Reliability analysis for radiographic measures of lumbar lordosis in adult scoliosis: a case–control study comparing 6 methods

Several methods are used to measure lumbar lordosis. In adult scoliosis patients, the measurement is difficult due to degenerative changes in the vertebral endplate as well as the coronal and sagittal deformity. We did the observational study with three examiners to determine the reliability of six methods for measuring the global lumbar lordosis in adult scoliosis patients. Ninety lateral lumbar radiographs were collected for the study. The radiographs were divided into normal (Cobb < 10°), low-grade (Cobb 10°–19°), high-grade (Cobb  ≥ 20°) group to determine the reliability of Cobb L1–S1, Cobb L1–L5, centroid, posterior tangent L1–S1, posterior tangent L1–L5 and TRALL method in adult scoliosis. The 90 lateral radiographs were measured twice by each of the three examiners using the six measurement methods. The data was analyzed to determine the inter- and intra-observer reliability. In general, for the six radiographic methods, the inter- and intra-class correlation coefficients (ICCs) were all ≥0.82. A comparison of the ICCs and 95% CI for the inter- and intra-observer reliability between the groups with varying degrees of scoliosis showed that, the reliability of the lordosis measurement decreased with increasing severity of scoliosis. In Cobb L1–S1, centroid and posterior tangent L1–S1 methods, the ICCs were relatively lower in the high-grade scoliosis group (≥0.60). And, the mean absolute difference (MAD) in these methods was high in the high-grade scoliosis group (≤7.17°). However, in the Cobb L1–L5 and posterior tangent L1–L5 method, the ICCs were ≥0.86 in all groups. And, in the TRALL method, the ICCs were ≥0.76 in all groups. In addition, in the Cobb L1–L5 and posterior tangent L1–L5 method, the MAD was ≤3.63°. And, in the TRALL method, the MAD was ≤3.84° in all groups. We concluded that the Cobb L1–L5 and the posterior tangent L1–L5 methods are reliable methods for measuring the global lumbar lordosis in adult scoliosis. And the TRALL method is more reliable method than other methods which include the L5–S1 joint in lordosis measurement.     

Radiographic analysis of lumbar lordosis: centroid, Cobb, TRALL, and Harrison posterior tangent methods

STUDY DESIGN: Delayed, repeated measures, with three examiners each twice digitizing thirty lateral lumbar radiographs. OBJECTIVES: To determine the reliability and clinical utility of the centroid, Cobb, tangential radiologic assessment of lumbar lordosis (TRALL), and Harrison posterior tangent line-drawing methods for analysis of lumbar lordosis. BACKGROUND DATA: Cobb's method is commonly used for curvature analysis on lateral lumbar radiographs, whereas the centroid, TRALL, and Harrison posterior tangent methods are not widely used. METHODS: Thirty lateral lumbar radiographs were digitized twice by each of three examiners. To evaluate reliability of determining global and segmental alignment, all four vertebral body corners of T12-S1 and the superior margin of the femur head were digitized. Angles created were segmental and global centroid, (two-line) Cobb angles, and intersections of posterior tangents. A global TRALL angle was determined. Means, standard deviations, mean absolute differences, interclass and intraclass correlation coefficients (ICC), and confidence intervals were calculated. RESULTS: The interobserver and intraobserver reliabilities of measuring all segmental and global angles were in the high range (ICCs > 0.83). The mean absolute differences of observers' measurements were small (0.6 degrees -2.0 degrees ). Distal segmental (L4-S1) and global angles of lumbar curvature were dependent on the method of measurement. CONCLUSIONS: All four radiographic methods had high reliability and low mean absolute differences of observers' measurements. Because it lacks a segmental analysis, the TRALL method is not recommended. The centroid, Cobb, and Harrison posterior tangent methods provide global and segmental angles. However, the centroid segmental method requires three segments and is less useful for a stability analysis.     

