Differences In Lumbar Lordosis Research Articles

How do we stand? Variations during repeated standing phases of asymptomatic subjects and low back pain patients

An irreproducible standing posture can lead to mis-interpretation of radiological measurements, wrong diagnoses and possibly unnecessary treatment. This study aimed to evaluate the differences in lumbar lordosis and sacrum orientation in six repetitive upright standing postures of 353 asymptomatic subjects (including 332 non-athletes and 21 athletes – soccer players) and 83 low back pain (LBP) patients using a non-invasive back-shape measurement device.In the standing position, all investigated cohorts displayed a large inter-subject variability in sacrum orientation (∼40°) and lumbar lordosis (∼53°). In the asymptomatic cohort (non-athletes), 51% of the subjects showed variations in lumbar lordosis of 10–20% in six repeated standing phases and 29% showed variations of even more than 20%. In the sacrum orientation, 53% of all asymptomatic subjects revealed variations of >20% and 31% of even more than 30%.It can be concluded that standing is highly individual and poorly reproducible. The reproducibility was independent of age, gender, body height and weight. LBP patients and athletes showed a similar variability as the asymptomatic cohort. The number of standing phases performed showed no positive effect on the reproducibility. Therefore, the variability in standing is not predictable but random, and thus does not reflect an individual specific behavioral pattern which can be reduced, for example, by repeated standing phases.

Hyperlordosis is Associated With Facet Joint Pathology at the Lower Lumbar Spine.

A retrospective study. Our study opted to clarify the remaining issues of lumbar lordosis (LL) with regard to (1) its physiological values, (2) age, (3) sex, and (4) facet joint (FJ) arthritis and orientation using computed tomography (CT) scans. Recent studies have questioned whether LL really decreases with age, but study sample sizes have been rather small and mostly been based on x-rays. As hyperlordosis increases the load transferred through the FJs, it seems plausible that hyperlordosis may lead to FJ arthritis at the lower lumbar spine. We retrospectively analyzed the CT scans of 620 individuals, with a mean age of 42.5 (range, 14-94) years, who presented to our traumatology department and underwent a whole-body CT scan, between 2008 and 2010. LL was evaluated between the superior endplates of L1 and S1. FJs of the lumbar spine were evaluated for arthritis and orientation between L2 and S1. (1) The mean LL was 49.0 degrees (SD 11.1 degrees; range, 11.4-80.1 degrees). (2) LL increased with age and there was a significant difference in LL in our age groups (30 y and below, 31-50, 51-70, and ≥71 y and above) (P=0.02). (3) There was no significant difference in LL between females and males (50 and 49 degrees) (P=0.17). (4) LL showed a significant linear association with FJ arthritis [P=0.0026, OR=1.022 (1.008-1.036)] and sagittal FJ orientation at L5/S1 (P=0.001). In a logistic regression analysis, the cutoff point for LL was 49.4 degrees. This is the largest CT-based study on LL and FJs. LL significantly increases with age. As a novelty finding, hyperlordosis is significantly associated with FJ arthritis and sagittal FJ orientation at the lower lumbar spine. Thus, hyperlordosis may present with back pain and patients may benefit from surgical correction, for example, in the setting of trauma.

Association between vertebral cross-sectional area and lumbar lordosis angle in adolescents.

