Interpreting radiographs 3: Radiology of the stifle joint of the horse.

The research article discusses the radiology of the stifle joint in horses. It details the radiographic techniques, anatomical insights and possible medical findings related to the largest joint in a horse’s body.

Radiographic Technique

• The paper mentions that performing stifle radiography under general anaesthesia offers numerous benefits, including improved standardization of exposure factors, reduced movement unsharpness, a wider range of possible projections, and enhanced radiation safety. However, the issues and risks associated with anesthesia must be taken into account.
• For improving radiographic quality, the paper recommends using a Dodger-T aluminium filter which can function with both standing and recumbent horses. This filter attenuates the primary beam through the soft tissue and thinner structures while also limiting the amount of scattered radiation.
• The paper advises taking radiographs from multiple angles particularly lateromedial (LM) and caudocranial (posteroanterior-PA) views. When taking the LM view in the standing position, the horse’s limb is recommended to be lifted and extended backward for improving access to the cassette and achieving accurate limb alignment.

Radiographic Anatomy and Incidental Findings

• The research describes the radiographic anatomy of the stifle, the largest joint in horses, and emphasizes the importance of understanding its complex structure.
• At birth, the ossification of the stifle is incomplete which gives it a significantly different radiographic appearance compared to a mature horse. Various features like prominent growth plates, wider joint space, less developed tibial spine, minimal ossification of the fibula, and other irregularities can be observed in a newborn.
• As the horse matures, these features transform. The distal femoral growth plate becomes irregular and wavy, early sclerosis can be observed, and the tibial tuberosity gets its separate ossification centre which fuses with the tibial shaft at around 9 to 12 months of age.
• Details about the radiographic evolution of the stifle’s anatomy, including the trochlear ridges and condyles, are discussed. The interpretation of these facets can provide necessary diagnostic information about the horse’s joint health and development.
• The research offers a list of incidental findings that can complicate radiographic interpretation and suggests their differential diagnoses. These incidental findings contribute to the complexities of reading stifle radiographic images and diagnosing potential joint abnormalities.