Thoracic kyphosis affects spinal loads and trunk muscle force

The intra- and inter-rater reliability of the tragus wall distance (TWD) measurement in non-pathological participants ages 18-34

OBJECTIVES

To assess intra-rater and inter-rater reliability of the tragus wall distance (TWD) measurement in non-pathologic individuals aged 18-34.

BACKGROUND

Physical therapists evaluate posture as a component of health status. A literature review suggests need for reliable clinical tools to assess head position.

METHODS

The TWD measurement is the horizontal distance between the tragus, the auricular cartilaginous flap anterior to the external auditory meatus, and a wall. Sixty-three adults aged 18-34 years were consecutively assigned to three raters for double-blinded repeated measures of TWD distance. Statistical analyses included descriptive statistics of the sample, interclass correlation coefficient (ICC), analysis of variance (ANOVA), t-tests (p < 0.05), and Pearson correlation coefficients to quantify correlations between raters and repeated measures.

RESULTS

ANOVA results for intra-rater reliability indicated consistency among individual raters. All raters demonstrated significant correlations across repeated measures, ICC = 0.92-0.94. ANOVA and t-test results did not support inter-rater reliability. However, ICC = 0.90, standard error of measurement = 0.22, and Pearson R = 0.84 supported inter-rater reliability. The evidence suggests that although the absolute TWD measurement values may not be reliable among raters, relative change between TWD measures demonstrates high inter-rater reliability.

CONCLUSIONS

TWD measurement has high intra-rater reliability. TWD measurement of a single patient by multiple raters is not supported.

The effect of thoracic kyphosis and sagittal plane alignment on vertebral compressive loading

To better understand the biomechanical mechanisms underlying the association between hyperkyphosis of the thoracic spine and risk of vertebral fracture and other degenerative spinal pathology, we used a previously validated musculoskeletal model of the spine to determine how thoracic kyphosis angle and spinal posture affect vertebral compressive loading. We simulated an age-related increase in thoracic kyphosis (T(1) -T(12) Cobb angle 50-75 degrees) during two different activities (relaxed standing and standing with 5-kg weights in the hands) and three different posture conditions: (1) an increase in thoracic kyphosis with no postural adjustment (uncompensated posture); (2) an increase in thoracic kyphosis with a concomitant increase in pelvic tilt that maintains a stable center of mass and horizontal eye gaze (compensated posture); and (3) an increase in thoracic kyphosis with a concomitant increase in lumbar lordosis that also maintains a stable center of mass and horizontal eye gaze (congruent posture). For all posture conditions, compressive loading increased with increasing thoracic kyphosis, with loading increasing more in the thoracolumbar and lumbar regions than in the mid-thoracic region. Loading increased the most for the uncompensated posture, followed by the compensated posture, with the congruent posture almost completely mitigating any increases in loading with increased thoracic kyphosis. These findings indicate that both thoracic kyphosis and spinal posture influence vertebral loading during daily activities, implying that thoracic kyphosis measurements alone are not sufficient to characterize the impact of spinal curvature on vertebral loading.

Physical Capability Scale

The purpose of this study was to describe the psychometric testing of the Basic Physical Capability Scale. The study was a secondary data analysis of combined data sets from three studies. Study participants included 93 older adults, recruited from 2 acute-care settings and 110 older adults living in long-term care facilities. Rasch analysis was used for the testing of the measurement model. There was some support for construct validity based on the fit of the items to the scale across both samples. In addition, there was support for hypothesis testing as physical function was significantly associated with physical capability. There was evidence for internal consistency (Alpha coefficients of .77-.83) and interrater reliability based on an intraclass correlation of .81. This study provided preliminary support for the reliability and validity of the Basic Physical Capability Scale, and guidance for scale revisions and continued use.

