Ch 50 - The shoulder Flashcards

1
Q

At what age do the glenoid and proximal humeral physes fuse?

A

Glenoid - by 6mo
Proximal humerus - by 12mo

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2
Q

What is the ratio of glenoid to humeral head ratio?

A

1:2.5

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3
Q

What are the three zones of the labrum?

A
  • Transitional zone (collagen fibers in a fishnet-like pattern)
  • Circular fiber zone
  • Meniscal fold

The labrum is highly vascularised (except along the free margin) and is loosely attached to the glenoid

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4
Q

How thick is the hyaline cartilage of the shoulder joint?

A

approx 1mm in 20-25kg dogs

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5
Q

What shape are the collateral ligaments of the shoulder?

A
  • Medial glenohumeral ligament is Y-shaped
  • Lateral glenohumeral ligament is a thick band
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6
Q

What structure function to keep the tendon of the origin of the biceps brachii within the intertubercular groove?

A

Transverse humeral retinaculum

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7
Q

What are the normal flexion and extension angles of the shoulder in the dog and cat?

A

Dog
- extension 165
- flexion 57

Cat
- extension 164
- flexion 32

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8
Q

List the passive mechanisms of shoulder stability

A
  • Limited joint volume
  • Adhesion/cohesion mechanism
  • Concavity compression
  • Capsuloligamentous restraints
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9
Q

What are the main active stabilisers of the shoulder?

A
  • Supraspinatus
  • Infraspinatus
  • Teres minor
  • Subscapularis

And to a lesser extent:
- Biceps brachii
- Long head of the triceps
- Deltoideus
- Teres major

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10
Q

What type of mechanoreceptors are within the collateral ligaments?
What is their function?

A
  • Type I, II and III mechanoreceptors
  • Type I (Ruffini) are the most common
  • Allow ligaments to work as sensory structures to actively contribute to shoulder stability via reflex arcs with the associated musculature
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11
Q

What is the optimum concentration of iodine for arthrography when VT angiography is performed?

A

60mg/ml

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12
Q

What percentage of shoulder pathology is extra-articular and therefore would be missed on arthroscopy?

A

15%

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13
Q

What is the recommended angle for excision arthroplasty of the glenoid?

A
  • Distolateral to proximomedial osteotomy of the scapular neck
  • Being careful to protect the suprascapular nerve
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14
Q

What is the outcome of excisional arthroplasty?

A
  • Good-to-excellent in small dogs
  • Unknown in large breeds
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15
Q

What angle of shoulder is aimed for in arthrodesis?
What landmark should be used for the rotation alignment?

A
  • 105-110 degrees
  • The greater tubercle should be positioned craniodistal to the acromion and slightly medial in the sagittal plane
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16
Q

What is the reported outcome after shoulder arthrodesis?

A
  • Good-to-excellent
  • Normal or near-normal gait in 12 weeks
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17
Q

What is the most common location of shoulder OCD?
How often is this disease bilateral?

A
  • caudocentral or caudomedial aspect of the humeral head, usually opposite the caudoventral rim of the glenoid
  • 27-68% bilateral
18
Q

What percentage of OCD cases will have a nonmineralised cartilage flap trapped within the tendon sheath of the biceps?

A

Approx 10%

19
Q

What are the approach options of debridement of a shoulder OCD flap?

A

Caudal
- requires assistant for retraction
- results in less loss of RoM and improve weight bearing in first month

Caudolateral interdeltoideus approach
- Craniodorsal retraction of infraspinatus and teres minor
- Better protection of caudal circumflex humeral artery and axillary nerve

Craniolateral
- Included tenotomy of infraspinatus tendon
- Greater exposure of caudal aspect of humeral head but limits access to caudal joint pouch

20
Q

What is glenoid dysplasia?
What breeds are predisposed?
What does it cause?
What is the treatment?

A
  • Glenoid dysplasia is hypoplasia or aplasia of the glenoid resulting in grossly abnormal articulation
  • Toy breeds (Toy and Min poodle, Chihuahua, Pom, Sheltieetc)
  • Results in medial luxation of the shoulder
  • Tx: Arthrodesis or excision arthroplasty with an acceptable return to function
21
Q

What is multiple epiphyseal dysplasia?
What is the treatment?

A
  • A rare defect in the ossification of the epiphyses of long bones, vertebrae, cuboidal bones and apophyses
  • Severe lameness, resembles bony changes seen with congenital hypothyroidism
  • Tx: euthanasia
22
Q

In what breed has focal humeral head dysplasia been reported?

