Mechanical factors play a role in pathogenesis of primary osteoarthritis of the hip. Torsion measures were made to detect whether there is a causal relationship between increase or decrease of femoral anteversion, acetabular anteversion, and osteoarthritis. There are no studies in the literature indicating a relationship between axial plane coverage and osteoarthritis of the hip. Deficient axial plane coverage of femoral head may also play a role in pathogenesis of osteoarthritis.
Thirty patients with primary osteoarthritis of the hip and 29 control cases were included in the study. We used the method of Anda et al. (Acta Radiol Diagn 27:443-447, 1986; Comput Assist Tomogr 15:115-120, 1991) to measure axial plane anterior, posterior coverages in patients with primary osteoarthritis of the hip. The computerized tomography sections and pelvic radiographs indicated good frontal plane coverage and spherical femoral head. In addition to anterior acetabular sector angle, posterior acetabular sector angle, horizontal acetabular sector angles for axial plane coverage detection, femoral anteversion, acetabular anteversion, and McKibbin instability index were also measured.
Posterior coverage was lower at osteoarthritic hips than the control group's hips (96.0 ± 16.7, 104.2 ± 10.6) (p < 0.05).
The results may indicate that in addition to other mechanical factors, axial plane coverage, especially the posterior coverage deficiency, may play a role in the pathogenesis of hip osteoarthritis.