SYNOPSIS: Diffusion-weighted imaging (DWI) is an application of magnetic resonance imaging that allows the measurement of water movement within and between tissues. Originally developed as a way of detecting early signs of stroke or brain disease, DWI is now being used to study physiologic events within the musculoskeletal system. The accurate measurement of water diffusion can provide important information regarding tissue responses associated with trauma and disease, as well as offer insight toward the mechanism by which physical therapy interventions affect tissues. The purpose of this paper is to discuss the rationale for DWI and its potential clinical and research applications for patients with musculoskeletal disorders. Specific examples of the use of DWI for patients with painful spinal disorders are used as illustrations.

J Orthop Sports Phys Ther 2011;41(11):887-895, Epub 4 September 2011. doi:10.2519/jospt.2011.3744

KEY WORDS: back pain, degenerative disc disease, muscle injury, physical therapy

STUDY DESIGN: Cross-sectional. OBJECTIVE: To develop a new magnetic resonance imaging (MRI) measure for the diffusive properties of the healthy cervical multifidus and to determine the interrater and intrarater reliability of the measurement. BACKGROUND: Diffusion-weighted MRI, via calculation of the apparent diffusion coefficient (ADC), provides a representation of microscopic movements of water molecules in human tissues and may be useful to assess structural changes in neck muscle, as has been observed following whiplash. The optimal imaging parameters, however, have not been established. METHODS: A diffusion-weighted MRI measure was developed, and, for the basic examination, the right cervical multifidus muscle at the C5 level was studied. A total of 6 asymptomatic volunteer individuals (3 females and 3 males) underwent a single diffusion-weighted MRI scan. Interrater and intrarater agreement was evaluated using Bland-Altman plots and intraclass correlation coefficients. RESULTS: Mean ADC^b0-b50 and ADC^b50-250 were significantly different from one another (P = .03). The plots confirmed the agreement of raters for ADC of the right cervical multifidus at C5. CONCLUSIONS: A quantitative and reliable diffusion-weighted MRI measure of cervical multifidus ADC has been described. There appears to be a fast and slow component ADC for the healthy multifidus, suggesting changes in extracellular and intracellular volume. Further comparative study is needed to quantify ADCs in the neck muscles in patients with traumatic whiplash.

J Orthop Sports Phys Ther 2010;40(11):722-728, Epub 1 September 2010. doi:10.2519/jospt.2010.3423

KEY WORDS: cervical spine, magnetic resonance imaging, radiology

STUDY DESIGN: Single-group, prospective, repeated-measures design. OBJECTIVES: To determine differences in the changes of diffusion of water in the L5-S1 intervertebral disc between subjects with nonspecific low back pain (LBP) who reported an immediate reduction in pain intensity of 2 or greater on an 11-point (0-10) numeric rating scale after a 10-minute session of lumbar joint mobilization, followed by prone press-up exercises, compared to those who did not report an immediate reduction in pain intensity of 2 or greater on the pain scale. BACKGROUND: Combining lumbar joint mobilization and prone press-up exercises is a common intervention for patients with LBP; however, there is conflicting evidence regarding the effectiveness and efficacy of this approach. Increased knowledge of the physiologic effects of the combined use of these treatments, and the relationship to pain reports, can lead to refinement of their clinical application. METHODS: Twenty adults, aged 22 to 54, participated in this study. All subjects reported LBP of at least 2 on an 11-point (0-10) verbally administered numeric rating scale at the time of enrollment in the study and were classified as being candidates for the combination of joint mobilization and prone press-ups. Subjects underwent T2- and diffusion-weighted lumbar magnetic resonance imaging scans before and immediately after receiving a 10-minute session of lumbar pressures in a posterior-to-anterior direction and prone press-up exercises. Subjects who reported a decrease in current pain intensity of 2 or greater immediately following treatment were classified as immediate responders, while the remainder were classified as not-immediate responders. The apparent diffusion coefficient, representing the diffusion of water in the nucleus pulposis, was calculated from the midsagittal diffusion-weighted images. RESULTS: Following treatment, immediate responders (n = 10) had a mean increase in the apparent diffusion coefficient in the middle portion of the L5-S1 intervertebral disc of 4.2% compared to a mean decrease of 1.6% for the not-immediate responders (P<.005). CONCLUSION: In a group of subjects with LBP, who were classified as being candidates for extension-based treatment, the report of an immediate reduction in pain intensity of 2/10 of greater after a treatment of posterior-to-anterior–directed pressures, followed by prone press-up exercises, was associated with an increase in diffusion of water in the nuclear region of the L5-S1 intervertebral disc. Subjects who did not report a pain reduction of at least 2/10 did not have a change in diffusion.

