title: Radiographic markers of femoroacetabular impingement: correlation of herniation pit and femoral bump with a positive cross-over ratio.
abstract: Introduction. The goal of this study was to research the association of femoral bumps and herniation pits with the overlap-ratio of the cross-over sign. Methods. Pelvic X-rays and CT-scans of 2925 patients with good assessment of the anterior and the posterior acetabular wall and absence of neutral pelvic tilt were enrolled in the investigation. Finally pelvic X-rays were assessed for the presence of a positive cross-over sign, and CT-scans for a femoral bump or a herniation pit. Additionally, if a positive cross-over sign was discovered, the overlap-ratio was calculated. Results. A femoral bump was found in 53.3% (n = 1559), and a herniation pit in 27.2% (n = 796) of all hips. The overlap-ratio correlated positively with the presence of a femoral bump, while a negative correlation between the overlap-ratio and the presence of a herniation pit was found. The latter was significantly more often combined with a femoral bump than without. Conclusions. We detected an increased prevalence of femoral bump with increasing overlap-ratios of the cross-over sign indicating a relation to biomechanical stress. The observed decreased prevalence of herniation pits with increasing overlap-ratios could be explained by reduced mechanical stress due to nontightened iliofemoral ligament in the presence of retroversion of the acetabulum.
authors.affiliation: Department of Surgery, Division of Trauma Surgery, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Max J
authors.initials: MJ
authors.lastname: Scheyerer
authors.affiliation: R Adams Cowley Shock Trauma Center, University of Maryland Medical Systems, 22 S. Greene Street, Baltimore, MD 21201, USA.
authors.forename: Carol E
authors.initials: CE
authors.lastname: Copeland
authors.affiliation: R Adams Cowley Shock Trauma Center, University of Maryland Medical Systems, 22 S. Greene Street, Baltimore, MD 21201, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Stromberg
authors.affiliation: Department of Surgery, Division of Trauma Surgery, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ruckstuhl
authors.affiliation: Department of Surgery, Division of Trauma Surgery, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland ; R Adams Cowley Shock Trauma Center, University of Maryland Medical Systems, 22 S. Greene Street, Baltimore, MD 21201, USA.
authors.forename: Clément M L
authors.initials: CM
authors.lastname: Werner