An analysis of tibial cartilage in horses and cows shows significant differences, revealing how horses have developed into “well evolved joggers” while cattle are more like “domesticated couch potatoes”, say British researchers.
The researchers from the Department of Mechanical Engineering at the University of Bath say their findings may ultimately help to better understand human knee weakness.
The paper, published in the journal, Naturwissenschaften, shows that a new technique could give medics a better understanding of osteoarthritis in the knees of humans.
Professor Richie Gill, author of the paper from the university’s Centre for Orthopaedic Biomechanics, said: “For human knees, a common failure is osteoarthritis, which is the result of degradation of cartilage within the knee joint.
“The cartilage is needed to provide a low-friction, self-lubricating surface that can bear loads and permit movement. When this breaks down, the sufferer will experience pain and a loss of movement.”
He said there was a good understanding in medicine about the biochemistry and genetics of the materials that make up cartilage, but relatively little was known about how they contributed to the bulk properties of cartilage and how they worked in a joint.
“Understanding the mechanical properties of cartilage within the knee isn’t trivial,” he said.
“Traditionally, to do this you would need to surgically remove significant amounts of cartilage from the knee, and this would require the use of cumbersome equipment. There is a clear need to develop a simple technique that will allow the testing of small tissue samples.”
The research team at Bath developed such a technique, using it to compare the knees of horses and cows. The insights into horse and cow knees were made possible by the use of a novel analytical measuring technique based on the shearing of small biopsy samples, called Dynamic Shear Analysis.
Gill continued: “Dynamic Shear Analysis, or DSA, can give us detailed measurements of the behaviour of a material. We have been able to use this method to test the collagen network that makes up cartilage.”
The researchers chose the knees of horses and cows for comparison in order to test that their method worked as expected.
It is already known that there are correlations between the lifestyle of an animal and the form and function of its knees. Horse knees are those of “well evolved joggers”, whereas cows are more those of “domesticated couch potatoes”, the researchers said.
“Overall, we saw highly significant differences between the cartilage of horses and cows,” Gill said.
“Horse cartilage is thicker, compresses less and has a greater resistance to deformation – it almost certainly developed this way to allow for the speeds at which horses travel, and increased pressure on the knee joint.
“Our observations have implications for the study of human knee cartilage and its diseases,” he said.
“Evolutionary pressures in human knees may have increased our knee range of motion, but not driven significant change in cartilage material properties.”
He said DSA could offer a new, powerful means to understand osteoarthritis and classify knee-joint failures.
The full research paper, which is a collaboration between the universities of Bath, Oxford and Sheffield, can be accessed here.