Stress Fractures in Adolescent AthletesAndrew D. Goodwillie, MD, Eric Nussbaum, ATC and Charles J. Gatt Jr., MD

University of Medicine and Dentistry of New Jersey - Robert Wood Johnson Medical SchoolNone of the authors listed above have any conflicts of interest

Between September 2007 and December 2009, stressfractures in adolescent athletes were prospectively submittedto an online database by local high-school athletic trainers. Forevery radiographically confirmed stress fracture, astandardized online form that detailed each athlete’sdemographics, fracture pattern, clinical presentation, sport,level of participation, training intensity and dietary habits wascompleted. The database created is reported and analyzedwithin this study.

Adolescent stress fractures are an underappreciated entity inthe athletic community and sports literature, especially in theadolescent athlete. Significant gender differences highlight theimportance of understanding more about this injury.Furthermore, our data suggests that the intensity of trainingprotocols and level of participation may place adolescents at asignificantly higher risk of developing a stress injury.

Tibia, 48%

Metatarsal, 19%

Fibula, 10%

Spine, 6%

Pelvis, 6%

Hindfoot, 4%Femur, 4%

This study reports the epidemiology of stress fractures in theadolescent athlete. To date, there are no comprehensivestudies published on this injury in patients under the age of18. We conducted a community surveillance of stress fracturesin high school athletes to highlight the importance of thisinjury as well as reporting significant gender differences thatexist within this age group.

230 stress fractures were reported in 189 athletes (74 males;115 females) from 57 high-schools. The tibia (48%) was themost frequently involved bone, followed by the metatarsal(19%), fibula (10%), spine (6%), pelvis (6%), hindfoot (4%), andfemur (4%). Varsity athletes sustained the majority of thefractures (64%) within this study. The most common sportsthat caused fractures in males were track (26%), football (23%)and cross-country (19%), and in females track (28%) and crosscountry (23%). Male athletes sustained fractures at an olderage (15.97 yrs vs. 15.46 yrs, P<0.005), higher grade (10.56 vs.10.14, P<0.01), and at a higher body-mass index (BMI) (22.5vs. 20.8, P<0.001) than female athletes. Males also got moresleep (P=0.001) and had more intense weight lifting schedules(1.50 vs. 0.78 sessions a week, P<0.001) than their femalecounterparts.

Figure 2: Distribution of adolescent stress fractures by anatomic location and levelof sport participation. Male athletes have a statistically higher proportion of stressfractures located within the spine than compared with female athletes (9.4% vs.2.6%; P<0.05). In addition, almost twice as many stress fractures were observed atthe varsity level than all other competitive levels combined (64% vs. 36%).

Males Females P value

Patient Demographics

N 74 115

*Age (yrs) 16 (SD + 1.22) 15.5 (SD + 1.16) P < 0.005

*Grade 10.6 (SD + 1.09) 10.1 (SD + 1.07) P < 0.01

*BMI (kg/cm2) 22.5 (SD + 4.06) 20.8 (SD + 2.6) P < 0.001

Pain Scale (0-10) 7.2 (SD + 1.36) 7.3 (SD + 1.47) P = 0.69

Prior Stress Fx (%) 5.4 8.7 NS

Training Regimen

Middle School/Freshman/Sophmore (%) 15.1 12.3 NS

Junior Varsity (%) 21.9 22.8 NS

Varsity (%) 63.1 64.9 NS

Year schedule (# seasons/yr) 2.3 (SD + 0.74) 2.4 (SD + 0.76) P = 0.65

Weekly schedule (# sessions/wk) 6.1 (SD + 0.59) 5.9 (SD + 0.62) P = 0.46

Duration (# hrs/wk) 15.1 (SD + 3.68) 14.6 (SD + 3.51) P = 0.49

*Weight schedule (# weights/wk) 1.5 (SD + 1.61) 0.78 (SD + 1.09) P < 0.001

Hardwood training (%) 31.10% 38.30% NS

Dietary Habits

Supplements (Y/N) 41.9% / 58.1% 30.4% / 69.6% NS

Balanced meals (Y/N) 87.8% / 12.2% 88.7% / 11.3% NS

*Dairy intake (# servings/day) 2.97 (SD + 1.88) 2.3 (SD + 0.01) P = 0.01

Caffeine (# servings/day) 0.9 (SD + 1.08) 0.9 (SD + 1.34) P = 0.79

*Sleep (# hrs/night) 7.6 (SD + 0.81) 7.11 (SD + 0.91) P = 0.001

Table 1: Patient demographics, training regimen and dietary habits of adolescentpatients with documented stress fractures. Gender differences at a statisticallysignificant value of P < 0.01 are highlighted. Male athletes sustain stress fracturesat an older age, at a higher BMI, sleep for longer and participate in a more intenselifting schedule than female athletes.

Figure 3: X-ray radiographs and MRI T2-sequences of a 13-year-old baseball playershowing a right proximal tibial posterior metaphyseal stress fracture withcircumferential periosteal reaction and surrounding soft tissue edema.

0

10

20

30

40

50

60

1914

5 6

17

0 2 40 1 0 1 1 0 0 0

32

27

14 12

0

145 0

4 2 2 0 0 1 1 1

Male Female

Figure 1: Distribution of adolescent stress fractures by type of sport and gender.The tendency is for stress fractures to occur in more ‘running intense’ sports. Thesports most associated with stress fractures in male athletes are track (26%),football (23%) and cross country (19%). For female athletes the sports mostassociated with stress fracture are track (28%) and cross country (23%).

Middle School

1%

Freshman11%

Sophmore2%

Junior Varsity22%

Varsity64%