Severity Of Hip Dysplasia Research Articles

Radiographically Apparent Acetabular Sourcil Landmarks Are Created by Comparable Regions of the Pelvis With Extraarticular Bone Variably Confounding Estimates of Joint Coverage.

The severity of hip dysplasia is characterized by radiographic measurements that require user definition of the acetabular sourcil edge, a bony landmark for which the corresponding three-dimensional (3D) anatomy is not well defined in any imaging plane. To use digitally reconstructed radiographs to determine: (1) What 3D anatomy is contributing to the "acetabular sourcil" location used to make lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) measurements in standing AP and false-profile radiographic views, respectively? (2) How do intraobserver and interobserver agreement in LCEA and ACEA translate into agreement of the 3D anatomy being evaluated? (3) How distinct are regions around the acetabular rim circumference that are evaluated by LCEA and ACEA measurements on radiographs? Between January 2018 and May 2019, 72 patients were indicated for periacetabular osteotomy to treat hip dysplasia or acetabular retroversion at our institution. From these patients, a series of 10 patients were identified of the first 12 patients in 2018 who were treated with periacetabular osteotomy, excluding two with missing or low-quality clinical imaging. A second series of 10 patients was identified of the first 11 patients in 2019 who were treated with periacetabular osteotomy and concurrent hip arthroscopy, excluding one who was missing clinical imaging. Pelvis and femoral bone surface models were generated from CT scans of these two series of 10 patients. There were 15 female and five male patients, with a median patient age of 18 years (IQR 17 to 23 years), a preoperative LCEA of 22° (IQR 18° to 24°), and a preoperative ACEA of 23° (IQR 18° to 27°). Exclusion criteria included missing preoperative CT or standard clinical radiographic imaging or severe joint incongruity. To address our first study question, digitally reconstructed radiographs matching each patient's standing AP and false-profile clinical radiographs were created from the segmented CT volumes. A board-certified orthopaedic surgeon and three trained researchers measured LCEA and ACEA on the digitally reconstructed radiographs, and the selected sourcil points were projected back into coordinates in the 3D anatomic space. To address our second study question, intraobserver and interobserver agreement in radiographic coverage angles were related to variations in 3D coordinates of the selected bony anatomy. Lastly, to address our third study question, 3D locations around the acetabular rim identified as contributing to the lateral and anterior sourcil points were summarized across patients in a clockface coordinate system, and statistical analysis of the "time" separating the 3D acetabular contributions of the sourcil edges was performed. The 3D anatomy contributing to the lateral sourcil was a variable length (27 mm [IQR 15 to 34 mm]) span of the laterosuperior acetabular edges, with contributions by the anterior inferior iliac spine in 35% (7 of 20) of hips. The anterior sourcil reflected a 28-mm (IQR 25 to 31 mm) span of bone from the medial ilium (posterior-medial to the anterior-inferior iliac spine and anterior-lateral to the arcuate line) to the anterior and lateral edges of the acetabulum. Interobserver variability was good for LCEA (intraclass correlation coefficient [ICC] 0.82 to 0.83) and moderate to good for ACEA (ICC 0.73 to 0.79), whereas the agreement in identified 3D sourcil locations varied widely (ICC 0.32 to 0.95). The acetabular edge of the 3D anatomy contributing to the anterior sourcil overlapped the circumferential range of the acetabular rim contributing to the lateral sourcil. Projection of two-dimensional radiographic landmarks contributing to the diagnosis of structural hip deformity into 3D allowed for the identification of the overlapping bony anatomy contributing to radiographically visible anterior and lateral sourcil edges. This work leveraging digitally reconstructed radiographs and 3D pelvis anatomy has found that bone outside the joint contributes to the radiographic appearance of the sourcil and may variably confound estimates of joint coverage. Furthermore, the substantial overlap between the acetabular bone contributing to measurement of the LCEA and ACEA would indicate that these angles measure similar acetabular deformity, and that additional measures are needed to assess anterior coverage independent of lateral coverage.

