Comparison of Early Measurements of the Distraction Index, Norberg Angle on Distracted View and the Official Radiographic Evaluation of the Hips of 215 Dogs from Two Guide Dog Training Schools

Abstract

Objectives The main purpose of this article is to evaluate the correlation between the distraction index (DI) and Norberg angle values in distracted hips (distraction Norberg angle, DNA) at 4 months of age and the official hip score based on the Fédération Cynologique Internationale (FCI) grid at 12 months of age.

Methods For dogs (n = 215) from two guide dog training organizations, the DI and DNA were measured by a single expert on distraction radiographs performed at 4 months of age. The FCI score was determined by the same expert at 12 months of age on a standard hip-extended view.

Statistical analysis included receiver operating characteristic curve analysis and concordance correlation coefficient calculation.

Results The mean DI was 0.48, the mean DNA was 86.5° and 59.5% of hips had an A FCI score. The concordance correlation coefficient of DI and DNA was 0.78. The DI threshold for D- and E-scored hips that was associated with the least misclassification was 0.58 (sensitivity [Se] = 0.6, specificity [Sp] = 0.82). The DNA threshold that was associated with the least misclassification was 85° (Se = 0.83, Sp = 0.68).

Clinical Significance DNA has a fair correlation with DI at 4 months and reflects hip passive laxity. D and E FCI scores at 12 months cannot be reliably predicted from the 4 months value of DI or DNA but 96% of hips with DI < 0.58 at 4 months had an A, B or C FCI score at 12 months of age. Similarly, 98% of hips with DNA > 85° at 4 months had an A, B or C FCI score at 12 months of age.

Keywords

hip dysplasia - distraction index - distracted Norberg angle - FCI grade

Author Contributions

All authors contributed to conception of study, study design, and acquisition of data and data analysis and interpretation. All authors drafted, revised and approved the submitted manuscript.

