Page 67 - Clinical Manual of Small Animal Endosurgery

Diagnostic Arthroscopy 55

viewed region of the joint just cranial to the arthroscope tip. It is prefer-
able to maintain the scope position and to manipulate the needle and
not the arthroscope until triangulation is achieved. A deep, 3 mm longi-
tudinal incision is made adjacent to the needle, creating a soft-tissue
tunnel access to the joint, and a blunt trocar is directed down the soft-
tissue tunnel and into the joint cavity, passing parallel to and next to the
needle. Once the obturator is visualised by the scope, the needle is
removed. An instrument cannula is inserted into the joint over the obtu-
rator, followed by a blunt probe in exchange for the obturator. Once the
blunt probe is visualised, instrumented inspection of the joint begins.
Continued pronation of the distal antebrachium is essential to maintain
a working space within the medial aspect of the elbow joint.
The coronoid region is probed to assess the integrity of its overlying
cartilage and to determine if the coronoid region is stable or conversely
if fragmentation of the coronoid process is present. Probing of the car-
tilage may reveal abnormally soft cartilage, mild chondromalacia or
fissuring. If an unstable coronoid fragment is present, yellow avascular
bone is visible on the underside of the fragment and on the coronoid
bed. On occasions, a coronoid fragment remains in situ still covered with
a layer of cartilage, through which the yellowed avascular bone of the
fissure plane is visible. These fragments in situ may be easily displaced
in some cases by gentle probe pressure, or they may be rigid. Occasion-
ally, a needle inserted into a fissure demonstrates fragment instability.
Most elbows affected by disease in the coronoid region also have
cartilaginous injury to the medial aspect of the humeral condyle. These
changes range from mild fibrillation through fissuring to flap formation
and eburnation with exposure of extensive areas of subchondral bone
(Grade 5 lesions). Mildly fibrillated or fissured chondral lesions should
be gently probed to assess the integrity of the cartilage to try to identify
loose cartilage flaps in situ. Examination of the humeral condyle may
identify the presence of a cartilage fissure consistent with incomplete
ossification of the humeral condyle. Confirmation of the presence of such
a fissure may be assisted by firm pronation of the antebrachium, which
can open the fissure making it more readily identifiable.
In addition to investigation of ulnar coronoid lesions (also known as
medial compartment disease), other indications for investigative elbow
arthroscopy include:

• assessment of articular cartilage integrity when there is ununited
anconeal process (since this lesion often occurs in association with
additional developmental pathology within the elbow),
• assessment of articular tissues, for example investigation of synovial
disease (such as sepsis, immune-mediated disease or neoplasia),
• investigation of traumatic injuries to the articular surfaces and
subchondral bone,
• investigation of unexplained elbow pain.