Penn & OFA Hip Certification

Canine hip dysplasia (CHD) is a serious orthopedic developmental disorder that leads to varying degrees of osteoarthritis, restricted joint mobility, pain and lameness.  This complex disease has been defined as a biomechanical disorder characterized by primary hip joint laxity in immature animals resulting in incongruency, abnormal mechanical forces and secondary development of degenerative joint disease (DJD).  Although hip joint laxity is not the sole factor in the development of CHD, studies have shown passive hip joint laxity to be the most important parameter in determining the risk of developing DJD of the coxofemoral joint.

PennHip is a new radiographic procedure which involves special positioning and equipment in order to accurately measure the patients passive hip laxity (4).  The PennHip's quantitative value, called the distraction index, has been shown to be superior to other radiographic objective (Norberg angle) or subjective (OFA score) values in determining the patient's passive hip laxity and therefore in predicting the patients susceptibility to CHD as well (1).   CHD prediction has been shown to be acceptably accurate in patients as young as four months of age and the correlation between passive hip laxity and later development of hip DJD was shown to increase when the hips were evaluated at 6 and 12 months of age.

The early estimate of a patients hip integrity is invaluable no matter if the dog's intended purpose is breeding stock, working or simply a family pet.  Estimates of heritability of passive hip laxity, as measured by the distraction index, are high and suggest the use of the distraction index as a selection criteria should result in a more rapid progress in reducing the incidence and severity of CHD than previous methods .   For breeders this means the PennHip database will allow informed selection of breeding stock based on hip tightness compared to other members of the same breed and to determine the progress they are making with their breeding program in reducing the amount of hip laxity in their dogs.  For pet owners, this means an earlier determination of their pets susceptibility to development of DJD which could allow the veterinarian, if indicated, to develop a lifestyle regimen to hopefully minimize disease expression.   Early identification of individuals with a high susceptibility for developing DJD is important since there presently is no medical or surgical cure for CHD and studies have shown changes in lifestyle (i.e. caloric intake) or use of medication (i.e. polysulfated glycosaminoglycans) must be instituted early on in the course of the disease in order to have the optimal benefits.