Influence of hamstring muscles extensibility on spinal curvatures and pelvic tilt in highly trained cyclists

The purpose of this study was to determine the influence of hamstring muscles extensibility in standing, maximal trunk flexion with knees extended and on the bicycle in lower handlebar-hands position of highly trained cyclists. Ninety-six cyclists were recruited for the study (mean ± SD, age: 30.36 ± 5.98 years). Sagittal spinal curvatures and pelvic tilt were measured in the standing position, maximal trunk flexion with knees extended (sit-and-reach test) and while sitting on a bicycle in lower handlebar-hand position using a Spinal Mouse system. Hamstring muscles extensibility was determined in both legs by passive straight leg raise test (PSLR). The sample was divided into three groups according to PSLR angle: (1) reduced extensibility (PSLR < 80º; n = 30), (2) moderate hamstring extensibility group (PSLR = 80º - 90º; n = 35), and (3) high hamstring extensibility (PSLR = > 90º; n = 31). ANOVA analysis showed significant differences among groups for thoracic (p < 0.001) and pelvic tilt (p < 0.001) angles in the sit-and-reach test. No differences were found between groups for standing and on the bicycle position. Post hoc analysis showed significant differences in all pairwise comparisons for thoracic angle (p < 0.01) and pelvic angle (p < 0.001) in the sit-and-reach test. No differences were found in lumbar angle in any posture. In conclusion, the hamstring muscles extensibility influence the thoracic and pelvic postures when maximal trunk flexion with knees extended is performed, but not when cyclists are seated on their bicycles.

The prevalence of MRI-defined spinal pathoanatomies and their association with modic changes in individuals seeking care for low back pain

Modic changes are of increasing interest, however their age and gender prevalence are not well described. To date, the associations between Modic changes and other common vertebral pathologies have only been described in small samples (n < 100). Our aim was, in a large dataset of people with low back pain, to (1) describe the prevalence of a range of spinal pathoanatomies, and (2) examine the association between Modic changes and stages of intervertebral disc (IVD) pathology. Common pathologies were coded from the lumbar spine MRIs from 4,233 consecutive people imaged while attending a publicly-funded secondary care outpatient facility in Denmark. Prevalence data were calculated by pathology and by vertebral level. Prevalence was also calculated by age and gender categories for Modic changes. The association between stages of IVD pathology (degeneration, bulge, herniation) and Modic changes at L4/5 and L5/S1 was expressed using prevalence ratios (PR) and 95% confidence intervals. The prevalence of Modic changes and IVD pathology were greater in L4/5 and L5/S1, compared with the upper lumbar spine. There was no significant gender difference in prevalence of Modic changes (p = 0.11). The prevalence of IVD disc pathology occurring concurrently with Modic changes ranged from 11.5 to 17.5% (Type 1), 8.5 to 12.7% (Type 2) and 17.1 to 25.6% (Type 1 and/or 2) while the prevalence occurring in the absence of Modic changes ranged from 0.5 to 6.3% (Type 1), 0.3 to 4.9 (Type 2), 0.8 to 9.7% (Type 1 and/or 2). The associated PR for IVD pathology occurring concurrently with Modic changes ranged from 1.8 to 29.2 (p < 0.05). The highest PR (29.2) was between degeneration and Modic changes, indicating that it is rare for Modic changes to occur without disc degeneration. Spinal pathoanatomy was common in this population, particularly IVD pathologies, and a consistent trend of a relatively greater prevalence in the lower lumbar spine was identified. Modic changes were more likely to be present among individuals with IVD pathology than without, which may implicate mechanical factors as being one aetiological pathway for Modic changes, although other hypotheses may equally explain this association.

Vulnerability of healthy vertebrae in patients with and without previous vertebral fracture

Vertebral deformities are associated with a marked increase in morbidity, mortality, and burden in terms of sanitary expenditures. Patients with vertebral fractures have a negative impact in their health, less quality of life, and loss of functional capacity and independence. The purpose of this study was to explore the vulnerability of healthy vertebrae in patients who have sustained already a compression fracture and in patients who do not have prevalent fractures in the thoracic spine; and to explore the association of the deformity in healthy vertebrae with different variables, such as bone mineral density (BMD), body mass index, age, loss of height, presence of clinical kyphosis, history of other osteoporotic fractures, and falls occurring during the last year. Clinical data and complementary studies from 175 postmenopausal outpatients were analyzed. These women (age: 69.7±11.1 years) had not received any treatment for osteoporosis. Anteroposterior and lateral radiographs of the thoracic spine and bone densitometry of the hip were obtained; morphometry was performed in 1575 thoracic vertebrae from T4 to T12. The angle of wedging of each vertebral body was calculated using a trigonometric formula. Then, the sum of wedge angles of vertebral bodies (SWA) was determined, and Cobb angle was measured. In patients with vertebral fractures, after excluding the angles of fractured vertebral bodies, the mean wedge angle of the remaining vertebrae (MWAhealthy) was calculated. The same procedure was followed in patients without vertebral fractures. MWAhealthy was considered as an indicator of the structural vulnerability of non-fractured vertebrae. Patients with prevalent fractures had lower BMD, wider Cobb angle, and higher sum of wedge angles than patients without vertebral fractures. The proportion of patients with accentuation of clinical kyphosis was higher in the group with prevalent vertebral fractures. A highly significant difference was found in the MWAhealthy, which was higher in patients with prevalent fractures (4.1±1.3° vs. 3.0±1.1°; p<0.001). Patients showing vertebral fractures had 7.1±4.2 cm height loss in average, significantly superior than that found among non-fractured women (3.6±3.2 cm; p<0.01). In multivariate analysis, the increase of MWAhealthy was associated with advancing age (p<0.02), lower femoral neck BMD (p<0.005), presence of clinical kyphosis (p<0.01) and vertebral fractures (p<0.02). This study presents evidence that a series of factors independently influence the increase in wedging deformity of vertebral bodies that are not fractured yet. These factors could contribute to an increased vulnerability of the vertebrae, making them more susceptible to fracture.

