PennHIP -

The University of

Pennsylvania Hip Improvement Program

What is PennHIP?

PennHIP is a not-for-profit veterinary health service at the University of Pennsylvania.

PennHIP is a multifaceted radiographic screening method 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 (OA).

Osteoarthritis, also known as degenerative joint disease (DJD), is the hallmark of hip dysplasia (HD).
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. 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, prediction and genetic basis of hip dysplasia.

PennHIP publishes its findings in scientific journals. Published information is disseminated to all
PennHIP members; it is also shared with interested breed clubs and routinely appears in
publications within the dog fancy.

PennHIP is composed of three major components:

A diagnostic radiographic technique
A network of trained veterinarians
A medical database for scientific analysis

PennHIP at a Glance

The PennHIP method is a novel 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 are used to obtain accurate and precise
measurements of joint laxity and congruity. The hip-extended view is used to obtain supplementary
information regarding the existence of osteoarthritis (OA) of the hip joint. (The hip-extended view
is the conventional radiographic view used to evaluate the integrity of the canine hip joint.) The
PennHIP technique is more accurate than the current standard, and it has been shown to be a
better predictor for the onset of OA.

The radiographs pictured here are of the same dog, yet the hip joint laxties in each view look
very different. Notice that the hips in the distraction view appear to be much looser than they do
in the hip-extended view.

The obvious contrast in joint laxity between the distraction and hip-extended views
demonstrates the fundamental difference between the two radiographs. The looser
the joint on the distraction view, the greater is the chance that the hip will develop OA.
The hip-extended view tends to mask true hip joint laxity because the joint capsule is
wound up into a tightened orientation when the hips are extended. This explains why
measurable joint laxity on the distraction view is always greater than the measurable
laxity from the hip-extended view. In fact, distraction laxity is up to 11 times greater
depending on the breed of dog under study.

The compression view is used to determine the "goodness of fit" of the femoral
heads into the acetabula. In a hip with OA, the remodeling that occurs in the
acetabulum and/or the femoral head, will often result in an ill-fitting "ball" and "socket".

Distraction View

Compression View

Hip-Extended View

To summarize, PennHIP method:

Obtains OA readings from the standard hip-extended view
Obtains hip joint congruity readings from the compression view
Obtains quantitative measurements of hip joint laxity from the distraction view.