Page 72 - Clinical Manual of Small Animal Endosurgery

60 Clinical Manual of Small Animal Endosurgery

preparation. This technique requires a degree of experience and details
are described elsewhere.
When the appearance of the soft tissue raises a suspicion of sinister
disease, rather than indicating developmental, degenerative disease or
traumatic injury, a biopsy forceps can be used through the instrument
cannula in place of the blunt probe to obtain a tissue biopsy for his-
topathological analysis and/or bacterial culture.

Investigative arthroscopy of the stifle

Current indications for investigative stifle arthroscopy include the inves-
tigation of undiagnosed stifle pain or of stifle effusion of uncertain origin.
Arthroscopy of the stifle joint requires some technical skill and successful
arthroscopic experience in other joints is recommended prior to under-
taking stifle arthroscopy. An assistant is invaluable in order to maintain
the limb in a suitable position, to flex and extend the joint and to apply
varus and valgus force when required during the procedure. Generally,
with the patient in dorsal recumbency, a cranial parapatellar arthroscope
portal is used, just lateral to the insertion of the patellar ligament. The
stifle joint must be flushed with irrigation fluid throughout the arthro-
scopic procedure to maintain a clear field of view because of the tendency
for the intra-articular structures (fat pad and proliferated synovium) to
obscure the arthroscope tip otherwise. A pressurised fluid pump is rec-
ommended to achieve a constant delivery of fluid at steady pressure and
a wide-lumen fenestrated egress cannula is necessary for fluid flow
without extravasation into the peri-articular structures. Proliferative
synovitis is commonly encountered in the stifle joint and a motorised
shaver is necessary to remove excessive synovial villi and the normal fat
pad from around the arthroscope tip to give a good intra-articular view.
Once a clear visual path is created, which is normally several times
the diameter of the arthroscope, a visual inspection of the joint is
performed.
The principles of arthroscopic inspection follow the routine of inspect-
ing the articular cartilage and grading cartilage lesions, where present,
using the modified Outerbridge scale (Table 2.2), and recording the find-
ings on a chart specific to the stifle joint (Table 2.4). The femoral con-
dyles and the articular surface of the patella are viewed and inspected
in a systematic manner. If osteochondrosis/osteochondritis is suspected
from the diagnostic work-up, areas of thickened or fissured cartilage
should be probed to identify regions of unstable osteochondritis disse-
cans cartilage in situ.
Additionally, the integrity of the cranial and caudal cruciate ligaments
is inspected visually, and by probing to establish functional integrity. The
menisci are inspected for evidence of fibrillation or tearing. Obtaining a
good view of the menisci is challenging, requiring coordinated valgus/
varus stressing of the limb with directed rotation of the distal limb by