Optimizing reliability of digital inclinometer and flexicurve ruler measures of spine curvatures in postmenopausal women with osteoporosis of the spine: an illustration of the use of generalizability theory

The study illustrates the application of generalizability theory (G-theory) to identify measurement protocols that optimize reliability of two clinical methods for assessing spine curvatures in women with osteoporosis. Triplicate measures of spine curvatures were acquired for 9 postmenopausal women with spine osteoporosis by two raters during a single visit using a digital inclinometer and a flexicurve ruler. G-coefficients were estimated using a G-study, and a measurement protocol that optimized inter-rater and inter-trial reliability was identified using follow-up decision studies. The G-theory provides reliability estimates for measurement devices which can be generalized to different clinical contexts and/or measurement designs.

Biomechanics of vertebral fractures and the vertebral fracture cascade

Vertebral fractures (VFxs) are the most common osteoporotic fracture, and are a strong risk factor for future fracture. The presence of a VFx greatly increases the risk of sustaining subsequent VFxs-a phenomenon often referred to as the "vertebral fracture cascade." VFxs do not occur uniformly along the spine, but occur more often at the mid-thoracic and thoracolumbar regions than elsewhere. It is likely that both the vertebral fracture cascade and the bimodal distribution of VFx along the spine are attributable to biomechanical factors. VFxs occur when the forces applied to the vertebral body exceed its strength. Loading on the spine is primarily determined by a person's height, weight, muscle forces, and the task or movement performed, but can also be affected by other factors, such as spinal curvature and invertebral disk deterioration. Vertebral strength is determined mainly by bone size, shape, and bone mineral density, and secondarily by bone microarchitecture, collagen characteristics, and microdamage. Better understanding of VFx etiology is hampered by the fact that most VFxs do not come to clinical attention; therefore, the factors and activities that cause VFxs remain ill defined, including possible differences in the etiology of acute fractures versus those of slow onset. Additional research is needed to elucidate the precise mechanical, morphologic, and biological mechanisms that underlie VFx to improve strategies for assessing VFx risk and preventing the vertebral fracture cascade.

Comparison of two heights for forward-placed trunk support with standing work

Two forward-placed supports with different heights are investigated using human motion capture and EMG. Ten male participants stood in 10 degrees increments of trunk flexion between 0 and 40 degrees for three conditions; leaning on a desk adjusted to the height of the pelvis, leaning on a prototype support at the height of the sternum and with no external support. Low back and hip extensor muscle activity was reduced by an average 60% with leaning against the prototype compared to the no-support condition whereas leaning on a desk produced no significant change in muscle activity. Supported conditions resulted in greater forward displacement of the trunk by at least two-fold compared to no-support representing a longer reach distance. No adverse changes in kinematics indicate that either support blocked segmental flexion of the pelvis, lumbar spine or thoracic spine. These findings suggest that leaning against a higher-placed trunk support could be beneficial for tasks requiring forward flexion.

Biplanar measurement of thoracolumbar curvature in older adults using an electromagnetic tracking device

Singh DK, Bailey M, Lee R. Biplanar measurement of thoracolumbar curvature in older adults using an electromagnetic tracking device.