A comparative analysis of 4 curvature measurement methods in early-onset scoliosis

STUDY DESIGN.: Observational study with 3 examiners. OBJECTIVE.: The aim of this study was to enhance the reproducibility and reliability of coronal curvature measurements in early-onset scoliosis. SUMMARY OF BACKGROUND DATA.: Previous reports show high variability of the Cobb method, especially on the measurement of the immature spine. METHODS.: A total of 115 whole-spine posteroanterior radiographs were collected to compare the reliability of the Cobb, lateral tangent, pedicle, and centroid methods in early-onset scoliosis. Radiographs were measured twice by each of the 3 examiners using the 4 measurement methods. Statistical analysis was performed to determine the inter- and intraobserver reliability. RESULTS.: In this study, total inter- and intraobserver inter- and intraclass correlation coefficients (ICCs) in 115 radiographs were excellent in all methods (ICCs >0.961). However, mean absolute differences (MADs) in the lateral tangent method were less than 3.78°, which was higher than other methods (MADs <2.95°). In analysis of different severity groups (<15°, 15°-30°, and >30°), total inter- and intraobserver ICCs gradually increased with increasing the severity of the deformity, whereas MADs of each severity group were similar despite their increased measurement scale. Particularly, interobserver ICCs and MADs of lateral tangent method were more than 0.474 and less than 3.76° with poor reliability, which showed high variability in the less deformed spine group (<15°). However, intraobserver ICCs and MADs of pedicle method were more than 0.853 and less than 2.61°, interobserver ICCs and MADs were more than 0.729 and less than 2.86° with excellent reliability, which showed constantly high reliability regardless of coronal curvature severity. CONCLUSION.: In this study, the pedicle method showed constantly higher ICCs and lower MAD values in the early-onset scoliosis regardless of severity. However, the other 3 methods showed lower ICCs and higher MAD values, which showed lowest reliability in the lateral tangent method. For improved treatment of early-onset scoliosis, we recommend the pedicle method for measuring curvature regardless of severity.     

Body posture and backpack loading: an upright magnetic resonance imaging study of the adult lumbar spine

Purpose

Axial loading of the spine while supine, simulating upright posture, decreases intervertebral disc (IVD) height and lumbar length and increases lumbar lordosis. The purpose of this study is to measure the adult lumbar spine’s response to upright posture and a backpack load using upright magnetic resonance imaging (MRI). We hypothesize that higher spinal loads, while upright and with a backpack, will compress lumbar length and IVD height as well as decrease lumbar lordosis.

Methods

Six volunteers (45 ± 6 years) underwent 0.6 T MRI scans of the lumbar spine while supine, upright, and upright with a 10 % body weight (BW) backpack. Main outcomes were IVD height, lumbar spinal length (distance between anterior–superior corners of L1 and S1), and lumbar lordosis (Cobb angle between the superior endplates of L1 and S1).

Results

The 10 % BW load significantly compressed the L4–L5 and L5–S1 IVDs relative to supine (p < 0.05). The upright and upright plus 10 % BW backpack conditions significantly compressed the anterior height of L5–S1 relative to supine (p < 0.05), but did not significantly change the lumbar length or lumbar lordosis.

Conclusions

The L4–L5 and L5–S1 IVDs compress, particularly anteriorly, when transitioning from supine to upright position with a 10 % BW backpack. This study is the first radiographic analysis to describe the adult lumbar spine wearing common backpack loads. The novel upright MRI protocol described allows for functional, in vivo, loaded measurements of the spine that enables the study of spinal biomechanics and therapeutic interventions.     

Effect of lordosis angle change after lumbar/lumbosacral fusion on sacrum angular displacement: a finite element study

Purpose

To assess and characterize the sacrum angular displacements in response to lumbar lordosis after lumbar/lumbosacral fusion.

Methods

A finite element model of the lower lumbar spine-pelvis was established and used to simulate the posterior fusion at L3–L5 and L4–S1. The lordosis angle in the fusion segments was set to five different conditions with respect to the intact model: 10° less than intact, 5° less than intact, same as intact, 5° more than intact, and 10° more than intact. Variations of the sacrum angular displacements with lordosis changes were analyzed under loading setting of axial compression, flexion, extension, lateral bending, and axial rotation.

Results

Compared with the intact lordosis, both increased and decreased lumbar lordosis angles caused the sacrum angular displacements to be increased. The lordosis angle increased by 10° induced the most substantial increase in sacrum angular displacements. In addition, the sacrum angular displacements of the L4–S1 fusion model at different lordosis angles were higher than those of the L3–L5 fusion model.

