evidence-based practice • Low back pain • Spinal manipulation


   Introduction
Top
 Abstract
 Introduction
Method
 Results
 Discussion
 Conclusion
 Appendix
 References
 
Many interventions used by physical therapists in the management of patients with low back pain (LBP) lack evidence supporting their effectiveness.1–4 For example, interventions such as thermal modalities, electrical stimulation, and biofeedback have not been studied sufficiently, whereas interventions such as transcutaneous electrical nerve stimulation, mechanical traction, and ultrasound have been studied and found to be ineffective.3,4 The evidence regarding exercise interventions for patients with LBP has been equivocal. Exercise has generally been reported to be ineffective for patients with acute LBP, but is usually recommended for patients with chronic LBP.1,2,5 Spinal manipulation is one intervention for patients with LBP that is supported by evidence.1 Clinical practice guidelines published in the United States,4 the United Kingdom,6 and New Zealand7 recommend manipulation for patients with LBP of less than 4 to 6 weeks' duration who do not have signs of nerve root compression.

The American Physical Therapy Association's Guide to Physical Therapist Practice (Guide) defines mobilization/manipulation as "a manual therapy technique comprising a continuum of skilled passive movements to the joints and/or related soft tissues that are applied at varying speeds and amplitudes, including a small-amplitude/high-velocity therapeutic movement."8(p688) The Guide lists mobilization/manipulation as an intervention appropriate for the care of patients with spinal disorders.8 In clinical practice, and in systematic reviews of research evidence, spinal manipulation is usually distinguished from spinal mobilization.9,10 Spinal mobilization involves low-velocity, passive movements of a joint within or at the limit of its range of motion (ROM), whereas spinal manipulation involves a high-velocity thrust to a joint beyond its restricted ROM.9,11 Some evidence supports the use of spinal manipulation rather than mobilization.1 In 2 studies,12,13 spinal manipulation was compared with spinal mobilization for patients with LBP. Superior results with the use of manipulation were found in both studies.

Despite evidence supporting the use of spinal manipulation for patients with LBP, the intervention appears to be underutilized by physical therapists. Jette and Jette14 reported on the interventions used by physical therapists in clinics located in the United States in the management of over 1,000 patients with LBP prior to the generation of most clinical practice guidelines recommending the use of manipulation. Mobilization/manipulation was utilized during the course of care for 35% of the patients. The authors did not distinguish between manipulation and mobilization, and therefore it is likely that spinal manipulation was actually utilized in a much smaller percentage of patients. Several interventions lacking evidence were used at much higher rates, including flexibility exercises (81%) and thermal modalities (86%).14 Studies conducted outside the United States, and after the publication of clinical practice guidelines, reflect similar patterns. Li and Bombardier10 recently surveyed 569 physical therapists in Canada regarding their treatment beliefs and recommendations for patients with LBP. Only 30% of the therapists surveyed reported that they believed spinal manipulation to be an effective intervention in the management of most patients with LBP. The percentages of respondents expressing beliefs in the effectiveness of several interventions without evidence were higher, including ice (82%), spinal mobilization (80%), heat (66%), electrical stimulation (53%), and mechanical traction (36%).10 Gracey et al,15 in a study of 1,062 patients managed for LBP in Ireland, reported utilization of spinal manipulation in 9% of patients, compared with mobilization (44%), electrotherapy (30%), heat (19%), and traction (15%).