Lumbar lordosis (LL) is more prominent in women than in men, but the mechanisms responsible for this discrepancy are poorly defined. A recent study indicates that newborn girls have smaller vertebral cross-sectional area (CSA) when compared to boys—a difference that persists throughout life and is independent of body size. We determined the relations between vertebral cross-sectional area (CSA) and LL angle and whether sex differences in lumbar lordosis are related to sex differences in vertebral CSA. Using multi-planar magnetic resonance imaging (MRI), we measured vertebral cross-sectional area (CSA) and vertebral height of the spine of 40 healthy boys and 40 girls, ages 9–13 years. Measures of the CSA of the lumbar vertebrae significantly differed between sexes (9.38 ± 1.46 vs. 7.93 ± 0.69 in boys and girls, respectively; P < 0.0001), while the degree of LL was significantly greater in girls than in boys (23.7 ± 6.1 vs. 27.6 ± 8.0 in boys and girls, respectively; P = 0.02). When all subjects were analyzed together, values for LL angle were negatively correlated to vertebral CSA (r = -0.47; P < 0.0001); this was also true when boys and girls were analyzed separately. Multivariate regression analysis indicated that vertebral CSA was independently associated with LL, even after accounting for sex, age, height or vertebral height, and weight. Similar negative relations were present when thoracic vertebrae were analyzed (Model P < 0.0001, R2 = 0.37, thoracic vertebral CSA slope P < 0.0001), suggesting that deficient vertebral cross-sectional dimensions are not merely the consequence of the anterior lumbar curvature. We conclude that vertebral CSA is negatively associated with LL, and that the greater degree of LL in females could, at least in part, be due to smaller vertebral cross-sectional dimensions. Studies are needed to examine the potential relations between vertebral CSA and spinal conditions known to be associated with increased LL, such as spondylolysis and spondylolisthesis.

Facet Joint Orientation and Sagittal Spinopelvic Alignment in Patients with Degenerative Lumbar Scoliosis

The purpose of this study was to evaluate the association between lumbar spine facet joint orientation and tropism, sagittal spinopelvic alignment, and rotational deformity, identified by radiographic and computed tomography (CT) measurements, in degenerative lumbar scoliosis (DLS). Standing whole-spine sagittal radiographs and CT scans, including the pelvis, were performed and analyzed in 60 DLS patients (16 males, 44 females; mean age 65 years). Cobb angle, pelvic incidence (PI) and lumbar lordosis (LL) were measured on standing lumbar radiographs. Facet joint orientation on both sides at L3/4, L4/5, and L5/S1 was determined from transverse-plane CT. Facet joint tropism was defined as a difference in symmetry of more than 10 degrees between the orientations of the facet joints. There were significant differences in the incidence of facet joint tropism between the two groups at L3/4, L4/5, and L5/S1 (P = 0.011, P = 0.043, and P = 0.004, respectively). LL was significantly smaller in type II DLS (P = 0.049). Facet joint orientation, pelvic incidence, and Cobb angle did not differ between groups. No significant correlation between LL and PI was observed in either group. This study provides a reliability analysis of rotational deformity in patients with DLS. In conclusion, we observed a significant relationship between facet joint tropism and rotational deformity in patients with DLS. Furthermore, the different types of DLS demonstrated significant differences in LL that may induce spinal symptoms.

Lumbar Sagittal Plane Spinal Curvature and Junior-Level Cricket Players

Lumbar lordosis may be a risk factor for injury in junior-level athletes involved in sport which requires excessive amounts of extension. The purpose of this study was to examine the relationship between lumbar lordosis in junior-level cricket players with and without previous low back injury. Results demonstrated a statistically significant difference in lumbar lordosis between the two groups (LBI = 42.53 ± 9.10°; no LBI = 30.33 ± 8.36°; p &lt; .01), with previous lower back injury accounting for 32% variation in lumbar lordosis (p &lt; .01). The results indicate lumbar lordosis may be an issue worth examining in those athletes who partake in sports which have high levels of extension; but, as there is no accepted definition to lumbar postures, it is difficult to accurately interpret measurement results.

Change in lumbar lordosis during prone lying knee flexion test in subjects with and without low back pain.

BackgroundProne lying knee flexion (PLKF) is one of the clinical tests used for assessment of the lumbo-pelvic movement pattern. Considerable increase in lumbar lordosis during this test has been considered as impairment of movement patterns in lumbar-pelvic region. However, no study has directly evaluated the change in lordosis during active PLKF test in subjects with low back pain (LBP). The purpose of this study was to investigate the change of lumbar lordosis in PLKF test in subjects with and without LBP.MethodsA convenience sample of 80 subjects participated in the study. Subjects were categorized into two groups: those with chronic non-specific LBP (N = 40, mean age: 40.84 ± 17.59) and with no history of LBP (N = 40, mean age: 23.57 ± 10.61). Lumbar lordosis was measured with flexible ruler, first in prone position and then on active PKF test in both subjects with and without LBP. Data was analyzed by using statistical methods such as, independent t-test and paired t-test.ResultsThere were statistically significant differences in lumbar lordosis between prone position and after active PLKF in both subjects with and without LBP (P < 0.0001). The amount of change in lordosis during PLKF test was not significant between the two groups (P = 0.65). However these changes were greater among patients with LBP.ConclusionIncrease in lumbar lordosis during this test may be due to excessive flexibility of movement of the lumbar spine in the direction of extension and abnormal movement patterns in the individuals with LBP.