Conclusion

The sacrum angular displacements occur as a result of the fusion surgery (L4–S1) and the changes in lumbar lordosis.     

Vertebral centroid measurement of lumbar lordosis compared with the Cobb technique.

STUDY DESIGN: An observational study in which vertebral centroid measurement of lumbar lordosis, developed in this study, was used to examine lumbar curvature. The intra- and interobserver reliability of the vertebral centroid measurement of lumbar lordosis and the Cobb technique were compared. OBJECTIVES: To evaluate the reliability of a new method of measuring lumbar lordosis and to examine the changes in the lordotic curve from 0 degree to 90 degrees flexion of the trunk. SUMMARY OF BACKGROUND DATA: Several different methods are used to measure lumbar lordosis. The Cobb technique, based on measurement of vertebral endplates, is the method most frequently adopted for clinical diagnosis. However, because of the variations in the vertebral endplate architecture, the vertebral surface angle is difficult to identify. This reduces the reliability of the Cobb technique. METHODS: Lateral radiographs of 16 study participants were taken from the upright position to a trunk flexion of 90 degrees in 30 degrees increments. The lumbar lordotic curve was measured by three observers individually using two applications of the traditional Cobb technique and the vertebral centroid measurement of lumbar lordosis. RESULTS: Correlation coefficients of lumbar lordosis between the two methods ranged from 0.589 to 0.772 with participants standing upright (all P < 0.05). Interobserver reliability coefficients were 0.903 for vertebral centroid measurement of lumbar lordosis, 0.826 for Cobb (L1-L5), and 0.784 for Cobb (L1-S1), although the three measurements all revealed an excellent intraobserver reproducibility (r greater than 0.9). The vertebral centroid measurement of lumbar lordosis showed the smallest mean absolute differences between any two observers' measurements (< 1.7 degrees). CONCLUSIONS: The findings from this study indicate that the vertebral centroid measurement of lumbar lordosis is more reliable than the Cobb method for assessing lumbar lordosis. The vertebral centroid measurement of lumbar lordosis also can be used to evaluate the actual lumbar curvature in outline at various angles of trunk flexion.     

Radiographic evaluation of ventral instability in lumbar spondylolisthesis: do we need extension radiographs in routine exams?

Purpose

To determine the usefulness of acquiring extension radiographs for the evaluation of the degree of spondylolisthesis.

Methods

Routine radiographs of the lumbar spine were retrospectively evaluated in 87 patients (mean-age 63, range 32–86) by two independent radiologists. All patients received radiographs in standing neutral, flexion and extension position. Vertebral body depth, sagittal translational displacement and lordosis angle were measured and slip percentage (SP) was calculated on standing neutral, flexion and extension radiographs. Statistical analysis was performed with a two-sided t test. Inter- and intraobserver reliability was assessed using the kappa-coefficient.

Results

There was no statistically significant SP-difference between neutral standing and extension images. Ventral instability was diagnosed in 25–34 % (cut-off >8 % SP-difference) for neutral versus flexion comparison. The detection rate of flexion–extension radiographs representing the extremes of motion was lower with 15–22 %. Inter- and intraobserver reliability was good to excellent.

Conclusion

Slip percentage in routine standing extension radiography ultimately does not differ from that obtained in a static neutral standing view. Extension radiography may therefore be omitted in a routine work-up of ventral instability in lumbar spondylolisthesis.     

Computerized assessment of sagittal curvatures of the spine: comparison between Cobb and tangent circles techniques

OBJECTIVE: The tangent circles technique has been proposed as an alternative to the Cobb angle technique to assess sagittal curves of the spine. However, it has never been compared directly to the Cobb technique. This study compares the reproducibility and clinical relevance of the maximum Cobb angle and tangent circles techniques. METHOD: Standing sagittal radiographs of the spine of 10 adolescents with idiopathic scoliosis, 10 adolescents with spondylolisthesis, and 10 healthy adolescents were used. Thoracic kyphosis (TK) and lumbar lordosis (LL) were measured by 3 observers using the maximum Cobb angle and the tangent circles techniques. Intra- and interobserver intraclass correlation coefficients (ICCs) were calculated. RESULT: Intra- and interobserver ICCs for TK were 0.88 and 0.85, respectively, for the maximum Cobb angle technique, and 0.94 and 0.83, respectively, for the tangent circles technique. Intra- and interobserver ICCs for LL were 0.97 and 0.77, respectively, for the maximum Cobb angle technique, and 0.88 and 0.94, respectively, for the tangent circles technique. The 2 techniques were highly correlated for the measurement of the TK (r=0.93) and LL (r=0.88). CONCLUSION: Both techniques provide excellent intra- and interobserver reproducibility. Tangent circles technique may be a good alternative to the Cobb angle technique because it allows the evaluation of the global geometry of sagittal spinal curves, especially when there is limited visibility of bony structures on radiographs.     