Several reasons have been offered for the apparent dissonance between current practice guidelines and the low utilization of spinal manipulation by physical therapists. Chief among these reasons appears to be a concern about the risk-benefit ratio for spinal manipulation.16,17 The benefits of lumbar spinal manipulation have been well documented; however, little research has been conducted on the risks of spinal manipulation, particularly for patients with LBP. The most serious risks associated with spinal manipulation occur when techniques are performed on the cervical spine.18 The most serious risk of manipulation of the lumbar spine is cauda equina syndrome.19 The level of risk, however, appears to be extremely low, with an estimated occurrence of less than once per 100 million lumbar manipulation procedures.20 Haldeman and Rubenstein19 reviewed the literature over a 77-year period and found 10 reports of cauda equina syndrome occurring as a result of lumbar spine manipulation. The risk of cauda equina syndrome from manipulation of the lumbar spine is thought to increase when manipulation is performed under anesthesia or in the presence of sciatica.20 Avoiding these situations likely reduces the risk of cauda equina syndrome.

Although serious complications resulting from lumbar spine manipulation appear to be very rare, less serious adverse effects have been reported to be more common.21 Senstrad et al,21 in a survey of 1,058 patients receiving spinal manipulation by chiropractors in Norway, reported no instances of cauda equina or other severe complications, but they did note that 55% of the patients reported at least one adverse effect related to the intervention. These adverse effects represented a worsening of the patient's clinical status, at least in the short term. The most common adverse effects were local discomfort (53%) or radiating discomfort (10%), headache (12%), and fatigue (11%). Leboeuf-Yde et al22 reported on 1,858 spinal manipulations performed on 625 patients by chiropractors in Sweden. In that study, 44% of the patients reported experiencing increased symptoms, including local discomfort, headache, and fatigue, following manipulation, and in 19% of these cases, the increased symptoms persisted for greater than 48 hours. No serious complications were reported.22 These studies did not distinguish manipulations performed on the lumbar spine from those performed on other regions of the spine, making it difficult to assess the prevalence of these adverse effects in patients receiving only lumbar spinal manipulation.

Based on the extremely low risk of serious complications from lumbar spinal manipulation reported in the literature, it appears that the primary risk that therapists need to consider when weighing a decision to use lumbar manipulation techniques is the possibility that the patient's symptoms will worsen or, at least, fail to improve. Researchers reporting on the prevalence of adverse effects of spinal manipulation did not attempt to describe the clinical presentation of patients whose status was worsened as a result of lumbar spine manipulation.21,22 If the clinical presentation of patients unlikely to benefit from lumbar spine manipulation could be characterized, this information could be particularly useful for clinicians considering the risk-benefit ratio of utilizing manipulation for a specific patient with LBP.

We have previously reported on a cohort of 71 patients with LBP, each of whom underwent 1 or 2 sessions of lumbar spinal manipulation performed by physical therapists.23 Our initial purpose in performing this study was to develop a clinical prediction rule that could assist physical therapists in identifying patients with LBP who are highly likely to experience a dramatic (50% or more) decrease in self-reported disability following 1 or 2 manipulation interventions. Thirty-two patients (45%) reported dramatic decreases in disability. We believe that patients with a high likelihood of experiencing 50% or more reduction in disability should be managed with spinal manipulation, and therefore we developed a clinical prediction rule to assist clinicians in identifying these patients.23 As a secondary analysis, we were interested in characterizing the clinical response of those patients who did not experience a dramatic decrease in disability.

None of the patients in this small sample experienced any serious complications as a result of the manipulation. Many patients experienced a decrease in disability—measured using the Modified Oswestry Questionnaire—that exceeded the minimum clinically important difference of the instrument24 but did not reach our threshold for a dramatic decrease. We believe that these individuals could be managed with spinal manipulation; however, because treatment effects were smaller, the possibility that other interventions might be more effective could not be excluded. A smaller group of patients in our initial study did not appear to show any clinically meaningful improvement in disability with the manipulation, and a few patients even experienced an increase in disability. We became interested in characterizing the group of patients who did not show any improvement with spinal manipulation, because we believed this could help clinicians identify which patients may be better suited to a different intervention. The purpose of the analysis in this article is to identify variables that are associated with a lack of improvement, or worsening, in the clinical status of patients with LBP who are managed with spinal manipulation.


