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Cobb angle

About: Cobb angle is a research topic. Over the lifetime, 3549 publications have been published within this topic receiving 65006 citations.


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Journal ArticleDOI
TL;DR: To quantitate the intrinsic error in measurement, fifty anteroposterior radiographs of patients who had scoliosis were each measured on six separate occasions by four orthopaedic surgeons using the Cobb method.
Abstract: To quantitate the intrinsic error in measurement, fifty anteroposterior radiographs of patients who had scoliosis were each measured on six separate occasions by four orthopaedic surgeons using the Cobb method For the first two measurements (Set I), each observer selected the end-vertebrae of the curve; for the next two measurements (Set II), the end-vertebrae were pre-selected and constant The last two measurements (Set III) were obtained in the same manner as Set II, except that each examiner used the same protractor rather than the one that he carried with him The pooled results of all four observers suggested that the 95 per cent confidence limit for intraobserver variability was 49 degrees for Set I, 38 degrees for Set II, and 28 degrees for Set III The interobserver variability was 72 degrees for Set I and 63 degrees for Sets II and III The mean angles differed significantly between observers, but the difference was smaller when the observers used the same protractor

540 citations

Journal ArticleDOI
15 Jul 2005-Spine
TL;DR: Investigation in adults undergoing long posterior spinal fusion found incidence of proximal junctional kyphosis was high, but SRS-24 scores were not significantly affected in patients with PJK, and the sagittal C7 plumb was not significantly more positive in PJK patients.
Abstract: Study design To analyze patient outcomes and risk factors associated with proximal junctional kyphosis (PJK) in adults undergoing long posterior spinal fusion. Objectives To determine the incidence of PJK and its effect on patient outcomes and to identify any risk factors associated with developing PJK. Summary of background data The incidence of PJK and its affect on outcomes in adult deformity patients is unknown. No study has concentrated on outcomes of patients with PJK. Risk factors for developing PJK are unknown. Methods Radiographic data on 81 consecutive adult deformity patients with minimum 2-year follow-up (average 5.3 years, range 2-16 years) treated with long instrumented segmental posterior spinal fusion was collected. Preoperative diagnosis was adult scoliosis, sagittal imbalance or both. Radiographic measurements analyzed included the sagittal Cobb angle at the proximal junction on preoperative, early postoperative, and final follow-up standing long cassette radiographs. Additional measurements used for analysis included the C7-Sacrum sagittal plumb and the T5-T12 sagittal Cobb. Postoperative SRS-24 scores were available on 73 patients. Results Incidence of PJK as defined was 26%. Patients with PJK did not have lower outcomes scores. PJK did not produce a more positive sagittal C7 plumb. PJK was more common at T3 in the upper thoracic spine. Conclusions Incidence of proximal junctional kyphosis was high, but SRS-24 scores were not significantly affected in patients with PJK. The sagittal C7 plumb was not significantly more positive in PJK patients. No patient, radiographic, or instrumentation variables were identified as risk factors for developing PJK.

526 citations

Journal ArticleDOI
TL;DR: Reliability was not significantly improved when the end-vertebrae of the curve had been pre-selected, and if one were to be 95 per cent confident that a measured difference represented a true change, the difference would have to be 10 degrees for scoliosis radiographs and 11 degrees for kyphosis radiographs.
Abstract: Interobserver variations for measurements of the Cobb angle on radiographs of patients who had kyphosis were comparable with those on the radiographs of patients who had scoliosis. Four staff orthopaedists and one physical therapist measured eight radiographs that showed scoliosis and twenty that showed kyphosis. The measurements were made on two occasions and in random order. For scoliosis, the average difference between readings was 3.8 degrees, and 95 per cent of the differences were 8 degrees or less (range, 0 to 10 degrees). These findings were in keeping with those of other published reports. For kyphosis, the average difference between readings was 3.3 degrees, and 95 per cent of the differences were 7 degrees or less (range, 0 to 30 degrees). One investigator rated the kyphosis radiographs with respect to clarity. There was a trend to less variation with clearer radiographs, but this was not significant. The end-vertebrae were pre-selected for some radiographs and were freely chosen by the interpreter for others. Reliability was not significantly improved when the end-vertebrae of the curve had been pre-selected. Using the statistical method called tolerance limits, we determined that if one were to be 95 per cent confident that a measured difference represented a true change, the difference would have to be 10 degrees for scoliosis radiographs and 11 degrees for kyphosis radiographs. The probability that a measured difference is due to measurement error alone (that is, a false-positive reading) was calculated.