Indication for preoperative MRI of neural axis abnormalities in patients with presumed thoracolumbar/lumbar idiopathic scoliosis

Purpose

The purpose of this study was to investigate the incidence of neural axis abnormalities in patients with presumed “idiopathic” thoracolumbar or lumbar scoliosis by magnetic resonance imaging (MRI) and try to determine which clinical and radiographic characteristics correlate with neural axis abnormalities on MRI in these patients.

Methods

The database of a single spinal deformity center was retrospectively reviewed to identify all patients with a primary diagnosis of idiopathic scoliosis (IS) between January 2003 and August 2011. A total of 446 patients with main thoracolumbar or lumbar curves were identified. Radiographic parameters including main curve Cobb angles, location of curve apex, span of main curve, thoracic kyphosis (T5–T12), thoracolumbar junction kyphosis (T10–L2), lumbar lordosis (L1–S1), and sagittal and coronal balance were measured.

Results

Neural axis abnormalities were detected in 35 (7.8 %) patients. For patients with neural axis abnormalities, a higher proportion of male gender and long thoracolumbar curves were presented. In these patients, the mean age was smaller and the mean Cobb angle of main curve was larger. Greater thoracic kyphosis (≥30°) was more frequently found in those with neural axis abnormalities. The incidences of thoracolumbar junction hyperkyphosis were similar between two groups (P > 0.05). There was no difference between two groups as to lumbar lordosis and coronal and sagittal balance.

Conclusion

We recommend the routine use of MRI in the patients with one or more of the following characteristics: right curves, long curve span, apex at thoracolumbar spine and hyperthoracic kyphosis.     

Correlation between clinical outcome and spinopelvic parameters in ankylosing spondylitis

Purpose

Little data are available on the relationship between sagittal spinopelvic parameters and health related quality of life (HRQOL) in ankylosing spondylitis (AS) patients. The aim of this study was to identify the relationships between spinopelvic parameters and HRQOL in AS.

Methods

The study and control groups comprised 107 AS patients and 40 controls. All underwent anteroposterior and lateral radiographs of the whole spine including hip joints and completed clinical questionnaires. The radiographic parameters examined were sacral slope, pelvic tilt, pelvic incidence, thoracic kyphosis, lumbar lordosis, and sagittal vertical axis. A Visual Analogue Scale (VAS: 0–10) score for back pain, the Oswestry disability index (ODI) questionnaire, Scoliosis Research Society (SRS-22) questionnaire and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were administered to evaluate QOL. Statistical analysis was performed to identify significant differences between the study and control groups. In addition, correlations between radiological parameters and clinical questionnaires were sought.

Results

The AS patients and controls were found to be significantly different in terms of sagittal vertical axis, sacral slope, pelvic tilt, pelvic incidence, and lumbar lordosis. However, no significant intergroup difference was observed for thoracic kyphosis (P > 0.05). Of the 107 AS patients, there were 18 women and 89 men. Correlation analysis revealed significant relationships between radiographic parameters and clinical outcomes. Multiple regression analysis was performed to identify predictors of clinical outcome, and the results obtained revealed that sagittal vertical axis and sacral slope significantly predicted VAS, ODI and BASDAI scores and that sagittal vertical axis and lumbar lordosis predicted SRS-22 scores.

Conclusions

AS patients and normal controls were found to be significantly different in terms of sagittal spinopelvic parameters. Correlation analysis revealed significant relationships between radiographic parameters and clinical outcomes. In particular, sagittal vertical axis, sacral slope and lumbar lordosis were found to be significant parameters in prediction of clinical outcomes in AS patient.     

