The epidemiology of Schmorl's nodes and their correlation to radiographic degeneration in 4,151 subjects.

PURPOSE: Schmorl's nodes (SNs) are commonly seen in vertebral imaging of the normal adult population referred for different reasons and are duly noted by the radiologist. However, little is known about their etiology: either SNs are perceived as largely inert developmental or congenital herniations of disc tissue into weak areas of the vertebral end-plates, or they are perceived as a common pathological pathway of different adverse and general factors such as malignancy, trauma, infection, osteoporosis, Paget's disease and so forth. A commonly accepted morphological definition of what precisely constitute SNs does not exist, and consequently prevalences vary wildly in the literature. In the present study of 4,151 standardized lateral radiographs of the lumbar spine in an adult, Caucasian population between 22 and 93 years (median age 63 years, M 1,533, W 2,618). METHODS: We investigated prevalence, distribution and epidemiologic relationships of SNs. RESULTS: SNs occur primarily in the upper part of the lumbar spine, and usually there are multiple lesions in the same individual. We could not establish any significant correlation between SNs and gender, age, BMI, height, weight or occupational exposure for heavy lifting. The overall prevalence was 3.8%. We did not find any significant correlations between SNs and overall degeneration of the lumbar spine. CONCLUSION: We found a prevalence of SNs in the lower end of the spectrum than hitherto reported.

Degenerative lumbar spondylolisthesis: an epidemiological perspective: the Copenhagen Osteoarthritis Study.

STUDY DESIGN: A cross-sectional epidemiological survey of 4151 participants of the Copenhagen Osteoarthritis Study. OBJECTIVE: To identify prevalences and individual risk factors for degenerative lumbar spondylolisthesis. SUMMARY OF BACKGROUND DATA: The Copenhagen Osteoarthritis Study has registered health parameters since 1976. In 1993, standardized, lateral radiographs of the lumbar spine were recorded. There were 1533 men and 2618 women. METHODS: Statistical correlations were made between degenerative spondylolisthesis, and physical, occupational, and general epidemiological data. RESULTS: A total of 254 cases of lumbar slip were found (males 2.7%, females 8.4%). In females, no significant relationship between age at menopause or childbirths and the presence of degenerative spondylolisthesis were found. In women, relationships between body mass index (BMI) in 1976 and L4 olisthesis (P = 0.001), and between BMI in 1993 and both L4 and L5 olisthesis were found (L4: P = 0.003; L5: P = 0.006). Lumbar lordosis was associated with degenerative spondylolisthesis in women. Occupational exposures to daily lifting or smoking were not associated with degenerative spondylolisthesis. Degenerative spondylolisthesis was associated with increased age in both sexes (L4: P < 0.001; L5: P < 0.001). CONCLUSIONS: BMI longitudinally and at index evaluations, age, and angle of lordosis were significantly associated with degenerative spondylolisthesis in women. In men, no individual risk factors for degenerative spondylolisthesis were found, save increased age.

Pelvic orientation and assessment of hip dysplasia in adults.

BACKGROUND: The study was performed to qualify the source material of 4151 pelvic radiographs for the research into the relationship between unrecognised childhood hip disorders and the development of hip osteoarthrosis, and to investigate the effect of varying degrees of pelvic tilt and rotation on the measurements of radiographic indices of hip dysplasia. MATERIAL AND METHODS: We investigated the effect of varying pelvic orientation on radiographic measurements of acetabular dysplasia using a cadaver model. Results from the cadaver study were used to validate the radiographic assessments of acetabular dysplasia in the longitudinal survey cohort of the Copenhagen City Heart Study (CCHS; Osteoarthrosis Sub-study). 1) Cadaver pelvises and proximal femurs from a male and a female donor were mounted anatomically in holding devices allowing independent inclination/reclination and rotation. An AP pelvic radiograph was recorded at each 3 degrees increment. The most widely used radiographic parameters of hip dysplasia were assessed. 2) Critical limits of acceptable rotation and inclination/reclination of pelvises were determined on 4151 standing, standardised pelvic radiographs of the CCHS cohort. RESULTS: Wiberg's CE angle, Sharp's angle, the x-coordinate of Goodman's Cartesian coordinate system, and the acetabular depth ratio were significantly affected by varying rotation and inclination/reclination of the cadaver pelvises. Femoral head extrusion index was not significantly affected within the applied rotation and inclination/reclination of the cadaver study. Application of the corresponding critical limits of Tönnis' foramen obturator index of 0.7-1.8 meant that 188 of 4151 (4.5%) of the CCHS-III pelvic radiographs had to be omitted from further studies. INTERPRETATION: To ensure a neutral starting point and reproducible readings, especially in epidemiological and clinical studies, and when performing preoperative planning and follow-up of patients undergoing redirectional pelvic osteotomies, it is important that all aspects of the radiographic examination are controlled and reproducible. Furthermore, we found that studies of acetabular dysplasia based on supine urograms or colon radiographs without information about pelvic orientation, centering of the X-ray beam and tube to film distance, run a serious risk of erroneous measurements.