How a knee joint injury leads to knee arthritis

Knee Joint Injury

With Dylan Hartley being ruled out of the Six Nations with what his club called ‘grumbly knee’ and his doctor pinpointed as something worse, the spotlight shines once again on sporting knee injuries – and their knock-on effects. And a new study bears out the undeniable link between knee injuries of today and the problems it can bring on tomorrow; pinpointing the effect that knee injuries can have on the joint, and why it can lead to knee osteoarthritis later in life.

The study – a collaboration between the University of Eastern Finland and the Massachusetts Institute of Technology – demonstrates that articular cartilage degenerates specifically around injury areas when the fluid flow velocity becomes excessive. The findings, which were reported in Scientific Reports, presented a new mechanobiological model for cartilage degeneration, by implementing tissue deformation and fluid flow as mechanisms for cartilage breakdown when a normal dynamic loading – such as walking – is applied to the joint.

A new model that could make a real difference

The researchers discovered that different mechanisms, such as fluid flow and tissue deformation, have the potential to cause cartilage degradation after a knee injury. According to the research team, fluid flow and tissue deformation are plausible mechanisms leading to osteoarthritis, but increased fluid flow from cartilage seems to be better in line with the experiments.

Why is this important? Because this new model could be used to predict osteoarthritis in personal medicine, which would be a huge boost to the medical community: if doctors can be armed with more refined data, they could have a better shot at mapping out the best possible rehabilitation protocol. Furthermore, this model could identify high and low-risk lesions in the cartilage for osteoarthritis development and suggest an optimal and individual rehabilitation protocol.

“Our findings indicate that after an injury in the knee and subsequent tissue loading, osteoarthritis is caused by easy leakage of proteoglycans through the injury surface by high fluid outflow,” Gustavo A. Orozco of the University of Eastern Finland explains.

Taking a knee to long-term problems

Obviously, this isn’t going to help Dylan in the short term – and, like other athletes who have succumbed to knee injury, he is highly likely to suffer the consequences of arthritis as a result of his injury. In a 2017 study of retired rugby players studying concussion, the secondary outcome was that there was a high prevalence of arthritis, due to the fast, hard-contact nature of the sport and the stress it places on the knees.

And as we know, not only do knee injuries have the potential to cause osteoarthritis in the future, but so can the operations to put knee injuries right, including cruciate ligament repair and meniscectomy procedures.

Therefore, any new developments in the field of knee treatment are to be welcomed in both the short and long term – not only for the benefit of the sport, but for the athletes concerned when they are long into their retirement.