Scared scientists by the resurgence of mysterious extra bones in humans

Scientists are puzzled by the resurgence of what they supposed to be an extra bone gone behind the knee.

At the turn of the century, about one in ten had a fabella, a bean-shaped bone that, like the patella, fits into the tendons.

Scientists had assumed that the population rate had remained stable or decreased. But research has now revealed that nearly four in ten people – nearly four times the rate of 100 years ago – now have a bone surplus.

Researchers examined more than 21,000 150-year-old knee records from more than 27 countries.

"We do not know what fabella's function is – no one has ever examined her!" Said Dr. Michael Berthaume, lead author of the study at Imperial College London, in a statement.

"Fabella can behave like other sesamoid bones to help reduce tendon friction, to redirect muscle forces or, as in the case of the patella, to increase the mechanical strength of this muscle. Or it could do nothing at all.

The results were published in the Journal of Anatomy on April 17 and showed that in 1918, fabelles were present in 11.2% of the world's population. In 2018, they were present at 39%.

Fabella is a sesamoid bone, a term used to describe the bones that develop in the tendon. The patella is the largest sesamoid bone in the human body.

Berthaume said, "We are being taught that the human skeleton contains 206 bones, but our study challenges this. Fabella is a bone that has no apparent function and can cause some pain and discomfort to some. It may be necessary to remove it if it causes problems.

"Maybe the fabella will soon be known as the skeletal appendix," Berthaume said.

The study revealed a statistical correlation between the presence of bone and arthritis. People with osteoarthritis knee were twice as likely to have extra bone, which can also hinder knee surgery. The interesting question is why it makes such a comeback, "Berthaume said.

One theory is nutrition. "We have found evidence of the resurgence of fabella worldwide and one of the few environmental changes that has affected most countries in the world is the improvement of nutrition."

A mysterious knee linked to arthritis is three times more common than 100 years ago – an exciting new job @MBerthaume @ImperialBioeng https://t.co/OkLcuUwbui

– Imperial Medicine (@ImperialMed) April 17, 2019

Another theory is that the bone is not as useless as we think, but can provide a mechanical advantage, as it does in old world monkeys, where it acts like a kneecap.

Berthaume said, "The average human being today is better fed, which means we are bigger and heavier. This is accompanied by longer shins and larger calf muscles, changes that exert increasing pressure on the knee. This could explain why fabellae are more common now than they once were. "

Bones have long been known to develop and strengthen in response to mechanical forces.

Researchers speculate that a fabella can form under the influence of certain mechanical forces. However, they believe that there is probably a genetic element – not all people can be able to form one of the extra bones.