Ch 12 Shoulder Flashcards
How much (%) bone mineral content can be removed before it is radiographically visible?
up to 30%
What is 5?
Deltoid tuberosity
Where is the lesser tubercle?
3 (medial)
2: Greater tubercle (lateral)
Where is the greater tubercle? Lesser?
Greater: 9
Lesser 7
Centres of ossification in an immature dog.
A = supraglenoid tubercle
B = humeral head
C = greater tubercle.
NOT a fracture.
Which species has clavicles?
Cats
Mineralization of the supraspinatus tendon of insertion
avulsion fracture of the supraglenoid tubercle
new bone formation in the bicipital groove (*) due to bicipital tenosynovitis.
Intra-articular avulsion fracture of the supraglenoid tubercle.
Which type. of scapulohumeral joint luxation is most common in toy breeds?
Medial luxations, they are usually congenital.
NB cranial/caudal luxations of the scapulohumeral joint are very rare overall.
Fractures of the head of the humerus are usually seen in…
…young animals with open growing physes.
Salter–Harris type I fracture of the proximal physis of the humerus in a cat.
Which type of scapulohumeral joint luxation is usually seen as a result of trauma?
Lateral
NB cranial/caudal luxations of the scapulohumeral joint are very rare overall.
Traumatic medial shoulder luxation
Arrow: fracture of the medial glenoid rim
The book states that traumatic luxations are seen primarily as a result of trauma.
partial rupture of a biceps tendon
When is congenital shoulder luxation apparent i.e. when would a case like this present?
3-8 months of age
Or older - as the luxation may not happen until after skeletal maturity, but the dog is anatomically predisposed, so it is inevitable from birth.
With traumatic luxation or subluxation, what (else) should you look for (besides radiographic evidence of displacement of the humerus)?
Fracture of the medial glenoid rim
What is a typical radiographic sign of congenital luxation or subluxation?
Flattened / shallow glenoid cavity
What is a predilection site (on the humerus) for OCD/OC?
Caudal humeral head
Osteochondrosis is an abnormality of _______________ ossification.
Endochondral. This is at the epiphysis, where the epiphyseal cartilage fails to form subchondral bone, and instead there is thickened abnormal cartilage that is easily injured.
What is the difference between OC and OCD - when is it OCD?
OCD is a form of OC, when the cartilage has a fissure, and consequently there is a flap.
This flap can dislodge > be resobred, stay static as a free intra-articular body (joint mouse), or be nourished by snovial fluid (and grow, eventually ossify),
What are the possibilities for a dislodged piece of OCD cartilage flap?
- Resorption
- Stay the same, remain as a “joint mouse”, i.e. intra-articular free body. Potentially mineralise.
- Grow (with nourishment from the synovial fluid), eventually ossify
- Get stuck / lodged in different places and potentially cause lameness (or not) - between articular surfaces, in the biceps tendon sheath, or most commonly, in the caudal pouch of the joint. Rarely in the subcapsular bursa.