Repositioning error in low back pain. Comparing trunk repositioning error in subjects with chronic low back pain and control subjects

STUDY DESIGN: Repositioning error of the trunk was tested in 20 subjects with chronic low back pain and in 20 control subjects. The 3Space Tracker (Polhemus, Colchester, VT), a device that measures three-dimensional position in space, was used to determine the subject's trunk position. OBJECTIVES: To determine whether repositioning error is different in subjects with chronic low back pain than in control subjects. SUMMARY OF BACKGROUND DATA: Proprioception allows the body to maintain proper orientation during static and dynamic activities. In peripheral joint injuries, researchers have demonstrated a loss of some aspects of proprioception and improvement in outcome with retraining. Although the components of proprioception in subjects with low back pain have not been well studied, it is thought that these persons lose some elements of proprioception that can be measured in a quantifiable way. If so, then rehabilitation to improve these deficits is important. In this pilot study, one aspect of proprioception, repositioning error, was examined. METHODS: The subjects attempted to replicate target positions of the trunk in flexion, extension, lateral bending, and lateral rotation. Repositioning error was calculated as the absolute difference between the actual and the subject-replicated target positions. RESULTS: No significant difference was found in repositioning error between the control subjects and the persons with chronic low back pain. CONCLUSIONS: Because proprioception is complex and entails the use of many afferent receptors, it is difficult to measure any one afferent deficiency discretely. The authors believe that this study, in which one aspect of proprioception was measured in an indirect manner, provides important background information on low back position sense. Further studies analyzing aspects of proprioception in subjects with low back pain are recommended.     

Decoupling of bilateral paraspinal excitation in subjects with low back pain.

This study compared bilateral paraspinal excitation in normal subjects and subjects with low back pain. Comparison was made between six control subjects and seven low back pain subjects who performed maximum-effort isometric trunk extension in minimum elapsed time at two trunk angles. Electromyographic signals were collected bilaterally from the paraspinal musculature. The time- and amplitude-normalized electromyographic data were analyzed using a repeatability criterion sensitive to temporal and amplitude differences. This analysis showed that low back pain subjects demonstrated temporal and amplitude decoupling of the paraspinal musculature bilaterally. Low back pain subjects also demonstrated clinically meaningful disruptions between paraspinal excitation and isometric trunk extension moment. This method may be useful in quantifying neuromotor control in low back pain for initial and follow-up clinical evaluation for static and dynamic functional tests.     

Provocative discography in volunteer subjects with mild persistent low back pain.

BACKGROUND CONTEXT: Whether discographic injections would be positive in subjects with benign persistent "backache" who are not seeking treatment is unknown. This information is important, because benign backache undoubtedly co-exists in patients with chronic low back pain (CLBP) illness that is not discogenicin origin. If these subjects had a high rate of positive discography, the high background incidence of common backache would allow many positive tests in patients in whom discogenic processes were unrelated to their severe CLBP illness. Conversely, if subjects with benign low back pain rarely if ever had significant concordant pain reproduction on disc injections, the basic tenet of discographic diagnosis would be strengthened. PURPOSE: To compare, using a strict experimental design, the relative pain and concordancy response to provocative discography in subjects with clinically insignificant "backache" and clinical subjects with CLBP illness considering surgical treatment. STUDY DESIGN: Comparison of experimental disc injections in subjects with persistent mild backache and those with chronic low back pain (CLBP) illness. PATIENT SAMPLE: Twenty-five subjects with mild persistent low back pain (LBP) were recruited for an experimental discography study. Subjects were recruited from a clinical study of patients having had cervical spine surgery. Inclusion criteria required that subjects not be receiving or seeking medical treatment for LBP, be taking no medications for backache, have no activity restrictions because of LBP, and have normal psychometric scores. To more closely approximate the pain behavior in CLBP illness, 50% (12) of the "backache" group were recruited with a chronic painful condition (neck/shoulder) unrelated to the low back. CLBP subjects, patients coming to discography for consideration of surgical treatment, were used as control subjects. OUTCOME MEASURES: Results of discography were determined using the criteria of Walsh et al.: pain response of 3 or greater, two or more pain behaviors, a negative "control" discographic injection, and a similar or exact concordancy rating. METHODS: Discography was performed on experimental subjects and control patients. Experienced raters, who were blinded to control versus experimental status of the subjects, scored the magnetic resonance image, discogram, psychometric tests and discography videotapes of the subjects' pain behavior. RESULTS: Thirteen of 25 volunteer subjects had pain rated as "bad" or worse with disc injection. There were 12 painful and fully concordant disc injections in 9 of these 25 "backache" subjects (36%). These injections met all the Walsh et al. criteria for a positive diagnosis of discogenic pain. All positive discs had annular disruption to or through the outer annulus. Of the 9 subjects with positive discograms, 3 had no chronic pain states and 6 did. All subjects with positive injections had negative control discs. In comparison, in 52 subjects with CLBP illness 38 (73%) had at least one positive disc injection. CONCLUSIONS: In a group of volunteer subjects with persistent "backache," 36% were found to have significant pain on disc injection, which is reported to be concordant with their usual pain. The presence of positive concordant pain responses and negative control discs in 33% of subjects without CLBP illness seriously challenges the specificity of provocative discography in identifying a clinically relevant spinal pathology.     