Centroid method: an alternative method of determining coronal curvature in scoliosis. A comparative study versus Cobb method in the degenerative spine

Background contextAlthough the Cobb method is considered the gold standard, the centroid method may offer a reasonable alternative in adult scoliosis because it has better inter- and intraobserver reliabilities in adolescent scoliosis.PurposeTo compare the reliabilities of the Cobb and the centroid methods for measuring coronal curvature in degenerative scoliosis in older patients.Study designObservational study involving three examiners.Patient sampleSixty whole spine posteroanterior (PA) radiographs were collected.Outcome measuresData were analyzed to determine inter- and intraobserver reliabilities.MethodsSixty whole spine PA radiographs of patients older than 60 years were collected to compare the reliabilities of the centroid and the Cobb methods for measuring coronal curvature in degenerative scoliosis. Three examiners using both methods independently measured radiographs twice. Data were analyzed to determine inter- and intraobserver reliabilities.ResultsIntraobserver comparisons of all the 60 radiographs revealed that inter- and intraclass correlation coefficients (ICCs) of the Cobb and the centroid methods were both excellent (greater than 0.979 vs. greater than 0.918), and mean absolute differences (MADs) were similar (less than 1.58 vs. less than 2.02). In interobserver comparisons, ICCs of the Cobb method were higher than that of the centroid method (greater than 0.922 vs. greater than 0.799), and the MADs of the Cobb method were lower than that of the centroid method (less than 2.91 vs. less than 4.84). Comparisons of radiographs subdivided by severity showed that the ICCs of the Cobb and the centroid methods were both excellent (greater than 0.819 vs. greater than 0.801), and their MADs were similar (less than 2.29 vs. less than 2.53) for intraobserver comparisons. Interobserver comparisons showed that ICCs and MADs were dependent on the severity of coronal curvature, and the ICCs of the Cobb method (greater than 0.698) were greater than that of the centroid method (greater than 0.507). Furthermore, MAD values for the Cobb method were lower than that for the centroid method (less than 3.59 vs. less than 6.07). Moreover, these results are contradictory to the previous study, which showed the higher reliability of the centroid method in measures of adolescent scoliosis.ConclusionsIn the present study, the reliability of the centroid method was found to be more susceptible to the severity of disease in older patients, despite its demonstrated greater reliability in adolescent scoliosis. Our findings show that the selective use of these two methods in old and young patients can increase the reliabilities of measurements made.     

Vertebral Bodies or Discs: Which Contributes More to Human-like Lumbar Lordosis?

Background

The attainment of upright posture, with its requisite lumbar lordosis, was a major turning point in human evolution. Nonhuman primates have small lordosis angles, whereas the human spine exhibits distinct lumbar lordosis (30°–80°). We assume the lumbar spine of the pronograde ancestors of modern humans was like those of extant nonhuman primates, but which spinal components changed in the transition from small lordosis angles to large ones is not fully understood.

Questions/Purposes

We wished to determine the relative contribution of vertebral bodies and intervertebral discs to lordosis angles in extant primates and humans.

Methods

We measured the lordosis, intervertebral disc, and vertebral body angles of 100 modern humans (orthograde primates) and 56 macaques (pronograde primates) on lateral radiographs of the lumbar spine (humans–standing, macaques–side-lying).

Results

The humans exhibited larger lordosis angles (51°) and vertebral body wedging (5°) than did the macaques (15° and ?25°, respectively). The differences in wedging of the intervertebral discs, however, were much less pronounced (46° versus 40°).

Conclusions

These observations suggest the transition from pronograde to orthograde posture (ie, the lordosis angle) resulted mainly from an increase in vertebral body wedging and only in small part from the increase in wedging of the intervertebral discs.     

