Developmental Hip Disorders PDF

24/08/20 Developmental diseases of the hip 227.417 SEMSTIII Andrew Worth Hip Dysplasia Polygenic, multifactorial, developmental All breeds of dogs, humans and rarely in cats. Most common in large breed/ rapidly growing. Clinically it may manifest as lamenes...

24/08/20 Developmental diseases of the hip 227.417 SEMSTIII Andrew Worth Hip Dysplasia Polygenic, multifactorial, developmental All breeds of dogs, humans and rarely in cats. Most common in large breed/ rapidly growing. Clinically it may manifest as lameness or gait abnormality in puppies (with joint instability) and as the major cause of secondary osteoarthrosis (DJD) in older dogs 1 24/08/20 2  24/08/20 6 & 17 month old Newfoudland The role of genetics Heritability is reported as 0.25 (Reed et al JAVMA to 0.6 (Smith & Coworkers PennHip) 2000 using OFA scores) This is an indication of the degree to which the sire and dams phenotype is reflected in the offspring The trait is complicated in its mode of inheritance New work on the dog genome may lead to the development of genetic tests 3  24/08/20 Progress on understanding the genetics of CHD QTL analysis revealed 19 candidate loci on nine different chromosomes CFA9, paraoxonase-2 (PON2) on dog chromosome CFA14 and fibronectin-1 (FN1), fibrillin-2 gene (FBN2) FBN2 gene is associated with four phenotypic markers for the presence of CHD (NA, DI, DLS ,OFA hip grade Environmental Factors - Nutrition Early work suggested lack of calcium or high phosphorus to calcium ratio might have a causative effect High protein diets have been incriminated by some trials but this is disputed by others Overall calorie intake, ie excessive energy is now reported to be a risk Environmental Factors - Nutrition For dogs between 6 wks and 1yr of age, the freq & severity of CHD and OA were reduced markedly in labradors by limiting food consumption by 25% compared to ad lib fed littermates Overfeeding itself does not cause CHD, it maximises trait expression in genetically susceptible individuals 4  24/08/20 Steroid hormones & Relaxin Testosterone and estradiol-17B have been detected in the serum of labrador pups from dysplastic, but not from non- dysplastic matings Relaxin has also been reported to persist in the serum of dysplastic labrador bitches throughout lactation instead of only the first 1-2 wks as usual Exercise Controversy still rages over the beneficial or detrimental effects of exercise in the development of CHD The hip is stabilised primarily by the surrounding muscles therefore muscle development should be helpful But high impact exercise and prolonged weight bearing aggravates subluxation CHD pathogenesis The coxofemoral joint is normal at birth Genetically susceptible dogs become dysplastic when the primary muscle mass supporting the joint fails to mature at the same rate as the skeletal structures The most important time in the develop- ment of the hip joint is the first 60 days If the forces of activity and weight-bearing exceed muscle forces this leads to loss of congruity 5  24/08/20 Pathogenesis cont Joint effusion and stretching of the joint capsule can occur as early as 3 months Instability causes the dorsal acetabular rim to be subjected to abnormal loads Microfractures of the DAR and labral tears Cartilage injury results and DJD ensues Periarticular fibrosis and DJD set-in The dorsal acetabular rim is subjected to abnormal loads 6  24/08/20 Clinical Signs Young dogs Old dogs Ø As early as 3 mths Ø >1 year Ø Peak at 6 months Ø Often no signs as Ø Due to instability pup or got better till Ø Exercise intolerance much older dog Ø Exercise intolerance Ø Difficulty rising Ø Lameness & jt pain Ø Lameness & jt pain Ø Difficulty rising Ø Bunny-hopping gait and base narrow or Ø Worse after rest wide stance Ø Muscle atrophy Labrador pup same hip at 6 at 6 mths years Early diagnosis of hip dysplasia o Laxity can be detected by; Ortolani sign, Barden’s sign, Distraction index (from 4 months PennHIP® reliable o Xrays may show subluxation but there are false negatives o Radiographic DJD documented by OFA (extended VD) radiographs but in dogs 0.4 18kg have poorer outcomes? Cranio-lateral approach to the hip Don’t cut perpendicular to neck Do exercise the dog immediately 24  24/08/20 Excision arthroplasty of the hip joint in dogs and cats W. Off; U. Matis Department of Small Animal Surgery and Reproduction, Ludwig-Maximilians-University, Munich, Germany. From 1978 to 1989, 132 dogs and 51 cats underwent femoral head and neck ostectomy. Clinical and radiographic re-evaluations were carried out an average of four years postoperatively in 81 (44%) of the animals, and gait analysis was also done in 17. The functional results were rated good in 38% of patients, satisfactory in 20%, and poor in 42%. However 96% of the owners were satisfied with the results. Kinetic and kinematic measurements showed that although femoral head and neck resection alleviated pain, it resulted in functional deficits in small as well as large breed dogs. These deficits were not visible during rapid movement. Legg-Calve-Perthes Disease Aseptic necrosis of the femoral head Small breeds, esp terriers, juveniles Clinical signs from 5 months Male & female equally affected May be bilateral, commonly unilateral Inherited, autosomal recessive gene Ischaemia followed by trabecular collapse and deformity of the bone Painful hip, diagnosed by radiography Treatment of choice is FHO Radiography -focal areas of reduced opacity within head -widened and irregular joint space -later the head becomes flattened and there is remodelling of the acetabulum 25 24/08/20 26