Thousands of Danish adolescents have knee pain

Diet and lifestyle 5. mar 2020 3 min Professor Michael Skovdal Rathleff Written by Kristian Sjøgren

A passion for sports means that 6–7% of all 10- to 19-year-olds in Denmark have knee pain. This affects their quality of life and can influence their job prospects. The good news is that new research shows that they can change this by structuring their training properly.

When a PhD student named Michael Skovdal Rathleff contacted an upper-secondary school teacher in western Denmark 10 years ago, little did she know that her observations in the school gym would lead to a long-term research project with far-reaching implications.

The teacher had noted that 10–15% of the students did not attend her physical education classes and that they often gave knee pain as the reason.

Today, 10 years later, Michael Skovdal Rathleff is no longer a PhD student but a professor at the Department of Health Science and Technology at Aalborg University.

His latest research shows that many adolescents have knee pain because they are passionate about their sport. Fortunately, his research also shows that if these adolescents plan their training and recovery properly, they can avoid getting knee pain again.

“In the beginning, we did not know whether these adolescents actually had knee pain, how long the pain lasted, what caused it or whether it disappeared again. We have investigated this for the past 10 years, and our results show that about 6–7% of all adolescents actually have knee pain, and if nothing is done, this can become a chronic condition that can seriously affect their quality of life,” explains Michael Skovdal Rathleff.

His latest results were recently published in the Journal of Orthopaedic and Sports Physical Therapy.

Knee pain should not be treated with rest and relaxation

According to Michael Skovdal Rathleff, the inappropriate myth is that young people should just give their sore knees a break for a couple of weeks and then the pain will disappear again.

Unfortunately, this is not true, and in a study of 500 adolescents with knee pain, Michael Skovdal Rathleff and colleagues showed that as many as 40% experience chronic pain even 5 years later.

Many of these adolescents with knee pain take painkillers so that they can play football, tennis or handball.

In the long term, this pain seriously affects their level of activity as young adults and their choice of jobs.

“Many adolescents go from being very active to being completely inactive because the pain becomes too great. One challenge in general practice is the lack of knowledge. That is why many general practitioners have advised adolescents to rest and relax,” explains Michael Skovdal Rathleff.

Pain starts as early as 10 years old

In a previous study, Michael Skovdal Rathleff focused on 15- to 19-year-olds, but the new study shows that 10- to 14-year-olds have the same problems.

The usual problem is that they are part of a sports community because they play a sport. When they no longer play their sport, they disappear from this community, which is why many continue to play football or other sports despite knee pain.

“We have compared these adolescents and a woman on Denmark’s national football team. She trains about 9 hours a week, and these adolescents train up to 13 hours a week. The bodies of many of these adolescents cannot withstand that kind of strain,” says Michael Skovdal Rathleff.

Adolescents with painful knees are just as active as their friends with pain-free knees

In the new study, the researchers studied and worked with 252 10- to 14-year-olds; 202 had various types of knee pain (151 had patellofemoral pain and 51 had Osgood-Schlatter disease), and 50 were controls.

The researchers used questionnaire surveys and studied adolescents’ physical activity and hip and knee strength to investigate how knee pain influenced their activity level and quality of life.

The results showed that adolescents with knee pain were no less physically active than their peers without knee pain. They simply suppressed the pain and participated at the same level as everyone else.

The study also found that adolescents with knee pain reported a lower quality of life.

In addition, the physical measurements showed that the adolescents with patellofemoral pain in their knees had less strength in their hips than the controls. The adolescents with Osgood-Schlatter disease had less knee strength than the controls.

“Our results show that these adolescents continue to exercise even though they have knee pain, and one third may take painkillers before training just to be part of the community,” explains Michael Skovdal Rathleff.

Pain disappears with reduced training

Fortunately, Michael Skovdal Rathleff’s research also shows that something can be done for these adolescents.

In a separate study, the research team investigated whether they could alleviate the knee pain by helping the adolescents to structure their approach to training, so they could play their sport without having to take painkillers.

The treatment strategy simply involved getting these adolescents to reduce the number of training hours per week and then slowly build up again, while continuing to monitor the knee pain and do some simple exercises at home.

According to Michael Skovdal Rathleff, the important thing is to provide these adolescents with the tools to push themselves and yet restrain themselves when needed.

The study showed that the structured approach to training alleviated the pain, enabling the adolescents to play their sport without pain again.

“Adolescents need to learn how to reduce their sports participation and how to listen to their bodies. If you cannot get adolescents to do this, their pain can become chronic. This can affect not only their participation in sports but also their quality of life and job prospects as adults. It is therefore important to do something about this as early as possible,” says Michael Skovdal Rathleff.

The researchers from Aalborg University have published a pamphlet containing good advice and guidance for adolescents with knee pain.

Pain, sports participation, and physical function in 10–14 year olds with patellofemoral pain and Osgood Schlatter: a matched cross-sectional study of 252 adolescents” has been published in the Journal of Orthopaedic and Sports Physical Therapy. In 2017, the Novo Nordisk Foundation awarded a grant to Michael Skovdal Rathleff for the project Patient Outcomes Matter: the Development of a New Patient-reported Outcome Measure for Adolescents with Anterior Knee Pain.

The Department of Clinical Medicine was established on January 1st, 2013. The department has its physical location at Aalborg University Hospital wher...

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