The sourcil roundness index is a useful measure for quantifying acetabular concavity asphericity

This study aimed to clarify the clinical utility of the sourcil roundness index (SRI), a novel index for quantifying the asphericity of the acetabular concavity, by determining (1) the difference in the SRI between dysplastic and normal hips and (2) the correlation between the SRI and radiographic parameters of hip dysplasia. We reviewed standing anteroposterior pelvic radiographs of 109 dysplastic and 40 normal hips. The SRI was determined as the ratio of the distance from the medial edge of the sourcil to the most concave point of the acetabular sourcil (A) to the distance from the medial to the lateral edge of the sourcil (B). The formula for SRI is (A/B) × 100–50 (%), with an SRI of 0% indicating a perfectly spherical acetabulum, and higher SRI values indicating a more aspherical shape. The median SRI was greater in patients with hip dysplasia than in normal hips (5.9% vs. − 1.4%; p < 0.001). Furthermore, the median SRI was greater in the severe dysplasia subgroup (18.9%) than in the moderate (3.5%) and borderline-to-mild (− 1.3%) dysplasia subgroups (p < 0.05). Quantification of acetabular concavity asphericity by the SRI showed that dysplastic hips had a more lateral acetabular concave point than normal hips, and that the severity of hip dysplasia had an effect on the acetabular concavity asphericity.

Severity of hip dysplasia as the major factor affecting outcome of closed reduction in children with hip dysplasia.

The objective of this study was to analyze a multicenter cohort of children with developmental dysplasia of the hip (DDH) who underwent treatment with closed reduction. We sought to report the effects that severity of hip dysplasia and age have on the development of femoral head avascular necrosis (AVN) and the need for additional procedures. All patients with DDH and minimum 2 years of follow-up who underwent closed reduction were identified. The following variables were recorded: sex, laterality of hip involvement, age, acetabular index (AI), and International Hip Dysplasia Institute (IHDI) grade. The effects of patient age and pre-procedure IHDI grade on the rate of AVN and need for additional procedures after the closed reduction were analyzed using an alpha of 0.05. Seventy-eight total hips were included in the final analysis. The average patient age was 12 months. AVN of the femoral head was reported in 24 hips (30.8%) and 32 hips (41.0%) required additional surgery. Higher pre-op IHDI grade was associated with higher risk of developing Bucholz-Ogden grades II-IV AVN of the femoral head ( P = 0.025) and requiring additional surgery ( P = 0.033) regardless of patient age. There were no statistically significant differences for the effect of age on the measured outcomes ( P > 0.05). These findings suggest that severity of dislocation (IHDI grade) is a significant risk factor for the development of AVN and need for additional procedure.

Translated article] Correlation between femoral version and severity of hip dysplasia in patients with advanced osteoarthritis prior to total hip arthroplasty

IntroductionDevelopmental dysplasia of the hip (DDH) is a condition which comprises a number of joint abnormalities, including modifications in femoral version and neck-shaft angle (CCD), as well as a probable progression to osteoarthritis in certain cases. The main objective of this research was to find a correlation between femoral version and severity of DDH in patients with advanced osteoarthritis prior to joint replacement, which has not been previously reported. A secondary aim was to describe the modification of CCD as the severity of DDH increases. Materials and methodPatients over the age of 15 with dysplastic hips and severe osteoarthritis prior to total hip arthroplasty were assessed between March 2018 and February 2019. Cases with any previous hip surgery were excluded. Anteroposterior pelvis X-rays and femoral computed tomography (CT) were performed; femoral version was measured in CT and CCD was evaluated both in X-rays (2 observers: A and B) and CT (one observer: musculoskeletal radiologist). Severity of DDH was defined by observers A and B according to Crowe classification in X-rays. Statistical analysis was performed on SPSS v.21. Shapiro–Wilk test was used to confirm a normal data distribution. Intraclass correlation coefficient (ICC) determined the level of agreement between observers A and B. Pearson test assessed the correlation between femoral version and Crowe classification (positive if >0.5). Student's t test evaluated the statistical significance, which was defined as P<0.05. ResultsOne-year assessment; 42 patients (54 hips), 76% women. Mean age 52.7 years. 45 hips completed the imaging set, 9 hips were assessed only with X-rays. 48%, 16%, 7% and 28% were classified as Crowe I, II, III and IV (100% interobserver agreement). Crowe classes were grouped as I, II/III and IV due to a low number of cases classified as II and III. Mean femoral version was 21.73°, 26.8° and 43.58°, respectively. ICC between observers A and B for CCD measured in X-rays was 0.96. Mean CCD measured in X-rays for each group (I, II/III and IV) was 148.11°, 147.7° and 147°, and in CT was 131.21°, 127.9° and 122.14°, respectively. A significant difference was found in femoral version between groups I and IV (P=0.0002) and II/III and IV (P=0.042). Pearson correlation between femoral version and severity of DDH was positive (r=0.52; P=0.0002). A significant difference between CCD measured in CT was found between groups I and IV (P=0.003). ConclusionsA significant increase in femoral version related to severity of DDH and a positive correlation between these 2 features were found. Furthermore, a significant decrease in CCD between groups I and IV measured in CT was revealed. These findings would be helpful for preoperative planning of total hip replacement in osteoarthritis secondary to DDH, because once the surgeon has assessed the severity of DDH on X-rays or CT, an increased femoral version could be expected. Therefore, availability of specific implants such as conic, modular or cemented stems is critical, in order to modify the femoral anteversion to normal values in the most severe cases.

