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One in every 40 elite soccer players will have to sit out games or practices because of "jumper's knee," or patellar tendinopathy, an injury more commonly found in basketball and volleyball players, suggests a new study.
But a researcher not connected to the new data said many more will continue to play through the pain of the chronic injury, which has no known cure - and no clear prevention strategy.
"The rate and severity of many of the overuse complaints (such as jumper's knee) have raised discussion about how to monitor and adapt load on individual players," Martin Hagglund, the study's lead author from Linkoping University in Sweden, said.
Tendon injury
The injury of the tendon connecting the kneecap to the tibia "typically has a gradual onset," explained Dr Roald Bahr, from the Norwegian School of Sport Sciences in Oslo.
"It could make itself known in one training session, but usually more gradually over weeks or even months. In the beginning there's just a slight ache, but as you continue playing, it becomes more and more bothersome," Dr Bahr, who was not involved in the new study, said.
Dr Bahr's own research found that one in seven elite athletes across a range of sports reported symptoms of jumper's knee.
In the new study, Hagglund and his colleagues recorded injuries that had caused players on 51 elite male European soccer teams - a total of more than 2,000 athletes - to miss game or practice time.
The study
Over the course of almost a decade, team doctors and trainers reported 137 cases of jumper's knee - accounting for 1.5% of all injuries. An average of one in 40 players missed time due to that injury each season.
Athletes who spent more hours training and in competition were more likely to get jumper's knee. However, there was no difference in injury rates based on whether teams played on natural grass or artificial turf - a harder surface that some believe may increase the risk of injury.
Most of the injuries caused players to miss less than a week on the field, but one in 10 was severe, taking players out for a month or more.
Hagglund said that if players start to develop symptoms of jumper's knee, an adapted training programme - one that puts less force on the tendon - could help reduce the injury's severity.
Rehabilitation
"Better safe than quick when it comes to rehabilitation of the injury," he said. "The re-injury rate is high and the condition may be more severe and longstanding if early warning signs are ignored and if the athlete (returns) to play too soon with inadequate rehabilitation."
Dr Bahr said that many players with this injury, however, never end up taking time off - they just play through the pain. In part, that may be the case because there's no "cure-all type of treatment," he said - most players just do physical therapy to work on the tendon.
This new study, published in the American Journal of Sports Medicine, would only reflect the most severe cases of jumper's knee that forced athletes to miss practise or games, he added.
Dr Bahr said the injury is most common in players who have recently made a sharp increase in the amount of training they do, and in the intensity of that training - such as when athletes start playing on an elite or professional team for the first time.
"The bottom line of why this occurs we think is: too much, too often, too soon," Dr Bahr said. "Too much training, training too often, and increasing your training loads too quickly."
Dr Bahr said because of that, not many recreational soccer players or kids will get jumper's knee. But, he added, the story of jumper's knee in elite athletes is similar to that of Achilles tendon injures in recreational runners or "tennis elbow" injuries in casual athletes who increase their training quickly. (Reuters Health/ June 2011)
