Contributors: Justin Goggin, Patsy Whelehan
Species: Canine | Classification: Techniques
- Accurate centering is essential when radiographing any joint.
- High resolution film-screen combinations are required.
- A grid is necessary when tissue thickness >10 cm.
- kV should not exceed about 60.
- Close collimation is essential to avoid scatter.
- If general anesthesia is not used, then sedation with analgesia is suggested.
- The film must include the whole joint, with soft tissues, must be correctly exposed and developed and free from movement blur and artefact.
- 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 lameness arising from the shoulder.
- → Bony injury: fracture or dislocation Shoulder: luxation - traumatic .
- → Osteochondrosis Shoulder: osteochondrosis .
- → Bony neoplasia , or soft tissue neoplasia Synovial cell sarcoma , invading bone.
- → Investigation of soft tissue injury.
- → Inflammatory, infectious or degenerative osteoarthrosis.
- → Congenital elbow luxation.
- Low cost and readily available.
- Poor positioning can make subtle pathology impossible to detect.
- The presence of severe pain can make the procedure difficult in a conscious patient.
- Radiation exposure to patient/personnel.
- Dependent upon the method of chemical restraint (GA or sedation).
- 10-15 min 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?
- Shows glenoid cavity and head of humerus.
- Demonstrates joint space.
- Shows soft tissue swelling and joint effusions.
- Can show calcification in tendons.
Lateral oblique views may be necessary to visualize some osteochondritis dissecans (OCD) lesions.
- Necessary for minimum radiographic evaluation.
- Essential second view in cases of known or suspected fracture.
- Usually necessary in cases of dislocation.
- Useful to confirm or further assess osteochondrosis lesions.
- Most useful as part of a contrast arthrogram.
- May be useful in plain radiography to demonstrate calcification in the bicipital tendon, or bony change secondary to bicipital tendon damage.
- Also helpful to differentiate supraspinatous calcification from biceps tendon disease.
- Radiographer or veterinary nurse/technician carrying out radiography.
- X-ray machine.
- Cassettes with high definition screens.
- Processing facilities.
- Immobilization and positioning aids: sandbags, foam wedges, tying tapes.
- Protective clothing (lead-rubber aprons).
- Film ID system.
- High output X-ray machine.
- Rare Earth high definition screens.
- Automatic processing facilities.
- Film ID camera.
- X-ray film.
- Pharmaceuticals for chemical restraint.
- Film ID card or tape.
- 1-2 competent people.
- 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 to avoid superimposition of the scapulotium joint and thoracic structures and secure.
- 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 - Caudocranial projection
- Place the patient in dorsal recumbency in a trough and immobilize.
- Rotate the thorax slightly 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.
Reasons for Treatment Failure
- Inadequate sedation.
- Incomplete studies (one view only) lead to inaccurate diagnosis.
- Poor technique: inaccurate positioning or collimation, wrong exposure factors, failure to label film.
- Poor processing.
- Equipment failure.