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

• Published in: Clinical orthopaedics and related research 2015-05, Vol.473 (5), p.1712-1723
• Main Authors: van Bosse, Harold, Wedge, John H., Babyn, Paul
• Format: Article
• Language: English
• Subjects: Acetabulum - abnormalities; Acetabulum - diagnostic imaging; Adolescent; Adult; Child; Clinical Research; Conservative Orthopedics; Female; Hip; Hip Dislocation, Congenital - diagnostic imaging; Hip Joint - abnormalities; Hip Joint - diagnostic imaging; Humans; Imaging, Three-Dimensional; Male; Medicine; Medicine & Public Health; Orthopedics; Predictive Value of Tests; Prognosis; Radiographic Image Interpretation, Computer-Assisted; Retrospective Studies; Sex Factors; Sports Medicine; Surgery; Surgical Orthopedics; Tomography, X-Ray Computed; Young Adult
• ISSN: 0009-921X; 1528-1132
• DOI: 10.1007/s11999-014-4103-y

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