Anteroposterior curvatures of the spine in adolescent athletes.

To assess the shape of anteroposterior vertebral curvatures in adolescents who practice team sports. 57 females and 104 males aged 14-17 years, playing volleyball, basketball or handball, and 63 females and 99 males as a control group. A Rippstein plurimeter was used to measure the angles of thoracic kyphosis and lumbar lordosis. The study has revealed significant differences in lumbar lordosis in male athletes compared to the control (p=0.01). Male volleyball players had greater thoracic kyphosis (p=0.002) than basketball players. Female athletes had lower thoracic kyphosis than the control group (p < 0.01). Normal values of thoracic kyphosis were more frequent in female athletes and male handball players whereas normal lumbar lordosis was more frequently seen in female volleyball players and male control group. Our investigations revealed significant (p < 0.05) correlations between the anteroposterior curvature of the spine and somatic parameters. Differences in thoracic kyphosis or lumbar lordosis among the athletes and the control group might be due to postural muscles strengthening as a result of regular engagement in intensive exercise. The variability of anteroposterior spine curvatures may not only be associated with directional physical activity; some contribution of the somatic structure is also possible.

Long fusion from sacrum to thoracic spine for adult spinal deformity with sagittal imbalance: upper versus lower thoracic spine as site of upper instrumented vertebra.

Despite increasing numbers of patients with adult spinal deformity, it is unclear how to select the optimal upper instrumented vertebra (UIV) in long fusion surgery for these patients. The purpose of this study was to compare the use of vertebrae in the upper thoracic (UT) versus lower thoracic (LT) spine as the upper instrumented vertebra in long fusion surgery for adult spinal deformity. Patients who underwent fusion from the sacrum to the thoracic spine for adult spinal deformity with sagittal imbalance at a single medical center were studied. The patients with a sagittal vertical axis (SVA) ≥ 40 mm who had radiographs and completed the 12-item Short-Form Health Survey (SF-12) preoperatively and at final follow-up (≥ 2 years postoperatively) were included. Eighty patients (mean age of 61.1 ± 10.9 years; 69 women and 11 men) met the inclusion criteria. There were 31 patients in the UT group and 49 patients in the LT group. The mean follow-up period was 3.6 ± 1.6 years. The physical component summary (PCS) score of the SF-12 significantly improved from the preoperative assessment to final follow-up in each group (UT, 34 to 41; LT, 29 to 37; p = 0.001). This improvement reached the minimum clinically important difference in both groups. There was no significant difference in PCS score improvement between the 2 groups (p = 0.8). The UT group had significantly greater preoperative lumbar lordosis (28° vs 18°, p = 0.03) and greater thoracic kyphosis (36° vs 18°, p = 0.001). After surgery, there was no significant difference in lumbar lordosis or thoracic kyphosis. The UT group had significantly greater postoperative cervicothoracic kyphosis (20° vs 11°, p = 0.009). The UT group tended to maintain a smaller positive SVA (51 vs 73 mm, p = 0.08) and smaller T-1 spinopelvic inclination (-2.6° vs 0.6°, p = 0.06). The LT group tended to have more proximal junctional kyphosis (PJK), although the difference did not reach statistical significance. Radiographic PJK was 32% in the UT group and 41% in the LT group (p = 0.4). Surgical PJK was 6.4% in the UT group and 10% in the LT group (p = 0.6). Both the UT and LT groups demonstrated significant improvement in clinical and radiographic outcomes. A significant difference was not observed in improvement of clinical outcomes between the 2 groups.

