Vet Comp Orthop Traumatol 2024; 37(01): 030-036
DOI: 10.1055/s-0043-1772696
Original Research

Influence of Femoral Position and Pelvic Projection on Norberg Angle Measurements

1   Clinic of Small Animal Surgery and Reproduction, Centre of Veterinary Clinical Medicine, LMU Munich, Germany
2   Queen Mother Hospital for Animals, The Royal Veterinary College, University of London, London, United Kingdom
Andreas Brühschwein
1   Clinic of Small Animal Surgery and Reproduction, Centre of Veterinary Clinical Medicine, LMU Munich, Germany
Sarah Hauser
1   Clinic of Small Animal Surgery and Reproduction, Centre of Veterinary Clinical Medicine, LMU Munich, Germany
Anne-Sophie Hoffmann
1   Clinic of Small Animal Surgery and Reproduction, Centre of Veterinary Clinical Medicine, LMU Munich, Germany
Andrea Meyer-Lindenberg
1   Clinic of Small Animal Surgery and Reproduction, Centre of Veterinary Clinical Medicine, LMU Munich, Germany
› Author Affiliations
Funding We would like to thank the VET Research program of the Veterinary Faculty of the Ludwig Maximilian University of Munich for the financial support provided.


Objective Canine hip dysplasia is a common orthopaedic disease in dogs. The Norberg angle value is a measure of hip joint laxity. The aim of this study was to quantify the degree of rotation necessary to consider the radiograph as inadequately positioned and to determine the influence of rotation on the Norberg angle.

Study Design Three sets of radiographs with different positioning and projections were acquired using 10 canine cadavers. Rotation of the pelvis was simulated by rotating the X-ray tube without changing the position of the patient.

Results In dorsoventral projections, the Norberg angle value is increased by 3.2 to 5.8%. Due to rotation along the long axis, the Norberg angle increases on one side and decreases on the contralateral side by approximately the same value. Rotation of greater than 2 degrees in a lateral direction is visually perceived by the observer as tilted. Rotation of the projection in the caudoventral to craniodorsal direction causes mild increase of the Norberg angle (≤1%), while rotation of the projection in a cranioventral to caudodorsal direction causes moderate (≤2%) decrease of the Norberg angle. Rotation of less than –10 degrees (caudoventral to craniodorsal) or greater than 10 degrees (cranioventral to caudodorsal) is visually perceived as tilted.

Conclusion Tilted images that are subjectively perceived evaluable have only little effect on the Norberg angle and are therefore probably acceptable. Dorsoventral projections can be recognized based on the proximal position of the patella and should be excluded from evaluation, as the Norberg angle value can be falsely increased.

Authors' Contribution

A.M.L. was responsible for conception and design of the study. J.K., A.B., S.H., and A.S.H. were responsible for acquisition of data. J.K., A.B., S.H., A.S.H., A.M.L. analyzed and interpreted the data. J.K. and A.B. were responsible for drafting the article. J.K., A.B., S.H., A.S.H., and A.M.L. revised the article for intellectual content. All the authors approved the final version of the article.

Supplementary Material

Publication History

Received: 22 February 2023

Accepted: 25 July 2023

Article published online:
25 August 2023

© 2023. Thieme. All rights reserved.

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany

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