UNDERSTANDING ELBOW DYSPLASIA

 

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The IEWG elbow dysplasia grading scheme

- An explanation for owners and breeders -

This article has been prepared by Leanne Fitzsimmons. For further information please call on
1300 300 892 or email on via@online-vets.com




The expression 'Elbow Dysplasia' (ED) is used to describe abnormal development of the elbow joint. Regardless of the inciting cause, secondary osteoarthritic changes are used to identify the presence of ED as well as to grade its severity. The main primary causes of ED are:


• osteochondritis dissecans (OCD) of the medial humeral condyle

• fragmented medial coronoid process (FCP) of the ulna

• ununited anconeal process (UAP) of the ulna

• humero-radio-ulna joint incongruity (elbow joint incongruity).



  A          B

The flexed lateral radiograph of the elbow is required for elbow dysplasia assessment. The image [A] depicts a normal elbow while in [B] the anconeal process [arrow] has failed to unite to the ulna.



ED is recognized clinically in growing dogs, usually presenting as lameness from 5-6 months of age. Lameness is not a good indicator of elbow status, however, as many dogs with ED are sound (ie they are subclinically affected). Dogs with subclinical ED are capable of producing clinically affected (lame) progeny, so it is also important to monitor ED in the progeny of breeding stock. Many breeds are susceptible to ED but there is a higher incidence in certain breeds.

The most important causal factor of ED is the genetic make-up of the dog. Other factors, such as growth rate, diet and level of exercise may influence the severity of ED in an individual dog, but those (environmental) factors cannot prevent the disorder or reduce the potential of the dog to pass the disease on to offspring. ED has a high heritability, similar to that of Hip Dysplasia.

The scheme designed by the International Elbow Working Group (IEWG) is based on taking radiographs of the elbow to identify and grade signs of elbow osteoarthritis. By selecting animals with the best elbows you can successively reduce the incidence of ED in the progeny of your breeding stock. The radiographic projection recommended to grade dogs for ED is a well flexed medio-lateral view of the elbow joint. Dogs must be at least 12 months old when the radiographs are taken. The radiographic view displays the anconeal process, which enables any signs of ED to be numerically graded using the system created by the IEWG. It is the thickness of any enthesophyte (new bone) formation on the non-articular surface of the anconeal process that is measured.


Grading System:

• Grade 0 = normal elbows (no enthesophyte formation)

• Grade 1 = Mild ED (<2mm thickness of new bone formation)

• Grade 2 = Moderate ED or a primary lesion (2mm to <5 mm of new bone)

• Grade 3 = Severe ED (5+ mm of new bone formation or UAP)



For additional information about elbow dysplasia, follow this link:
http://www.offa.org/edproc.html