• References

• 1 Schnelle GB. Congenital subluxation of the coxofemoral joint in the dog. Univ Pa Bull 1937; 65: 15-16
• 2 Henricson B, Norberg I, Olsson SE. On the etiology and pathogenesis of hip dysplasia: a comparative review. J Small Anim Pract 1966; 7 (11) 673-688
• 3 Jessen CR, Spurrell FA. Radiographic detection of canine hip dysplasia in known age groups. Proceedings of the Canine Hip Dysplasia Symposium and Workshop; October 19-20, 1972; St. Louis, Missouri, United States. 93–100
• 4 Snavely JG. The genetic aspects of hip dysplasia in dogs. J Am Vet Med Assoc 1959; 135 (04) 201-207
• 5 Kaman CH, Gossling HR. A breeding program to reduce hip dysplasia in German shepherd dogs. J Am Vet Med Assoc 1967; 151 (05) 562-571
• 6 Henricson B, Ljunggren G, Olsson SE. , et al. Hip dysplasia in Sweden: controlled breeding programs. Proceedings of the Canine Hip Dysplasia Symposium and Workshop; 1973; Columbia, Missouri, United States. 141–151
• 7 Riser WH. An analysis of the current status of hip dysplasia in the dog. J Am Vet Med Assoc 1964; 144: 709-721
• 8 Hedhammar A, Olsson SE, Andersson SA. , et al. Canine hip dysplasia: study of heritability in 401 litters of German Shepherd dogs. J Am Vet Med Assoc 1979; 174 (09) 1012-1016
• 9 Boernfors S, Palsson K, Skude G. Hereditary aspects of hip dysplasia in German Shepherd dogs. J Am Vet Med Assoc 1964; 145: 15-20
• 10 Jenny-Gredig V, Kieliger J, Müller A, Eggenberger E. Today's status of the hip joint dysplasia control in Switzerland [Article in German]. Schweiz Arch Tierheilkd 1970; 112 (09) 487-490
• 11 Flückiger M. Scoring radiographs for canine hip dysplasia - the big three organisations in the world. Eur J Companion Anim Pract 2007; 17: 135-140
• 12 Jessen CR, Spurrell FA. Radiographic detection of canine hip dysplasia in known age groups. In: Proceedings of the Canine Hip Dysplasia Symposium and Workshop, St Louis, MO; 1972: 93–100
• 13 Adams WM, Dueland RT, Meinen J, O'Brien RT, Giuliano E, Nordheim EV. Early detection of canine hip dysplasia: comparison of two palpation and five radiographic methods. J Am Anim Hosp Assoc 1998; 34 (04) 339-347
• 14 Smith GK, Biery DN, Gregor TP. New concepts of coxofemoral joint stability and the development of a clinical stress-radiographic method for quantitating hip joint laxity in the dog. J Am Vet Med Assoc 1990; 196 (01) 59-70
• 15 Smith GK, Gregor TP, McKelvie PJ. , et al. PennHIP Training Seminar and Reference Material, Synbiotics Corporation, San Diego; 2002
• 16 Powers MY, Karbe GT, Gregor TP. , et al. Evaluation of the relationship between Orthopedic Foundation for Animals' hip joint scores and PennHIP distraction index values in dogs. J Am Vet Med Assoc 2010; 237 (05) 532-541
• 17 Smith GK, Gregor TP, Rhodes WH, Biery DN. Coxofemoral joint laxity from distraction radiography and its contemporaneous and prospective correlation with laxity, subjective score, and evidence of degenerative joint disease from conventional hip-extended radiography in dogs. Am J Vet Res 1993; 54 (07) 1021-1042
• 18 Smith GK, Hill CM, Gregor TP, Olson K. Reliability of the hip distraction index in two-month-old German shepherd dogs. J Am Vet Med Assoc 1998; 212 (10) 1560-1563
• 19 Heyman SJ, Smith GK, Cofone MA. Biomechanical study of the effect of coxofemoral positioning on passive hip joint laxity in dogs. Am J Vet Res 1993; 54 (02) 210-215
• 20 Adams WM, Dueland RT, Daniels R, Fialkowski JP, Nordheim EV. Comparison of two palpation, four radiographic and three ultrasound methods for early detection of mild to moderate canine hip dysplasia. Vet Radiol Ultrasound 2000; 41 (06) 484-490
• 21 Vezzoni A, Dravelli G, Corbari A. , et al. Early diagnosis of canine hip dysplasia. Eur J Companion Anim Pract 2005; 15: 173-184
• 22 Malm S, Fikse F, Egenvall A. , et al. Association between radiographic assessment of hip status and subsequent incidence of veterinary care and mortality related to hip dysplasia in insured Swedish dogs. Prev Vet Med 2010; 93 (2-3): 222-232
• 23 Robin X, Turck N, Hainard A. , et al. pROC: an open-source package for R and S+ to analyze and compare ROC curves. BMC Bioinformatics 2011; 12: 77
• 24 Lin LI. A concordance correlation coefficient to evaluate reproducibility. Biometrics 1989; 45 (01) 255-268
• 25 Lin K. A note on the concordance correlation coefficient. Biometrics 2000; 56: 324-325
• 26 Smith GK, Mayhew PD, Kapatkin AS, McKelvie PJ, Shofer FS, Gregor TP. Evaluation of risk factors for degenerative joint disease associated with hip dysplasia in German Shepherd Dogs, Golden Retrievers, Labrador Retrievers, and Rottweilers. J Am Vet Med Assoc 2001; 219 (12) 1719-1724
• 27 Runge JJ, Kelly SP, Gregor TP, Kotwal S, Smith GK. Distraction index as a risk factor for osteoarthritis associated with hip dysplasia in four large dog breeds. J Small Anim Pract 2010; 51 (05) 264-269
• 28 Ginja MM, Gonzalo-Orden JM, Melo-Pinto P. , et al. Early hip laxity examination in predicting moderate and severe hip dysplasia in Estrela mountain dog. J Small Anim Pract 2008; 49 (12) 641-646
• 29 Gaspar AR, Hayes G, Ginja C, Ginja MM, Todhunter RJ. The Norberg angle is not an accurate predictor of canine hip conformation based on the distraction index and the dorsolateral subluxation score. Prev Vet Med 2016; 135: 47-52
• 30 Vezzoni A, Dravelli G, Vezzoni L. , et al. Comparison of conservative management and juvenile pubic symphysiodesis in the early treatment of canine hip dysplasia. Vet Comp Orthop Traumatol 2008; 21 (03) 267-279
• 31 Fujiki M, Kurima Y, Yamanokuchi K, Misumi K, Sakamoto H. Computed tomographic evaluation of growth-related changes in the hip joints of young dogs. Am J Vet Res 2007; 68 (07) 730-734
• 32 Smith GK, LaFond E, Gregor TP, Lawler DF, Nie RC. Within- and between-examiner repeatability of distraction indices of the hip joints in dogs. Am J Vet Res 1997; 58 (10) 1076-1077