OBJECTIVES

To develop a new biplanar method of thoracolumbar curvature measurement by using an electromagnetic tracking device and to study the effects of aging on the thoracolumbar curvature.

DESIGN

Cross-sectional study.

SETTING

Human movement laboratory.

PARTICIPANTS

Healthy (N=52, 26 younger and 26 older) volunteers.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

An electromagnetic tracking device was used to trace the thoracolumbar curvature by recording the positions of the spinous processes of the spine. The coordinates of the curvature were fitted with polynomial equations, and the magnitudes of thoracic kyphosis, lumbar lordosis, and lateral thoracic and lumbar curves were determined.

RESULTS

The present technique was shown to be highly reliable in measuring thoracolumbar curvature with an intraclass correlation coefficient of more than .90. The mean thoracic kyphosis (-46.95 degrees +/-11.41 degrees ) in the older adults was significantly larger than that in the younger adults (-38.82 degrees +/-9.86 degrees ) (P<.01). However, there were no significant differences in lumbar lordosis and lateral curvatures between the 2 subject groups.

CONCLUSIONS

The present study provided evidence of an increase in thoracic kyphosis in older adults. The method of measurement presented in this study was found to provide reliable biplanar data that will be useful in a clinical setting.

Effects of an exercise and manual therapy program on physical impairments, function and quality-of-life in people with osteoporotic vertebral fracture: a randomised, single-blind controlled pilot trial

BACKGROUND

This randomised, single-blind controlled pilot trial aimed to determine the effectiveness of a physiotherapy program, including exercise and manual therapy, in reducing impairments and improving physical function and health-related quality of life in people with a history of painful osteoporotic vertebral fracture.

METHODS

20 participants were randomly allocated to an intervention (n = 11) or control (n = 9) group. The intervention group attended individual sessions with an experienced clinician once a week for 10 weeks and performed daily home exercises with adherence monitored by a self-report diary. The control group received no treatment. Blinded assessment was conducted at baseline and 11 weeks. Questionnaires assessed self-reported changes in back pain, physical function, and health-related quality of life. Objective measures of thoracic kyphosis, back and shoulder muscle endurance (Timed Loaded Standing Test), and function (Timed Up and Go test) were also taken.

RESULTS

Compared with the control group, the intervention group showed significant reductions in pain during movement (mean difference (95% CI) -1.8 (-3.5 to -0.1)) and at rest (-2.0 (-3.8 to -0.2)) and significantly greater improvements in Qualeffo physical function (-4.8 (-9.2 to -0.5)) and the Timed Loaded Standing test (46.7 (16.1 to 77.3) secs). For the perceived change in back pain over the 10 weeks, 9/11 (82%) participants in the intervention group rated their pain as 'much better' compared with only 1/9 (11%) participants in the control group.

CONCLUSION

Despite the modest sample size, these results support the benefits of exercise and manual therapy in the clinical management of patients with osteoporotic vertebral fractures, but need to be confirmed in a larger sample.

TRIAL REGISTRATION

NCT00638768.

Postural taping decreases thoracic kyphosis but does not influence trunk muscle electromyographic activity or balance in women with osteoporosis

BACKGROUND

Greater thoracic kyphosis is associated with increased biomechanical loading of the spine which is potentially problematic in individuals with osteoporotic vertebral fractures. Conservative interventions that reduce thoracic kyphosis warrant further investigation. This study aimed to investigate the effects of therapeutic postural taping on thoracic posture. Secondary aims explored the effects of taping on trunk muscle activity and balance.

METHODS

Fifteen women with osteoporotic vertebral fractures participated in this within-participant design study. Three taping conditions were randomly applied: therapeutic taping, control taping and no taping. Angle of thoracic kyphosis was measured after each condition. Force plate-derived balance parameters and trunk muscle electromyographic activity (EMG) were recorded during three static standing tasks of 40s duration.

RESULTS

There was a significant main effect of postural taping on thoracic kyphosis (p=0.026), with a greater reduction in thoracic kyphosis after taping compared with both control tape and no tape. There were no effects of taping on EMG or balance parameters.

CONCLUSIONS

The results of this study demonstrate that the application of postural therapeutic tape in a population with osteoporotic vertebral fractures induced an immediate reduction in thoracic kyphosis. Further research is needed to investigate the underlying mechanisms associated with this decrease in kyphosis.