Radiographic findings have an association with weight bearing and locomotion in English bulldogs

BackgroundEnglish bulldogs are known to be prone to skeletal problems, but knowledge is lacking of the effect of these problems on locomotion and function. This study was undertaken to report the conformational, orthopaedic and radiographic findings in a cohort of English bulldogs in Finland and to evaluate how these findings affect weight bearing and locomotion of the dogs. Twenty-eight English bulldogs were prospectively recruited to this cross-sectional study. An orthopaedic examination, measurements of conformation, static and dynamic weight bearing, and radiographic examinations of elbow, hip, stifle joints and spine were done.ResultsThe English bulldogs carried a mean of 67.3% and 62.1% of their body weight in front limbs while standing and trotting, respectively. Front and hind limb lameness was seen in 20.8% (5/24) and 12.5% (3/24) of dogs, respectively. At orthopaedic examination, abnormal palpation findings (i.e. pain response, crepitation, swelling or subjectively decreased range of motion) were observed in a median of one joint (range 0–5) in each dog. Medial patellar luxation was diagnosed in 33.0% (8/24) of the evaluated dogs. At radiographic examination, elbow dysplasia was diagnosed in 48.2% (27/56) of elbow joints and severe hip dysplasia in 55.4% (31/56) of hip joints. The grade of elbow dysplasia was negatively associated with the ratio of static weight bearing between the front and hind limbs (slope estimate − 1.46, 95% CI − 2.75 to − 0.16, P = 0.03) and in dynamic weight bearing the ratio of total pressure index between the front and hind limbs (slope estimate − 0.088, 95% CI − 0.164 to 0.025, P = 0.03). The severity of hip dysplasia or hip osteoarthritis was not associated with the amount of static or dynamic weight bearing, but all except one dog were diagnosed with Fédération Cynologique Internationale grade C, D or E hips (dysplastic). In the spine, 78.6% (22/28) of the dogs had at least one malformed vertebra.ConclusionsOrthopaedic diseases and abnormal radiographic findings were common in the English bulldogs studied. The static weight bearing of the dogs was heavily distributed to the front limbs. With increasing severity of elbow dysplasia, the static and dynamic weight bearing shifted from dysplastic elbows to hind limbs.

Effectiveness of Canine Hip Dysplasia and Elbow Dysplasia Improvement Programs in Six UK Pedigree Breeds.

Hip and elbow dysplasia are common disorders in larger dog breeds and crosses, and a known contributory factor to osteoarthritis, lameness and reduced mobility. Screening schemes evaluating the severity of hip and elbow dysplasia in the UK are administered by the British Veterinary Association (BVA) and the Kennel Club (KC). The BVA/KC Hip Dysplasia scoring scheme is over 50 years old, having originated in 1965, and has operated in its current form since 1983. The BVA/KC Elbow Dysplasia grading scheme commenced more recently in 1998 and is based on the International Elbow Working Group guidelines. Hip score and elbow grade data on a considerable number of dogs in the UK have been generated from these two screening schemes. This study analyses data from dogs of six breeds scored from 1990 to present, to establish any determinable trends in hip score and elbow grade parameters, and to examine whether the implementation of such schemes has had a positive influence on hip and elbow health. A range of criteria, including the rate of participation in the screening schemes, hip score and elbow grade parameters (e.g., median, mean, standard deviation), and estimated breeding values (EBVs) were analyzed, both in the overall population and also among breeding animals. The results show a general decline in hip score parameters (median, mean, standard deviation, and 75th percentile), revealing a reduction in the prevalence and severity of hip dysplasia. There was a more modest decline in mean elbow grade within breeds. The proportion of sires and dams (of dogs born per year) with no hip score or elbow grade fell substantially over time, demonstrating good participation in the screening schemes. In most breeds, the scores of sires and dams are demonstrably improving. There is a declining genetic trend as ascertained by EBVs for both hip scores and elbow grades in most breeds, implying that the improvement observed is due in part to selection for improvement in hip and elbow health as described by the respective screening schemes.

