Page 94 - Clinical Manual of Small Animal Endosurgery

82 Clinical Manual of Small Animal Endosurgery

Arthroscopically assisted surgery of the biceps tendon

Inflammation or injury to the biceps tendon causes shoulder pain and
lameness. Examination of affected individuals may reveal shoulder pain
but it is often difficult to localise which structures are the source of
discomfort in a painful shoulder. Arthroscopic investigation is hence
valuable in identifying biceps tendon pathology and discriminating
biceps lesions from other shoulder problems. Biceps tendon pathology
in dogs is still incompletely understood and direct trauma, indirect
trauma and repetitive strain injury are each thought to be responsible
for clinical cases of biceps disease. A degenerative process may pre-
dispose the tendon to injury under physiological loading as observed
in other tendon and ligament injuries in dogs. Direct trauma to the
biceps tendon can lead to gross tearing of tendon fibres while indirect
trauma due to compression from spinatus muscle tendonopathy and
mineralisation can be responsible for damage to the biceps tendon in
some cases. A diagnosis of biceps tendon pathology may be suggested
by preoperative investigations but a definitive diagnosis requires arthro-
scopic visualisation in most cases. Supportive investigative findings
include radiological evidence of mineralisation of the biceps groove
or the spinatus muscle tendons of insertion, or abnormal filling of the
tendon sheath on shoulder arthrography. Ultrasonographic or magnetic
resonance imaging may additionally show lesions affecting the spinatus
muscles, or the substance of the biceps tendon or of the bicipital sheath.
Patient positioning for arthroscopic surgery of the biceps tendon is as
described above. Generous clipping and aseptic preparation around the
cranial and medial aspect of the shoulder joint are prudent in case of the
necessary conversion of the procedure to an open approach. The shoul-
der joint is routinely preoperatively analgesed with ropivacaine and
distended with irrigation fluid. A good view of the cranial part of the
shoulder joint is most readily achieved by placing the arthroscope portal
slightly caudal (approximately 1 cm) to the tip of the acromion. Follow-
ing insertion of the arthroscope, the entire shoulder joint is inspected
and investigated for evidence of pathology and all findings are recorded.
Biceps pathology is commonly identified in association with chronic
synovitis and degenerative changes affecting other shoulder joint struc-
tures. Care should be taken to fully evaluate the significance of patho-
logical changes affecting the articular surfaces and structures of
mechanical importance including the glenohumeral ligaments and the
subscapularis tendon. The biceps tendon is inspected from its proximal
origin on the supraglenoid tuberosity to the distal extent of the tendon
in the distal recess of the biceps sheath. The tendon is evaluated for
evidence of fibre tearing, inflammation and synovitis, while the biceps
sheath is inspected for osteophyte formation, for synovial proliferation
and for evidence of external compression of the sheath and tendon
from spinatus tendonopathy. Synovial hypertrophy and proliferation are
common in degenerative shoulder joints and not specific to a single
structure within the joint itself. Consequently, synovial proliferation on