Hamstring muscle length and lumbar lordosis in subjects with different lifestyle and work setting: Comparison between individuals with and without chronic low back pain

Shortened hamstring muscle length has been noted in persons with low back pain (LBP). Prolonged sitting postures, such as those adopted during different work settings and sedentary lifestyle has been associated with hamstring shortness and LBP. The purpose of this study was to investigate the effect of lifestyle and work setting on hamstring length and lumbar lordosis in subjects with and without LBP and to identify the relationship between hamstring muscles length and lumbar lordosis in individuals with different lifestyle and work setting. A total of 508 subjects between the ages of 20 and 65 were selected. Subjects were categorized into two groups of individuals with and without LBP. A questionnaire was used to obtain information about the subjects' lifestyle and work setting. Hamstring muscle length and lumbar lordosis were measured in all subjects. The results showed no significant difference in the number of subjects with different work setting or lifestyle in individuals with and without LBP. Hamstring muscle length or lumbar lordosis was not affected by type of work setting and lifestyle. Our data showed significant difference in hamstring length and no significant difference in lumbar lordosis between subjects with and without LBP in all categories. Lumbar lordosis was not different between individuals with and without hamstring tightness in normal and LBP subjects with different work setting and lifestyle. The findings of this study did not support the assumption that work setting and sedentary lifestyle would lead to hamstring tightness in subjects with LBP. It seems that work setting and lifestyle was not a contributing factor for hamstring tightness in subjects with LBP.

Necessity of Whole Spine Standing Lateral Radiograph in Adults over 50 Years Old Who Have Degenerative Lumbar Disease: Comparison with Supine Lumbar Lateral Radiograph

Objectives: Sagittal imbalance cannot be predicted depending on the degree of lumbar lordosis. Thus, we tried to evaluate the necessity of whole spine standing lateral radiograph through comparison of the spinal and pelvic parameter between supine lumbar lateral radiograph and whole spine standing lateral radiograph. Summary of the Literature Review: No studies in the literature compare supine lumbar lateral radiograph and whole spine standing lateral radiograph. Materials and Methods: We randomly selected 50 males and 50 females among the patients over the age of 50 who visited our hospital for outpatient due to degenerative lumbar disease. Lumbar lordosis (sLL/wLL), sacral slope (sSS/wSS), and pelvic tilt (sPT/ wPT) were measured and compared respectively by supine lumbar lateral radiograph and whole spine standing lateral radiograph. We categorized as group AI (sLL 5 cm) by whole spine standing lateral radiograph and analyzed them. Results: There were no statistical difference in lumbar lordosis (sLL/wLL: 35.1˚/37.7˚) and pelvic parameter (sSS/wSS: 32˚/31.7˚, sPT/ wPT: 24.3˚/24.2˚. sPI/wPI: 56.3˚/58.2˚) between supine lumbar lateral radiograph and whole spine standing lateral radiograph, and there were also no statistical difference between two groups (group AI & AII) in SVA, lumbar lordosis and pelvic parameter. Pelvic parameter compared by supine lumbar lateral radiograph and whole spine standing lateral radiograph based on sagittal balance was no significant difference, but lumbar lordosis appeared statistical difference. Conclusion: Sagittal imbalance appears quite a lot in patients with degenerative lumbar disease and supine lateral radiograph can’t reflect the whole sagittal imbalance. So, whole spine standing lateral radiograph should be performed routinely to analyze the sagittal alignment.

Difference of Sagittal Spinopelvic Alignments between Degenerative Spondylolisthesis and Isthmic Spondylolisthesis

