Karl-Philipp Kienle, Presenter: Nothing to Disclose

Johannes Keck, Abstract Co-Author: Nothing to Disclose

Stefan F. Werlen MD, Abstract Co-Author: Nothing to Disclose

Young-Jo Kim MD, PhD, Abstract Co-Author: Nothing to Disclose

Klaus A. Siebenrock MD, PhD, Abstract Co-Author: Nothing to Disclose

Tallal Charles Mamisch MD, Abstract Co-Author: Consultant, Siemens AG

For preserving therapy, corrective possibilities as well as understanding of the pathophysiology and risk factors of diseases, such as developmental dysplasia of the hip (DDH) or femoroacetabular impingement (FAI) normative data are necessary. Our purpose was to assess acetabular morphology by MRI during baseline and 1-year follow up of asymptomatic volunteers, aged 9-16 years, to obtain physiological data, as a base for understanding and comparing to pathological disease process

All 331 pupils from a primary- and high-school were asked to take part in this study and 64 of them (127 asymptomatic hips) obtained baseline and follow up MRI on 3T scanner. We analyzed on 7 radial images around the acetabulum, rotating from anterior to superior to posterior: (1) acetabular diameter (width of the cup), (2) acetabular-extension (elongation of the acetabular edges and therefore a deepening of the acetabulum), (3) acetabular depth as defined by Pfirrmann et al, to correlate the extension to the centre of the femoral head and (4) the beta-angle, as distance to the head-neck offset and looked at the relation to age, status of the epiphyseal scar and location in the joint

The effect of age on the acetabular diameter showed an highly significant (p<0.001) increase. The acetabular extension, also growth by age highly significant (p<0.001), but in relation to the femoral shape, objectified by the acetabular depth, we couldn’t find significant changes (p>0.05). The beta angle decreases with growing older, but not significantly (p>0.05). Dividing the population into three groups, one with open epiphysis at both time points, the second one with open phisis in baseline and closed in follow-up and the last one with a closed scar at both times, we found high significance (p<0.001) for changes during 1 year for acetabular diameter and extension, but not for depth (p>0.05). Significance could be found for the beta angle (p<0.05). Significant changes could mostly be found in the superior, ventral superior and dorsal superior parts.

Within our normal cohort we saw an increase of acetabular diameter and extension, but without changes in its depth. Hardly changes could be observed for the beta angle.

Assessment of acetabular normative data with comparison to pathological values offers the chance to detect and understand pathological changes for the development of preserving strategies and therapy.

Kienle, K, Keck, J, Werlen, S, Kim, Y, Siebenrock, K, Mamisch, T, Physiological Acetabular Morphology and Its Changes during Maturation: MR Assessments in a 1-year Follow-up of Sixty-Four Asymptomatic Volunteers Ranging in Age from 9–16 Years.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11008278.html