Ventral acetabular sector angle

Ventral acetabular sector angle

  • Acronym: VASA

Definition

Stephan Mahler

The ventral acetabular sector angle is a measurement used to assess the anatomy of the hip joint in dogs, in particular the lateral slope of the acetabular roof. It is determined from a 2D CT images in a transversal plane. The dog is placed in dorsal recumbency with hip joints extended, adducted, and rotated slightly internally. Measurement is performed on three contiguous images that include an acetabular fossa, a well-defined acetabular sourcil, a round head of femur, and a fovea capitis.

A line is drawn on the horizontal pelvic axis defined as a line through the center of both femoral heads. Depending on authors, the center of the femoral heads is defined as the center of the best fit circle delimiting the femoral head (Andronescu et al 2015) or the midpoint of a line drawn perpendicular to a straight line that connects the caudal articular cartilage margins on the dorsal and ventral articular surfaces of the femoral head (Lopez et al. 2008). The ventral acetabular sector angle is the angle between the horizontal pelvic axis and a line that extends ventrally from the center of the femoral head to the ventrolateral border of the lunate surface.

Andronescu et al. (2015) published ventral acetabular sector angle in 46 dogs with various osteoarthritis scores combined at each age: 48.30 ± 5.37 (16 weeks) 46.61 ± 4.07 (32 weeks) 47.78 ± 3.65 (104 weeks)

Lopez et al (2008) found that the ventral acetabular sector angle in adult mixed-breed dogs with laxity of the hip joints was 49,4 ± 3,18° (range 27,6 - 61,2)

References

  • Andronescu et al. (2015). Associations between early radiographic and computed tomographic measures and canine hip joint osteoarthritis at maturity. American Journal of Veterinary Research, 76(1), 19–27. doi:10.2460/ajvr.76.1.19

  • Lopez et al. (2008) Relationships among measurements obtained by use of computed tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs. Am J Vet Res. Mar;69(3):362-70. doi: 10.2460/ajvr.69.3.362.

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