Hip Surveillance in Children With Cerebral Palsy.

Hip dysplasia is common in children with cerebral palsy (CP), especially in those children with notable functional impairment. Severity of hip dysplasia has been shown to correlate with higher Gross Motor Function Classification System levels. Migration percentage measured on AP pelvis radiographs is the key radiographic measure quantifying hip displacement in CP. Hip surveillance programs for children with CP exist in Europe, Australia, and parts of Canada and have been adopted as standard of care. These programs have demonstrated improved detection of hip subluxation and appropriate early intervention with a resultant decrease in the number of painful dislocations. Hip surveillance programs provide healthcare providers with guidance for a schedule of obtaining hip radiographs based on patients' age, Gross Motor Function Classification System level, and migration percentage. Although systematic surveillance programs have yet to be adopted in the United States, several centers and organizations are currently investigating the potential and efficacy of hip screening in CP.

Radiological Outcomes of Overhead Traction Therapy for Developmental Dysplasia of the Hip in Non-ambulatory Children.

Infants with a dislocated and unstable hip that does not lend itself to stabilisation may be treated using overhead traction to achieve gradual reduction of the hip joint. The aim of this paper was to analyse the radiological outcomes of overhead traction therapy and the effect of duration of traction on the occurrence of complications and final treatment outcomes. Material and methodd. A retrospective analysis of medical records of 26 children (34 affected hips) involved three independent observers assessing radiological parameters before the surgery and at follow-up visits at least two years after the therapy. Overhead traction was used for an average of 35 days (range: 15-43 days). Twenty six hips were treated solely with reduction and immobilisation in a 'human position' plaster cast. Three hips were qualified for surgery immediately after a preliminary traction period. Five hips showed a suboptimal result following the immobilisation period. A MANOVA model revealed that the following factors had a significant effect on the treatment outcome: superior centring ratio of Smith (with the lowest values recorded in patients with residual hip dysplasia, p = 0.001) and acetabular angle of Sharp (with the lowest values found in patients requiring surgery, p = 0.01). Statistical tests did not show a correlation between the duration of traction and disturbance of proximal femoral metaphysis growth assessed according to Bucholz and Ogden classification. Fifteen hips were classified as type I, eight hips were graded as type II and also eight hips as type III. The lowest values of acetabular angle of Sharp were recorded in patients requiring surgery and the lowest superior centring ratio of Smith was found in those with residual hip dysplasia. The duration of overhead traction did not directly correlate with the final outcome; it only seemed to be an indicator of the severity of hip dysplasia. Routine use of overhead traction before undertaking closed reduction does not probably decrease the incidence of proximal femoral growth disturbance.

Nuances of preoperative planning of total hip arthroplasty in patients with hip dysplasia

Purpose of the study - to evaluate in different groups of patients variability of anatomical changes that may affect the difference in the length of the lower extremities and affect on the results of the preoperative planning. Material and methods. As study material we used long film X-ays of 142 patients. A main group comprised 69 patients with varying severity of hip dysplasia. Control group consisted of 73 patients without hip pathology. All patients were performed long film X-rays, and measurements of relative and absolute lengths of the lower limbs, followed by analysis of the data. Results. Analysis of the measurements showed that none of the patients had absolutely equal length of the lower limbs, even in the control group in 56.2% of the observations noted the absolute difference of the lower extremities length more than 5 mm, and in 9.6% of patients - from 20 to 35 mm. In assessing the difference of the lower extremities length on AP pelvic view in the main group only one patient of 69 had the same length of the legs, and in 61 cases the difference was more than 5 mm, that it was clinically significant. Of practical interest is the fact that in the main group shortening of the operated limb was observed in 51 of 69 patients in AP views of the pelvis, but the results of measurements of the anatomical length of limbs long film X-rays compared with measurements of the relative shortening on the pelvis AP views showed that clinically significant difference exceeding 5 mm between measurements observed in 68.1% of cases. The greatest difference between the measurements of the limbs length on the pelvis AP views and long film X-rays observed in patients with unilateral hip dislocation and averaged 17.0 mm. Conclusion. Performing preoperative planning in patients with dysplasia only on pelvis AP views not allow properly compensate the difference of the lower extremities lengths, which may adversely affect the functional results of surgery and as a result, the patient’s satisfaction. Therefore, planning THA, especially at high hip dislocation, it is necessary to calculate the difference of the lower extremities lengths considering as the difference of the lengths on AP pelvis views and long film X-rays.

