Anterior and posterior thoracic cage translations in the sagittal plane have not been reported for their range of motion and effects on the lumbar spine and pelvis. Twenty subjects volunteered for ...full-spine radiography in neutral, anterior, and posterior thoracic cage translation postures in a standing position. While grasping an anterior vertical pole, with hands at elbow level, subjects were instructed on how to translate their thoracic cage without any flexion/extension, utilizing a full-length mirror. On the radiographs, all four vertebral body corners of T1 through S1 and the superior margin of the acetabulum were digitized. Segmental and global angles of thoracic kyphosis, sagittal lumbar curvature, and pelvic flexion/extension in translation postures were compared to alignment in the neutral posture. Using the femur heads as an origin, the mean range of thoracic cage translation, measured as horizontal movement of T12 from neutral posture, was found to be 85.1 mm anterior and 73 mm posterior. In anterior translation, the thoracic kyphosis is hypokyphotic (Cobb T1-T12 reduced by 16 degrees). In posterior translation, the segmental angles at T12-L1 and L1-L2 flexed, creating an "S" shape in the sagittal lumbar spine, while the thoracic kyphosis increased by 10 degrees. Using posterior tangents from L1 to L5 and T12 to S1, and Cobb angles at T12-S1, the lumbar curve reduced slightly (by less than 3.3 degrees for all global angle measurements) in anterior translation and reduced by 7.4 degrees, 5.7 degrees, and 8.1 degrees respectively in posterior thoracic translation. The angle of pelvic tilt (measured as the angle of intersection of a line through posterior-inferior S1 to the superior acetabulum and the horizontal) reduced by a mean of 15.9 degrees, and Ferguson's sacral base angle to horizontal reduced by a mean of 13.1 degrees in posterior translation. In anterior translation, pelvic tilt and Ferguson's sacral base angle increased by 15.1 degrees and 12.8 degrees, respectively. The findings of this study show that thoracic cage anterior/posterior translations cause significant changes in thoracic kyphosis (26 degrees ), lumbar curve, and pelvic tilt. An understanding of this main motion and consequent coupled movements might aid the understanding of spinal injury kinematics and spinal displacement analysis on full spine lateral radiographs of low back pain and spinal disorder populations.
Abstract Purpose The aim of this study was to determine the accuracy in measuring the pelvic orientations of a phantom model using the PosturePrint method. Methods In the Université du Québec à ...Trois-Rivières biomechanics laboratory, Trois-Rivières, Quebec, Canada, a mannequin was fixed on a rotating platform. For a set of 3 photographs (left lateral, anterior to posterior, right lateral) of each position, the mannequin pelvis was placed in 68 different postures on a stand, 61 cm from a wall, in front of a digital camera. The camera was at 83.8 cm in height and at 3.35 m from a calibrated wall grid. Mannequin postures were in 5 degrees of freedom: lateral translation (Tx), lateral flexion (Rz), axial rotation (Ry), flexion-extension (Rx), and anterior-posterior translation (Tz). Average errors were the differences of the positioned postures to the PosturePrint computed values. Results Mean and SD of computational errors for rotation displacements were Rx = 0.5° ± 0.8°, Ry = 1.3° ± 0.8°, and Rz = 0.5° ± 0.3°, and for translation, Tz = 1.2 ± 0.6 mm and Tx = 0.9 ± 0.5 mm. Conclusions The PosturePrint system allowed for accurate postural measurement of rotations and translations of a mannequin pelvis. The next step in evaluation of this product would be a reliability study on human subjects.
Background: Driving has been associated with signs and symptoms caused by vibrations. Sitting causes the pelvis to rotate backwards and the lumbar lordosis to reduce. Lumbar support and armrests ...reduce disc pressure and electromyographically recorded values. However, the ideal driver's seat and an optimal seated spinal model have not been described.
Objective: To determine an optimal automobile seat and an ideal spinal model of a driver.
Data Sources: Information was obtained from peer-reviewed scientific journals and texts, automotive engineering reports, and the National Library of Medicine.
Conclusion: Driving predisposes vehicle operators to low-back pain and degeneration. The optimal seat would have an adjustable seat back incline of 100° from horizontal, a changeable depth of seat back to front edge of seat bottom, adjustable height, an adjustable seat bottom incline, firm (dense) foam in the seat bottom cushion, horizontally and vertically adjustable lumbar support, adjustable bilateral arm rests, adjustable head restraint with lordosis pad, seat shock absorbers to dampen frequencies in the 1 to 20 Hz range, and linear front-back travel of the seat enabling drivers of all sizes to reach the pedals. The lumbar support should be pulsating in depth to reduce static load. The seat back should be damped to reduce rebounding of the torso in rear-end impacts. The optimal driver's spinal model would be the average Harrison model in a 10° posterior inclining seat back angle.
