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)
What are the active (dynamic) stabilizers of the shoulder joint? (4)
- muscles of the "rotator cuff":
- medially- subscapularis
- laterally- supraspinatus, infraspinatus, teres minor
What types of shoulder issues can you assess on physical exam? (4)
abduction angle, muscle atrophy, muscle pain/ myopathy, infraspinatus gait
What shoulder issues can you diagnose/ assess with radiographs? (4)
- muscle calcificatoin
- caudal glenoid fragment
What is US useful for in assess the shoulder?
assessing the muscles
What is the typical signalment and history of OCD patients?
- Large and giant breeds
- unilateral lameness (rarely bilateral) that waxes and wanes
What is the etiology of OCD? (2)
- nutrition (excessive Ca++ and calories in diet of young animals)
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
What are differentials for unilateral lameness that waxes and wanes in a young large breed dog? (3)
- elbow dysplasia
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
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
- --> OA management long-term
What is the etiology of medial shoulder instability (MSI)?
unknown- repetitive microtrauma/ overstretching suggested
What is the signalment and clinical signs of MSI?
- adult athletes (agility, flyball, hunting)
- mild-moerate chronic lameness
- decreased performance
- changes in gait
How is MSI diagnosed?
- 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
What is the treatment for MSI?
- mild/ moderate- physical therapy, hobbles
- severe- surgery to reconstruct with a prosthetic ligament
What are patohphysiology of biceps tendonitis/ tenosynovitis and supraspinatus calcification?
- degeneration +/- inflammation
- hypovascular areas at origin/ insertion--> hypoxia--> fibrocartilagenous transformation of tendon
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)
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
How is biceps/ supraspintus tendinopathy diagnosed?
- 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
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
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
What is the etiology of infraspinatus contracture?
secondary to degenerative changes due to trauma to the muscle fibers, nerves, or blood vessels
What is the pathophysiology of infraspinatus contracture?
fibrous connective tissue replaces the muscle
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)
How is congenital shoulder luxation managed?
- mild signs: conservative therapy
- surgery if severe: arthrodesis (rare), excisional arthroplasty, amputation
Describe congenital shoulder luxation.
- toy breed dogs
- medial luxation
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
What are orthopedic rule outs for forelimb lameness? (4)
- bone tumors (osteosarc- proximal humerus, distal femur)
- septic arthritis
What are neurologic rule outs for forelimb lameness? (3)
- cervical spinal cord or nerve root impingement
- nerve sheath tumor
- brachial plexus injury