Dorsal recumbent shoulder arthroscopy technique,
normal anatomy, & appearance of routine pathology
Chad Devitt, DVM, MS, Diplomate ACVS
Veterinary Referral Center of Colorado, Englewood, Colorado, USA
Most descriptions of shoulder arthroscopy techniques
position dogs in lateral recumbency with the affected limb
up allowing for consistent establishment of lateral optical
portal and caudolateral or craniolateral instrument. Dorsal
recumbent positioning with distal traction of the limb is
an alternate position allowing for additional assess to the
joint via the craniomedial portal.1,2The main advantage
of dorsal recumbent positioning is the view afforded via
the craniomedial portal. This allows for the surgeon to
change the optic port from the standard lateral portal to
the craniomedial portal to provide an improved view of
lateral intraarticular structures. The main disadvantage
of dorsal recumbent positioning is accommodating for
the inverted anatomy. While the anatomy is identical, it
is inverted making some familiar structures completely
unrecognizable to the naïve eye.
Working portals are established dependent on the
region of interest. The location of the caudolateral
portal is approximately 1 cm caudal and 1-2 cm distal
to the lateral portal. Needle-localization of working
portals facilitates proper orientation of working portals
to identified pathology. The general location of the caudal
lateral portal is determined by digital pressure in the
region and observing the deflection of the joint capsule.
Next, a nitinol needle (or a spinal needle) is inserted in the
proposed location and the needle is observed within the
joint. A stab incision is made at the needle puncture site
and the cannulated obturator and cannula is inserted over
the nitinol needle. The cannulated obturator is removed
leaving the cannula in place as the working portal.
Craniomedial portal can be established in lateral or
dorsal recumbency; however, this location is difficult to
utilize effectively in lateral recumbent positioning. Needlelocalization and creation from an outside-in technique
is possible, however, the author prefers an inside-out
technique. The craniomedial portal is established in
a triangular region bordered by the synovium covered
coracobrachialis tendon dorsally, subscapularis tendon
caudally, and the biceps tendon. The arthroscope tip is
driven to the triangular region and held securely against
the joint capsule while the arthroscope is removed from
the sheath. A switching stick is placed into the sheath and
advanced through the joint capsule and skin at the site of the
craniomedial portal from inside out. The arthroscope sheath
was removed leaving the SS spanning across the joint from
the lateral portal to the newly formed craniomedial portal.
The arthroscope sheath or working cannula is advanced
over the SS to establish the craniomedial portal. Viewing
via the craniomedial perspective is especially useful in dogs
with suspected shoulder instability. OCD flaps displaced
into the medial scapular recess can be more readily
accessed with this portal.
To perform dorsal recumbent shoulder arthroscopy,
patients are positioned with the aid of a vacuum-positioning
bag to maintain dorsiflexion of the cervical spine and axial
alignment. The limb is aseptically prepared in hanging leg
prep and draped in a standard fashion. Distal traction on the
limb is provided by an adjustable block and tackle secured
in an aseptically to a sturdy ceiling anchor. Distention of
the joint is necessary for consistent portal placement. A
spinal needle is inserted into the joint at the depression
between the cranial border of the acromion and dorsal
border of the greater tubercle. Proper placement into the
joint is confirmed by aspiration of synovial fluid. The joint
is distended with 10 mL of sterile distension fluid (i.e.,
LRS, NaCl). Care is required to prevent over distention and
rupture of the joint capsule. The author prefers to leave
the spinal needle in place as an egress portal. The optical
portal is established at the lateral location immediately
caudal and slightly distal to the acromion. This location
can vary dependent on the morphology of the acromion. A
stab incision made and the sheath with a blunt obturator
is advanced into the joint in a controlled manner. A distinct
pop is felt as the articular space is entered. As the obturator
is removed, the sheath is stabilized to prevent inadvertent
displacement from the joint. Rapid egress of distention fluid
should occur as the obturator is removed from the sheath.
ECVS proceedings 2011
99
small animal orthopaedic session
References
1. Devitt CM, Neely MR, Vanvechten BJ. Relationship
of physical examination test of shoulder instability to
arthroscopic findings in dogs. Veterinary surgery : VS :
the official journal of the American College of Veterinary
Surgeons 2007;36:661-668.
2. Cook JL, Cook CR. Bilateral shoulder and elbow arthroscopy
in dogs with forelimb lameness: diagnostic findings and
treatment outcomes. Veterinary surgery : VS 2009;38:224232.
small animal orthopaedic session
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ECVS proceedings 2011