Shoulder instability

Question 1

Causes of shoulder instability?

Answer 1

Congenital - due to glenoid dysplasia (small, medium breeds)
Acquired - trauma, chronic overuse

Question 2

Time of presentation for shoulder instability?

Answer 2

Congenital - between 3-10 months
Acquired - middle/old age, active athletic large breed dogs

Question 3

Cause of acquired shoulder instability?

Answer 3

Repetative microtrauma resuling in degeneration of soft tissues supporting the joint, mainly collateral ligaments

Question 4

Predisposition for shoulder instability?

Answer 4

Animals with underlying pathology predisposed

Question 5

Active joint stabilisers?

Answer 5

Mm. infraspinatus
Mm. supraspinatus
Mm. teres minuor
Mm. subscapularis

Question 6

Clinical presentation of shoulder instability?

Answer 6

Intermittent lameness, worse after exercise - chronic
Non-weightbearing lameness - acute

Question 7

Diagnosis of shoulder instability?

Answer 7

Based on detection of instability on orthopaedic exam under sedation/anesthesia
XR - OA changes
MRI - Soft tissue damage
Arthroschopy - assess damages in compartments of the shoulder

Question 8

Normal and abnormal abduction angles of shoulder?

Answer 8

normal: 30
abnormal: >50 degrees

Question 9

Treatment of shoulder instability?

Answer 9

Depends on diagnosis and degree of instability.
Conservative - NSAID, rest, physio, hydro, shockwave therapy
Surgery - prosthetic reinforcement or replacement of collatteral ligaments or reposition of collateral ligaments/biceps brachii/subcapsularis muscle

Shoulder hobbles for both!

Question 10

Prognosis, complication rate of surgical treatment of shoulder instability?

Answer 10

Prognosis is good
Overall complication rate: 10-15%

Question 11

Salvage procedures indicated when and what type in shoulder instability?

Answer 11

Indication: Severe or chronic shoulder joint instability
Procedure: Excision arthroplasty, shoulder joint arthrodesis

Question 12

Indications for salvage procedure of the shoulder?

Answer 12

• severe or chronic shoulder joint instability
• comminute articular fractures
• pain associated with OA
• dysplasia
• ostechondromatosis

Question 13

Prognosis and outcome of salvage procedures?

Answer 13

Prognosis: good for animals with normal neurovascular supply to affected limb
Outcome: Functional, pain-free lameness

Question 14

Passive mechanisms of the shoulder joint?

Answer 14

ligaments: medial and lateral glenohumeral ligament
capsular restraints
joint conformity
glenoid labrum
synovial adhesion and cohesion