Professional soccer players in the Netherlands were more likely to have a bone deformity in their hips if they had started playing soccer a lot before age 12. The hip deformity can lead to pain and joint damage.
The deformity is called a cam deformity and it is a small bit of extra bone that grows near the top of the femur, at the ball part that fits into the hip socket of the pelvis. The ball part of the femur becomes less spherical. It can form in response to high-impact sports practices during the time when the skeleton is growing rapidly.
Dutch researchers took x-rays of both hips of 63 professional soccer players. The average age of the players was 23. The players were asked to fill out a questionnaire asking when they started playing soccer and how often they played soccer while growing up. Most of the players started playing soccer at age 6 and joined a professional football club where they were expected to play four or more times a week between ages 12 and 13.
They found that 40% of the players who started playing soccer four or more times a week after age 12 had a cam deformity. However, 64% of those who started playing soccer four or more times a week before age 12 had such a deformity. Eighteen of the players had a deformity severe enough that they would probably develop osteoarthritis in the hip when they are older.
The researchers stated that there was a dose-response relationship between how often the athletes played soccer during their skeletal growth and the development of the cam deformity. In other words, the deformity appears to occur in response to the amount of soccer played during a growth spurt.
The study was published in the British Journal of Sports Medicine.