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Prognostic study, level II-1 (retrospective study).

Acetabular retroversion has been proposed to contribute to the development of osteoarthritis of the hip. For the diagnosis of this condition, conventional AP pelvic radiographs may represent a reliable, easily available diagnostic modality as they can be obtained with a reproducible technique allowing the anterior and posterior acetabular rims to be visible for assessment. This study was designed to: (i) determine cranial, central, and caudal anatomic acetabular version (AV) from cadaveric specimens; (ii) establish the validity and reliability of the radiographic measurements of central acetabular anteversion; and (iii) determine the validity and reliability of the radiographic ''cross-over-sign'' to detect acetabular retroversion. Using 43 desiccated pelvises (86 acetabuli) the anatomic AVs were measured at three different transverse planes (cranially, centrally, and caudally). From these pelvises, standardized AP pelvic radiographs were obtained. To directly measure central AV, a modified radiographic method is introduced for the use of AP pelvic radiographs. The validity and reliability of this radiographic method and of the radiographic crossover-sign to detect cranial acetabular retroversion were determined. The mean central and caudal anatomic AVs were approximately 208, and the mean cranial AV was 88. Cranial retroversion (AV < 08) was present in 19 of 86 hips (22%). A linear correlation was found between the central and cranial AV. Below 108 of central AV, all acetabuli were cranially retroverted. Between 108 and 208, 30% of the acetabuli were cranially retroverted, and above 208, only 1 of 45 acetabuli was cranially retroverted. The radiographic measurement of the central AV (20.3 AE 6.58) correlated strongly with the anatomic AV (20.1 AE 6.48). The sensitivity of the cross-over-sign to detect a cranial acetabular anteversion of less than 48 was 96%, its specificity 95%, and the positive predictive and negative predictive values 90% and 98%, respectively. Both the modified radiographic anteversion measurements and the cross-over-sign demonstrated substantial inter-and intraobserver reliability. Retroversion is almost exclusively a problem of the cranial acetabulum. The cranial AV is on average 128 lower than the central AV, with the latter directly measurable from AP pelvic radiographs. A central AV of less than 108 was associated with cranial retroversion. The presence of a positive cross-over-sign is a highly reliable indicator of cranial AV of <48. ß

No abstract