Shape and Variability of the Normal Medial Coronoid Process by Computed Tomography in Young Adult Labrador Retrievers

Area of Science:

• Veterinary Radiology
• Canine Orthopedics
• Comparative Anatomy

Background:

• Medial coronoid process disease (MCPD) is a primary cause of elbow dysplasia in young, large-breed dogs like Labrador Retrievers (LRs).
• Computed tomography (CT) is the preferred imaging modality for evaluating the medial coronoid process (MCP) due to its non-invasive nature and ability to avoid radial head superimposition.
• Understanding normal MCP morphology and density is crucial for diagnosing MCPD.

Purpose of the Study:

• To characterize the normal shape of the medial coronoid process (MCP) on CT scans in Labrador Retrievers.
• To assess the variability of MCP shape within the breed.
• To establish normal Hounsfield unit (HU) ranges for the MCP, medial radial head (MRH), and lateral radial head (LRH).

Main Methods:

• Retrospective descriptive study analyzing 51 normal elbow CT scans from South African guide dog LRs.
• Utilized a repeatable imaging alignment technique to assess MCP shape and measure HU values.
• Correlated MCP shape with the level of CT assessment and compared HU values between sexes and radial head structures.

Main Results:

• Identified three principal MCP shapes (ovoid, triangular, softly pointed) dependent on the CT assessment level.
• Male LRs exhibited significantly lower mean MCP HU compared to females.
• The MRH consistently showed higher HU values and greater attenuation than the LRH; proximal measurements were suboptimal due to volume averaging.

Conclusions:

• Normal MCP shape in LRs varies with CT assessment level, but these variations do not lead to misclassification of MCPD.
• Sex-based differences in MCP HU and consistent HU variations between MRH and LRH are important considerations for CT interpretation.
• Accurate HU measurements require avoiding overly proximal sampling to prevent volume averaging artifacts.