ObjectiveThe purpose of this study was to analyze the differences of spinopelvic parameters between degenerative spondylolisthesis (DSPL) and isthmic spondylolisthesis (ISPL) patients.MethodsThirty-four patients with DSPL and 19 patients with ISPL were included in this study. Spinopelvic parameters were evaluated on whole spine X-rays in a standing position. The following spinopelvic parameters were measured : pelvic incidence (PI), sacral slope, pelvic tilt (PT), lumbar lordosis (LL), and sagittal vertical axis from C7 plumb line (SVA). The population of patients was compared with a control population of 30 normal and asymptomatic adults.ResultsThere were statistically significant differences in LL (p=0.004) and SVA (p=0.005) between the DSPL and ISPL group. The LL of DSPL (42±13°) was significantly lower than that of the control group (48±11°; p=0.029), but that of ISPL (55±6°) was significantly greater than a control group (p=0.004). The SVA of DSPL (55±49 mm) was greater than that of a control group (<40 mm), but that of ISPL (21±22 mm) was within 40 mm as that of a control group. The PT of DSPL (24±7°) and ISPL (21±7°) was significantly greater than that of a control group (11±6°; p=0.000).ConclusionBoth symptomatic DSPL and ISPL patients had a greater PI than that of the asymptomatic control group. In conclusion, DSPL populations are likely to have global sagittal imbalance (high SVA) compared with ISPL populations because of the difference of lumbar lordosis between two groups.

Differences in pelvic parameters among Mexican, Caucasian, and Asian populations

The aim of this study was to describe the pelvic parameters in a sample of healthy Mexican volunteers and to compare them with previously reported data for Caucasian and Asian populations. This was a transversal study that included a sample population of healthy Mexican volunteers. Age, sex, and lateral radiographs of the lumbosacral region with the individual standing to obtain the pelvic parameters of pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), and lumbar lordosis (LL) were recorded in each volunteer. The data were compared with those previously published for Caucasian and Asian individuals. In total, 202 Mexican individuals (81 men and 121 women; mean age 46.5 years, range 18-85 years) were included. There were statistically significant differences between the Mexican and Caucasian control group with respect to PT (11.9° vs 15.78°, respectively) and PI (51.91° vs 56.68°, respectively). Comparison with the Asian population showed statistically significant differences in relation to the Mexican group in terms of the PT (11.5° vs 15.78°), PI (47.8° vs 56.68°), and SS (36.3° vs 40.89°). The mean LL was 60.17° for the Mexican group, 52.3° for the Asian group, and 61.3° for the Caucasian group. A significant difference in LL was found between the Mexican and Asian populations (p < 0.0001). A comparison of the values for pelvic parameters and lumbar lordosis across the different population samples revealed statistically significant differences, which can be attributed to the ethnic origin of the individuals.

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°±11.41°) in the older adults was significantly larger than that in the younger adults (−38.82°±9.86°) ( 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.

Spinal deformity following selective dorsal rhizotomy.

The authors performed a review of 79 patients treated by selective dorsal rhizotomy with laminoplasty, 78 of whom were ambulatory, to determine the prevalence of spinal deformities. The mean radiographic follow-up was 4.2 years, the mean clinical follow-up 5.8 years. Scoliosis (11 degrees -24 degrees ) was identified in 13 children, none of whom had a preexisting deformity. There were no significant differences between preoperative and follow-up thoracic kyphosis or lumbar lordosis, although there was a significant difference in lumbar lordosis between sitting and standing radiographs. No progressive or rigid hyperlordotic deformities were observed in the lumbar spine. Spondylolisthesis was identified in nine children (12%) (8/9 grade I), and one patient required an arthrodesis for pain. Spondylolisthesis was correlated with greater lumbar lordosis, stronger hip abductors, and increased popliteal femoral angles preoperatively, and with stronger hip flexors postoperatively. Back pain was identified in 4 of the 79 patients at last follow-up, 2 of whom had spondylolisthesis. As some cases of spondylolisthesis will remain asymptomatic, periodic radiographic follow-up is recommended.

Epidemiology of low back pain in the elderly: correlation withlumbar lordosis

We carried out an epidemiologic study to determine the prevalence of low back pain in elderly Japanese and to examine the correlation with lumbar lordosis in sagittal planeradiographs. Low back pain is an enormous clinical and public health problem. With the increasing use of spinal instrumentation, the measurement of lumbar lordosis is thought to be important. However, in elderly Japanese, the prevalence of low back pain and its correlation with lumbar lordosis is not clear. Five hundred and nine people, aged 50–85 years, were examined, and 489 subjects met our criteria. Clinical findings, physical status, and the visual analogue scale (VAS) of pain were examined in these subjects. Measurements and determination of total lordosis from L1-S1 were made from standing radiographs. Forty-eight percent of the subjects had experienced low back pain within the previous 3 months. Women had low back pain more frequently (P=0.006).There was a significant difference in lumbar lordosis between the groups with and without low back pain (P=0.0006).Lumbar lordosis was approximately 4° less in the low back pain group and there was no relationship to age or sex in either group. VAS was significantly inversely correlated with lumbar lordosis (P=0.025, at rest). The body mass index (BMI) of the low back pain group was higher in women, but the difference was not significant (P=0.06). In conclusion, lumbar lordosis was defined and its prevalence in elderly Japanese was reported together with VAS and physical data used to compare the two groups.

