Radiography: shoulder

• Accurate centering is essential when radiographing any joint.
• High definition film-screen combinations are required.
• A grid is not necessary.
• kV should not exceed about 50.
• Close collimation is essential.
• If general anesthesia is not used, then heavy sedation with analgesia is needed.
• The film must include the whole joint, with soft tissues, must be correctly exposed and developed and free from movement blur and artifact.
• The anatomical marker must be clearly visible, along with the patient's identification, the date, and the name of the hospital or practice.

• An important diagnostic aid in determining the cause of a lameness arising from the shoulder.
• Bony injury: fracture or dislocation Shoulder: luxation - traumatic.
• Bony neoplasia or soft tissue neoplasia invading bone Synovial sarcoma.
• Investigation of soft tissue injury.
• Joint effusion, swelling .

Advantages

• Non-invasive.
• Straightforward.

Disadvantages

• Poor positioning can make subtle pathology impossible to detect.
• The presence of severe pain can make the procedure difficult in a conscious patient.

Preparation

• Dependent upon the method of chemical restraint (GA or sedation).

Procedure

• 10 to 15 minutes, or longer, dependent upon skill of radiographer.

Criteria for choosing test

Is the examination appropriate?

• Can you make the diagnosis without it?
• Can it tell you what you need to know?
• Will your management be affected by the radiological findings?

Choosing the right projections

Lateral: standard projection

• Shows glenoid cavity and head of humerus.
• Demonstrates joint space.
• Shows soft tissue swelling and joint effusions.
• Can show calcification in tendons.

Craniocaudal: second standard projection, or supplementary

• Essential second view in cases of known or suspected fracture.
• Usually necessary in cases of dislocation.

Other involvement

• Radiographer, or Technician carrying out radiography.

Minimum equipment

• X-ray machine.
• Cassettes with high definition screens.
• Processing facilities.
• Immobilization and positioning aids: sandbags, foam wedges, tying tapes.
• Protective clothing (lead-rubber aprons).

Ideal equipment

• High output X-ray machine.
• Rare earth high definition screens.
• Automatic processing facilities.

Minimum consumables

• X-ray film.
• Pharmaceuticals for chemical restraint.

• One to two competent people.
• Sandbags.
• Foam wedges.
• Tying tapes.
• Positioning trough.

Step 1 - Lateral projection

• Place the patient in lateral recumbency on the side to be examined and immobilize.
• Use a sandbag to hold the contralateral limb out of the field caudally and dorsally .
• Use a tie to distract the affected limb well cranially, and secure.
• With foam wedges, pad under the elbow to ensure the humerus is parallel to the film.
  Locate by palpation of the lateral aspect of the shoulder joint space.
• Center with a vertical beam directly through the joint space .
• Collimate to include the entire glenoid cavity, the soft tissues of the joint, and the proximal third of the humerus .

Step 2 - Craniocaudal projection

• Place the patient in dorsal recumbency in a trough and immobilize.
• Rotate the thorax away from the affected side .
• Using a tie, extend the affected limb as far cranially as possible and secure.
• Adjust position of thorax and limb to ensure the joint is in the true craniocaudal position.
• Center the vertical beam through the joint space by palpation of the lateral aspect.
• Collimate to include the soft tissues of the joint and the proximal third of the humerus .

Step 3 - Cranioproximal-craniodistal (bicipital groove) projection

• Place the patient in sternal recumbency .
• Flex the shoulder and the elbow.
• Abduct the radius slightly so that it does not lie beneath the shoulder.
• Palpate the groove on the cranial aspect of the head of humerus and direct the beam tangentially through it.
• Collimate closely.

• Inadequate sedation.
• Poor technique: inaccurate positioning or centering, wrong exposure factors.
• Poor processing.
• Equipment failure.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Allan G S (2000) Radiographic features of feline joint disease. Vet Clin North Am Small Anim Pract 30 (2), 281-302 PubMed.