How many runners have stopped playing their favorite sport when diagnosed with osteoarthritis of the knee? For a long time there has been a misconception that running would promote osteoarthritis and that, all things cease, one should put an end to one's (more or less budding) career as a marathon runner. Unfortunately, health professionals have largely concurred in conveying the received idea that running damages the knees, for lack of scientific proof to the contrary.
Osteoarthritis is a joint disease that evolves through inflammatory crises and which will see the articular cartilage degrade until it sometimes completely disappears and thus requires the replacement of the joint by a total prosthesis. In France, 10 million people are affected by a diagnosis of osteoarthritis. This joint disease affects the knees in 30% of cases and the hips in 10% of cases.
Although cartilage damage is often referred to as being pathognomonic for osteoarthritis – that is to say that it is a specific symptom of it – this disease is not, however, limited to the simple degradation of articular cartilage. Indeed, it is all the tissues that make up the joint that is affected. During the pain crisis, the synovial membrane, the tissue that lines the inside of the joint, becomes inflamed and, through a chain reaction, causes the production of enzymes that will degrade the articular cartilage.
Thus, the articular cartilage that encrusts the bones making up the joint could be damaged just as much – or even more – by biochemical factors than by mechanical factors like running. This hypothesis is supported by the existence of risk factors for developing osteoarthritis, which are metabolic diseases such as diabetes, high blood pressure or obesity.
The annual meeting of the American Academy of Surgery was held between March 7 and 12 in Las Vegas, USA. Dr. Matthew James Hartwell, who is a researcher in orthopedic surgery and sports medicine at the University of California (San Francisco), presented the results of a study carried out on a cohort of 3,804 runners who participated in the Chicago Marathon in 2019 or 2021. These runners were questioned with 30 questions aimed at evaluating, among other things, their running history (number of years of running, average weekly mileage over the past year, average running pace , number of marathons completed, etc.).
Another part of the survey looked at the medical aspect: assessment of knee and hip health (hip and knee pain in the past year that prevented running, history of pain, family risk factors for hip or knee osteoarthritis, past surgeries… On average, the runners who responded to the survey were just under 44 years old and ran 45 kilometers per week.
The results of the study are without appeal. There are many risk factors for developing osteoarthritis: the existence of old injuries, a history of knee or hip surgery, age, family history and body mass index. On the other hand, the number of years of practice of running, the number of marathons completed, the weekly mileage and the average running pace did not prove to be risk factors. Dr Hartwell stated that the prevalence (i.e. the number of cases relative to the total population) of hip and knee osteoarthritis was 7.3% in his study and that the risk factors risk were the same in runners as in non-runners. Finally, during his speech, Dr. Hartwell regretted that the injunction to stop the practice of running by doctors is still too frequent (in one out of two cases, according to the survey).
We bet that this new study, which confirms what we already knew, will change mentalities and the way we look at the intimate link between physical activity and osteoarthritis. However, some nuances must be made: if the total cessation of running is now to be excluded, physical activity must be modulated according to the symptoms and more or less inflammatory phases. Those who suffer from osteoarthritis and wish to pursue their favorite sport should contact their physiotherapist, he will be able to give them good advice and support them in their sports project.
* Stéphane Demorand is a masseur-physiotherapist, liberal practitioner. Holder of a university degree in health food and micronutrition and a university degree in legal litigation expertise, he works as a consultant. He is also a consultant in the prevention of musculoskeletal disorders.