Segmental lumbar lordosis: manual versus computer-assisted measurement using seven different techniques

OBJECTIVES: Obliteration of end-plate landmarks by interbody fusion has made the traditional measurement of segmental lumbar lordosis nearly impossible. Because the L4-L5 and L5-S1 levels are most likely to be subjected to fusion procedures or arthroplasty and contribute to more than half of normal lumbar lordosis, it is crucial to identify a reproducible and accurate means of measuring segmental lordosis at these levels. METHODS: Twelve spinal surgeons measured lordosis at L4-L5 and L5-S1 on 10 separate radiographs using three techniques for L4-L5 and four techniques for L5-S1. With use of identical radiographs, measurements first were made using a manual method and then were repeated with a computer-assisted method. Measurements were analyzed for both intraobserver and interobserver error. RESULTS: The individual data demonstrated an intraobserver variance of 9.56 and a standard deviation of 3.092 for computerized measurements compared with 7.742 and 2.782 for manual measurements. The interobserver variance was 4.107 with a standard deviation of 2.027 for the computerized group compared with 4.221 and 2.055 for manual measurements. When analyzed as a group to evaluate interobserver error, the pooled data yielded variance of 19.235 for the computerized group and 19.117 for the manual measurements. CONCLUSIONS: Variance calculations identified the Cobb technique and the posterior vertebral body technique as the least variable measurement techniques for the L4-L5 and L5-S1 levels, respectively; however, there was no statistical significance. In direct comparison, the manual and computer-assisted techniques were found to be statistically equivalent with similar degrees of variance. We believe that the anterior vertebral technique, which did not demonstrate a significant difference from other techniques, will prove to be the most reliable method of assessing segmental lumbar lordosis in patients before surgery, after interbody fusion, and after motion-sparing disc arthroplasty.     

Measurements of lumbopelvic lordosis using the pelvic radius technique as it correlates with sagittal spinal balance and sacral translation.

BACKGROUND CONTEXT: Maintenance of normal lumbar lordosis is important in the treatment of spinal disorders. Many attempts have been made to quantify normal sagittal spinal alignment and lordosis using a C7 plumb line and segmental angulations of the spinal vertebrae. Little attention has been given to pelvic compensation as it correlates to lumbar lordosis and overall sagittal spinal alignment. Better methods of measuring lordosis, which correlate with sagittal spinal balance and pelvic compensation, are needed in treating patients with spinal disorders. PURPOSE: To determine the correlation between lumbopelvic lordosis, pelvic rotation and sagittal spinal balance and standardize a method for measuring lumbopelvic lordosis, sacral translation, and sagittal spinal alignment. STUDY DESIGN: Sagittal alignments using the C7 plumb line, Cobb angles, sacral plumb line and the pelvic radius (PR) technique were used to measure standing 36-inch lateral radiographs of patients with various spinal disorders. PATIENT SAMPLE: A review of the records identified 62 patients with various spinal pathologies presenting to the (RGW) spine clinic that had standing lateral spine radiographs. Only radiographs that allowed positive identification of the C7 vertebral body, the entire thoracolumbar spine, the sacrum and both femoral heads were studied. These criteria allowed inclusion of 28 subjects in this study. The final population had 12 women and 16 men with an average age of 52 years (SD, 16.6 years; range, 20 to 84 years). OUTCOME MEASURES: No outcomes measures were used in this study. METHODS: Measurements for sagittal spinal balance and lumbopelvic lordosis were made on 36-inch standing lateral radiographs of adult patients. Measurements included the C7 plumb line, segmental angulations of spinal vertebrae (Cobb angles), sacral translation and the PR technique for lumbopelvic lordosis. Data were analyzed for significant correlation between lumbopelvic lordosis, sagittal spinal balance, sacral translation and total segmental lumbar lordosis using the Cobb method. RESULTS: Our population averaged 50 degrees of total segmental lumbar lordosis from L1 to S1 (SD, 14.3; maximum, 89.5; minimum, 17.9). Nearly 75% of total segmental lumbar lordosis measured from L1 to S1 can be accounted for through the L4 to S1 superior end plates and 47% through L5 to S1 superior end plates in our population. Total segmental lumbar lordosis correlated with total thoracic kyphosis (r=0.45, p=.008). Total segmental lumbar lordosis measured by the Cobb method significantly correlated with sagittal spinal balance (r=-0.35, p=.022) and sacral translation (r=0.41, p=.016). Measurements for lumbopelvic lordosis significantly correlated with sagittal spinal balance (r=-0.33, p=.042), sacral translation (r=-0.70, p=.00002) and total segmental lumbar lordosis (r=0.82, p<.000001). Measurements for sacral translation and sagittal spinal balance also correlated significantly (r=0.35, p=.034). CONCLUSIONS: Sacral translation, the C7 plumb line and lumbopelvic lordosis are useful measures for sagittal spinal balance. Lumbopelvic lordosis and sacral translation can be correlated to the sagittal spinal balance. Understanding these measurements and the range of lumbopelvic compensation can be extremely helpful in treating patients with spinal pathology and in avoidance of flatback deformity. Application of these measures would be especially helpful in the treatment of patients with spinal fusion, degenerative spondylosis, disc disease, fractures, and in the prevention of sagittal malalignment.     