A

Boerboel (Arthrodesis)

23
Q

What is the radiographic hallmark of Hypertrophic Osteodystrophy?

A

“Double physis” - irregular radiolucent line in the metaphysis, parallel to and seperate from the physis

24
Q

What is this disease?
Is it clinically significant?

A

Incomplete ossification of the caudal glenoid
- Often asymptomatic but can be a cause of lameness if mobile
- Arthroscopy to comfirm if mobile and can remove the fragment

25
Q

What is chondrocalcinosis?
What breeds are overrepresented?
What gross lesions are seen?
Is it clinically significant?

A
  • Chondrocalcinosis is deposition of hydroxyapatite in the articular cratilage, “pseudogout”
  • Overrepresented in the Greyhound and GSD
  • Gross lesions: small pits in cartilage surface, scarring, scoring and cracking, often unilateral
  • Often found incidentally at necropsy, clinical significance unknown
26
Q

What disease process is shown in the following radiograph?

A

Multiple epiphyseal dysplasia (note the severely irregular and misshapen humeral head)

27
Q

Lists tests which can be done to test for biceps tendinopathy

A
  • Biceps tendon test
  • Drawer test - Places direct pressure against the tendon and associated sheath (doe not test for tearing/rupture)
  • Biceps retraction test - Grasping the tendon of insertion at cranial elbow and pulling caudally whilst weight-bearing

All tests are assessing for a pain response

28
Q

What are the surgical options for biceps tendinopathy?

A
  • Tenodesis
  • Tenotomy (using hooded arthroscope knife or bipolar). Further studies needed to asses if joint stability is effected
29
Q

What breeds are predisposed to medial displacement of the biceps tendon of origin?
What are the surgial options?

A
  • Greyhounds, Afghan hounds, GSD, Border Collies
  • Primary reconstruction of the transverse humeral retinaculum and/or augmentation with screws and PDS or staples and polypropylene mesh
  • Prognosis excellent
30
Q

What breeds are predisponsed to calcification of the biceps tendon of origin?

A

Labs and Rottweilers

31
Q

What is the surgical treatment of supraspinatus tendinopathy?

A

Excision of calcified tissue (controversial if medical vs surgical treatment is best)

32
Q

What is the most common direction of shoulder luxation?

A

Medial (approx 80%)

33
Q

What is the normal shoulder abduction angle

A

Approx 30 degrees (vs 50 with instability)

34
Q

What treatment options are available for stabilisation of the shoulder joint?

A
  • Transposition of the tendon of origin of the biceps or supraspinatus (84.5% good to excellent outcome)
  • Augmentation of medial collateral with suture (better than transposition)
  • Imbrication of tendon of subscapularis muscle
  • Radiofrequency induced thermal modification (RITM)
  • Excision arthroplasty
  • Arthrodesis (85.7% good to excellent)

Transposition techniques result in altered biomechanics, incongruency and OA. Placement of heavy synthetic suture preferred method in a V-shaped manner with screw and washer bone tunnels or anchours

35
Q

What coaptation is used for closed reduction of traumatic shoulder luxation?

A

Velpeau

36
Q

What is the range of grades of muscle strain injury?

A

Grade 1 = minimal tearing of individual muscle fibres

up to Grade 4 = Complete muscle rupture requiring debridement and repair

37
Q

What are some clinical features of teres minor myopathy?
Treatment of choice?

A
  • Prominent pain with reduced shoulder flexion
  • Tx: excision of entire muscle, excellent prognosis
38
Q

What breeds are predisposed to infraspinatus contracture?
What is meant by a biphasic history?
What are some characteristic gait features?

A
  • Brittany spaniel, Pointers, Labs

Biphasic
- Acute painful pain, swelling and lameness
- Chronic, static, nonpainful gait abnormality

Gait
- elbow adduction, shoulder abduction
- external rotation of antebrachium
- circumdution of limb with carpal flip

39
Q

List the treatment option of villonodular synovitis

A
  • Synovectomy
  • Radiation therapy
  • anti-TNF-a administration
  • excision arthroplasty or arthrodesis
40
Q

What is the disease seen in the radiograph?
What are the treatment options?

A

Synovial chondrometaplasia
- a proliferative disorder of undiffernetiated stem cells. Fibroblast-like cells are transformed into chondroblastic cells under the influence of the extracellular chondroid matrix material

Treatment
- Good outcome with debridement of nodules, loose body removal and synovial stripping
- Excision arthroplasty or arthrodesis