   Method
Top
 Abstract
 Introduction
 Method
Results
 Discussion
 Conclusion
 Appendix
 References
 
Subjects

This study involved a prospective cohort of patients with LBP recruited from 2 outpatient facilities: Brooke Army Medical Center and Wilford Hall Air Force Medical Center. All data were obtained in a previous study,23 and in this report the data are analyzed to answer a different question. The primary purpose of this study was to identify clinical variables associated with a lack of improvement with a spinal manipulation technique. All subjects met the following inclusion criteria: age between 18 and 60 years; referral for physical therapy with a diagnosis related to the lumbosacral spine; a chief complaint of pain or numbness in the lumbar spine, buttock, and/or lower extremity; and a baseline Modified Oswestry Low Back Pain Disability Questionnaire (OSW) score24 of at least 30%. Exclusion criteria were: current pregnancy, signs consistent with nerve root compression (positive straight-leg-raise [SLR] test at less than 45° or diminished lower-extremity force, sensation, or reflexes), prior lumbar spine surgery, or a history of osteoporosis or spinal fracture.

Seventy-five subjects were participants in this study, and 71 (95%) completed the intervention protocol. Four subjects did not return after the initial session. Two of these subjects left the study due to personal or work-related circumstances, 1 subject dropped out due to complications from an ongoing episode of gastrointestinal distress, and 1 subject did not return for follow-up. Data from these 4 subjects were not included in the analysis. Of the 71 subjects who completed the study, the mean age was 37.6 years (SD=10.6, range=19–59), and the mean initial OSW score was 42.4 (SD=11.7, range=30–86). The mean OSW score at the conclusion of the study was 25.1 (SD=13.9, range=0–64). Based on the criteria used in this study, 20 subjects (28%) were categorized as not improved with manipulation, and 51 subjects were improved. The mean change on the OSW for the subjects who improved was 25.1 points (SD=14.2, range=6–72, median=22). For the subjects who did not improve, the mean change on the OSW was 0.0 points (SD=3.6, range=–10–4, median=0) (Fig. 1). The mean percentage of change on the OSW was 57.2% (SD=25.0%, range=16%–100%, median=58.9%) for the subjects who improved and –0.03% (SD=0.10%, range =–29%–13%, median = 0.0%) for the subjects who did not improve.


Figure 1
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[in a new window] 		Figure 1. Initial and final modified Oswestry Low Back Pain Disability Questionnaire scores for subjects who did not improve (n=20) and subjects who improved (n=51). The mean change was 25.1 points (SD=14.2) for the subjects who improved and 0.0 points (SD=3.6) for the subjects who did not improve.

 
Descriptive statistics for the total sample, and for subjects who improved or did not improve, at baseline are contained in Tables 1GoGo through 4. Interrater reliability of data obtained for the physical examination variables was assessed on 55 subjects. These subjects did not differ from the entire sample with respect to age, sex, initial OSW score, or duration of symptoms (P>.05). The results for both the categorical and continuous variables are contained in Table 5.


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[in a new window] 		Table 1. Baseline Variables From the Self-Reports and Patient History

 

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[in a new window] 		Table 2. Variables From the Baseline Clinical Examination Used in This Study

 

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[in a new window] 		Table 3. Variables for Range of Motion (in Degrees) From the Baseline Clinical Examination Used in This Study

 

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[in a new window] 		Table 4. Tests for Sacroiliac Region Dysfunction Used in This Studya

 

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[in a new window] 		Table 5. Interrater Reliability of Data Obtained for the Physical Examination Itemsa

 
Therapists

Eight licensed physical therapists participated in this study. All therapists were associated with the US Army-Baylor University Post-professional Doctoral Program in Orthopaedic and Manual Physical Therapy. Four therapists were residents in the program, and 4 therapists were instructors. This 18-month program is designed to provide physical therapists serving in the US military with advanced training in orthopedic and manual physical therapy. All participating therapists had at least 3 years of clinical experience and used manual therapy, including lumbar spine manipulation techniques, in patient care. A 1-day training session covering the examination and intervention aspects of the study was conducted for all therapists.

