Page 81 - Clinical Manual of Small Animal Endosurgery

Operative Arthroscopy 69

Fig. 3.2 Ropivacaine is injected intra-articularly prior to performing
arthroscopic surgery.

joint with irrigation fluid (lactated Ringer’s solution; Figs 3.4–3.6). Easy
injection and detection of back pressure on the syringe plunger confirm
correct needle location in the articular space. Maintenance of plunger
pressure is helpful to keep the joint distended while making the arthro-
scope portal. The medial epicondyle of the humerus is palpated and the
orientation of the long axis of the humerus is confirmed. With reference
to a radiograph of the patient’s elbow joint, the humero-ulnar joint space
is estimated as it lies distal to the epicondyle. At this level, a point
approximately 5 mm caudal to the medial epicondyle is used and a
‘locator’ needle is inserted perpendicular to the skin surface, dropping
vertically into the joint space (Fig. 3.7). Fluid egress confirms puncture
of the joint pouch, but placement between the articular surfaces of the
humero-ulnar joint requires deeper penetration (Fig. 3.3). The soft-tissue
tunnel arthroscope portal is created with a 2–3 mm skin incision made
with a no. 11 or 15 blade (Fig. 3.8) and subsequently the arthroscope
cannula and blunt obturator are inserted into the joint space directly
following the direction of the locator needle. It is helpful for the assistant
to distract the medial aspect of the joint space through a combination
of pronation and valgus stress on the distal antebrachium. The surgeon
braces the cannula against the skin surface of the elbow to avoid over-
zealous and deep penetration of the joint that can damage articular
structures. Once the joint is entered, the trocar is removed and fluid
escapes from the cannula, confirming correct placement. Vigorous flush-
ing using the remaining fluid in the distension syringe expels bleeding
created during scope insertion. The arthroscope is inserted and locked
with a Luer-lock to the cannula and the pressurised fluid line is connected
to the scope cannula, while the fluid egress is enlarged, if necessary, by
placing a large-bore needle (14 gauge) alongside the needle used for