Parâmetros radiográficos de displasia coxofemoral na raça Rottweiler

In this study, 139 radiographs of the Rottweiller breed dog, 44 males and 95 females were evaluated. Radiographs were classified by the degree of hip dysplasia, and we measured the angle of inclination, Norberg angle, the cortical index and percentage of coverage of the femoral head on both sides. The aim of this study was to evaluate that parameters based on gender and age of animals correlating them with the incidence and severity of hip dysplasia. In dysplastic dogs the mean Norberg angle was 100.09 ± 7.86 °, the mean percent coverage of the femoral head was 41.50 ± 8.59%, the mean femoral cortical index was 0.33 ± 0.04, and the femoral angle mean was 153.06 ± 9.81 °. Higher inclination angles were associated with smaller angles of Norberg and lowest percentage of coverage of the femoral head. In this study gender, cortical index and angle of inclination did not show any association with the DCF.

Success of Pavlik Harness Treatment Decreases in Patients ≥ 4 Months and in Ultrasonographically Dislocated Hips in Developmental Dysplasia of the Hip.

Treatment of developmental dysplasia of the hip (DDH) using the Pavlik harness has been a widely used method in patients between 0 and 6 months of age for many years. However, the factors influencing the success rate of this treatment modality have still not exactly been determined as a result of the limited number of clinical studies with higher level of evidence. We, therefore, asked whether (1) patient-related variables such as age, gender, and laterality; coexisting risk factors including family history, breech presentation, intrauterine packing, first-born girl, oligohydroamnios, and swaddling; and (2) the severity of hip dysplasia, defined by ultrasonography, are associated with differences in the success rate of Pavlik harness treatment in infants with DDH. Between 2012 and 2014, we treated 153 children (≤ 6 months of age) with DDH using the Pavlik harness. Hip dysplasia apart from coexisting neuromuscular disorders, congenital abnormalities, or syndromes was our inclusion criteria. Of patients thus treated, 130 (85%) were available for the evaluation of patient- and hip-related variables against the success of Pavlik harness treatment. Mean age of these patients on day of diagnosis and initiation of treatment was 108 days. The diagnostic and followup examinations of the hips were made by ultrasonography using Graf's method. Pavlik harness treatment was initiated in Graf Type IIa- and worse hips and treatment was considered "successful" when a Graf Type I hip was achieved. Pavlik harness treatment was successful in 92 (71%) patients (130 of 181 hips [72%]). Age was the only patient-related variable influencing the success rate of the treatment; the mean age of children in whom Pavlik harness treatment succeeded (97 ± 38 days; 95% confidence interval [CI], 90-112) was lower than the age of those who failed (135 ± 37 days; 95% CI, 123-147; p < 0.001). The highest success rate was obtained in children younger than age 3 months (37 of 40 [93%]) and the lowest one older than age 5 months (nine of 24 [37%]) (p < 0.001). The threshold age value related to an increased risk of failure was found to be 4 months and older, which had a sensitivity of 66% and a specificity of 77% (p < 0.001). A higher initial α angle was observed in the hips in which the treatment succeeded (53° ± 6°; 95% CI, 51°-53°) than in those that failed (47° ± 7°; 95% CI, 45°-50°; p < 0.001). The threshold α angle value related to an increased risk of treatment failure was 46° and less, which had a sensitivity of 47% and a specificity of 86% (p < 0.001). Dislocated hips (Graf Type III and IV hips) had the lowest rate of treatment success (five of 19 [26%] and two of four [50%], respectively), whereas Graf Type IIa- hips had the highest (27 of 29 [93%]) (p < 0.001). We conclude that Pavlik harness treatment is less effective in children at and over the age of 4 months at the time the harness is first applied as well as in hips with complete dislocations and hips with severely deficient acetabular bony roofs. In such older patients and worse hip types, the use of initial Pavlik harness treatment needs to be revisited. Future studies, comparing the outcomes of the Pavlik harness treatment and other types of interventions in such patients and hip types, are needed. Level III, therapeutic study.

Hip dysplasia in dogs: treatment options and decision making

HIP dysplasia remains a common orthopaedic disease of dogs despite many years of selective breeding based on early detection of affected animals through the British Veterinary Association/Kennel Club (BVA/KC) Hip...

