Screening methods of coxofemural dysplasia in dogs

The major desideratum of the screening action of the hip dysplasia is the early discovery of the disease and its highlighting at an early stage. Hip dysplasia is interpreted as an abnormal and / or defective development of the hip (hip joint), which can cause excessive wear of the articular cartilage due to the support of body weight leading to the development of arthritis, often called degenerative joint disease or simply osteoarthritis, these terms being used randomly. All these morphofunctional changes can be detected early, by different methods of observation, which necessarily involve X-ray radiological examination, performing a complex analysis of the images studied, according to the recommendations of various international organizations such as FCI Fédération Cynologique Internationale (FCI) - score which includes measuring the Norberg angle, the Orthopedic Foundation for Animals (OFA), the PennHIP Program - which involves measuring hip laxity, etc.

The slope of the pelvis is variable in dogs but does not show correlation with femoral subluxation

The aim of this study was to investigate the variability of the slope of the pelvis in different dog breeds and the correlation between pelvic slope and femoral subluxation. The sacrum–pelvis angle (SPA), the angulation between the sacrum and the axis of the ilium was created to represent the differences in the slope of the pelvis on lateral pelvic radiographs. The Norberg angle (NA) was used to quantify the femoral subluxation on hip-extended radiographs. Archived standard ventrodorsal hip radiographs and lateral lumbosacral radiographs of the same dogs were retrieved and a single observer measured the SPA and the NA in each case. A total of 180 dogs from six different breeds were sampled. The SPA varied between 40° and 71.5° and the NA between 71.2° and 113.9°. The findings indicated that there are significant individual and interbreed variations in the slope of the pelvis. However, no significant relationship between the slope of the pelvis and femoral subluxation could be identified.

Distraction index and Norberg angle to distinguish dysplastic and non-dysplastic hips based on FCI score

Objective Radiographic hip scoring according to the Fédération Cynologique Internationale (FCI) and PennHIP (Pennsylvania Hip Improvement Program) method was performed with the purpose to compare the PennHIP and FCI results as well as coxofemoral joint laxity by correlation of Norberg angle and distraction index measurements. Materials and methods A total of 167 dogs of various breeds presented for official screening examination in a veterinary teaching hospital in Germany were included. Using receiver operating characteristic analysis, the best Norberg angle and distraction index cut-off values to distinguish between dysplastic and non-dysplastic groups based on FCI grades and to distinguish between lax and tight hip joints according to the PennHIP proposal were calculated. Results More than one third (38.2 %) of dogs that passed the breeding criterions according to FCI (grades A and B) were in the half of the population with lax hip joints and should not be used for breeding according to the PennHIP proposal. A cut-off value for the distraction index of 0.44 with sensitivity of 82.7 % and specificity of 84.2 % was superior to the best cut-off value for the Norberg angle at 101.8° with sensitivity of 82.7 % and specificity of 71.9 % to discriminate between non-dysplastic joints (A, B) and dysplastic joints (C, D, E). Conclusions and clinical relevance Our results show a limited impact of laxity on the FCI grading. Breeding selection processes that are based on the FCI method could profit by an additional and complementary use of the distraction index.

3D printing of canine hip dysplasia: anatomic models and radiographs

ABSTRACT Canine Hip Dysplasia (CHD) is a highly prevalent articular pathological condition. In this sense, radiography becomes an important diagnostic method to determine the presence and severity of the disease. The objective was to create 3D models and their respective radiographs representing the CHD (3D AMCHD). The research was carried out in the Laboratory of 3D Educational Technologies of UFAC, under no. 23107.007273/2017-49 (CEUA/UFAC). A canine skeleton (hip bone, femurs and patellae) was used without anatomical deformities compatible with DCF (pelvis, femurs and patella), which were scanned in order to obtain the files of the base model. In these files the deformations representing the different degrees of CHD were performed. Subsequently, the 3D AMCHD files were printed, mounted and X-rayed. The 3D AMCHD represented the bone deformations of the different degrees of CHD. In the radiographs of the 3D AMCHD it was possible to observe and determine each of the bones that constituted the hip joints. This allowed to reproduce the correct positioning to represent the CHD diagnosis and establish the precise points to determine the Norberg angle. In this way, it was evidenced that the 3D AMCHD can be a possible tool to be used in the Teaching of Veterinary Medicine.

