How Are Dysplastic Hips Different? A Three-dimensional CT Study

Abstract

Background Surgical correction of acetabular dysplasia can postpone or prevent joint degeneration. The specific abnormalities that make up the dysplastic hip are controversial. Questions/purposes (1) What are the relative size, shape, and orientations of the typical nondysplastic hip? (2) How do these variables differ in the developmentally dysplastic hip? (3) Are there version differences between the acetabuli of dysplastic and nondysplastic hips? (4) Are there pairs of variables in which the change in one is always accompanied by a change in the other for both nondysplastic and dysplastic acetabuli? Methods Of 117 consecutive three-dimensional (3-D) CT scans performed for hip dysplasia between March 1988 and October 1995, 48 met criteria of developmentally dysplastic hips by plain radiography. These were retrospectively compared with 55 pelvic 3-D CT scans culled from 81 consecutive scans performed for reasons other than hip dysplasia (ie, hip pain, trauma, infection) that did not affect the hip or pelvic landmarks. The 3-D reconstructions were orientated anatomically for standardization of the measurements to be compared. Representative 3-D volumes of the acetabular space were constructed from which we could measure anatomic positions and dimensional information. One author performed all image orientation and measurements. Results Nondysplastic acetabuli are essentially hemispheric with height equal to width and twice the depth. The dysplastic acetabuli were elongated in females (52.4 ± 6.2 mm for dysplastic versus 46.5 ± 4.6 mm for nondysplastic (mean difference, 5.0; 95% confidence interval [CI], 1.9-8.0; p = 0.002) and shallower in both females (18.7 ± 4.9 mm for dysplastic versus 23.6 ± 4.0 mm for nondysplastic; mean difference, 6.5; 95% CI, 4.4-8.5; p \ 0.0001) and males (21.1 ± 4.8 mm for dysplastic versus 25.0 ± 4.3 mm for nondysplastic, mean difference, 5.3; 95% CI, 2.6-8.1; p = 0.0002); width was similar to that of nondysplastic hips. Acetabular openings were slightly more vertical than nondysplastic hips in females (5°; 95% CI, 1.9-8.1; p = 0.002) but not in male subjects. The dysplastic acetabuli were smaller in volume (18% in females, p = 0.002, and 19% in males, p = 0.0012) and had less space occupied by the femoral head compared with nondysplastic hips (p \ 0

Sexual Dimorphism of Acetabular Anatomy Based on Three-dimensional Computed Tomography Images of Pelvises

“…This finding is also congruent with available descriptions presented in the literature, surprisingly rare as they are [8,28,29]. The paucity of descriptions of acetabular volume and surface may be associated with the fact that the measurements used are more practical from the viewpoint of surgical treatment, i.e.…”

“…Fakt ten jest również zgodny z dotychczasowymi, choć zaskakująco rzadkimi, opisami w literaturze [8,28,29]. Niedobór opisów objętości i powierzchni panewki może wiązać się z faktem, że stosowane są pomiary bardziej praktyczne w aspekcie leczenia operacyjnego, tj.…”

Is Increased Acetabular Cartilage or Fossa Size Associated With Pincer Femoroacetabular Impingement?

“…We found that dysplastic hips are globally deficient in both cartilage and fossa dimensions. A previous three-dimensional CT study described a volumetric decrease of 18% to 19% in dysplastic hips compared with normal hips [5]. Another CTbased study reported a 26% decrease in contact area in dysplastic hips compared with normal hips [12].…”

“…Previous studies using CT of human hips have measured the contours of the bony acetabulum [13], the relative coverage of the femoral head by the acetabulum in developmental dysplasia of the hip [1,2,5,7], and the contact pressure between the acetabulum and the femoral head [12]. However, these studies have focused on normal and dysplastic hips and did not directly visualize the articular cartilage using MR. Steppacher and colleagues [27] used MR radial sequences to examine protrusio, deep, and retroverted acetabula, finding that retroverted acetabula had smaller cartilage surfaces than deep and protrusio acetabula.…”

Hip Dysplasia in the Young Adult

“…decreased depth. This leads not only to the classic anterior insufficiency but also, potentially, to lateral, posterior, or global deficiency 17 . Even with mild hip dysplasia, the poor coverage of the femoral head, the relative lateralization of the hip center of rotation, and the smaller contact area between the femoral head and the dysplastic acetabulum can produce an asymmetric concentration of force across the hip joint and secondary articular cartilage and labral damage [18][19][20] .…”