Safe zone for the superior gluteal nerve in the transgluteal approach to the dysplastic hip: Intraoperative evaluation using a nerve stimulator

Background The superior gluteal nerve can be damaged during the transgluteal approach to the hip in total hip arthroplasty.Methods We studied 30 patients with hip dysplasia who underwent total hip arthroplasty through the transgluteal approach. The course of the inferior branch of the superior gluteal nerve was identified using a nerve stimulator. The distance between the nerve and the tip of the greater trochanter was measured.Results The mean distance was 37 (25–45) mm at the anterior third, 40 (30–50) mm at the middle third, and 44 (35–55) mm at the posterior third of the gluteus medius. The distance was influenced by the severity of hip dysplasia and decreased as the degree of hip dysplasia became more severe.Interpretation A 3-cm safe zone is appropriate in most dysplastic hips. In severely dysplastic hips, however, the superior gluteal nerve occasionally coursed within 3 cm of the tip of the greater trochanter. In such hips, a nerve stimulator can be used to identify the nerve.

Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Primary Total Replacement of the Dysplastic Hip*†

Developmental abnormalities following such childhood conditions as congenital dislocation and dysplasia of the hip, Legg-Calve-Perthes disease, and slipped capital femoral epiphysis are the most common cause of secondary osteoarthritis of the hip3,43 and may be a cause of degeneration in a large portion of patients with so-called idiopathic osteoarthritis of the hip43. Despite concerted screening programs, a large number of patients still have the sequelae of dysplasia or dislocation of the hip in adulthood37,117. The severity of hip dysplasia varies widely, ranging from the shallow acetabulum to the completely dislocated and so-called high-riding hip. Osteoarthritis of the hip secondary to hip dysplasia, therefore, presents a broad spectrum of reconstructive challenges. Hips that have mild anatomical abnormalities can be treated with standard primary total hip replacements, but until recently others would have been labeled unreconstructible16. Because patients who have hip dysplasia are often young and active, it is critical to understand the complexities of total hip replacement in this group and to plan any interventions meticulously. To this end, the nature and the extent of the preoperative deformities and abnormalities must be understood, and the problems that have been obstacles to obtaining satisfactory fixation with acceptable long-term function must be addressed. In this paper, we present an overview of the classification and assessment of the dysplastic hip with secondary osteoarthritis and summarize the current knowledge about total hip arthroplasty in patients who have this disorder. A thorough understanding of both the clinical and the radiographic anatomy of the dysplastic hip is necessary in order to plan and perform a reconstruction of the hip that will yield satisfactory long-term results. This anatomy may be distorted by the primary disorder and by the effects of previous operations. The anatomical abnormalities that are …

Prevalence and inheritance of and selection for hip dysplasia in seven breeds of dogs in Sweden and benefit:cost analysis of a screening and control program

Objective To determine the prevalence and changes over time in the prevalence of hip dysplasia; to ascertain whether prevalence or severity of hip dysplasia was associated with sex of the dogs, age at which coxofemoral joint status was evaluated, or ancestral background; to determine the effects of selective breeding; and to conduct an economic evaluation of the hip dysplasia program operated by the Swedish Kennel Club. Design Analysis of radiographic evaluations of coxofemoral joint conformity. Animals 83,229 dogs from 7 breeds registered by the Swedish Kennel Club. Procedure All radiographs were scrutinized by a single radiologist (LA), and coxofemoral joint conformation was classified as normal or dysplastic, with the degree of dysplasia classified as 1, 2, 3, or 4. Results Decreasing prevalence of hip dysplasia corresponding to selection of breeding stock and high heritabilities was found. Sex differences were documented in 3 of the breeds. This was interpreted as breed differences in the distribution of genes related to hip dysplasia. Economic analyses showed that costs of screening and registration of coxofemoral joints was less than the value of dogs estimated to have been saved from moderate, severe, or very severe hip dysplasia in 6 of the breeds. Clinical Implications Documented effects of age suggest that all dogs should be screened at the same age, rather than screening a few dogs at an older, more revealing age. In screening and control programs based on an open registry with access to family records, decreasing prevalence of hip dysplasia can be expected, and related to selection of breeding stock.

Plasma Amino Acids in Dogs with Osteochondrosis or Hip Dysplasia

Radiography of the hip joints of mature dogs has shown that hip dysplasia is quite common in many middle and large size breeds in Norway. The heritability of hip dysplasia has been estimated in several studies to be between 0.2 and 0.6 (Hedhammar et al 1979). This indicates that environmental factors are important for development and severity of hip dysplasia.