J Orthop Sports Phys Ther 2010;40(5):256-264, Epub 12 March 2010. doi:10.2519/jospt.2010.3284

KEY WORDS: low back pain, magnetic resonance imaging, manual therapy

STUDY DESIGN: Prospective, repeated measures obtained under treatment and control conditions. OBJECTIVES: The purposes of this study were to provide preliminary evidence regarding the immediate change in the diffusion of water in the nuclear region of normal and degenerative lumbar intervertebral discs (IVDs) following a single session of lumbar joint mobilization, and to compare these findings to the immediate change in the diffusion of water following a 10-minute session of prone lying. BACKGROUND: There is conflicting evidence regarding the effectiveness and efficacy of lumbar joint mobilization. Increased knowledge of the physiologic effects of lumbar joint mobilization can lead to refinement of its clinical application. METHODS AND MEASURES: A total of 24 people (15 males and 9 females), ranging in age from 22 to 58 years, participated in this study. All subjects had a history of activity-limiting low back pain. Diffusion-weighted magnetic resonance images (DW-MRIs) were obtained immediately before and after a 10-minute session of lumbar joint mobilization. At least 1 month later, a second session was performed in which DW-MRIs were obtained immediately before and after a 10-minute session of prone lying. RESULTS: Following lumbar joint mobilization, a significant increase (P = .002) in the mean values for diffusion of water was observed within degenerative IVDs at L5-S1 (22.2% increase; effect size, 0.97). Degenerative IVDs at L1-2 to L4-5 and normal IVDs at L1-2 to L5-S1 did not demonstrate a change in diffusion following joint mobilization. Prone lying was not associated with a change in diffusion for normal or degenerative IVDs. CONCLUSIONS: The stimulus provided by lumbar joint mobilization may influence the diffusion of water in degenerative IVDs at L5-S1; however, these are preliminary findings and the relationship of these findings to pain and function needs further investigation. LEVEL OF EVIDENCE: Therapy, level 5.

J Orthop Sports Phys Ther 2009;39(1):4-11, Epub 24 October 2008. doi:10.2519/jospt.2009.2994

KEY WORDS: back pain, lumbar disc disease, lumbar spine, manual therapy, physical therapy

SYNOPSIS: Degeneration of the lumbar intervertebral discs (IVDs) is highly prevalent in adults and is nearly universal in the elderly population. Degenerative changes within, and adjacent to, the IVDs are likely to contribute to a variety of pain syndromes; however, the exact association between these findings and symptoms remains speculative. Recent research has provided new information regarding the etiology, pathophysiology, and clinical relevance of degeneration of the IVD. This information will assist clinicians and researchers in understanding the development and clinical course of lumbar disc degeneration, as well as its potential impact upon patients seeking physical therapy care for back pain. The purposes of this clinical commentary are to review the structure and metabolic capacity of the normal and degenerative lumbar IVD, and to discuss factors that influence the onset and progression of disc degeneration. Lumbar magnetic resonance images will be used to illustrate the common findings associated with this condition. LEVEL OF EVIDENCE: Diagnosis, level 5.

J Orthop Sports Phys Ther. 2008;38(6):329-340, published online 12 March 2008. doi:10.2519/jospt.2008.2768

KEY WORDS: back pain, lumbar disc, MRI, rehabilitation

Current best evidence suggest that, when adjusting for risk, a substantial number of patients receiving outpatient physical therapy report good outcomes and have lower cost of care or frequency of adverse events when compared to pharmacologic or invasive procedures. In other words, physical therapy care, supported by the best available research evidence, is often a bargain when compared to other treatment approaches. However, a question that must be asked is, "How much do patients value their physical therapy care?"

