Dorsal metacarpal cortex ultrasound speed and bone size and shape.

The research was focused on how ultrasound speed as measured by the Sunlight Medical’s ‘Omnisense’ machine, through the dorsal cortex of the third metacarpal bone (MC3) in Thoroughbred racehorses, relates to the shape and size of this bone. The study concludes that higher ultrasound speeds correspond to thinner dorsal cortices, and that this technology can be leveraged to predict how a horse’s bone might respond to exercise, thus minimizing the risk of injury.

Background and Purpose

• The study focuses on the relationship between ultrasound speed measured through the dorsal cortex (DC) of the third metacarpal bone (MC3) in Thoroughbred racehorses, and the shape and size of this bone.
• The dorsal cortex of the MC3 in these horses is known to enlarge when the animals are exposed to high-speed exercise for the first time.
• The researchers aim to determine if this ultrasound speed, specifically measured on the surface 3-5 mm of the midshaft dorsal cortex of MC3, can be directly linked to the midshaft shape and size of these racehorses’ MC3 bones at the same stage of training.

Methodology

• The study included two groups of Thoroughbred racehorses: sixteen 2-year-olds, and sixteen aged between 3 to 6 years. All of these animals were exercising at racing speed at the same training stable.
• Each horse’s ultrasound speed was measured, and radiographs were taken to measure their MC3’s midshaft size (width of DC) and shape (calculated as a function of the widths of the dorsal cortex, palmar cortex, and medulla).

Findings

• The study discovered significant linear relationships between ultrasound speed and radiographic bone size and shape measurements.
• Higher ultrasound speeds were found to correspond to bones with thinner dorsal cortices, both in absolute terms and when considered proportionately, across both groups of racehorses.

Implications

• The use of ultrasound speed measurement with Sunlight Medical’s Omnisense machine could allow for more precise and detailed predictions to be made about how a horse’s MC3 bone would respond to exercise, relative to radiographic size and shape measurements alone.
• These findings could help predict when a horse can race after a change in bone shape with minimum risk of injury to the new bone surface.