PIE- How to take a radiograph of a dogs shoulder

What two views are used to take a radiograph of a dogs shoulder?

-Lateral view

• Technically this is a medio-lateral view

-Caudo-cranial view

• dog will need to be anaesthetised for caudo-cranial view

where does the xray beam enter and exit in lateral view

 x ray beam will enter the through the

medial aspect of the shoulder joint and exit through the

lateral aspect to to the table

where does the xray beam enter and exit in caudo cranial view

the x ray beam enters through the

shoulder joint, it enters effectively from Caudally and exits cranial.

Describe the limbs and neck in lateral view

• The dog is in lateral recumbency with the leg to be imaged against the table

• The limb to be radiographed is pulled into extension using a rope tie

  • this also pulls the shoulder joint away from the neck soft tissues

• The upper limb is moved caudally out of the way with a rope tie

• The neck is flexed dorsally and secured using a sandbag

  • this moves the cervical spine so it does not superimpose over the shoulder joint

What are the steps to taking a lateral view to radiograph the shoulder?

• Place a foam pad under the chest to ensure the dog is parallel to the table and assist shoulder extension

• The exposed area should include the distal 50% of the scapula and proximal 50% of the humerus

• Use L / R label

how can we detect the acromion

just by sliding our fingers underneath the dog and palpating.

where centre for lateral view

The centre of collimation should be the shoulder joint (just distal to the acromion)

where collimate for lateral view

• Collimate to include soft tissues cranial and caudal to shoulder

What should be seen in a well positioned lateral view radiograph of the shoulder?

• In a well positioned radiograph the joint space should be well visualised and there should be no overlying tissue

• Some radiographers deliberately try to overlie the shoulder joint with the trachea to increase contrast

label

• acromion process

• spine of scapula

• scapula

• humeral head

• humerus

• glenoid cavity

• greater tubercle

Describe the position of dog in caudo-cranial view for shoulder radiograph

• The dog is put in dorsal recumbency with the limb to be radiographed pulled into extension (X-rays enter caudal aspect and exits cranial aspect of the shoulder)

• The limb is pulled slightly away from the midline (approx. 5 degrees)

• A sandbag may be use to push the head and neck slightly away from the limb to reduce superimposition

• Use L/R label

how should the long axis of scapula and humerus be in the caudo cranial view

Aim to hold the long axis of scapula and humerus in line with each other

• see the joint space nice and prominently demonstrating the radiograph is suitably positioned.

how centre caudo cranial

Centre at the middle of the shoulder joint (just distal to the acromion)

how collimate in caudo cranial view

Collimate to include the distal 50% of the scapula and proximal 50% of the humerus

Collimate to include the lateral and medial soft tissues

label

• scapula

• spine of scapula

• acromion process

• greater tubercle

• intertubercle groove

• coracoid process

• lesser tubercle

• supraglenoid process

• glenoid cavity

• humerus

What should be seen in a well positioned caudo-cranial view of a shoulder radiograph?

§A well positioned radiograph has the scapula and humerus in line with each other

§Centering on the middle of the joint means there is good visualisation of the joint space

Problems that can occur with a cranio-caudal (not caudo-cranial) view of a shoulder...

The cranio-caudal view can result in magnification distortion as it is difficult to get the shoulder close to the table

This technique would be common in the standing horse but not in dogs

what common pathology of the shoulder is there

• medial shoulder luxation

• osteochondrosis

• chronic shoulder arthrosis

medial shoulder luxation

Describe a medial shoulder luxation due to trauma

unusual position of humeral head compared to glenoid cavity of the scapula

-Humeral head has been displaced medially

Describe osteochrondrosis

-Cartilage defect associated with an underlying bone problem

-Causes flattened appearance of humeral head

-Multiple disc like depressions of humeral head

Osteochondrosis

-Red arrows show disc like depressions

What will osteochondrosis (developmental) present as?

Loss of rounded contour of caudal surface of humeral head

Radiolucent defect

May have surrounding sclerosis

May have calcified free body in joint

label

• flattened/ indent of the humeral head

• partially calcified flap of cartilage → displaced from joint capsule

What will be seen in chronic shoulder arthrosis?

Lots of new bone (osteophytes)

Underlying cause often not evident

• label the normal

• sclerosis and osteophytes

• sclerosis, uneven joint space, osteophytes (New bone)

WHAT do we expect to see at normal joint

 nicely rounded and smooth margin to the

head of the humerus and look at the margins of

the distal part of the scapula spine and the joint

space here.

So nice and smooth and nice.