ofa-hip-rating-explanation

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The phenotypic evaluation of hips done by the Orthopedic Foundation for Animals falls into seven different categories. Those
categories are normal (Excellent, Good, Fair), Borderline, and dysplastic (Mild, Moderate, Severe). Once each of the radiologists
classifies the hip into one of the 7 phenotypes above, the final hip grade is decided by a consensus of the 3 independent outside
evaluations. Examples would be:

Two radiologists reported excellent, one good—the final grade would be excellent
One radiologist reported excellent, one good, one fair—the final grade would be good
One radiologist reported fair, two radiologists reported mild—the final grade would be mild

The hip grades of excellent, good and fair are within normal limits and are given OFA numbers. This information is accepted by
AKC on dogs with permanent identification (tattoo, microchip) and is in the public domain. Radiographs of borderline, mild,
moderate and severely dysplastic hip grades are reviewed by the OFA radiologist and a radiographic report is generated
documenting the abnormal radiographic findings. Unless the owner has chosen the open database, dysplastic hip grades are not in
the public domain.

EXCELLENT HIP JOINT CONFORMATION

This classification is assigned for superior conformation in
comparison to other animals of the same age and breed.
There is a deep seated ball (femoral head) which fits tightly into a
well-formed socket (acetabulum) with minimal joint space.
There is almost complete coverage of the socket over the ball.

GOOD HIP JOINT CONFORMATION

Slightly less than superior but a well-formed congruent hip joint is
visualized. The ball fits well into the socket and good coverage is present.

FAIR HIP JOINT CONFORMATION

(Figure 3): Assigned where minor irregularities in the hip joint exist. The hip joint is wider than a good hip phenotype. This is due
to the ball slightly slipping out of the socket causing a minor degree of joint incongruency. There may also be slight inward
deviation of the weight-bearing surface of the socket (dorsal acetabular rim) causing the socket to appear slightly shallow (Figure
4). This can be a normal finding in some breeds however, such as the Chinese Shar Pei, Chow Chow, and Poodle.

BORDERLINE HIP JOINT CONFORMATION

There is no clear cut consensus between the radiologists to place the hip into a given category of normal or dysplastic. There is
usually more incongruency present than what occurs in the minor amount found in a fair but there are no arthritic changes
present that definitively diagnose the hip joint being dysplastic. There also may be a bony projection present on any of the areas
of the hip anatomy illustrated above that can not accurately be assessed as being an abnormal arthritic change or as a normal
anatomic variant for that individual dog. To increase the accuracy of a correct diagnosis, it is recommended to repeat the
radiographs at a later date (usually 6 months). This allows the radiologist to compare the initial film with the most recent film over
a given time period and assess for progressive arthritic changes that would be expected if the dog was truly dysplastic. Most dogs
with this grade (over 50%) show no change in hip conformation over time and receive a normal hip rating; usually a fair hip
phenotype.

MILD HIP JOINT CONFORMATION

There is significant subluxation present where the ball is partially
out of the socket causing an incongruent increased joint space.
The socket is usually shallow only partially covering the ball. There
are usually no arthritic changes present with this classification and if
the dog is young (24 to 30 months of age), there is an option to
resubmit an radiograph when the dog is older so it can be
reevaluated a second time. Most dogs will remain dysplastic
showing progression of the disease with early arthritic changes.
Since HD is a chronic, progressive disease, the older the dog, the
more accurate the diagnosis of HD (or lack of HD).

MODERATE HIP JOINT CONFORMATION

There is significant subluxation present where the ball is barely seated into a shallow socket causing joint incongruency. There are
secondary arthritic bone changes usually along the femoral neck and head (termed remodeling), acetabular rim changes (termed
osteophytes or bone spurs) and various degrees of trabecular bone pattern changes called sclerosis. Once arthritis is reported,
there is only continued progression of arthritis over time.

SEVERE HIP JOINT CONFORMATION

Assigned where radiographic evidence of marked dysplasia exists.
There is significant subluxation present where the ball is partly or
completely out of a shallow socket. Like moderate HD, there are
also large amounts of secondary arthritic bone changes along the
femoral neck and head, acetabular rim changes and large amounts
of abnormal bone pattern changes.