Baseline Measures

All subjects initially completed several self-report measures and underwent a physical examination by the treating physical therapist during the initial session. The following self-report measures were completed:

After completion of the self-report measures, all subjects gave a history and underwent a physical examination. The history taking and physical examination were performed by the first physical therapist. The physical examination was then repeated during the same session by a second therapist in order to evaluate the interrater reliability of data obtained for the examination items. The second therapist performed the physical examination items only and was masked to the results of the first therapist's examination. The second therapist became the treating therapist. The results of the first physical examination were used for the data analysis.

Taking the history included recording the subject's age and sex from the medical record and interviewing the subject regarding the duration of current symptoms and mode of onset (gradual or sudden). Subjects were asked about a prior history of LBP. If a prior history was present, subjects were asked if they perceived the frequency of their LBP episodes to be increasing, decreasing, or remaining the same. Subjects were asked to rank sitting, standing, and walking as to which was the worst and best with respect to their symptoms. The physical examination included several components. The methods for conducting and grading of the physical examination are described in the Appendix.35–49 The components of the physical examination are listed below:

Intervention

All subjects received the same intervention protocol. After the initial examination was complete, the treating physical therapist performed a manipulation technique that has been found to be effective for reducing short-term disability in previous pilot studies.64,65 The subject was positioned supine on the examining table. The therapist stood opposite the side to be manipulated and passively side-bent the subject's spine to the opposite side (ie, away from the therapist). The therapist then passively rotated the patient in the direction opposite to the side bending and delivered a thrust over the ASIS (Fig. 2). The side to be manipulated was determined with the following algorithm. First, if the standing flexion test was positive, the side found to be positive was manipulated; if the standing flexion test was negative, the side of greater tenderness during the sacral sulcus palpation test was manipulated. If both sides were tender, or if neither side was tender, the side reported by the subject to be more symptomatic was manipulated. If the subject could not identify a more symptomatic side, the therapist flipped a coin to determine the side to manipulate. This algorithm was designed to provide a consistent approach to determining the side of manipulation. Cibulka et al42 found changes on both sides of the pelvis following the application of this manipulation technique; therefore, we believe it is likely that the technique affects both sides of the pelvis.


Figure 2
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[in a new window] 		Figure 2. Manipulation technique used in this study. Reprinted with permission from Lippincott Williams & Wilkins from: Flynn TW, Fritz JM, Whitman JM, et al. A clinical prediction rule for classifying patients with low back pain who demonstrate short-term improvement with spinal manipulation. Spine. 2002;27:2835–2843.

 
After the initial manipulation attempt, the physical therapist recorded whether a "pop" was heard or felt by either the therapist or the subject. If a pop was heard or felt, the therapist proceeded to the other treatment components. If no pop was heard or felt, the therapist attempted the manipulation again. If no pop was heard or felt on the second attempt, the therapist next attempted to manipulate the other side. A maximum of 2 attempts per side were permitted. If no pop was heard or felt after the fourth attempt, the therapist proceeded with the other treatment components.

The additional treatment components included during the initial session were (1) instruction to perform supine pelvic tilt exercises for ROM and (2) advice to remain as active as possible within the limits of the subject's symptoms. Subjects were instructed to lie supine with their hips and knees flexed and to alternately tilt the pelvis in an anterior and posterior direction in a pain-free ROM. Subjects were told to perform this activity for 10 repetitions, 3 to 4 times per day. Exercise for ROM was included along with manipulation in previous studies demonstrating the effectiveness of this manipulation technique.64,65 The instruction to remain as active as possible is consistent with recommendations in clinical practice guidelines for the management of individuals with acute LBP.4,6 Adherence to these instructions was not assessed.