474 citations

Journal ArticleDOI
01 Oct 1997-Spine
TL;DR: The correlation between the pedicle cortical penetration rate and the preoperative Cobb angle, vertebral rotation or level, or site of screw insertion was statistically insignificant and Curve correction in the cases of mainly hook instrumentation was slightly greater than with hooks, but not to a statistically significant extent.
Abstract: Study design A prospective study of the accuracy of thoracic pedicle screw placement in patients with idiopathic scoliosis. Objectives To evaluate the accuracy of thoracic pedicle screw placement in the surgical management of idiopathic scoliosis and to establish its risks and benefits. Summary of background data Lumbar pedicle screw instrumentation has proven to be reliable and effective in the surgical management of scoliosis. No reports exist on the accuracy and benefits of pedicle screw instrumentation of the thoracic spine in scoliosis surgery. Methods One hundred and twenty thoracic pedicle screws in 32 consecutively treated patients with idiopathic scoliosis were investigated immediately after surgery by computed tomography scans that were analyzed by three examiners. Results Thirty (25%) of the screws penetrated the pedicle cortex or the vertebral body anterior cortex. Ten screws (8.3%) penetrated the medial cortex of the pedicle by an average of 1.5 mm and a maximum of 3.0 mm. Seventeen screws (14.2%) penetrated laterally by an average of 2.1 mm. There were two cases of caudad penetration. Three screws penetrated the anterior vertebral cortex, of which two also penetrated the pedicle cortex. Also, one of these three screws was replaced because of its direct proximity to the thoracic aorta. There were no neurologic complications. The correlation between the pedicle cortical penetration rate and the preoperative Cobb angle, vertebral rotation or level, or site of screw insertion was statistically insignificant (P > 0.05). Curve correction in the cases of mainly hook instrumentation averaged 52.5% versus 59.2% in the cases of mainly screw instrumentation. This difference was statistically insignificant (P > 0.05). Conclusions Pedicle or vertebral body cortical penetration occurred with 25% of the screws but with no neurologic compromise. Curve correction was slightly greater than with hooks, but not to a statistically significant extent.

473 citations

Journal ArticleDOI
15 Aug 2000-Spine
TL;DR: Although both methods are reliable with the majority of correlation coefficients in the high range (ICC > 0.7), from the literature, the posterior tangent method has a smaller standard error of measurement than four-line Cobb methods.
Abstract: STUDY DESIGN Thirty lateral cervical radiographs were digitized twice by three examiners to compare reliability of the Cobb and posterior tangent methods. OBJECTIVES To determine the reliability of the Cobb and Harrison posterior tangent methods and to compare and contrast these two methods. SUMMARY OF BACKGROUND DATA Cobb's method is commonly used on both anteroposterior and lateral radiographs, whereas the posterior tangent method is not widely used. METHODS A blind, repeated-measures design was used. Thirty lateral cervical radiographs were digitized twice by each of three examiners. To evaluate reliability of determining global and segmental alignment, vertebral bodies of C1-T1 were digitized. Angles created were two global two-line Cobb angles (C1-C7 and C2-C7), segmental Cobb angles from C2 to C7, and posterior tangents drawn at each posterior vertebral body margin. Cobb's method and the posterior tangent method are compared and contrasted with these data. RESULTS Of 34 intraclass and interclass correlation coefficients, 28 were in the high range (>0.7), and 6 were in the good range (0.6-0.7). The Cobb method at C1-C7 overestimated the cervical curvature (-54 degrees ) and, at C2-C7 it underestimated the cervical curve (-17 degrees ), whereas the posterior tangents were the slopes along the curve (-26 degrees from C2 to C7). The inferior vertebral endplates and posterior body margins did not meet at 90 degrees (C2: 105 degrees +/- 5.2 degrees, C3: 99.7 degrees +/- 5.2 degrees, C4: 99.9 degrees +/- 5.8 degrees, C5: 96.1 degrees +/- 4.5 degrees, C6: 97.0 degrees +/- 3.8 degrees, C7: 95.4 degrees +/- 4.1 degrees ), which caused the segmental Cobb angles to underestimate lordosis at C2-C3, C4-C5, and C6-C7. CONCLUSIONS Although both methods are reliable with the majority of correlation coefficients in the high range (ICC > 0.7), from the literature, the posterior tangent method has a smaller standard error of measurement than four-line Cobb methods. Global Cobb angles compare only the ends of the cervical curve and cannot delineate what happens to the curve internally. Posterior tangents are the slopes along the curve and can provide an analysis of any buckled areas of the cervical curve. The posterior tangent method is part of an engineering analysis (first derivative) and more accurately depicts cervical curvature than the Cobb method.

407 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023202
2022477
2021294
2020306
2019262
2018213