Feb. 15, 2011 -- Stress fractures in teenage athletes are under-reported and more likely to affect girls than boys, according to new research.
Track, cross country, basketball, soccer, and football were the top sports activities linked with stress fractures in the study.
''Parents should be aware, this is a problem, and it's a greater problem than people necessarily think," says Andrew Goodwillie, MD, chief resident at University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School.
He is presenting the findings this week at the 2011 annual meeting of the American Academy of Orthopaedic Surgeons in San Diego.
The good news? "Stress fractures are fairly easy to treat," Goodwillie tells WebMD. Resting six to eight weeks is typically enough time to recover, he says.
Stress fractures are due to overuse, occurring when muscles get fatigued and can't absorb added shock. The muscles then transfer the stress overload to the bone, resulting in a tiny crack or stress fracture, according to the American Academy of Orthopaedic Surgeons.
The most common symptom is pain with activity, which decreases with rest.
Most Common Types of Stress Fractures
Goodwillie and colleagues evaluated stress fracture reports submitted by athletic trainers from 57 high schools between September 2007 and December 2010.
For every report, the trainer completed an online form, answering questions about fracture pattern, the sport involved, level of participation, and training intensity.
In all, 230 stress fractures were reported in 189 athletes, affecting 115 girls (61%) and 74 boys (39%).
The bones most often fractured were:
- Tibia (shin bone): 48%
- Long bones in the forefoot: 19%
- Spine: 6%
- Pelvis: 6%
- Hindfoot: 4%
- Femur (thigh bone): 4%
Varsity athletes were most likely to get a stress fracture, accounting for 64% of the cases.
Boys were most likely to get fractures from track, football, and cross country; girls from track and cross country.
The average age of boys when a fracture occurred was nearly 16; for girls, it was about 15 1/2.
The training schedules of the boys and girls were similar, with boys putting in 6.1 sessions a week and girls, 5.9, Goodwillie found.
As to why girls had more stress fractures, ''we can't explain [that] from our data," Goodwillie says. In adults, however, the sex differences have been explained by what experts call the ''female athlete triad" -- the possibility that female athletes may have eating disorders, infrequent menstrual cycles, and osteoporosis. As bone mass decreases, the chances of a stress fracture rise.
Reducing the Risk of Stress Fractures
Alison Field, ScD, is an associate professor of pediatrics, Children's Hospital Boston, who has also researched the topic. She reviewed the study findings for WebMD but was not involved in the research.
It's not surprising that boys got fewer stress fractures, Field says. "Boys have greater bone mass density and unfortunately many female athletes are very lean and may not have regular menstrual cycles due to their low weight and/or high training volume. The absence of menstrual cycles increases the risk of fracture."
Teens can take measures to reduce the risk of stress fractures. ''Try to replace some high-impact training with some lower-impact training, such as using an elliptical machine, and making sure that females do not lose the menstrual cycle or have it become very irregular," Field says.
Another way to minimize the risk, according to the American Academy of Orthopaedic Surgeons, is to build the intensity of an activity slowly, such as increasing running mileage gradually.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.