Lateral: 4 year old Labrador retriever

• Note positioning:
  • Superimposition of femoral condyles
  • Superimposition of fabellae
  • Beam centred on stifle joint
• Appropriate exposure allows definition of large infra-patellar fat shadow
  • Note small triangular shaped joint fluid shadow
  • Fascial planes caudal to joint are identifiable and not displaced.
• Note smooth, rounded outlines to all bones.
• No signs of osteophyte formation.
  • It is not unusual to see what looks like an ostephyte forming at the distal pole of the patella - that is normal.
  • In contrast, any irregularity on either fabella is considered abnormal.
• The sizes and shapes of the joint fluid/infra-patellar fat shadows should be evaluated very carefully.
  • Synovitis/joint effusion is the first sign of stifle joint OA which is most commonly caused by cruciate ligament  pathology.