Contributors: Patsy Whelehan

 Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading

Introduction

  • A high definition film-screen combination is required.
  • Joints at both ends of bone should always be included.
  • Soft tissues should be included.
  • General anesthesia or heavy sedation is required.
  • The film should 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.

Uses

Advantages

  • Non-invasive.
  • Straightforward.

Time Required

Preparation

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

Procedure

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

Decision Taking

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
  • Usually enables detection of fractures.
  • May detect neoplastic conditions.
Craniocaudal
  • Essential to have this second view where fracture is suspected or to assess fracture fully.
  • Necessary for full assessment of neoplastic conditions.

Requirements

Personnel

Other involvement

  • Radiographer or Technician carrying out radiography.

Materials Required

Minimum equipment

  • X-ray machine.
  • Cassettes with high definition or fast screens, depending on size of patient.
  • 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 screens.
  • Automatic processing facilities.

Minimum consumables

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

Preparation

Restraint

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

Procedure

Core Procedure

Step 1 - Lateral

  • Position the patient in lateral recumbency on the side to be examined and immobilize. Alternatively, position the thorax in dorsal recumbency in a trough and rotate the patient towards the affected side, abducting the femur.
  • Use a sandbag and/or tie to hold the contralateral limb dorsally away from the field.
  • Flex the hip and stifle on the affected side slightly.
  • Use padding under the dorsal pelvis and the distal limb as necessary to achieve a true lateral position of the femur, parallel to the film.
  • Center the vertical beam at mid-shaft.
  • Collimate to include the hip and the stifle, as well as the soft tissues cranial and caudal to the shaft   Stifle: normal immature - radiograph lateral  .

Step 2 - Craniocaudal

  • Position the patient in dorsal recumbency in a trough.
  • Rotate slightly away from the affected side and immobilize.
  • Extend the affected limb caudally and secure with a tie.
  • Further adjust the position of the trunk to ensure that the femur is in a true craniocaudal position.
    In the likely event that the femur is not horizontal, angle the beam until it is perpendicular to the shaft and elevate the caudal edge of the cassette to bring it as near perpendicular to the beam as possible.This technique is unlikely to result in an undistorted view of the stifle. Where this is necessary it is important to center separately for the stifle, as with all joint radiography.
  • Center the beam at mid-shaft.
  • Collimate to include both joints, and the lateral and medial skin surfaces.

Aftercare

Outcomes

Reasons for Treatment Failure

Poor technique

  • The most common problem here is inadequate extension of the hip and/or the stifle for the craniocaudal view. This is often due to the limitations of the patient's condition. While angulation of the beam and film can help, a distorted view is sometimes still obtained. It may be necessary to resort to a separate caudocranial view of the distal femur (see stifle).
  • Inadequate sedation.
  • Poor processing.
  • Equipment failure.

Further Reading

Publications

Refereed papers