The second treatment session occurred 2 to 4 days following the initial visit. Each subject completed the OSW prior to beginning the second session. The treating physical therapist calculated the percentage of improvement in OSW scores using the formula: (initial OSW score – follow-up OSW score)/(initial OSW score) x 100%. If the percentage of improvement was equal to or greater than 50%, the intervention was categorized as successful, and participation in the study was ended. If the percentage of improvement was less than 50%, the therapist repeated the physical examination and the manipulation protocol as outlined for the initial visit, and the subject returned for a third treatment session 2 to 4 days after the second session. During the third session, the subject again completed the OSW, and the percentage of improvement from the initial OSW score was calculated. If the percentage of improvement was 50% or greater, the intervention was categorized as successful, and study participation was ended. If the percentage of improvement was less than 50%, the intervention was categorized as not successful.

Subjects whose intervention was not successful with manipulation were further examined to identify the subgroup of subjects who not only did not reach the success threshold (50% improvement in OSW score), but did not show any improvement. Based on previous work24,66 demonstrating the minimum clinically important difference in OSW scores to be 4 to 6 points, we categorized any subject who did not show greater than 5 points of improvement in the OSW score from initial treatment session to the third treatment session as having made no improvement. We believe that the inability to achieve even a minimum clinically important change in disability represents a treatment failure.

Data Analysis

Descriptive statistics (mean, standard deviation) were calculated for all baseline variables. Interrater reliability statistics were calculated for all physical examination variables using the results obtained by the first and second raters during the initial visit. Kappa coefficients and 95% confidence intervals (CIs) were calculated for variables graded as positive or negative.67 Weighted kappa coefficients with 95% CIs were calculated for variables graded on ordinal scales (nonorganic signs, status change with movement testing, segmental mobility judgments, and SI region symmetry tests).68 Equal weighting for each interval was used to incrementally penalize each level of disagreement. Intraclass correlation coefficients (model 2,1) with 95% CIs were calculated for each continuous baseline measure (lumbar, hip, and SLR ROM variables).

We classified the outcome of the manipulation as having shown improvement or having shown no improvement. Subjects categorized as showing no improvement were those subjects who demonstrated 5 points or less of improvement on the OSW by the time of the third treatment. All other subjects were categorized as having improved. This group included subjects reaching the threshold for success during the treatment based on a 50% or greater improvement on the OSW as well as those subjects who did not meet the threshold for success but did demonstrate 6 points or more of improvement on the OSW by the third treatment session. Because our study was a secondary analysis, we did not anticipate having adequate power to perform inferential and multivariate assessments of our data. We therefore did not adjust the significance level in our study, and we chose to calculate descriptive statistics to examine the relationship between individual baseline variables and treatment outcome. All baseline variables were analyzed for univariate significance with manipulation outcome. Pearson chi-square tests were used for nominal and ordinal baseline variables, and independent sample t tests were used for continuous baseline variables. A significance level of P<.05 was used for all comparisons.

The relative contributions of each variable with a univariate relationship to manipulation outcome were further explored using logistic regression analysis. All variables with a univariate relationship were entered into a logistic regression model with manipulation outcome as the dependent variable. Variables were entered in a standard manner (ie, all independent variables were entered at once). The goodness-of-fit of the final regression model was tested with the Hosmer-Lemeshow statistic.69 The proportion of variance explained by the final model was determined using the Nagelkerke R2 statistic.70 For the final model, adjusted odds ratios (AORs) and 95% CIs were calculated for each independent variable to estimate the increase in odds of failure given a one-unit change in the independent variable with the other independent variables held constant.69


   Results
Top
 Abstract
 Introduction
 Method
 Results
Discussion
 Conclusion
 Appendix
 References
 
The univariate relationships between the baseline variables and manipulation outcome are shown in Tables 1 through 4. Three variables from the self-reports and history were related to outcome: the duration of symptoms, the presence of LBP only, and having hypomobility in the lumbar spine with spring testing. Further examination of these variables showed that having a longer duration of symptoms, not having LBP only (ie, having buttock/lower-extremity symptoms), and not having some hypomobility in the lumbar spine were associated with lack of improvement with manipulation.

