Re: [PyrNet-L] penn hip question

[Kshoffman@aol.com]

In a message dated 02/09/2000 6:42:00 PM Eastern Standard Time, 
ahasper@mmcable.com writes:

<< ok i'm feeling really stupid right now *L* but what is Penn hip? is it just
 a normal xray of the hips?>>

No, it is not the typical normal xray of the hip, generally referred to as 
the traditional "extended view" that OFA and other registries require.  With 
the extended view the dog is on its back and the legs are pulled straight 
down and must be symmetrically positioned relative to the spine and pelvis, 
no tilting in either direction, knees in alignment.  This type of xray is 
merely looking at the hip joint conformation for signs of: 1) joint laxity 
(ball not tightly and deeply seated in the socket which can vary within a 
range of non-acceptable and acceptable, the tightest fit possible being most 
desired); 2) joint remodeling, i.e., wearing of the edges of the acetabulum 
or socket the ball fits into, and/or wearing or flattening on the edges of 
the ball portion of the femur head or thickening in the neck portion of the 
femur; 3) other signs of degenerative joint disease such as arthritic 
changes; and 4) the angle at which the ball goes into the socket. (Possibly 
other variables I am neglecting.)  This view for hip joint evaluation is 
generally predictive pretty predictive between 12 and 24 mos of age, however, 
OFA's data from years ago showed them it is most predictive if done at 24 mos 
of age or greater, so this is why the 24 mos required for final 
certification.  They will however evaluate and issue a preliminary report and 
rating prior to this age, just not a certification.  OFA and GDC evaluate 
such films (3 opinions generally) and assign consensus passing ratings of 
fair, good, or excellent.  There are also affected ratings of mild, moderate, 
severe, and there is a "borderline" rating which indicates repeat the film in 
some period of time as the results were questionable but not clearly affected.

PennHip is different.  PennHip uses a compression/distraction method of 
viewing the hip joint in an effort to gauge and predict joint laxity.  The 
dog is in a frog leg position as I recall and first the hips are pushed in as 
tight as possible and an xray shot, then some pressure is applied to the hip 
joints to move them away from the socket (not enough to injure, mind you) and 
this view also shot.  The former is compression, the latter distraction.  
They then take various different measurements to compare the amount of joint 
laxity between the two views, and these in turn are compared to other 
representatives of the breed and other representatives over all breeds as 
well.  It is a very quantitative, measurement related means of evaluation and 
supposedly quite precise. It is all based on the premise that excessive joint 
laxity is the number one contributing factor as far as predicting future hip 
dysplasia.  It is supposedly 90-95% predictive as early as 16 wks of age, 
100% predictive at later ages, probably from 12 mos on. A number of 
measurements are taken and included in a formula or score that is called the 
"distraction index" and it is a number between 0 and 1 for each hip.  Zero 
equals no laxity, one equals the most laxity.

Over all breeds, they say that any dog with DI less than 0.25 will never 
become dysplastic.  Dogs that fall between 0.25-0.50 *may* become dysplastic, 
the higher the DI the higher the risk, and dogs between 0.50-1.0 are very 
likely or sure to become dysplastic, again the higher the rating the worse 
the risk and presumably the more severe the case.  They also still do the OFA 
type extended view as part of a PennHip exam (I believe they still include 
that as part of the evaluation) originally included primarily to compare the 
results of the extended view and rating method to the results of the more 
quantitative distraction index method.

PennHip ratings are also going to necessarily be breed related, that is some 
breeds may always fall within a certain range that may be considered 
acceptable for that breed, but perhaps not within that most optimal range 
across all breeds.  For example, I believe it is not all that common for a 
Great Pyr to get a PennHip DI < 0.25, more often as I recall most OFA passing 
Pyrs get DI ratings in the 0.20-.40 range with the high 0.2's to the low to 
mid 0.3's being common. 

<< is it something i should specifically request to
 have done at the vets? Maya will be a year old on Feb 14th, I can't believe
 a year has went by already since we got her *L* but i've noticed her
 slightly drooping, walking with a slight limp etc.. once in awhile in the
 hindquarters for the past couple of days, i'm not sure if she's twisted her
 leg while playing with the new pup Hardy in one of the many holes she's dug
 or what, but we are making an appointment to have her xrayed now to see
 exactly what's wrong with her.>>

Sounds like a good idea.  Regardless of method, your vet will likely put her 
under anesthesia as is commonly done for OFA views and I believe required for 
PennHip method.  Only certain vets are certified to do PennHip whereas any 
vet *can* do OFA view (but some are better skilled than others in my 
opinion.)  If you can locate a PennHip certified vet nearby it would be 
interesting to go that route and get both ratings, OFA and Pennhip.  We 
really don't have enough PennHip data at this point in Pyrs to know exactly 
what to make of the current range of DI's we see in the breed, so 
contributions of data always help.  PennHip may be a tad more expensive, but 
likely not much more if anesthesia will be used with OFA anyway.

If your bitch is around a year of age, and has been limping on and off, I 
would definitely have xrays done to determine what the problem is.  One year 
of age is a prime time for many different growth related lameness disorders, 
not just hip dysplasia.

Kelley Hoffman
kshoffman@aol.com