Reliability of centroid, Cobb, and Harrison posterior tangent methods: which to choose for analysis of thoracic kyphosis

STUDY DESIGN: Thirty lateral thoracic radiographs were digitized twice by each of the three examiners. OBJECTIVES: To determine the reliability of the centroid, Cobb, and Harrison posterior tangent methods when applied to analysis of thoracic kyphosis. BACKGROUND DATA: Reliability studies on measurements of thoracic kyphosis are rare. METHODS: Blind, repeated-measures design was used. Thirty lateral thoracic radiographs were digitized twice by each of three examiners. To evaluate reliability of determining global and segmental alignment, vertebral bodies of T1-T12 were digitized. Centroids at the intersection of vertebral body diagonals and tangents to posterior vertebral bodies were constructed by computer. Also the computer constructed global and segmental centroid angles, Cobb angles (two-line method), and posterior tangent intersection angles from T1 to T12. Interclass and Intraclass correlation coefficients for these data were calculated and interpreted. RESULTS: From the points selected by examiners, all three methods have similar high ICC values for the global angles (> 0.94). For the segmental angles, the interobserver and intraobserver reliability is also very similar for all three methods, with ICCs in the good and excellent ranges (0.59-0.75 and 0.75-1.0, respectively). The mean absolute differences of observers' measurements are low, similar, and in the range of 0.9 degrees to 2.5 degrees. CONCLUSIONS: The centroid, two-line Cobb, and Harrison posterior tangent methods, when applied to measurements of kyphosis, are all reliable and have similar small error ranges. The centroid method does not give an accurate segmental analysis, uses more points and more time in clinical applications, and results in smaller angles of total kyphosis than the Cobb or posterior tangent methods. The posterior tangents are the slopes along the curve.     

Dynamic motion characteristics of the lower lumbar spine: implication to lumbar pathology and surgical treatment

Purpose

Many studies have reported on the segmental motion range of the lumbar spine using various in vitro and in vivo experimental designs. However, the in vivo weightbearing dynamic motion characteristics of the L4–5 and L5–S1 motion segments are still not clearly described in literature. This study investigated in vivo motion of the lumbar spine during a weight-lifting activity.

Methods

Ten asymptomatic subjects (M/F: 5/5; age: 40–60 years) were recruited. The lumbar segment of each subject was MRI-scanned to construct 3D models of the L2–S1 vertebrae. The lumbar spine was then imaged using a dual fluoroscopic imaging system as the subject performed a weight-lifting activity from a lumbar flexion position (45°) to maximal extension position. The 3D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral positions along the motion path. The relative translations and rotations of each motion segment were analyzed.

Results

All vertebral motion segments, L2–3, L3–4, L4–5 and L5–S1, rotated similarly during the lifting motion. L4–5 showed the largest anterior-posterior (AP) translation with 2.9 ± 1.5 mm and was significantly larger than L5–S1 (p < 0.05). L5–S1 showed the largest proximal–distal (PD) translation with 2.8 ± 0.9 mm and was significantly larger than all other motion segments (p < 0.05).

Conclusions

The lower lumbar motion segments L4–5 and L5–S1 showed larger AP and PD translations, respectively, than the higher vertebral motion segments during the weight-lifting motion. The data provide insight into the physiological motion characteristics of the lumbar spine and potential mechanical mechanisms of lumbar disease development.     

Sagittal balance correction of idiopathic scoliosis using the in situ contouring technique

Purpose

Idiopathic scoliosis can lead to sagittal imbalance. The relationship between thoracic hyper- and hypo-kyphotic segments, vertebral rotation and coronal curve was determined. The effect of segmental sagittal correction by in situ contouring was analyzed.

