Page 88 - Clinical Manual of Small Animal Endosurgery

76 Clinical Manual of Small Animal Endosurgery

the cannula, drawing the fragment through the soft-tissue envelope.
If the fragment is very large, it is necessary to increase the size of
the instrument portal to accept sufficiently large grasping forceps for
retrieval. In this circumstance it is preferable to work without using
an instrument cannula to enable retrieval of a large fragment directly
through the soft tissues. Large fragments can also be removed piecemeal
by breaking off manageable fragments with the grasping forceps. Care
should be taken to avoid damaging the delicate forceps when using
this technique. A third method to remove a separated coronoid fragment
is to burr the fragment using a hand burr or a power burr. Motorised
burring has the advantage of being rapid; furthermore, the suction
attached to the burr sleeve efficiently removes the osteochondral debris,
maintaining a clear view and preventing loss of debris into the joint
space. Some workers continue to debride the coronoid region to several
burr diameters below the height of the articular surface of the radial
head in an attempt to remove additional diseased bone from the coronoid
process. The therapeutic value of this technique has not been assessed
and the rationale behind this deliberate removal of subchondral bone
from the coronoid bed is the highly variable outcome observed among
clinical cases following simple retrieval of the coronoid fragment without
additional treatment of the lesion. Following lavage of the joint to
remove debris, remaining lavage fluid is aspirated using the egress needle
and portals are closed with simple skin sutures. A repeat injection con-
taining ropivacaine with morphine is given using the same doses as
calculated for the preoperative administration to augment the postopera-
tive analgesia protocol.

Arthroscopically assisted surgery of osteochondral lesions of the medial aspect
of the humeral condyle
A change in the understanding of elbow dysplasia has led to a shift in
the description of the lesions typically seen affecting the medial humeral
condyle that were traditionally known as osteochondrosis. Histopatho-
logical analysis of these lesions has identified similar pathological changes
to those seen in the ‘transchondral fracture’ that occur in traumatic
injuries in adolescent human beings. Consequently, the term ‘osteochon-
dral’ lesion is used to describe the flaps of cartilage and underlying
subchondral bone seen affecting the medial aspect of the humeral condyle.
These lesions often occur in association with arthroscopically visible
disease of the coronoid process and they also occur in apparent isolation,
although, in such circumstances, current opinion suggests that there
is normally subchondral disease of the ulna, even if there is no grossly
abnormal overlying cartilage.
The medial aspect of the humeral condyle is readily viewed and
treated using the portals already described above, though sometimes it
may be necessary to place the arthroscope portal a few millimetres
further caudally to view the entirety of a large osteochondral lesion. The
entire joint should be systematically inspected as described above for