Influence of Femoral Position and Pelvic Projection on Norberg Angle Measurements

Abstract

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.

Keywords

radiography - positioning - Norberg angle - canine hip dysplasia

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.

Publikationsverlauf

Eingereicht: 22. Februar 2023

Angenommen: 25. Juli 2023

Artikel online veröffentlicht:
25. August 2023

• References

• 1 Johnson JA, Austin C, Breur GJ. Incidence of canine appendicular musculoskeletal disorders in 16 veterinary teaching hospitals from 1980 through 1989. Vet Comp Orthop Traumatol 1994; 7: 56-69
• 2 Leppänen M, Saloniemi H. Controlling canine hip dysplasia in Finland. Prev Vet Med 1999; 42 (02) 121-131
• 3 Silvestre AM, Ginja MM, Ferreira AJ, Colaço J. Comparison of estimates of hip dysplasia genetic parameters in Estrela Mountain Dog using linear and threshold models. J Anim Sci 2007; 85 (08) 1880-1884
• 4 Freeman B, Evans VB, McEwan NR. Canine hip dysplasia in Irish water spaniels: two decades of gradual improvement. Vet Rec 2013; 173 (03) 72
• 5 Flückiger M. Scoring radiographs for canine hip dysplasia: the big three organisations in the world. Eur J Companion Anim Pract 2007; 17: 135-140
• 6 Klimt U. Zum Problem der “Lockeren Hüfte” beim Hund. Röntgenuntersuchungen zur lagerungsbedingten Verschieblichkeit des Femurkopfes bei der Diagnostik der Hüftgelenksdysplasie (HD) (Doctoral thesis). Gießen: Justus-Liebig-Universität Gießen; 1990
• 7 Flückiger M. How to take and read hip joint radiographs in a structured way. Eur J Comp Anim Pract 2007; 17: 133-134
• 8 Genevois JP, Cachon T, Fau D. et al. Canine hip dysplasia radiographic screening. Prevalence of rotation of the pelvis along its length axis in 7,012 conventional hip extended radiographs. Vet Comp Orthop Traumatol 2007; 20 (04) 296-298
• 9 van der Bom MJ, Groote ME, Vincken KL, Beek FJ, Bartels LW. Pelvic rotation and tilt can cause misinterpretation of the acetabular index measured on radiographs. Clin Orthop Relat Res 2011; 469 (06) 1743-1749
• 10 Henninger W. Der Kraniolaterale Pfannenrand Des Kaninen Hüftgelenks: Ein Beitrag Zur Hüftgelenkdysplasie. Vienna: VetmedUni Vienna; 1992
• 11 Bausman JA, Wendelburg KL. Evaluation of the effect of pelvic tilt in the coronal plane on the Norberg angle measured in ventrodorsal radiographic views of a canine hip joint bone model. Am J Vet Res 2010; 71 (11) 1348-1353
• 12 Broeckx BJ, Verhoeven G, Coopman F. et al. The effects of positioning, reason for screening and the referring veterinarian on prevalence estimates of canine hip dysplasia. Vet J 2014; 201 (03) 378-384
• 13 Verhoeven GE, Coopman F, Duchateau L, Bosmans T, Van Ryssen B, Van Bree H. Interobserver agreement on the assessability of standard ventrodorsal hip-extended radiographs and its effect on agreement in the diagnosis of canine hip dysplasia and on routine FCI scoring. Vet Radiol Ultrasound 2009; 50 (03) 259-263
• 14 Verhoeven GE, Fortrie RR, Duchateau L. et al. The effect of a technical quality assessment of hip-extended radiographs on interobserver agreement in the diagnosis of canine hip dysplasia. Vet Radiol Ultrasound 2010; 51 (05) 498-503
• 15 Löffler K. Die Bedeutung der Lagerung bei der röntgenologischen HD-Beurteilung. Waltham Report 1990; 30: 41-48
• 16 Amort K, Ondreka N, Tellhelm B. Röntgendiagnostik der Hüftgelenksdysplasie: Anfertigung der Röntgenaufnahmen, Befunde und Besonderheiten. Kleintiermedizin. 2013; 05: 212-226
• 17 Rhodes WM. Positioning of the canine hips for radiography. Vet Radiol 1961; 2 (01) 39-40
• 18 Flückiger MA, Steffen F, Hässig M, Morgan JP. Asymmetrical lumbosacral transitional vertebrae in dogs may promote asymmetrical hip joint development. Vet Comp Orthop Traumatol 2017; 30 (02) 137-142
• 19 Martins J, Colaço BJ, Ferreira AJ, Ginja MM. Analysis of pelvic rotation on the standard hip ventrodorsal extended radiographic view. Vet Comp Orthop Traumatol 2016; 29 (01) 68-74
• 20 Thompson R, Roe SC, Robertson ID. Effects of pelvic positioning and simulated dorsal acetabular rim remodeling on the radiographic shape of the dorsal acetabular edge. Vet Radiol Ultrasound 2007; 48 (01) 8-13
• 21 Klever J, de Motte A, Meyer-Lindenberg A, Brühschwein A. Evaluation and comparison of self-made and commercial calibration markers for radiographic magnification correction in veterinary digital radiography. Vet Comp Orthop Traumatol 2022; 35 (01) 10-17
• 22 Saunders JH, Godefroid T, Snaps FR, François A, Farnir F, Balligand M. Comparison of ventrodorsal and dorsoventral radiographic projections for hip dysplasia diagnosis. Vet Rec 1999; 145 (04) 109-110
• 23 Tannast M, Murphy SB, Langlotz F, Anderson SE, Siebenrock KA. Estimation of pelvic tilt on anteroposterior X-rays: a comparison of six parameters. Skeletal Radiol 2006; 35 (03) 149-155
• 24 Klever J, Brühschwein A, Meyer-Lindenberg A. Distraction index and Norberg angle to distinguish dysplastic and non-dysplastic hips based on FCI score. Tierarztl Prax Ausg K Klientiere Heimtiere 2020; 48 (04) 250-258
• 25 Bushberg J, Seibert J, Leidholdt E, Boone J. The Essential Physics of Medical Imaging. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012