||Non-fusion of the Anconeus
Common names or abbreviations:
Anconeal process (UAP)
Description or definition:
dog’s forelimb from the elbow to the wrist is comprised of two bones
called the radius and the ulna. The
top end of the ulna has
a curved indentation which allows the rounded bottom of the humerus
(upper leg bone) to fit together and form a joint. The top lip of
this notch is called the anconeal process, and the bottom lip of
this notch is called the coronoid process. The
use of the word process refers to the fact that this is a part of the
bone that articulates, or moves, with another bone.
a normal dog is growing, the anconeal process (AP) fuses with the ulna.
The AP should become fully united (fused) with the ulna by the time the
dog is 4-5 months old. But if it does not unite, it can detach
completely and float in the joint capsule, causing pain and eventual
is considered to be a form of osteochondritis, with the same
causative factors, heredity, injury, and diet. For more
information see the separate listing for osteochondrosis
/ osteochondritis dissecans
joint incongruity can lead to UAP if the radius grows relatively faster
than the ulna. For
more information on joint incongruity see the separate GTF listing for
premature closure of the distal ulnar physis.
pain, standing with pasterns turned inward and toes out, standing or
moving with elbows out, thickened
AP is enclosed within the joint capsule and is only visible in x-rays
taken from a specific angle with the elbow partially flexed.
are many different surgical options for AP. Surgical
removal of the fragment is possible, however, can result in instability
of the joint and continued degenerative joint disease. If the
problem is diagnosed very early, the AP can sometimes be permanently
fixed to the ulna. Unfortunately, in many cases the AP is already
too damaged for this repair by the time diagnosis is made.
possible option is ulnar osteotomy (surgical division or excision of the
bone, or a portion of the bone) to relieve the pressure on the anconeal
process. In theory, with the pressure removed, the anconeal
process can fuse normally. This procedure, in appropriate
cases, is reported to be very effective in restoring pain‑free use
of the elbow and delaying the progression of DJD. With any form of
surgery, degenerative joint disease (DJD) is still likely to develop,
but at a much slower rate.
more information about this condition, or if your dog is experiencing
lameness, consult your veterinarian for advice.
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