Several variables related to ROM of the hip had a relationship with manipulation outcome (Tab. 3). Two variables were related to MR (left hip MR ROM and discrepancy in MR ROM between the left and right hips), 2 variables were related to LR (left hip LR ROM and average LR ROM), and 2 variables were related to total hip rotation ROM (left hip total rotation ROM and average total hip rotation ROM). In order to reduce multicolinearity, the Pearson correlation coefficients among all the hip ROM variables were examined. Correlations existed between left hip LR and average LR (r=.94, P<.01), between left hip total rotation and average total hip rotation (r=.95, P<.01), and between hip MR discrepancy and left hip MR ROM (r=.25, P=.03). We eliminated the measures specific to the left hip from further consideration because we believed the average rotation and discrepancy values would be more generalizable. Average hip LR and average hip total rotation ROM also were highly correlated (r=.83, P<.01). Because average total hip rotation had a smaller probability value than average LR in its relationship with manipulation outcome, we eliminated average LR from further consideration. We therefore retained 2 hip ROM variables for further consideration: hip MR discrepancy and average total hip rotation ROM. Further examination of these 2 variables indicated that less discrepancy in MR ROM between the left and right hips and less average total hip rotation ROM were associated with not improving with manipulation.

Two tests for SI region dysfunction had a relationship with manipulation outcome: one test of symmetry (pubic tubercle asymmetry in a supine position) and one provocation test (Gaenslen sign) (Tab. 4). Further examination of these variables revealed that not improving with manipulation was associated with asymmetry of the pubic tubercles and with a positive Gaenslen sign. Because the assessment of pubic tubercle asymmetry had a negative kappa value, indicating that the level of agreement was less than that expected by chance, we excluded this variable from further analysis.

A total of 6 baseline variables had univariate relationships with manipulation outcome and were retained for further examination: duration of symptoms, having LBP only, some lumbar hypomobility, average total hip rotation ROM, MR ROM discrepancy, and Gaenslen sign. The 6 variables were entered into a logistic regression model. The final model fit the data (Hosmer-Lemeshow {kappa}2=4.87, P=.77). The Nagelkerke R2 value for the final model was .63, indicating that the 6 variables explained 63% of the variance in manipulation outcome. The AOR values for the 6 independent variables are given in Table 6. The only variable with an AOR that was not statistically significant in the final multivariate model was having LBP only.


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[in a new window] 		Table 6. Logistic Regression Analysis With Manipulation Outcome as the Dependent Variable and Variables With Univariate Relationships With Outcome as the Independent Variablea

 

   Discussion
Top
 Abstract
 Introduction
 Method
 Results
 Discussion
Conclusion
 Appendix
 References
 
In our previous publication, we developed a clinical prediction rule that sought to identify patients with LBP who had a high likelihood of experiencing dramatic success with spinal manipulation (50% or greater reduction in disability).23 The clinical prediction rule developed had 5 factors (Fig. 3). The presence of at least 4 of these 5 factors was associated with an increased likelihood of experiencing a dramatic decrease in disability (positive likelihood ratio=24.4). This result provided a first approximation of which variables may permit clinicians to identify patients with LBP who should be managed with manipulation because their probability of experiencing dramatic success is very high. The clinical response of subjects who did not experience dramatic success ranged from clinically important, but not dramatic, improvement to no improvement or even a worsening of disability. We believe spinal manipulation may be a viable intervention for patients who experience clinically important, but not dramatic, improvement. Further research, however, may identify other interventions as being more effective for this group. Patients who do not improve at all, or who actually experience a worsening of disability, in our opinion, should not be managed with manipulation. Therefore, our goal in this report was to characterize the clinical presentation of this small subset of patients. Although further examination of the importance of these variables is needed, we believe this information would be important to physical therapists because it would permit an a priori identification of patients with LBP who are unlikely to respond to manipulation.