For the sagittal lumbar curvature, existing spinal models are based only on the anthropomorphic radiographic characteristics of one individual, or, at best, of only a few individuals. This raises ...questions of applicability of the modeling results to clinical situations. Because spinal coupling and loads on spinal tissues have been shown to be functions of the initial static posture, a rigorously derived neutral lumbar lordosis would be important for clinicians and spine researchers. This study presents modeling of the sagittal lumbar spine in the shape of an ellipse. Vertebral body and disc heights, derived from digitized lateral lumbar radiographs of 50 normal subjects, were used to create an ellipse along the posterior body margins from the inferior of T12 to the superior sacral base. Additional data to create an elliptical lumbar model were determined from a least-squares analysis of passing ellipses through the digitized posterior body points. This confirmed that an elliptical model closely fit the lumbar curvature with a least-squares error of 1.2 mm per digitized point. The elliptical model is approximately an 85 degrees portion of a quadrant. The semi-major and semi-minor axes, a and b, are parallel to the posterior body margin of T12 and parallel to the inferior body endplate of T12, respectively, with a semi-minor to semi-major radio of b/a=0.39. The elliptic model has a height-to-length ratio of H/L=0.963, where height is the vertical distance from inferior T12 to superior S1 and length is the arc length along George's line (along the posterior longitudinal ligament) from T12 to S1.
Abstract Objective The purpose of this study is to describe and evaluate the validity/accuracy of the computerized system PosturePrint for measuring head posture. Methods Computer analysis was ...compared with 125 measured positions of a mannequin head in 5 degrees of freedom. For each mannequin position, 3 digital photographs were obtained (left lateral, anteroposterior, and right lateral) and were processed through the PosturePrint computer system. For the head analysis, a headgear with 3 reflective markers was placed on a subject; and there were additional click-on markers at the ear tragus, upper lip, acromioclavicular joints, and episternal notch. Head postures were calculated as lateral translation ( T x ), lateral flexion ( R z ), axial rotation ( R y ), flexion-extension ( R x ), and anterior-posterior translation ( T z ). For an error analysis, PosturePrint algorithm calculations were compared with the true mannequin head positions. Furthermore, average head posture was determined in student volunteers (n = 40). Results Mean computational errors were R x = 1.3° (SD 0.6°) and T z = 1.1 mm (SD 0.5 mm) for sagittal displacements and R y = 1.1° (SD 0.7°), R z = 0.6° (SD 0.4°), and T x = 1.1 mm (SD 0.5 mm) for frontal view displacements. For the normal group, mean head displacements were 1.1° or less for all rotations and 1 mm or less for lateral translations ( T x ); and forward head posture ( T z ) averaged 3 cm. Conclusion From the mannequin positions, small mean errors indicate that the PosturePrint system is accurate. In the future, statistical research determining the correlation between head displacements, neck pain, function, and health status should be performed.
Pure annular dilation (PAD) is a recognized etiology of mitral regurgitation, yet few data exist to define the prognostic profile of this disorder relative to other etiologies, such as ischemia or ...myxomatous prolapse.
A total of 535 patients undergoing mitral repair at two institutions between 1993 and 2002 was retrospectively reviewed. PAD was defined as requiring only ring annuloplasty +/- cleft repair, without evidence of prolapse, regional wall motion abnormality, or infarction.
PAD was identified in 74 patients, while alternative etiologies were myxomatous prolapse (n = 290), ischemia (n = 141), and 'other' (n = 30). PAD patients were more often female (78%) than male (38%) (p < 0.001), more often hypertensive (37% versus 26%; p = 0.003), and had a left ventricular ejection fraction (LVEF) that was lower (0.41 +/- 0.12) than those in patients with prolapse (0.51 +/- 0.11; p < 0.01) but similar to values in ischemic patients (0.38 +/- 0.10). The valve size was smaller for PAD versus prolapse (ring size 24-26 mm in 71% versus 12%; p < 0.001). The unadjusted PAD prognosis was intermediate, with five-year survival being 70 +/- 8%, compared to 87 +/- 3% for prolapse and 56 +/- 5% for ischemia (p < 0.01). Survival adjusted for differences in baseline characteristics was not different among the three groups (p > 0.10).
PAD is a clinically distinct etiology of mitral regurgitation associated with female gender, small valve size, a lower LVEF, and hypertension. Early, more aggressive hypertension control might improve or minimize the consequences of this predominantly female cardiac disorder.
