Participants in an ongoing epidemiological study of the prevalence of vertebral osteoporotic fractures formed the pool from which suitable subjects were selected. These participants are examined at the University Hospital of Heraklion, Crete. Part of their comprehensive evaluation is to have anteroposterior and lateral spine X-rays taken in the standing position, using the same procedure and equipment. The main reason for using the same subjects from the aforementioned study was to avoid exposing any further people to radiation. In addition, as those subjects were exclusively women of postmenopausal age, the average age of the subjects was in the period where the frequency of osteoarthritis becomes maximum [1 (link),2 (link)]. Equally important, factors that are known to influence the sagittal curvature of the spine such as age and sex [25 (link)-28 (link)] would not confound the analysis.
All patients who had secondary osteoarthritis as well as patients whose lumbar curvature might have been altered from disease or iatrogenic intervention had to be excluded. Exclusion criteria were: 1) Congenital spinal diseases 2) Scoliosis 3) Spondylolisthesis - Spondylolysis 4) Vertebral fracture 5) History of spinal surgery 6) Inflammatory arthropathy 7) History of endocrine or metabolic disease.
All lumbar radiographs were examined on two separate occasions, independently, by two of the authors for the presence of features of osteoarthritis. The criteria used where those of Kellgren and Lawrence, and when evidence of two or more criteria were present, the diagnosis of lumbar osteoarthritis was made [29 (link)]. Interobserver agreement in detecting or excluding disease presence was 98%. If agreement was not reached, the patient was excluded from the study.
After the application of exclusion criteria, from 524 patients that were examined, only 145 were initially considered as potentially suitable. A further 33 patients were excluded after evaluation of spinal radiographs. The final sample consists of 112 postmenopausal women, aged 42-76 years old (mean 57.3 years).
After the designation of the final sample, lumbar lateral radiographs were digitized and measurements were made using the Cobb method with the assistance of a computer program. The use of computers for lumbar lordosis measurements has been shown to be at least equal, if not better, to the manual method [7 (link),30 (link),31 (link)]. Measurements were made from the top of L1 to the bottom of L5 as well as from the top of L1 to the top of S1. In addition, since several investigators have shown 50% to 75% of the total lordosis between L1 and S1 to be located at the bottom two motion segments [32 (link)-38 (link)], we also measured the angle between the bottom of L5 to the top of S1.
A priori power analysis showed that in order to have a power of 80% to detect a difference of as little as 10 degrees at the 0.05 level of significance assuming a standard deviation of 15 degrees, 35 women would be needed in each group. The increased enrolment improved the power of the study. Statistical analysis was performed using the one factor ANOVA model with no repeated measurements, chi - square test and for pairwise multiple comparisons, Ìann-Whitney test. All tests are two sided with p < 0.05 considered significant. The analysis was carried out using SPSS for Windows, Rel. 13.00. SPSS Inc. Chicago, IL.
The study protocol was approved by the Bioethics Board of the Faculty of Medicine, University of Crete. Written informed consent was obtained from all the subjects prior to their inclusion in the study.
All patients who had secondary osteoarthritis as well as patients whose lumbar curvature might have been altered from disease or iatrogenic intervention had to be excluded. Exclusion criteria were: 1) Congenital spinal diseases 2) Scoliosis 3) Spondylolisthesis - Spondylolysis 4) Vertebral fracture 5) History of spinal surgery 6) Inflammatory arthropathy 7) History of endocrine or metabolic disease.
All lumbar radiographs were examined on two separate occasions, independently, by two of the authors for the presence of features of osteoarthritis. The criteria used where those of Kellgren and Lawrence, and when evidence of two or more criteria were present, the diagnosis of lumbar osteoarthritis was made [29 (link)]. Interobserver agreement in detecting or excluding disease presence was 98%. If agreement was not reached, the patient was excluded from the study.
After the application of exclusion criteria, from 524 patients that were examined, only 145 were initially considered as potentially suitable. A further 33 patients were excluded after evaluation of spinal radiographs. The final sample consists of 112 postmenopausal women, aged 42-76 years old (mean 57.3 years).
After the designation of the final sample, lumbar lateral radiographs were digitized and measurements were made using the Cobb method with the assistance of a computer program. The use of computers for lumbar lordosis measurements has been shown to be at least equal, if not better, to the manual method [7 (link),30 (link),31 (link)]. Measurements were made from the top of L1 to the bottom of L5 as well as from the top of L1 to the top of S1. In addition, since several investigators have shown 50% to 75% of the total lordosis between L1 and S1 to be located at the bottom two motion segments [32 (link)-38 (link)], we also measured the angle between the bottom of L5 to the top of S1.
A priori power analysis showed that in order to have a power of 80% to detect a difference of as little as 10 degrees at the 0.05 level of significance assuming a standard deviation of 15 degrees, 35 women would be needed in each group. The increased enrolment improved the power of the study. Statistical analysis was performed using the one factor ANOVA model with no repeated measurements, chi - square test and for pairwise multiple comparisons, Ìann-Whitney test. All tests are two sided with p < 0.05 considered significant. The analysis was carried out using SPSS for Windows, Rel. 13.00. SPSS Inc. Chicago, IL.
The study protocol was approved by the Bioethics Board of the Faculty of Medicine, University of Crete. Written informed consent was obtained from all the subjects prior to their inclusion in the study.
Free full text: Click here