Figure 3
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[in a new window] 		Figure 3. Variables composing the clinical prediction rule identified in a previous study23 for predicting dramatic success with spinal manipulation. The presence of at least 4 of these findings was associated with an increased likelihood of dramatic improvement with spinal manipulation (positive likelihood ratio=24.4).23

 
We examined only one manipulation technique in this study. The technique used has been described as being directed at the SI region36,43; however, the validity of this claim has not been assessed. Some researchers have recently offered data questioning the specificity and mechanisms underlying spinal manipulation,71,72 and it is currently unknown which tissues are affected by this or other manipulation techniques. Further research is needed to determine whether substantive differences exist among the multitude of different manipulation techniques available for the lumbosacral region, or whether the results obtained using one technique can be generalized to other techniques. We combined the manipulation with ROM exercises because we believe this is frequently done in clinical practice. The results reported here, therefore, are specific to manipulation with ROM exercise. Although these results are preliminary, we were able to identify several variables that appear to be associated with an increased likelihood of not improving with this manipulation technique.

From the subjects' medical history, the most important factors associated with inability to improve were a longer duration of symptoms and the presence of symptoms distal to the low back. These findings appear consistent with those of previous reports. The greater effectiveness of manipulation in patients with relatively acute symptoms than in those with longer-standing symptoms has been identified in subgroup analyses of previously published randomized trials.11,73 Some authors4,74 believe manipulation to be contraindicated for patients with sciatica. We excluded patients with signs of nerve root compression; however, we still found that patients with symptoms into the buttock or lower extremity were more likely not to improve with manipulation. Ninety percent of the subjects who did not improve had symptoms distal to the low back, and 40% had symptoms distal to the knee, compared with 61% and 20%, respectively, for subjects who improved.

Relatively few physical examination findings were associated with manipulation outcome. Most of the examination variables associated with treatment failure were related to hip rotation ROM. In general, we found that subjects who did not improve with manipulation had less MR and LR ROM. In particular, we found that subjects who did not improve had less discrepancy in MR ROM between the left and right hips and had less total rotation ROM. Cibulka et al75 reported that patients with LBP suspected of having SI region dysfunction had greater LR than MR ROM on the painful side. The authors, however, did not link the ROM findings to the outcome of an intervention. We found that subjects who improved with manipulation had more ROM in both MR and LR and had greater side-to-side discrepancy in MR ROM. Other authors76–78 have reported data suggesting an association between limited hip rotation ROM, particularly IR, and LBP. Some authors37,75,79 have further speculated that a unilateral restriction in MR ROM in a patient with LBP may represent a unique pattern, indicating a specific intervention. Research is needed to explore the relationship between hip rotation ROM and manipulation outcome. Our data, however, suggest that this pattern may be well suited to treatment with spinal manipulation, whereas symmetrical MR ROM may not respond well to this manipulation technique.

Only one test for the SI region, the Gaenslen test, was found to be associated with manipulation outcome. One reason for the lack of association for many of the tests may be the inability to obtain reliable measurements. With a few exceptions, our findings were similar to those of other researchers; interrater reliability was generally poor for the palpation of symmetry of bony landmarks and motion tests, whereas acceptable reliability was found for pain provocation test measurements.40,80 We believe, however, that poor reliability may not be the sole explanation for the lack of association for the tests. Several tests that yielded data with acceptable reliability failed to show any relationship to the outcome of manipulation. Another explanation for the lack of utility of many of these tests may be related to faulty theories underlying their mechanisms. Most of these tests were developed based on theoretical assumptions that dysfunction in the spine, particularly the SI region, will result in bony misalignment and changes in movement patterns.43,81,82 Evidence to support these theories has not been found. Even if the theories are valid, some studies have shown that the available movements in the SI region are extremely small,83,84 raising doubts about the possibility that manual assessment could detect the subtle alterations that might occur.