Classification of nonspecific low back pain. I. Psychological involvement in low back pain. A clinical, descriptive approach.

An unselected sample of outpatient subjects (n = 330) with localized nonspecific low back pain (LBP) was studied. Investigation consisted of clinical assessment, physical examination, and psychiatric interview based on the DSM-III classification. A psychiatric disorder, according to the DSM-III criteria (axis I) was found in 41% of the subjects. Multiple correspondence analysis and cluster analysis were used to objectively identify clinical subtypes without preconceived theoretical models. Correspondence analyses suggested the existence of a 'psychological pain' syndrome consisting of several of the following symptoms: diffuse back pain, impossibility to assess intensity of pain on a pain scale, aggravation of pain by changing climate, by domestic activities or by psychological factors and dysesthesias in the back. Cluster analysis provided support for a four-group classification of low back pain, which may be interpreted through the relationships between psychological disturbances and the LBP clinical features. The results call for further investigation of the complex relationship between psychological disturbances and back pain. However, clinicians must be aware of the interest of a minimal psychiatric assessment in low back pain patients: psychiatric disorders frequently appear in these patients and an appropriate treatment of the psychiatric syndrome may reduce back pain.     

A study revealing a tall pelvis in subjects with low back pain

Modern anthropometric techniques were used to investigate two groups of subjects, one with various syndromes associated with pain in the lower back and the other a control group. Analysis confirmed previous reports that people prone to pain in the back have a greater standing height than people who are not. To investigate this further two new components of height, namely pelvic height and suprapelvic height, were calculated in addition to the established calculation of subischial height. Consecutive components, namely suprapelvic height, pelvic height and subischial height, together constituted the standing height of a subject. The main finding of this investigation was that the relatively large standing height of the subject prone to back pain was due only to the pelvic component.     

Repositioning accuracy and movement parameters in low back pain subjects and healthy control subjects

Study Design: A control group study with repeated measures. Objective: To compare trunk repositioning parameters in chronic low back pain (LBP) and healthy subjects. Summary and background data: Recent evidence suggests that chronic LBP patients exhibit deficits in trunk proprioception and motor control. Trunk repositioning and the various spatio-temporal parameters related to it can be used to evaluate sensori-motor control and movement strategies. Methods: Fifteen control subjects and 16 chronic LBP subjects participated in this study. Subjects were required to reproduce different trunk position in flexion (15°, 30° and 60°) and extension (15°). In the learning phase preceding each condition, visual feedback was provided. Following these learning trials, subjects were asked to perform ten consecutive trials without any feedback. Movement time, movement time variability and peak velocity were obtained and a temporal symmetry ratio was calculated. Peak angular position variability and absolute error in peak angular position were also calculated to evaluate spatial accuracy. Results: Two subgroups of LBP patients were identified. One subgroup of LBP subjects demonstrated longer movement time and smaller peak velocities and symmetry ratios than normal subjects. No group difference was observed for peak angular position variability and absolute error in peak angular position. Conclusion: Chronic LBP patients, when given a sufficient learning period, were able to reproduce trunk position with a spatial accuracy similar to control subjects. Some LBP subjects, however, showed modifications of movement time, peak velocity and acceleration parameters. We propose that the presence of persistent chronic pain could induce an alteration or an adaptation in the motor responses of chronic LBP subjects.     

