Hip shape is symmetric, non-dependent on limb dominance and gender-specific: implications for femoroacetabular impingement. A 3D CT analysis in asymptomatic subjects

Abstract

• Hip shape is symmetrical regardless of limb dominance. • Pincer/cam morphology is frequent in asymptomatic subjects (20 and 71%, respectively). • LCEA and acetabular version increases with age (5-7° between opposite age groups). • Femoral morphology is stable after physeal closure (in the absence of pathology). • Alpha and omega angle thresholds should be set according to sex.

Imaging Methodology for Hip Preservation: Techniques, Parameters, and Thresholds

“…Reference intervals (defined by a specific clinical outcome): Whereas the 97.5 percentile (upper limit) for, for example, the α values in the general population lies between 70 and 77 degrees, 51,52 the upper reference limits for α as defined by a specific clinical outcome (hip pain) would correspond to 57 to 60 degrees (which in turn corresponds approximately to the 50-75th percentile of the "epidemiological RefInt"). These values were determined having a specific clinical outcome in mind because they were associated with hip pain in specific studies.…”

“…9a), resulting in the L-CEA. 51,57,58 Surprisingly, the W-CEA is often connected with Ogata et al 59 and the L-CEA with Wiberg. 56 However, Ogata et al 59 suggested the same measurement as described earlier by Wiberg.…”

“…C, center of femoral head; F, fovea or medial margin of the sourcil; L, lateral edge of the acetabulum; W, sourcil/weightbearing lateral point according to Wiberg. corresponding to L-CEA may, in cases of overcoverage, be the most valuable from a preservation treatment perspective. 51,61 The reference values of W-CEA, L-CEA, and Ac-index with respect to overcoverage appear in ►Table 4. However, L-CEA RefInt are wide, and values of 23 to 33 degrees were suggested.…”

“…The RefInt and cutoff values for Ac-inclination were determined in large population-based cohorts evaluated by XR with mean values of 3.8 to 5.6 degrees (95% RefInt: À 7 to 15 degrees), in large asymptomatic cohorts evaluated by CT 51 with mean values of 3.4 AE 5.4 degrees (95% RefInt: À 8 to 14 degrees), and by MRI with mean values of 2.9 AE 5.4 degrees (95% RefInt: À 8 to 14 degrees). 53 Recently, a decision limit threshold of 6 degrees was suggested (sensitivity 65%, specificity 70%; area under the curve [AUC]: 0.709) to predict a symptomatic hip (with decreasing superior acetabular coverage; i.e., by increasing Ac-inclination, more symptomatic hips were found).…”

Hip and Advanced MSK Imaging: A Voyage to the Unknown

“…Hip joint imaging has been a personal enthusiasm of ours in both research and clinical practice. 1,2 It is our pleasure to present an issue on these topics with high-quality contributions from MSK radiologists and orthopaedic surgeons. These articles offer both an overview of current clinical perspectives and state-of-the-art imaging and also in-depth information of paramount significance for daily activities.…”