Methods

Pre- and post-operative radiographs of 54 scoliosis patients (Lenke 1 and 3) were analyzed at 8 years follow-up. Cobb angles and vertebral rotation were determined. Sagittal measurements were: kyphosis T4–T12, T4–T8 and T9–T12, lordosis L1–S1, T12–L2 and L3–S1, pelvic incidence, pelvic tilt, sacral slope, T1 and T9 tilt.

Results

Thoracic and lumbar curves were significantly reduced (p = 0.0001). Spino-pelvic parameters, T1 and T9 tilt were not modified. The global T4–T12 kyphosis decreased by 2.1° on average (p = 0.066). Segmental analysis evidenced a significant decrease of T4–T8 hyperkyphosis by 6.6° (p = 0.0001) and an increase of segmental hypokyphosis T9–T12 by 5.0° (p = 0.0001). Maximal vertebral rotation was located at T7, T8 or T9 and correlated (r = 0.422) with the cranial level of the hypokyphotic zone (p = 0.003). This vertebra or its adjacent levels corresponded to the coronal apex in 79.6 % of thoracic curves.

Conclusions

Lenke 1 and 3 curves can show normal global kyphosis, divided in cranial hyperkyphosis and caudal hypokyphosis. The cranial end of hypokyphosis corresponds to maximal rotation. These vertebrae have most migrated anteriorly and laterally. The sagittal apex between segmental hypo- and hyper-kyphosis corresponds to the coronal thoracic apex. A segmental sagittal imbalance correction is achieved by in situ contouring. The concept of segmental imbalance is useful when determining the levels on which surgical detorsion may be focused.     

Disk degeneration of the upper lumbar disks is associated with hip pain

Purpose

A possible cause of hip pain is the presence of radiating pain from the higher lumbar spine. Identification of factors associated with hip pain arising from the lumbar spine would aid the physician. The first step in identifying possible factors is to look at the association between hip pain and osteoarthritis of the lumbar spine.

Methods

In an open population based study of people 55 years and older (Rotterdam study), 2,819 lumbar radiographs were scored for the presence and severity of individual radiographic features of disk degeneration. Hip osteoarthritis was scored on anteroposterior pelvic radiographs, and questionnaires including self-reported hip pain were taken. Logistic regression adjusted for possible confounders was used to determine the association between self-reported hip pain and the individual radiographic features of lumbar disk degeneration.

Results

The presence of dis space narrowing grade ≥1 at level L1/L2 was significantly associated with hip pain in the last month (men OR = 2.0; 95 % CI 1.1–3.8 and women OR = 1.7; 95 % CI 1.1–2.5). The presence of disk space narrowing grade ≥1 at level L2/L3 was only significantly associated with hip pain in women. The strength of the associations increased for self-reported chronic hip pain, especially in men (L1/L2 OR = 2.5; 95 % CI 1.3–5.0). The presence of disk space narrowing at the lower levels (L3/L4/L5/S1) was not significantly associated with hip pain.

Conclusion

Our data provide evidence for an association between hip pain and disk space narrowing at disk level L1/L2 and L2/L3. In case of uncertainty of the cause of hip pain, evaluation of lumbar radiographs may help to identify those hip pain patients who might have pain arising from the lumbar spine.     

Posterior lumbar interbody fusion and segmental lumbar lordosis

Introduction

The sagittal plane of body produces a convex curve anteriorly referred to as the lordotic curve. Malalignment of lordotic curve leads to low back disorders and lumbar spinal surgery has been known to cause this. This study was a retrospective analysis of the effects of posterior lumbar interbody fusion using cages on segmental lumbar lordosis.

Materials and methods

We conducted a retrospective study involving 27 patients of which 16 were females and 11 were males. All patients underwent single level posterior lumbar interbody fusion with insertion of non-wedged intervertebral cage and pedicle screw fixation. Intraoperatively, all patients had a change from knee chest position to prone to augment their lumbar lordosis. The minimum follow up was 2 years and fusion was achieved in 21 patients.

Results

Segmental lordotic angles increased from 15.2° to 20.6° at L4/5 level and from 17.8° to 24.5° at L5/S1 level, preoperative to postoperative, respectively (P < 0.01 at both levels).

Conclusion

Thus apparently, posterior lumbar interbody fusion with insertion of non-wedged intervertebral cage and pedicle screw fixation results in creation and maintenance of lumbar lordosis.