Background: There is debate concerning the repeatability of posture over time, radiograph positioning repeatability, and radiograph line drawing reliability. These ideas seem to negate the use of ...before-and-after spinal radiographic imaging to detect and correct vertebral subluxations. Objective: To review the results of control groups in 6 clinical control trials with before-and-after radiographic measurements taken days, weeks, months, or years apart to accept or reject the hypothesis that radiographic analysis procedures are not repeatable, reliable, or reproducible. Data Sources: Six published control groups from original data. Other data were obtained from searches on MEDLINE, CHIROLARS, MANTIS, and CINAHL on radiographic reliability, posture, and positioning. Results: Comparison of initial and follow-up radiographic data for 6 control groups indicate that measured angles and distances between initial and follow-up radiograph measurements on lateral and anterior to posterior radiographs are not significantly different when utilizing Chiropractic Biophysics radiographic procedures. In 48 out of 50 measurements, the differences between initial and follow-up radiographs are less than 1.5° and 2 mm. These measurements indicate that posture is repeatable, radiographic positioning is repeatable, and radiographic line drawing analysis for spinal displacement is highly reliable. The scientific literature on these topics also indicates the repeatability of posture, radiographic positioning, and radiographic line drawing. Conclusions: Posture, radiographic positioning, and radiographic line drawing are all very reliable/repeatable. When Chiropractic Biophysics standardized procedures are used, any pre-to-post alignment changes in treatment groups are a result of the treatment procedures applied. These results contradict common claims made by several researchers and clinicians in the indexed literature. Chiropractic radiologic education and publications should reflect the recent literature, provide more support for posture analysis, radiographic positioning, radiographic line drawing analyses, and applications of posture and radiographic procedures for measuring spinal displacement on plain radiographs. (J Manipulative Physiol Ther 2003;26:87-98)
To determine projected Cobb angles associated with trunk list (side shift) posture, hypothesizing that the side shift "scoliotic" curvature would be similar to true scoliotic curvature in the early ...stages.
Anteroposterior (AP) radiographs of volunteers in neutral, in left, and right lateral translations of the thoracic cage (trunk list) were digitized.
Computer laboratory.
Fifteen healthy male volunteers.
Not applicable.
Cobb and Risser-Ferguson angles determined from digitizing vertebral body corners from T12 to L5 on 51 AP lumbar radiographs.
Using the horizontal displacement of T12 from S1, subjects could translate an average of 54.0 mm to the left and 52.5 mm to the right. The average digitized Cobb T12-L5 angle produced for the 30 translated postures was 16 degrees. Angles ranged from 2.6 degrees to 27.0 degrees. Risser-Ferguson angles averaged 10 degrees between T12 and L5. Statistical correlations were found between Cobb L1-5 and translation to the left (P=.015), Cobb T12-L5 and translation to the right (P=.024), Risser-Ferguson angle and translation to the left (P=.021), and the lumbosacral angle to the right and trunk translation to the right (P=.027).
During lateral translation of the thorax (trunk list), coupled lumbar lateral flexion resulted in the appearance of a pseudoscoliosis on AP radiographs. For this trunk list posture, Cobb angles are considerable (16 degrees ) and increase as the magnitude of trunk translation increases. Differentiating true structural scoliosis from this pseudoscoliosis would be clinically important. The small coupled axial rotation in trunk list is in contrast to the considerable degree of axial rotation observed in structural idiopathic scoliosis.
Measurements from lateral cervical radiographs of randomly selected patients are compared with two proposed ideal models.
To evaluate lordotic cervical curvatures from a large population base, to ...provide a geometric sagittal cervical spine model, and to test the validity of the model to predict measured angles and distances. Averages of ranges and normal values for cervical lordosis under conditions of static equilibrium are sought.
Seven angles and three distances were taken from 400 randomly selected lateral cervical radiographs of patients at a private clinic.
The radiographic measurements are compared with predicted values from our geometric sagittal cervical spine model and the Delmas ideal cervical model.
Values were predicted successfully by the geometric model with an average error of 5% compared with the radiographic measurements. The range of lordosis, measured at the posterior of C2 and C7, was 16.5-66 degrees, with a mean of 34 degrees. The average height-to-length ratio for the cervical spine was 0.97.
Predicted values from the geometric model were comparable with the measurements of the relative rotation angles at each vertebral interspace, absolute rotation angles from C2 to C7, and height-to-length ratios. A cervical lordosis of 34 degrees and a height-to-length ratio of 0.97 are suggested for clinical and theoretical outcomes.
The aim of this study was to compare flexicurve surface contour measurements of the cervical spine with radiographic measurements of cervical lordosis.
One examiner evaluated 96 patients with chronic ...neck pain in neutral posture using a flexible ruler, flexicurve, to measure sagittal contour of the skin over the cervical spine from the external occipital protuberance to the vertebra prominens. The flexicurve skin contour and neutral lateral radiographs were digitized and compared. The flexicurve and radiographs were categorized into height-length ratio, curve angle, curve depth, sum of depths, modified Ishihara's index, and inverse of radius. Mean values, SDs, mean differences, and limits of agreement were calculated. The differences between flexicurve measurement mean values and x-ray mean values were deemed significant if the lower limit of agreement exceeded 15% of the mean values for the x-ray measurements.
For all variables, except the height-length ratio, the mean values of the flexicurve variables differed significantly from the corresponding mean values of the radiographic measurements. All Pearson correlation coefficients were in the very poor range (
r < 0.15).
The flexicurve sagittal skin contour measurement has poor concurrent validity compared with established radiographic measurements of the cervical lordosis. The flexicurve tracings always predicted lordosis, overestimated the lordosis compared with x-ray values, and cannot discriminate between radiographic lordosis, straightened, S curves, and kyphotic alignments of the cervical curve.
PDF
