 |
Osteochondrosis/osteochondritis dissecans lesions of the
humeral condyle can be observed on the craniocaudal view radiograph of the elbow as a
subchondral bone defect that affects the trochlea (the medial portion) of the humeral
condyle. These lesions can be subtle and may not be identified unless the radiographs are
of good quality and evaluated carefully. The pronated oblique, craniocaudal view is often
of value in identifying lesions that may not be apparent on nonoblique craniocaudal view
radiographs. If the lesion is large, an irregular subchondral bone defect or flattening of
the articular surface of the medial condyle may be visible on the lateral view radiograph. |
| Secondary, degenerative changes are usually present in dogs
seven months of age and older. As previously stated osteochondrosis/osteochondritis
dissecans of the humeral condyle can and often occurs concurrently with fragmented
coronoid process. True osteochondrosis/osteochondritis dissecans lesions of the humeral
condyle can sometimes be difficult to distinguish radiographically from erosive lesions of
the trochlea of the humeral condyle induced by fragmented coronoid process particularly in
older dogs. |
 Radiographs of a dog's elbow affected with
osteochondritis dissecans. These are mild degenerative changes along the medial aspect of
the elbow. The lesion (circle) can only be readily visualized on the oblique view. |
 Approach to
the elbow using an osteotomy of the medial epicondyle to excise and debride an
ostochondritis disecans lesion. |
Treatment involves excision of the cartilage flap and
curettage of the subjacent subchondral bed. Some veterinary surgeons are now
treating these lesions with arthroscopy. Arthroscopy allows a greater extent of the joint
to be evaluated with the advantage of magnification. While the immediate postoperative
morbidity is probably less with arthroscopy than arthrotomy, the long-term functional
results are probably similar. |
| Several surgical approaches have been described
for approaching the medial compartment of the elbow. A recent study performed using
cadaver limbs evaluated articular cartilage exposure and immediate postoperative stability
afforded by three described approaches to the medial compartment of the elbow, an
osteotomy of the medial epicondyle, a longitudinal myotomy of the flexor carpi radialis
muscle, and a desmotomy of the medial collateral ligament which included a tenotomy of the
pronator teres muscle. The approach using an osteotomy of the medial epicondyle provided
significantly greater exposures of the humeral articular cartilage (22%) than either of
the other two approaches and the approach using a desmotomy of the medial collateral
ligament provided significantly greater exposure of the humeral articular cartilage
(16.5%) than the approach using a longitudinal myotomy of the flexor carpi radialis muscle
(6.6%). The immediate postoperative stability of the approach using an osteotomy of the
medial epicondyle and the approach using a longitudinal myotomy of the flexor carpi
radialis muscle were significantly greater than that of the approach using a desmotomy of
the medial collateral ligament. It must be noted, however, that testing of the limb was
performed with both the elbow and carpus in 90 of flexion to accentuate the soft tissue
contributions to valgus stability of the elbow. At lesser angles of elbow flexion,
interlocking of the anconeal process in the trochlea and olecranon fossa provided the
valgus stability of the elbow. This locking mechanism of the anconeal process in the
trochlea and olecranon fossa probably negates much of the morbidity of any surgical
approach to the medial compartment of the elbow and accounts for the lack of reported
complications associated with the use of the medial desmotomies in clinical cases. |
 Approach to
the medial aspect of the elbow using a muscle separating approach. |
 Approach to
the medial aspect of the elbow using a tenotomy of the pronator teres muscle. |
| We and others have experienced implant
complications in clinical cases in which we used an osteotomy of the medial epicondyle to
approach the medial compartment of the elbow and feel exposure of the trochlea of the
humeral condyle is sufficient to excise cartilage flaps and curette the lesion's bed using
a muscle separating approach between the flexor carpi radialis muscle and the pronator
teres muscle. In some instances exposure is sufficient by retracting the medial collateral
ligament but in many instances a medial desmotomy is required. A myotenotomy of the
pronator teres muscle can be performed if additional exposure is required; however, this
is seldom necessary and should be avoided in performance dogs. Osteochondritis dessicans
lesions of the humeral condyle may not always be obvious at surgery. If a lesion is
suspected based on the pre-operative radiographs and is not readily apparent at
arthrotomy, the articular surface of the trochlea of the humeral condyle should be probed
with a Freer periosteal elevator. In these instances the malacic cartilage will readily
separate from the adjacent unaffected cartilage. All diseased cartilage should be excised
and the subchondral bed curettaged. Osteochondritis dissecans lesions of the humeral
condyle should be differentiated from erosive or "kissing" lesions of the
trochlea of the humeral condyle which frequently occur in response to fragmented coronoid
process. |
 |
Removal of osteochondritis lesion of the humeral
condyle during arthrotomy
|
| Postoperatively the limb is placed in a soft
padded bandage for 2 to 4 days following surgery to limit swelling and exercise is
restricted for 3-4 weeks. The prognosis for return to function is again somewhat guarded
for dogs with osteochondrosis of the humeral condyle. The prognosis seems to be somewhat
dependent on the size of the lesion and the extent of degenerative joint disease present
at the time of surgery. Young dogs with small lesions and minimal degenerative joint
disease are stated to have a more favorable prognosis than older dogs with larger lesions
and more advanced degenerative joint disease. Although degenerative joint disease
progresses irrespective of surgical intervention, most dogs regain reasonable limb
function following surgery. Medical management of degenerative joint disease may be
necessary. Some dogs may have acceptable limb function to return to hunting and other
working activities. |