Characteristic dynamic differences between healthy and low back pain subjects

STUDY DESIGN: Open retrospective study. OBJECTIVES: To assess the functional capacity impairment of chronic low back pain (LBP) patients using characteristic dynamic changes. SETTING: Orthopaedics and Physiotherapy departments at Tel-Aviv, Israel. METHODS: Thirty-eight normal healthy volunteers and 607 chronic LBP patients were tested on a computerized 3-D lumbar dynamometer. The four major parameters measured were the maximal isometric torque (MIT), maximal velocity against 25% MIT and 50% MIT (MV25, MV50, respectively) and maximal torques in secondary axes (MST). All patients parameters were compared to the normal, healthy findings. RESULTS: All four parameters were found to be significantly different between healthy (or non-symptomatic) and symptomatic LBP subjects. CONCLUSIONS: The findings support the use of 3-D dynamometry and the four parameters mentioned to objectively classify patients with functional disability.     

Increased incidence and severity of somatic dysfunction in subjects with chronic low back pain

CONTEXT: Patients with back pain make more than 14 million office visits per year to US physicians. Many of these patients have chronic low back pain (LBP) and are assumed to have more somatic dysfunction than those without chronic LBP. OBJECTIVE: To investigate incidence and severity of somatic dysfunction of four lumbar vertebral segments (L1-L4). METHODS: Sixteen subjects with chronic LBP and 47 subjects without chronic LBP were each evaluated by two blinded examiners using reliable osteopathic palpatory tests. The incidence and severity of somatic dysfunction for each test were then analyzed within and between the study groups. Results: Resistance to anterior springing (P<.001) and tenderness (P=.002) were found at significantly greater incidence in the chronic LBP group than in the non-LBP group, but there were no significant differences between groups for incidence of tissue texture changes or static rotational asymmetry. Significantly greater severity of tissue texture changes (P=.006), static rotational asymmetry (P=.008), resistance to anterior springing (P<.001), and tenderness (P=.001) were observed in the chronic LBP group than in the non-LBP group. CONCLUSION: When compared with non-LBP subjects, chronic LBP subjects had overall greater severity for each of the four elements of somatic dysfunction evaluated, as well as greater incidence of resistance to anterior springing and tenderness. Somatic dysfunction is more severe in individuals with chronic LBP than in individuals without chronic LBP.     

Differences in repositioning error among patients with low back pain compared with control subjects

STUDY DESIGN: Trunk repositioning error was measured in 20 patients with chronic low back pain and 20 control subjects. OBJECTIVES: To measure trunk repositioning error as a method of measuring proprioception of the low back and to compare trunk repositioning error in patients with low back pain and in control subjects. SUMMARY OF BACKGROUND DATA: Although many current low back pain rehabilitation programs incorporate proprioceptive training, very little research has been performed on proprioception of the low back. METHODS: While standing with the legs and pelvis immobilized, the subject bent the trunk to a predetermined target position and then attempted to replicate the position. Repositioning error was calculated as the absolute difference between the actual target position and the subject-perceived target position. The multiple target positions in the frontal and sagittal planes were tested. Trunk position was measured with a 3Space Tracker, which analyzes the three-dimensional position of the body. RESULTS: Repositioning error in patients with low back pain was significantly higher than that of control subjects in flexion, and significantly lower than that of control subjects in extension. CONCLUSIONS: The increase in repositioning error of patients with low back pain during flexion implies that some aspects of proprioception are lost in patients with low back pain. The decrease in repositioning error in patients with low back pain in extension is not as easily explained, but could possibly be caused by increased activation of mechanoreceptors in facet joints.     

Different parts of erector spinae muscle fatigability in subjects with and without low back pain

Background contextThere is conflicting evidence regarding erector spinae muscle fatigability because previous studies have not considered the thoracic and lumbar components separately. These muscles have very different mechanical responses and, therefore, would be recruited differentially for the chosen task.PurposeThe present study was conducted to compare whether fatigability differences exist in the thoracic and lumbar parts of the erector spinae muscles in subjects with and without low back pain (LBP).Study designThis cross-sectional study was conducted in the Motion Analysis Lab at Cleveland State University.Patient sampleThe study sample included 40 subjects with LBP and 40 subjects without LBP.Outcome measuresThe fatigability of the erector spinae muscles was compared based on median frequency of electromyography (EMG) versus time. The level of pain of each subject was also compared using the Oswestry Disability Index.MethodsFatigue measurements were evaluated between groups based on the assessed sides as well as the thoracic and lumbar parts of the erector spinae muscles using surface EMG. A modified version of the isometric fatigue test as introduced by Sorensen was used to test the endurance of the erector spinae muscles.ResultsThere were significant median EMG frequency (F_{(1, 78)}=28.82, p=.001) differences in the thoracic and lumbar parts of the erector spinae muscles between subjects with and without LBP. The thoracic part had a significantly lower median EMG frequency than the lumbar part in subjects with LBP. The thoracic and lumbar parts of the erector spinae muscles had interactions with group (F_{(1, 78)}=47.88, p=.01] and age (F_{(1, 78)}=16.51, p=.01).ConclusionsThe results of this study suggested that subjects with LBP demonstrated higher fatigability of the erector spinae muscles at the thoracic part than at the lumbar part. The increased fatigability of the thoracic part needs to be emphasized in rehabilitation strategies for subjects with LBP. In addition, as age increased, the median frequency of the lumbar part of the erector spinae muscles significantly decreased. Understanding the anatomical and biomechanical characteristics of the erector spinae muscle may enhance clinical outcomes and rehabilitation strategies for subjects with LBP.     

