Table II.
Definition of study groups with the used in- and exclusion criteria are shown. The allocation to a specific group was performed based on the morphological analysis of the conventional anteroposterior pelvic radiograph and the cross-table lateral radiographs of the hip.
| Criteria | Definition | Hips (patients) |
|---|---|---|
| Inclusion | ||
| Hip dysplasia | LCE angle < 22°28 and/or anterior coverage < 14%28 independent of the neck-shaft-angle | 47 (29) |
| Acetabular retroversion | Positive crossover sign29 positive ischial spine sign6 positive posterior wall sign29 and retroversion index > 30%30 independent from alpha angle | 41 (33) |
| Cam-type FAI | alpha angle > 50°31 with neck-shaft angle of 120° to 140° and with normal acetabulum (LCE 23° to 33°)28 not all retroversion signs positive | 32 (24) |
| Total acetabular retroversion* | Positive crossover sign29 positive ischial spine sign6 positive posterior wall sign29 and retroversion index > 50%30 independent from α angle | 15 (9) |
| High acetabular anteversion† | Central acetabular anteversion > 25°32on CT scan and/or anterior coverage < 14%28 | 20 (17) |
| Exclusion | ||
| No obvious pathomorphology | No obvious acetabular and femoral deformities, normal LCE angle (22° to 34°), normal alpha angle (< 50°), normal femoral head coverage, symptomatic hip | 33 (33) |
| Severe overcoverage | LCE angle > 39°32 and/or protrusio acetabuli (defined as femoral head touching or crossing the ilioischial line), and/or total femoral coverage > 93%28 not all retroversion signs positive | 22 (14) |
| Overcoverage | LCE angle 34° to 39°28 with alpha angle < 50°, not all retroversion signs positive | 21 (11) |
| Mixed-type FAI | Mixed-type FAI was defined as combined overcoverage (LCE angle 35° to 39°) with an alpha angle > 50°, not all retroversion signs positive | 20 (20) |
| Valgus hips | Neck-shaft-angle > 139° | 18 (18) |
| Avascular necrosis | Avascular necrosis of the femoral head | 5 (5) |
| Control group | Patients with whole body CT scans for nonorthopaedic reasons (mostly multiple myeloma patients) | 48 (27) |
*
This group is a subgroup of the patients with acetabular retroversion.
†
This group is a subgroup of the patients with hip dysplasia .
FAI, femoroacetabular impingement; LCE, lateral centre edge angle.