Comparison of Reliability of Norberg Angle and Distraction Index as Measurements for Hip Laxity in Dogs

Objective The main purpose of the study was to compare reliability of measurements for the evaluation of hip joint laxity in 59 dogs. Materials and Methods Measurement of the distraction index (DI) of the PennHIP method and the Norberg angle (NA) of the Fédération Cynologique Internationale (FCI) scoring scheme as well as scoring according to the FCI scheme and the Swiss scoring scheme were performed by three observers at different level of experience. For each dog, two radiographs were acquired with each method by the same operator to evaluate intraoperator-reliability. Results Intraoperator-reliability was slightly better for the NA compared with the DI with an intraclass correlation coefficient (ICC) of 0.962 and 0.892 respectively. The ICC showed excellent results in intraobserver-reliability and interobserver-reliability for both the NA (ICC 0.975; 0.969) and the DI (ICC 0.986; 0.972). Thus, the NA as well as the DI can be considered as reliable measurements. The FCI scheme and the Swiss scoring scheme provide similar reliability. While the FCI scheme seems to be slightly more reliable in experienced observers (Kappa FCI 0.687; Kappa Swiss 0.681), the Swiss scoring scheme had a noticeable better reliability for the unexperienced observer (Kappa FCI 0.465; Kappa Swiss 0.514). Clinical Significance The Swiss scoring scheme provides a structured guideline for the interpretation of hip radiographs and can thus be recommended to unexperienced observers.

Genetic dissection of canine hip dysplasia phenotypes and osteoarthritis reveals three novel loci

Background Hip dysplasia and osteoarthritis continue to be prevalent problems in veterinary and human medicine. Canine hip dysplasia is particularly problematic as it massively affects several large-sized breeds and can cause a severe impairment of the quality of life. In Finland, the complex condition is categorized to five classes from normal to severe dysplasia, but the categorization includes several sub-traits: congruity of the joint, Norberg angle, subluxation degree of the joint, shape and depth of the acetabulum, and osteoarthritis. Hip dysplasia and osteoarthritis have been proposed to have separate genetic etiologies. Results Using Fédération Cynologique Internationale -standardized ventrodorsal radiographs, German shepherds were rigorously phenotyped for osteoarthritis, and for joint incongruity by Norberg angle and femoral head center position in relation to dorsal acetabular edge. The affected dogs were categorized into mild, moderate and severe dysplastic phenotypes using official hip scores. Three different genome-wide significant loci were uncovered. The strongest candidate genes for hip joint incongruity were noggin (NOG), a bone and joint developmental gene on chromosome 9, and nanos C2HC-type zinc finger 1 (NANOS1), a regulator of matrix metalloproteinase 14 (MMP14) on chromosome 28. Osteoarthritis mapped to a long intergenic region on chromosome 1, between genes encoding for NADPH oxidase 3 (NOX3), an intriguing candidate for articular cartilage degradation, and AT-rich interactive domain 1B (ARID1B) that has been previously linked to joint laxity. Conclusions Our findings highlight the complexity of canine hip dysplasia phenotypes. In particular, the results of this study point to the potential involvement of specific and partially distinct loci and genes or pathways in the development of incongruity, mild dysplasia, moderate-to-severe dysplasia and osteoarthritis of canine hip joints. Further studies should unravel the unique and common mechanisms for the various sub-traits.

