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.
small OC lesion with adjacent sclerosis involving the caudal aspect of the humeral head.
joint mouse within the subscapular bursa (arrowed), which is an uncommon finding
shoulder OC lesion
flattening and an irregular radiolucent subchondral defect involving the caudal aspect of the humeral head
What are 3 other findings that can be seen with an OC lesion i.e. the actual defect ?
- adjacent sclerosis
- osteoarthrosis in chronic cases
- vacuum phenomenon
positive-contrast arthrogram showing a detached cartilage flap lodged in the caudal pouch of the joint capsule (arrowed). In most cases, such a finding is associated with no clinical signs and can be left untreated.
Treat or don’t treat?
positive-contrast arthrogram showing a joint mouse in the bicipital tendon sheath within a larger pouch (arrowed). This joint mouse is not hindering the biceps tendon and can be left untreated.
Treat or don’t treat? Where is the joint mouse?
a joint mouse in the bicipital tendon sheath. This large joint mouse hinders the mechanical action of the biceps tendon and should be removed. Notice also that the cartilage flap looks fragmented (arrowed), meaning that smaller cartilage fragments may break off and form joint mice.
Can OC lesions occur in the scapula?
Yes, in the glenoid cavity - you need CT and arthroscopy to diagnose this.
OCD lesion - where is it?
Number 4 is a ‘second’ hyperechoic line (3 being the subchondral bed), which is US-pathognomonic for an OCD lesion.
1 is joint effusion.
2 is a normal part of the cartilage.
What is one theory behind shoulder dysplasia?
It is due to the faulty development of the caudal humeral head ossification centre - when it fails to form, the caudal humeral head collapses and cannot support the scapula/glenoid cavity, so then that doesn’t form well either (the concave surface becomes flat instead of concave).
separate ossification centre of
the caudal rim of the glenoid
What is the significance of the separate ossification centre of
the caudal rim of the glenoid?
In most instances - incidental finding.
However, IF the fragment is loosely embedded in the joint capsule, it can act as a free body in the joint > can cause synovitis and pain/lameness.
What are the typical locations of osteophytes of the shoulder?
- caudal humeral head
- caudal glenoid rim
- intertubercular groove
- superimposed over the humeral head
joint with bicipital tenosynovitis. Sclerosis is visible along the bicipital groove and supraglenoid tubercle, as well as irregular delineation of the tubercle.
What is the typical signalment for synovial sarcoma?
Male, middle-aged, large-breed dogs
ossification centre of the caudal rim of the
glenoid with the appearance of a fracture. This dog was presented with clinical shoulder lameness.
A shoulder joint with osteoarthrosis. It is
characterized by osteophytes on the caudal glenoid rim and caudal articular margin of the humeral head. Osteophytes in the cranial (white arrow) and caudal (black arrow) intertubercular regions are present, as well as superimposed on the humeral head.
What is the most sensitive radiological indicator of biciptal tenosynovitis?
Sclerosis along the biciptal groove
Other:
- dystrophic calcification of the tendon
- avulsion fractures of the attachment of the tendon
- demineralization of the supraglenoid tubercle
- osteophytes in the intertuber- cular groove
- mineralized fragments within the tendon sheath
biceps tendon pathology: dystrophic calcification of the tendon (arrowed) and new bone formation in the area of its attachment
avulsion fracture of the attachment of the biceps tendon: demineralization of the supraglenoid tubercle, osteophytes in the intertubercular groove and signs of osteoarthrosis are also visible.
Synovial sarcomas are of __________ origin.
Mesenchymal
Caption: proximal humerus with osteomyelitis. An osteolytic area surrounded by osteosclerosis and a proliferative periosteal reaction are visible. The radiological features should be differentiated from those of a primary bone neoplasm.
Referenced from text: In the early stages infectious and degenerative lesions may be possible differential diagnoses, and biopsies are required.
Etiology of synovial osteochondromatosis?
Idiopathic or Secondary (response to chronic irritation)
synovial osteochondromatosis
Positive-contrast arthrogram. Radiolucent nodules appear as filling defects within the joint
etiology of infraspinatus muscle contracture?
trauma, in hunting or working dogs
infraspinatus muscle
contracture, revealing narrowing of the lateral scapulohumeral joint space (arrowed)
clinical path of infraspinatus contracture?
acute lameness, shoulder pain and swelling
this then subsides
but 2-4 weeks later there is a gait abnormality (as the fibrosis and contracture occur)
Is there abduction or adduction of the elbow in infraspinatus contracture? How are the other parts of the leg positioned?
Adduction of the elbow
Abduction of the foreleg
external rotation of the carpus/paw
What part of the scapulohumeral joint is changed in infraspinatus contracture and which projection is best for detecting this?
The lateral may be narrowed (seen best on CC view)
Mineralisation at the supraspinatus tendon insertion is significant or insignificant?
This is a type of dystrophic mineralisation. Its significant is unknown, but rarely a primary cause of lameness.
Which breed is predisposed to supraspinatus muscle tendinopathy?
Rottweilers, or other large breeds
Which breed is predisposed to Calcinosis circumscripta?
GSD, most commonly young large-breeds
Calcinosis circumscripta lesions are usually solitary or multifocal?
solitary
Where are the typical locations of calcinosis circumscripta?
lateral metatarsus / digits
shoulder and elbow
spine
hip, footpads
tongue
cat suffering from
hypervitaminosis A, revealing proliferative new bone formation around the shoulder joint
