Conditions of the Shoulder

Question 1

describe skeletal anatomy of the shoulder

Answer 1

1. scapular spine
2. acromion
3. humeral head
4. glenoid cavity
5. greater tubercle
6. supraglenid tubercle

Question 2

what are the main stabilizers of the shoulder? (4)

Answer 2

1. joint capsule
2. medial and lateral glenohumeral ligaments
3. tendon of origin of biceps tendon: can cut this tendon and not cause over-instability if all other structures intact
4. rotator cuff muscles:
   -medial: subscapularis, coracobrachialis
   -lateral: supraspinatus, infraspinatus, teres minor

Question 3

describe the functional anatomy of the shoulder

Answer 3

1. ball-and-socket joint
2. majority of movement is flexion/extension
3. also capable of adduction/abduction, and circumduction

Question 4

what are 6 common conditions of the shoulder?

Question 5

describes biceps brachii tendinopathy

Answer 5

1. one of the most common shoulder conditions; in middle-aged/older medium to large-breed dogs, athletic/working dogs, weekend warriors (only active on weekends)
2. chronic repetitive overuse injury: causes micro-tears that cause inflammation and vicious cycle
3. clinical signs: lameness that worsens with exercise, improves with rest but often returns
4. diagnosis:
   -pain on direct palpation of biceps tendon (located in a groove medial to the greater tubercle
   -pain on biceps tendon: flex shoulder, extend elbow, and put pressure on biceps tendon
   -radiographs: look for mineralization within the biceps groove and rule out other sources of lameness
   -ultrasound: esp if radiographs inconclusive; look for mottling, increased fluid, vacancies, or discontinuity in the tendon architecture
   -MRI: when not getting a clear answer from above diagnostics
   -arthroscopy
5. treatment: physical rehab considered in ALL cases!!
   -if peracute/mild: rest 4-6 weeks, NSAIDs
   -acute/moderate: IA steroid injections and rest 4-6 weeks (triamcinolone 5mg/joint)
   -subacute/chronic/moderate: consider extracorporeal shockwave therapy
   -chronic/severe: surgery (arthroscopy)
   –option 1: tenodesis: cut and reattach
   –option 2: tenotomy (release)
6. prognosis: variable depending on severity and chronicity

Question 6

decribe supraspinatus tendinopathy

Answer 6

1. similar population and presentation as biceps tendinopathy, but common in rottweilers and labrador retrievers; suspect repetitive us einjury, can cause impingement of bicep tendon
2. diagnostics: similar to biceps tendinopathy (rads, US, CT, MRI)
3. treatment: physical rehab should be considered in ALL cases!
   -peractute/mild: rest 4-6 weeks, NSAIDs
   -acute to subactute, moderate/chronic: consider ECSW (no joint injections bc joint not involved)
   -chronic: surgical removal of mineralization
4. prognosis: dependent on severity and chronicity

Question 7

what is a common incidental finding on CTs in 40% of limbs with NO lameness?

Answer 7

tendon calcification! 90% of these cases have concurrent shoulder or elbow pathology so don’t be fooled and forget shoulder or elbow

Question 8

where is lameness most likely to come from in the forelimb?

Answer 8

from the elbow! pain on shoulder extension can actually be referred from the elbow, so do your best to try to actually isolate the shoulder during you exam, and if you get pain, go back to the elbow to double check!

Question 9

describe infraspintus muscle contracture

Answer 9

1. adult active working dogs (hunting): brittany spaniels, pointers, labs
2. could be repetitive use or traumatic in origin; tearing with subsequent fibrotic contracture of muscle tendon
3. biphasic history:
   -acute injury: lameness, swelling, pain on shoulder extension
   -improves over 2-6 weeks
   -develop non-painful chronic gait abnormality
4. exam findings:
   -classic externally rotated posture: shoulder abducted, elbow adducted, antebrachium externally rotated
   -inability to internally rotate forelimbs
   -typical mechanical lameness: circumduction of limb, carpal flip
5. treatment = surgery
   -tenotomy: tendon release and possible excision of contracted component
6. prognosis is good!

Question 10

describe medial shoulder instability

Answer 10

1. typically in adult working dogs or small.toy breed dogs with poor shoulder confirmation (shallow glenoid)
2. repetitive use injury; gradual tearing of the glenohumeral ligament and subscapularis tendon resulting in varying degrees of lameness
3. diagnosis:
   -exam findings: increased shoulder abduction (normal <30, abnormal >50, but angles are highly variable and reliability of this is highly debated)
   -MRI
   -arthroscopy: can have limitations if torn structures are extracapsular
4. treatment: physical rehab should be considered in ALL cases
   -peracute (mild): rest 4-6 weeks, NSAIDs, hobbles
   -acute to subacute, moderate/chronic: consider adding ECSW
   -chronic/severe: surgical stabilization, hobbles
5. prognosis variable depending on severity

Question 11

describe traumatic shoulder luxation

Answer 11

see other lecture

Question 12

describe congenital shoulder luxation

Answer 12

1. common in toy and small breed dogs (3-10 months old); glenoid dysplasia cases medial shoulder instability resulting in luxation
2. treatment options:
   -open reduction and stabilization
   -excision arthroplasty (glenoid excision)
   -arthrodesis

Question 13

describe osteochondrosis dissecans

Answer 13

1. common in young, large, and giant breed dogs
2. lameness onset typically around 4-8 months of age (can be later); often present unilateral lame despite bilateral disease; but exercise intolerance indicates bilateral lameness
3. exam findings:
   -muscle atrophy; esp if chronic
   -pain on shoulder hyperflexion/hyperextension
4. diagnosis: always check contralteral shoulder; bilateral disease is common!
   -radiographs: often but not always diagnostic, see flattening/radioluscent defect at CAUDAL HUMERAL HEAD and surrounding sclerosis
   -CT
   -arthroscopy: preferred if can’t afford CT AND arthroscopy
5. treatment: surgery
   -arthroscopy/arthrotomy: flap removal, abrasion arthroplasty, +/- cartilage resurfacing techniques
6. prognosis:
   -excellent short term
   -great long-term; OA will progress, may have subtle lameness long-term