One examination variable that appears to be important in identifying patients who are unlikely to improve with manipulation was the lack of hypomobility in the lumbar spine. While this finding is intuitively attractive because it implies that patients without joint stiffness do not need manipulation, we believe the finding must be interpreted cautiously, given the reliability of measurements obtained with this particular test. We examined the reliability of the therapist's judgment that some hypomobility was present in the lumbar spine or that no hypomobility was present, and we found a kappa value of .13. Kappa values for individual spinal levels ranged from .03 to .50. The percentage of agreement between the examiners was high (78%), and it is likely that the high prevalence of positive findings (85%) in our sample deflated the kappa coefficient somewhat.85 Further work is needed to improve the interrater agreement on judgments of segmental mobility to make these results more generalizable.

The majority of our subjects (72%) showed meaningful clinical improvement with lumbar spinal manipulation, even without any attempt to identify subjects who actually needed the intervention. This result is not surprising given the favorable results of clinical trials that have studied the effectiveness of lumbar spinal manipulation in groups of patients with LBP and no signs of nerve root compression.11,12,73 These findings also support the advice of clinical practice guidelines that advocate at least a trial of manipulation for all patients with a new onset of LBP who do not have signs of nerve root compression.4,6,7 Clinical practice guidelines are designed to assist clinical decision making for a group of patients with a particular clinical condition such as LBP.86 When examining large groups of patients undergoing intervention for LBP, therefore, manipulation should be observed to be in frequent use by evidence-based practitioners.

Practice guidelines, however, do not offer assistance in determining whether a specific patient being evaluated with LBP may be among the minority of patients unlikely to benefit from manipulation. The purpose of our study was to identify factors associated with an increased likelihood of not improving with lumbar spinal manipulation. We found that a longer symptom duration, the presence of symptoms distal to the low back, a lack of hypomobility in the lumbar spine, reduced hip rotation ROM, little discrepancy in hip MR ROM side-to-side, and a negative provocation test (Gaenslen test) were more common in subjects who did not improve with manipulation. If a patient exhibits several of these signs during an examination, the likelihood of improvement with manipulation may be minimal.

The results of our study are preliminary findings. We examined only one manipulation technique in one practice setting. We did not examine the long-term improvement with manipulation. Because this study was not a randomized trial, we cannot definitively connect the improvement, or lack of improvement, with the manipulation intervention. It is possible that the variables identified as associated with a lack of improvement with manipulation are generally poor prognostic factors for patients with LBP regardless of the intervention. Future studies using randomized subject assignment are needed to validate the relationship between the factors identified in this study and the outcome of management with a manipulation intervention.


   Conclusion
Top
 Abstract
 Introduction
 Method
 Results
 Discussion
 Conclusion
Appendix
 References
 
Most subjects showed some improvement with the manipulation intervention. In the smaller subset of subjects who did not improve, several factors were identified as useful for explaining the difference in manipulation outcome. Further research is warranted to address these questions and to improve physical therapists' ability to identify patients who are likely to respond to a particular intervention, such as lumbar spinal manipulation.


   Appendix
Top
 Abstract
 Introduction
 Method
 Results
 Discussion
 Conclusion
 Appendix
References
 


Figure 1
Figure 1
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[in a new window] 		Appendix Operational Definitions for Performance and Grading of the Physical Examinationa

 


   Footnotes
 
This work was supported by a Research Grant from the Foundation for Physical Therapy.

This study was approved by the institutional review boards at Brooke Army Medical Center and Wilford Hall Air Force Medical Center.

The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.


   References
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 Abstract
 Introduction
 Method
 Results
 Discussion
 Conclusion
 Appendix
 References
 

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