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What are the passive (static) stabilizers of the shoulder joint? (3)
- glenoid cavity of scapular
- joint capsule/ joint fluid cohesion
- collateral ligaments (medial/ lateral glenohumeral ligaments)
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What are the active (dynamic) stabilizers of the shoulder joint? (4)
- muscles of the "rotator cuff":
- medially- subscapularis
- laterally- supraspinatus, infraspinatus, teres minor
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What types of shoulder issues can you assess on physical exam? (4)
abduction angle, muscle atrophy, muscle pain/ myopathy, infraspinatus gait
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What shoulder issues can you diagnose/ assess with radiographs? (4)
- OCD
- arthritis
- muscle calcificatoin
- caudal glenoid fragment
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What is US useful for in assess the shoulder?
assessing the muscles
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What is the typical signalment and history of OCD patients?
- Large and giant breeds
- unilateral lameness (rarely bilateral) that waxes and wanes
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What is the etiology of OCD? (2)
- genetics
- nutrition (excessive Ca++ and calories in diet of young animals)
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Describe the pathophysiology of OCD.
abnormal endochondral ossification--> area of thicker cartilage (osteochondrosis)--> poor diffusion/ poor nutrition of the chondrocytes--> chondrocyte necrosis--> flaps up/ abnormal articular surface
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What are differentials for unilateral lameness that waxes and wanes in a young large breed dog? (3)
- OCD
- elbow dysplasia
- panosteitis
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How is OCD diagnosed? (4)
- PE: pain on ROM
- Radiographs***: multiple oblique views to see flap, notch in articular surface, evidence of joint disease
- CT: ideal but not required
- Arthrogram: may help to delineate defect
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What is the treatment for OCD?
- Surgical! (otherwise you just medically manage the ensuing DJD)
- osteochondroplasty= flap removal; debride flap--> currette/burr/shave to healthy bleeding subchondral bone
- osteochondral autograft transfer system
- resurfacing
- --> OA management long-term
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What is the etiology of medial shoulder instability (MSI)?
unknown- repetitive microtrauma/ overstretching suggested
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What is the signalment and clinical signs of MSI?
- adult athletes (agility, flyball, hunting)
- mild-moerate chronic lameness
- decreased performance
- changes in gait
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How is MSI diagnosed?
- [difficult]
- painful shoulder on abduction
- radiographs show mild OA but may be normal
- increased abduction angle
- MRI to look at intra- and extra-articular structures
- arthroscopy to look at intra-articular structures, medial glenohumeral ligament and subscapularis
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What is the treatment for MSI?
- mild/ moderate- physical therapy, hobbles
- severe- surgery to reconstruct with a prosthetic ligament
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What are patohphysiology of biceps tendonitis/ tenosynovitis and supraspinatus calcification?
- degeneration +/- inflammation
- hypovascular areas at origin/ insertion--> hypoxia--> fibrocartilagenous transformation of tendon
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What are etiologies of biceps tendonitis/ tenosynovitis and supraspinatus calcification?
- Primary: repetitive microtrauma, trauma, overuse
- Secondary: irritation/ inflammation due to other joint disease (OCD, supraspinatus, MSI)
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What is the signalment and history of patients with biceps/ supraspintus tendinopathy?
- middle-aged, medium to large breed athletic dogs
- progressive lameness, exacerbated with exercise
- differentials include elbow dysplasia, DJD/ OA, proximal humerus OSA
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How is biceps/ supraspintus tendinopathy diagnosed?
- [difficult]
- biceps: pain on biceps test (extend elbow and flex shoulder to stretch biceps)
- supraspinatus: pain on palpation of insertion on greater tubercle, shoulder flexion while elbow is flexed
- radiographs: mineralization on skyline view of insertions
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What is the treatment of biceps/ supraspintus tendinopathy?
- Biceps: PT/ rehab, medical is trimacinolone, surgical is tenotomy or tenodesis
- Supraspinatus: PT/ rehab, medical is shockwave therapy, surgical is tendon resection, release of transverse humeral ligament, or release incisions in supraspinatus
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What is the signalment and history of patients with infraspinatus contracture?
- medium to large breed dogs (sporting breeds common)
- may be biphasic with acute painful lameness that resolves, followed by static, chronic non-painful gait abnormality
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What is the etiology of infraspinatus contracture?
secondary to degenerative changes due to trauma to the muscle fibers, nerves, or blood vessels
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What is the pathophysiology of infraspinatus contracture?
fibrous connective tissue replaces the muscle
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How is infraspinatus contracture diagnosed and treated?
- PE: elbow held in adduction, antebrachium externally rotated--> decreased ROM
- treated with tenotomy of muscle insertion (good prognosis)
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How is congenital shoulder luxation managed?
- mild signs: conservative therapy
- surgery if severe: arthrodesis (rare), excisional arthroplasty, amputation
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Describe congenital shoulder luxation.
- congenital
- toy breed dogs
- medial luxation
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Describe traumatic shoulder luxation.
- almost always lateral
- lateral treated with spica splint
- medial is treated with velpeau splint to force humeral head laterally
- if surgery: stabilization, collateral repair, tendon transfer
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What are orthopedic rule outs for forelimb lameness? (4)
- bone tumors (osteosarc- proximal humerus, distal femur)
- fractures
- osteomyelitis
- septic arthritis
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What are neurologic rule outs for forelimb lameness? (3)
- cervical spinal cord or nerve root impingement
- nerve sheath tumor
- brachial plexus injury
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