Equine third metacarpal bone assessment by quantitative ultrasound and dual energy X-ray absorptiometry: an ex vivo study.

This study analyses two mechanical bone assessment methods applied to horses: Quantitative ultrasound (QUS) and dual energy X-ray absorptiometry (DXA) using horse metacarpal bones. The study finds both methods can be used for precise assessment, but they evaluate different properties and thus are complementary.

Study Objective and Methods

• The research aimed to evaluate the applicability and interrelationship of two different mechanical bone assessment techniques, Quantitative Ultrasound (QUS) and Dual Energy X-Ray Absorptiometry (DXA), on horses. These techniques were applied to the third metacarpal bone (MC III) of horse cadavers.
• QUS depends on the bone’s density and Young’s modulus, while DXA relies on the areal bone mineral density (BMD). Both MC IIIs from eleven randomly selected horse cadavers were sectioned into nine regions of interest (ROIs). These were then measured using the QUS device for speed of sound (SOS) and DXA for BMD evaluation.

Measurement and Evaluation

• The study evaluated full cortical thickness BMD (FcBMD), the overall aspect BMD, and a 4 mm cortical border slice BMD (4mmBMD).
• Each ROI of one MC III was measured ten times to determine the precision of QUS and DXA measurements.
• The research found differing SOS and BMD values at different aspects of MC III and at different levels for FcBMD and overall BMD.
• Data collected from SOS correlated with FcBMD, overall BMD, and 4 mmBMD data at various ROIs. Further, there was a strong correlation amongst FcBMD, overall BMD, and 4 mmBMD-data.

Accuracy and Implications of the Study

• The intra-operator coefficient of variation for the study was 1.3% for SOS measurements, and it ranged between 1.94% and 10.3% for BMD-measurements, indicating precision in the measurements.
• Both QUS and DXA can be used to precisely measure bone characteristics in horses. However, they evaluate different properties of the bone, which means they are complementary, not interchangeable, methods. Each assessment technique brings something different to the study of equine bone health.