The Importance of Precise Positioning

More than 30 years of experience doing hip radiographs has taught me many valuable things, the most important being that precise positioning is crucial to getting an accurate evaluation.

As I began to do more and more x-rays, I also began to see more and more films done by other veterinarians brought to me by owners/handlers who didn’t feel the official grade their dog had received was a true reflection of the dog’s hip conformation.  The more I spoke with these owners/handlers and the more x-rays I saw, a trend began to emerge.  Many of the reports issued to these owners with failing grades listed subluxation (either one-sided or two) as the only radiographic finding. I had realized long ago that imprecise positioning could often cause a non-dysplastic dog to look dysplastic. A tilted pelvis, patellas rotated outwardly or femurs not  parallel to one another can sometimes drastically change the appearance of the hip joint.

I then began to notice that once I had taken the x-rays and positioned them according to published standards of both the O.F.A. and the veterinary community, these dogs were now receiving passing grades!

For years I knew that my theory made perfect radiographic sense:  accurate assessments about the formation and structure of the hip joints can not be made without accurate positioning reflecting the true anatomical state of the hips.  But I didn’t have any proof to back that up.  Until recently.

I finally decided to do a small study.  I contacted owners of dogs who had come to me to have hip radiographs done after they had been done elsewhere and submitted to the O.F.A. This survey sample of 105 dogs was taken from patients/clients seen here at my clinic between January of 2003 and May of 2009.  Of the 105 surveys sent, I received 53 responses.   Among those 53 responses, 27 of the dogs had received failing grades with subluxation (either unilateral or bilateral) being the only radiographic finding.  As positional subluxation can often give the appearance of dysplasia, this is the group I focused on for the core of my study.

For an easy-to-read summary of my findings, click here.

To read my full study about the variation in O.F.A. grades in dogs with unilateral or bilateral coxofemoral subluxation only, click here.