The Role of Lumbar Lordosis, Vertebral End-Plate Inclination, Disc Height, and Facet Orientation in Degenerative Spondylolisthesis

Degenerative spondylolisthesis (DS) is a common condition of the aging spine, but the underlying pathomechanisms remain controversial. Most previous studies focused on the role of facet-joint alignment and reported a pronounced sagittal orientation. This, however, may also be a secondary feature to the slippage. This study analyzed several radiologic findings in the lower lumbar spine in 23 patients with DS (group A) and 40 age- and sex-matched controls (group B). Facet-joint angulation, intervertebral disc height, lordosis of the lumbar spine (L1-S1), and inclination of the L4, L5, and S1 end plates were assessed from neutral standing lateral radiographs and computed tomography (CT) or magnetic resonance imaging (MRI) investigations. Two findings were found to be significantly different between the groups. Facet joints were aligned more sagittal in group A, and the inclination of the vertebral end plates was more horizontal in group B. There was no statistical difference in lumbar lordosis or L4-5 disc height between the two groups, with disc height being decreased in both groups. In group A, more gliding was associated with a further decrease in disc space, pronounced sagittal alignment of the L4-5 facet joints, and a decrease in lumbar lordosis. We concluded that further studies should focus on the analysis of spinal alignment and lower lumbar end-plate orientation to identify patients at risk for development of DS.

Spinal shrinkage during work in a sitting posture compared to work in a standing posture

Objective. The objective was to measure the possible differences in shrinkage of the thoracolumbar spine in subjects working in a sitting and a standing posture for 6.5 h at work, in a realistic work environment. The isolated shrinkage of the thoracic and the lumbar spine was also examined. Study design. This study presents a new protocol to measure shrinkage of the thoracic and lumbar spine separately. Background. Controversies still exist with regard to the load on the spine in a sitting compared to a standing position. Some report that shrinkage is greatest in the sitting position while others report the reverse. However, nothing is known about the height reduction of the thoracic and the lumbar spine during loading for 6.5 h in a real work environment. Therefore, the behaviour of the thoracic and the lumbar spine under practical condition has to be investigated. Method. A stadiometer with a measurement error of 0.51 mm was used to measure changes in spinal height during work. To exclude first-time behaviour of the spine, a pre-test lasting 50 min was undertaken. The mean of the last three measurements was used as the reference height. During work, height measurements of the spine were performed every 20 min. To separate the behaviour of the thoracic and the lumbar spine, two benchmarks were placed at the vertebrae prominens and at the thoracic-lumbar junction. Shrinkage of the spine was investigated within three different cohorts: (I) work in a sitting posture for 6.5 h; (II) relaxed sitting for 2 h vs work for 2 h in a sitting position and (III) work in a standing position for 6.5 h. Results. Relaxed sitting leads to a gain in stature compared to work in a sitting position for 2 h. The major gain in stature occurred in the lumbar spine. Comparison of cohort (III) working in a standing position with cohort (I) working in a sitting position shows that the shrinkage of the spine is greatest when work is performed in a standing posture. The major differences were found in the shrinkage of the lumbar spine e.g. shrinkage of the lumbar spine in the standing cohort (III) was 4.16 mm compared to 1.73 mm in the sitting cohort (I). Conclusions. There is a gain in stature during relaxed sitting compared to work in a sitting posture. The load on the spine is greatest when work in a standing position is performed. The greater shrinkage of the lumbar spine during work in a standing position compared to a sitting posture is probably due to: (i) differences in lumbar lordosis and (ii) the effect of bending and torsion while handling the work materials.