J Orthop Sports Phys Ther 2008;38(2):34-35. doi:10.2519/jospt.2008.0113

KEY WORDS: patient-therapist relationship, value-based care

STUDY DESIGN: Observational, repeated measures design. OBJECTIVES: To determine the reliability of the apparent diffusion coefficient (ADC) calculated from diffusion-weighted magnetic resonance images (MRI) of the nuclear region of lumbar intervertebral discs (IVDs), to investigate the differences in the ADC based upon T₂-signal intensity, and to examine the test-retest variation in these measures obtained from subjects undergoing serial, diffusion-weighted MRI scans. BACKGROUND: Impaired diffusion of water within the lumbar IVD is a central characteristic of degenerative disc disease. Diffusion-weighted MRI scans can provide quantitative estimates of water diffusion and may be useful to evaluate the physiologic effects of healing or the change in hydration related to interventions such as traction, manual therapy, or exercise on normal and degenerative lumbar IVDs. METHODS AND MEASURES: Thirty subjects underwent T₂ -weighted and diffusion-weighted lumbar MRI scans. Twenty-one of these subjects underwent a second diffusion-weighted MRI scan 4 to 7 weeks after the initial scan. The ADC was calculated from midsagittal diffusion-weighted images for the IVDs of L1-2 to L5-S1.  To assess reliability, repeated measures of the ADC were performed on the first 16 scans. The T₂-signal of the nuclear region of each disc was classified as hyperintense, intermediate, or hypointense, and its relationship to the mean ADC of the nuclear region was determined. Test-retest variation in the ADC was described using the coefficient of variation (CV), plus or minus the width of the 95% confidence interval of the standard error of measurement (SEM). RESULTS: Intraclass correlation coefficients for estimates of intrarater and interrater reliability ranged from 0.95 to 0.99 and the SEM ranged from 0.006 to 0.026 X 10^-3 mm²/s. The mean ADC was significantly greater for hyperintense IVDs compared to intermediate and hypointense IVDs. The CV plus or minus the 95% CI of the SEM between scans ranged from 9.0% to 13.6% for all discs, 6.1% to 10.1% for hyperintense discs, and 13.1% to 23.7% for intermediate discs. The prevalence of hypointense discs was too low to make meaningful judgments about their normal degree of variation over time. CONCLUSION: The ADC of the nuclear region of the lumbar IVDs may be reliably measured from diffusion-weighted images. Degenerative discs had lower mean ADC values than normal discs but demonstrated greater variation between scans. Diffusion-weighted imaging may be a useful procedure to assess change in diffusion of water in lumbar discs that occurs over time.

J Orthop Sports Phys Ther. 2008;38(2):42-49, published online 21 September 2007. doi:10.2519/jospt.2008.2631 

KEY WORDS: back pain, degenerative disc disease, lumbar spine, MRI

Study Design: Psychometric evaluation of a cross-sectional survey. Objectives: To determine the validity of measures obtained from the MedRisk Instrument for Measuring Patient Satisfaction With Physical Therapy Care (MRPS) to differentiate between patient satisfaction with internal and external factors. Background: Self-report measures that sample a variety of items provide clinicians with an array of information that may assist in assessing patient satisfaction. An important measurement characteristic of these instruments is the ability to discriminate between different factors that may influence patient reports of satisfaction with care, ie, discriminant validity. In previous work, exploratory factor analysis suggested that the MRPS questionnaire has a 2-factor structure: ‘‘internal,’’ relating to the patient-therapist interaction, and ‘‘external,’’ describing nontherapist issues such as admissions and clinic environment. Methods and Measures: One thousand four hundred forty-nine adult patients completed the MRPS questionnaire upon finishing their course of outpatient physical therapy treatment. Discriminant validity of the 2-factor model was assessed using confirmatory factor analysis. The measures from the 2 factors were then evaluated for reliability by calculating the standard error of measurement (SEM), and for concurrent validity by correlating the mean score of the factors and individual items to global measures of satisfaction. Results: Confirmatory factor analysis supported a good to excellent model fit for the internal factor (7 items) and external factor (3 items). The SEM for the 2 factors was 0.19 and 0.24, indicating a low degree of measurement error. Both factors had high significant correlation with global measures of satisfaction (internal, r = 0.83 and 0.80; external, r = 0.71 and 0.71). All individual items within the 2 factors had significant correlations with global measures ranging from r =0.33 to 0.80. Conclusions: Our findings provide evidence of discriminant and concurrent validity of the 2-factor solution for the MRPS questionnaire for the sample that was tested. This 2-factor solution yields measures that are relatively free of error and may discriminate between internal and external factors influencing patient satisfaction. Patients who complete their course of physical therapy report that the professional interaction between the therapist and patient, especially the meaningful exchange of relevant information, is critical for patient satisfaction with care. The generalizability of our data to patients who do not complete their physical therapy care or who are receiving care in other health care environments is unknown.

J Orthop Sports Phys Ther. 2005;35(1):24-32. doi: 10.2519/jospt.2005.1471

Key Words: instrument validation, questionnaire, self-report, survey