Effect of the Dog positioning on X-Ray Table on Hip Dysplasia Parameter Evaluation

Objective The aim of this study was to evaluate the effect of pelvic tilting along the long axis and femoral rotation on Norberg angle (NA), subluxation index (SI) and subluxation category (SC) in the standard ventrodorsal hip extended (VDHE) radiographical view on live animals. Study Type This was a retrospective clinical study. Materials and Methods Pairs of VDHE views, one adequately positioned and the other with pelvic tilting or femoral internal or external rotation, were compared for the NA, SI and SC. Results On the malpositioned pelvis set, on the underside the mean ± SD NA was 98.7 ± 6.1°, the SI was 0.27 ± 0.12 and the SC was 2.8 ± 0.8 versus, on the acceptable set, the NA was 99.2 ± 6.4° (p > 0.05), the SI was 0.25 ± 0.12 (p < 0.05) and the SC was 2.3 ± 0.9 (p < 0.05); on the malpositioned upperside, the NA was 102.1 ± 6.4°, the SI was 0.21 ± 0.14 and the SC was 1.7 ± 1.1 versus, on the acceptable positioned set, the NA was 100.8 ± 6.7° (p < 0.05), the SI was 0.24 ± 0.15 (p < 0.05) and the SC was 2.3 ± 1.2 (p < 0.05). Femoral internal or external rotation sets did not show significant differences between malpositioned and acceptable positioned sets (p > 0.05). Conclusions In clinical practice, pelvic tilting along the long axis in VDHE view results in non-favourable hip changes in the NA, SI and SC on the underside and favourable on the upperside, and the internal or external femoral rotation did not affect these variables.

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

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.

Evolution of Radiographic Parameters of Canine Passive Hip Laxity at 4, 6 and 12 months: A Study of 306 Dogs

Objectives This article evaluates the variation in the distraction index (DI) and Norberg angle measurement with the femur in a neutral position and the hips distracted (distraction Norberg angle [DNA]) between 4, 6 and 12 months of age. Methods Radiographic data from dogs (n = 306) line-bred for favourable characteristics, including hip conformation, were reviewed. Dogs underwent stress radiographs, using a Vezzoni distractor, at 4, 6 and 12 months of age. The DI and DNA were calculated, and their evolution was studied for the total population and the sub-category of hips with a DI > 0.7. Results For the total population, the DI showed a significant increase from 4 to 6 months and a significant decrease at 12 months. For the hips with a DI > 0.7 at 4 months, DI at 6 and 12 months showed a significant decrease (0.14 and 0.26, respectively, on average). For the total population, the DNA followed the same pattern as the DI, and the values are significantly associated (p < 0.001). Clinical Significance The DI varies significantly from 4 to 12 months in dogs, and the time of radiographic evaluation of hip laxity may strongly influence the value of the DI. The DNA is strongly related to the DI, and its use as a more convenient indicator of hip laxity in dogs should be further investigated.

Comparison of Three Methods to Quantify Laxity in the Canine Hip Joint

Objectives Comparison of PennHIP and a novel method to diagnose hip laxity, called the Vezzoni modified Badertscher distension device technique. Methods In a total of 10 dogs, it was first assessed whether the distraction index (DI) from the PennHIP evaluation center could be reproduced by two individual observers. In the next two steps, the DI measurements made by the individual observers and the PennHIP evaluation center were compared with the laxity index (LI) measured on the Vezzoni modified Badertscher distension device view. Finally, the interobserver agreement of the DI, LI and Norberg angle was assessed and compared with classification criteria. Results The results were similar for the first three comparisons: there was no evidence for bias, the relation between DI and LI was linear and the variability was small. A comparison of the interobserver agreement showed that the measurement variability for the NA was substantial, while the reproducibility for the DI and LI was equal. Clinical Significance While the standard ventrodorsal hip extended radiograph is most commonly used for diagnosis and screening of canine hip dysplasia, it lacks sensitivity to diagnose laxity. To improve the identification of hip joint laxity, distraction-based radiographic techniques are helpful. The Vezzoni modified Badertscher distension device technique allows for a reliable in-house evaluation of canine hip joint laxity.