Birkenstock in the "Hip-Extended View"
(Dr. Nancy Hample stretching Birken's hips for an x-rays.)

The following information was taken form the PennHIP website. Please visit <http://www.vet.upenn.edu/research/centers/pennhip> for more specific and detailed information. You can also use the website to locate PennHIP certified veterinarians.

PennHIP stands for the University of Pennsylvania Hip Improvement Program. (Non-profit organization).

PennHIP is a multifaceted radiographic technology (x-ray) for hip evaluation. The technique assesses the quality of the canine hip and quantitatively measures canine hip joint laxity. The PennHIP method of evaluation is more accurate than the current standard in its ability to predict the onset of osteoarthritis. Osteoarthritis, also known as degenerative joint disease (DJD), is the hallmark of canine hip dysplasia (CHD) PennHIP is more than just a radiographic technique. It is also a network of veterinarians trained to perform the PennHIP methodology properly and, perhaps most importantly, it is a large scientific database that houses the PennHIP data. The radiographs are made by certified PennHIP members worldwide and are sent to the PennHIP analysis center for evaluation. The resulting data is stored in the database, which is continually monitored as it expands. As more information becomes available, the PennHIP laboratory is able to obtain more precise answers to questions about the etiology (cause), prediction and genetic basis of CHD.

The PennHIP method is a different way to assess, measure and interpret hip joint laxity. It consists of three separate radiographs: the distraction view, the compression view and the hip-extended view. The distraction view and compression view, developed by Dr. Smith, are used to obtain accurate and precise measurements of joint laxity and congruity. This is reported as the "Distraction Index" or DI. The lower the DI number, the better the hip is supposed to be. The hip-extended view is used to obtain supplementary information regarding the existence of DJD in the hip joint.

The Distraction Incex (DI) is a unitless number ranging from 0 to 1 (or more). It does not allude to a passing or failing score. Hips with DIs on the distraction view that are close to 0 are considered to be tight, while DIs close to 1 are considered to be very loose. The DI is an indication of the "percent out of joint" that the femoral head is displaced from the acetabulum. For example, DI=0.58 means the femoral head comes out of the joint by 58%, DI=0.75, 75% out of joint. This also makes interpretation of the DI more intuitive: a hip with a DI=0.50 is twice as lax as a hip with a DI=0.25.

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