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Knee injuries in children – what are the risk factors?

The dark cloud of the obesity crisis that currently hangs over our heads has meant that the focus has very much shifted to getting our children to be more active during school hours. This has also led to an increasing number of kids reporting injuries. In Denmark, 25% of all injuries in children and adolescents treated at hospitals each year are related to sport.



In this article:

  • What we know about knee injuries in children

  • What the researchers did

  • What type of knee injuries were the most common?

  • Risk factors for traumatic knee injuries in children

  • Risk factors for overuse knee injuries in children

  • Surprises in the results

  • What this means in practice

What we know about knee injuries in children


Most of the research in the past has focused on statistics from hospital settings. The problem with this is that the data only represents traumatic injuries that are bad enough for parents to take children to hospital and from working in school level sport in the UK, I can assure you that a parent will do nearly anything to avoid the busy A&E on a Saturday!


A further issue is that these studies give no information about growth-related overuse injuries which have been shown to be a lot more prevalent than traumatic knee injuries in kids. (1) I also find this in our clinic with Osgood-Schlatter’s being a very common diagnosis in growing children.


This has led a group of Norwegian researchers to conduct a study to find out what the true incidence of knee injuries was for kids between the ages of 8 and 15 years and also if they could identify any risk factors that may predispose a child to a knee injury.


What the researchers did


They enrolled 1326 children between the ages of 8 and 15 in the study and monitored them weekly, from 2011 until 2014, for musculoskeletal pain, sports participation and sports type.


They also specifically looked if any of the following factors increased the children’s’ risk of sustaining knee injuries:

  • Gender

  • Age

  • Height

  • Body mass index

  • General joint hypermobility

  • Having had a previous knee injury

  • Amount of organised sports participation

They monitored these factors repeatedly over time to ensure that they picked up any changes that may have occurred over the 3 years.


Playing football increased a childs risk of developing growth related overuse knee injuries.

What type of knee injuries were the most common?


A total of 952 knee injuries was reported during this period. Of this, 15% was traumatic knee injuries and 85% was overuse knee injuries.


The traumatic knee injuries consisted mainly of sprains and contusions (bruising), while traction apophysitis, e.g. Osgood-Schlatter’s and Sinding-Larsen-Johansson’s, made up most of the overuse knee injuries.


The researchers observed a peak in overuse knee injuries in the children between 11 and 12 years of age. This makes sense since children often experience growth spurts during these ages which predisposes them to traction apophysitis due to increased tension in the soft tissue.


Simply put, their bones grow quickly and their muscles and tendons lag behind. In practice this means that they become a lot less flexible and their ability to coordinate/control their movements decreases for a short period until the brain can figure out how to ‘drive’ this new body. This may put extra strain on the bit of cartilage that connects their tendon to the bone resulting in inflammation, pain and swelling in the area.


Risk factors for traumatic knee injuries in children


The only risk factor identified for sustaining a traumatic knee injury was taking part in tumbling gymnastics. None of the other factors appeared to increase the children’s risk of sustaining a traumatic knee injury.


When they looked at specific risk factors per sports type and sports participation they identified that the following increased a child’s risk of a traumatic knee injury:

  • Participating in soccer and handball four times per week

  • Participating in tumbling gymnastics twice a week

  • Participating in handball only once a week (This seems counterintuitive but it may likely be that these kids lacked the necessary skills to safely play the sport due to a lack of training, which then predisposed them to injury.)

Risk factors for overuse knee injuries in children


Girls appeared to be at greater risk of developing overuse knee injuries than boys. Having had a previous knee injury also put a child at a greater risk of developing an overuse injury.


The researchers also found that children participating in specific sports, e.g. soccer, handball, basket, rhythmic and tumbling gymnastics, more than twice a week had significantly higher odds of sustaining an overuse knee injury compared to children not participating in sports.


Participating in handball and soccer also increased a child’s odds compared to other sports.

Sports participation above two times per week in specific sports such as soccer, handball, dance, rhythmic and tumbling gymnastics increased the odds for both types of knee injury.


Surprises in the results


It surprised the researchers that having generally hypermobile joints did not predispose the children to knee injuries in this study, since a previous meta-analysis had found it to be a significant risk factor in other populations. They concluded that this finding may be due to the specific population of kids that they studied.


What this means in practice


This study on its own is not enough to make recommendations about the volume of sport that is good or bad for a child, but it give us a much better idea of the real extent to which children get injured from sport. Importantly, it also did not give us any information regarding the severity of the knee injuries or the time children had to refrain from sports, if any, so the situation may look a lot more gloomy than what it really is.


It did, however, highlight that overuse injuries is a bigger problem than traumatic injuries and that these tend to occur mostly in children when they experience growth spurts. I plan to write another blog next year where I'll share our clinic's treatment approach to children suffering with overuse knee injuries, e.g. Osgood Schlatter's. My advice for now is that if you suspect your child has an overuse knee injury to:

  • Make him/her take a break from any sports that aggravate it - usually jumping and running sports.

  • Stretch the quads three times a day - this should be done pain free.

  • They can use a foam roller to massage their quads.

  • Work on balance. They usually lose their ability to balance when they go through a growth spurt.

Let me know if you have any questions. Need more help with an injury? You can consult me online using Skype video calls.

Best wishes

Maryke

Sports Physiotherapist


References

  1. Jespersen, E., Rexen, C. T., Franz, C., Møller, N. C., Froberg, K., & Wedderkopp, N. (2015). Musculoskeletal extremity injuries in a cohort of schoolchildren aged 6–12: A 2.5-year prospective study. Scandinavian Journal of Medicine & Science in Sports, 25(2), 251-258.

  2. Junge, T., Runge, L., Juul-Kristensen, B., & Wedderkopp, N. (2015). Risk Factors for Knee Injuries in Children 8-15 Years: The CHAMPS-Study DK. Med Sci Sports Exerc, 10, 10.

  3. Pacey, V., Nicholson, L. L., Adams, R. D., Munn, J., & Munns, C. F. (2010). Generalized joint hypermobility and risk of lower limb joint injury during sport: a systematic review with meta-analysis. Am J Sports Med, 38(7), 1487-1497.

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