Features assessed during scoring

• See BVA/Kennel Club hip dysplasia scoring scheme for protocol BVA/Kennel Club hip dysplasia scheme.
• The scrutineers work from a table detailing the scores to be allocated for various radiographic features.

Norberg angle

• The Norberg angle is calculated using a medical orthopedic measurement device called an ischiometer .
• It represents an assessment both of the depth of the acetabulum and the presence of subluxation; a good Norberg angle exceeds 105° and penalty points are given for each block of 5° less than this, eg a Norberg angle of 92° scores 3.
• The center point of each femoral head is marked on the radiograph by finding one of the concentric circles drawn on the ischiometer which most nearly fits the femoral head.
• The centers are joined using a baseline, also drawn on the ischiometer, and a second line taken from the center of the each femoral head to the most craniolateral point of each acetabular surface.
• The angle between the two lines is measured for each hip .
• If the acetabulum is shallow or the femoral head is subluxated then the Norberg angle is reduced .

Subluxation

Cranial effective acetabular rim

Femoral head and neck exostoses

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Lust G, Todhunter R J, Erb H N et al (2001) Comparison of three radiographic methods for diagnosis of hip dysplasia in eight-month old dogs. JAVMA 219 (9), 1242-1246 PubMed.
• Dennis R (1998) A scheme to control hip dysplasia. Vet Nursing 13 (2), 55-60 T&F Online.
• Gibbs C (1997) The BVA/KC scoring scheme for control of hip dysplasia: interpretation of criteria. Vet Rec 141 (11), 275-284 PubMed.