Back muscle fatigability is associated with knee extensor inhibition in subjects with low back pain

STUDY DESIGN: Cross-sectional study of 25 male golfers with chronic low back pain and 16 healthy controls of similar age. OBJECTIVES: To assess the association between functional capacity of the back extensors and the quadriceps muscles. SUMMARY OF BACKGROUND DATA: Chronic low back pain has been shown to lead to changes in muscle activation patterns of the abdominals and the gluteus maximus. The effect of chronic low back pain on lower limb function has not been investigated. METHODS: Back extensor endurance was assessed by a Biering-S?rensen test; surface EMG was measured bilaterally on the erector spinae at T12 and L4--L5. Muscle inhibition in the quadriceps was assessed by applying an electrical twitch to the maximally contracted muscle. The associations between holding time, decrease in EMG median frequency (i.e., the slope of the regression line on median frequency vs. time), and muscle inhibition were compared for study participants with chronic low back pain and controls. RESULTS: Mean back extensor holding times were 88 +/- 30 seconds for study participants with chronic low back pain and 92 +/- 17 seconds for controls. Both groups showed bilaterally similar decreases in EMG median frequency at L4--L5 and T12; however, the slopes were significantly steeper at L4--L5 than T12. Study participants with chronic low back pain with poor back endurance had significantly higher muscle inhibition compared with study participants with chronic low back pain with good back endurance, whereas such an association was not evident in healthy controls. CONCLUSIONS: In golfers with chronic low back pain reduced back endurance was associated with significant inhibition of the knee extensors, indicating that this muscle group cannot be activated to a full extent. These findings suggest a possible association between back extensor fatigability and knee extensor dysfunction in male golfers with chronic low back pain.     

Inter-rater reliability of three standardized functional tests in patients with low back pain

Background  

Of all patients with low back pain, 85% are diagnosed as "non-specific lumbar pain". Lumbar instability has been described as one specific diagnosis which several authors have described as delayed muscular responses, impaired postural control as well as impaired muscular coordination among these patients. This has mostly been measured and evaluated in a laboratory setting. There are few standardized and evaluated functional tests, examining functional muscular coordination which are also applicable in the non-laboratory setting. In ordinary clinical work, tests of functional muscular coordination should be easy to apply. The aim of this present study was to therefore standardize and examine the inter-rater reliability of three functional tests of muscular functional coordination of the lumbar spine in patients with low back pain.     

Psychometric properties of the functional rating index in patients with low back pain

Main Problem: The purpose of this study was to validate the psychometric properties of the functional rating index (FRI), establish the instruments minimum clinically important difference (MCID), and compare its psychometric properties with the Oswestry questionnaire. Methods: This was a cohort study of patients with low back pain (LBP) undergoing physical therapy. One thirty one patients with a primary complaint of LBP participating in a clinical trial were assessed at baseline and at a 1- and 4-week follow-up. Test-re-test reliability was examined using the intraclass correlation coefficient, and validity was examined by determining the association between the FRI and Oswestry, a concurrent measure of disability. Responsiveness was examined by calculating the standard error of the measure, minimum detectable change, area under a receiver operating characteristic curve, and minimum clinically important difference. Changes in clinical status at each follow-up period were compared to the average of the patient and therapists perceived improvement using the 15-point global rating of change scale. Results: Test-retest reliability of the FRI was moderate, with an intraclass correlation coefficient equal to 0.63 (0.35, 0.80). Validity of the FRI was supported by a moderate correlation between the FRI and Oswestry (r=0.67, P<0.001). Area under the curve for the FRI was 0.93 (0.89, 0.98), and the minimum clinically important difference was approximately nine points. Conclusions: The FRI is less reliable than the Oswestry but appears to have comparable validity and responsiveness. Before the FRI can be recommended for widespread use in patients with neck and low back pain, it should be further tested in patients with neck pain.An erratum to this article can be found at