Bone Health in Sports Medicine: What Orthopaedists Should Know, and What to Tell Patients
By: Christina M. Morganti, M.D. and Andrea M. Spiker, M.D.
In recognition of May being Osteoporosis Awareness and Prevention Month, this month’s Inside AANA E-Newsletter article focuses on bone health in sports medicine. While there is improved recognition of bone health in orthopaedics in the setting of fragility fractures and osteoporosis, bone health has perhaps been underappreciated in the field of sports medicine. Sports medicine doctors often treat patients across the entire age spectrum, from the childhood years when bone is accruing until peak bone mass is achieved, to Masters athletes who are at the other end of the spectrum and losing bone with age. Our influences can be broad when optimizing bone health in athletes of all ages.
Approximately 90% of peak bone mass is achieved by age 20, and by age 30 it is at its maximum.1 Bone mass is maintained throughout midlife, and after age 50 it gradually declines. In women, in the five to 10 years after menopause, the decline is much more rapid than in men, up to 2% per year.1 Those with a suboptimal peak bone mass are more likely to develop osteoporosis over time. Genetics, medical conditions and lifestyle factors can all affect the peak bone mass that is obtained. In sports medicine, stress fractures, which are reported to be 10-20% of sports injuries overall, can signal suboptimal development of peak bone mass.2 Just as a fragility fracture is a sentinel event that should spur an evaluation for osteoporosis, a stress fracture should spur evaluation of bone health in athletes to improve the development of good bone health over the course of their lifetimes.
There are several risk factors for stress fractures including training errors, biomechanical inefficiencies, equipment issues, female sex, amenorrhea, prior stress fracture, vitamin D deficiency, calorie deficiency (including relative energy deficiency in sport, or RED-S), malabsorption, sleep deficit, family history of osteoporosis, participation in sports that emphasize a low body weight and a slight body type (such as dance, diving, distance running, wrestling, climbing) and underlying medical conditions.2 Athletes that present with a stress fracture should be counseled on optimal energy balance which includes an appropriate dose of exercise as well as adequate energy intake. Not all athletes with RED-S have an eating disorder. Many young athletes are simply on the run between school and practices and do not have time to take in optimal calories between activities. Others do not schedule adequate recovery time between workouts, including sleep.
One factor critical to optimum bone health is maintenance of adequate calcium and vitamin D intake. Adequate calcium intake can be via food sources. Teenage athletes should get 1,300 milligrams of calcium a day; post-menopausal women and men over 70 should get 1,200 mg per day; and most other ages should get 1,000 mg per day. There are many excellent dietary sources of calcium that are dairy or nondairy options. Optimally, food would be the primary source of calcium, but supplements can be added if dietary sources are inadequate.
Vitamin D is a vitamin and prohormone that has effects on genetic expression of over 2,000 genes in the skeletal system as well as modulatory effects on immune, cardiac and muscular functions. There are clear links between vitamin D levels and bone density, as well as vitamin D levels and muscle strength/performance. Many patients with nonspecific musculoskeletal pain have vitamin D deficiency. The positive effects of vitamin D supplementation were seen in those with a deficiency, but not necessarily in those who supplement despite a normal vitamin D level.3,4
Vitamin D levels should be checked after stress injury in athletes. The National Academy of Medicine recommends a level higher than 20 nanograms per milliliter for vitamin D, and other authors recommend levels of 40 ng/ml, citing evidence that sports performance is better at this higher level. Supplements are recommended to reach those levels if a blood test reveals that the athlete has low vitamin D. Levels over 60 ng/ml are thought to have potential for toxicity, although it’s not widely agreed upon. Because vitamin D levels are sometimes reported as nanomoles per liter (nmol/L) and nanograms per milliliter (ng/mL), sometimes the guidelines can cause confusion. One nmol/L equals about 2.5 ng/mL (for example, 30 ng/mL equals about 75 nmol/L).
The optimal source of vitamin D is sunlight, with very few food source options that are good for vitamin D intake. The amount of sunlight necessary for adequate vitamin D production varies related to latitude, season and amount of skin exposure as well as age and skin color. At the latitude of Spain in the spring and summer, with 25% of skin exposure, only about 10 minutes of sunlight at noon is necessary; in the winter with 10% skin exposure, two hours of noon sun are required. Older individuals and those with a darker complexion are much less efficient in vitamin D production. Additionally, because of skin cancer risk, those who protect themselves from sun exposure with sunscreen or by sun evasion are at risk for deficiency; as a result, vitamin D supplementation is recommended. Recommendations vary depending on which guideline is followed; however, the Endocrine Society recommends starting with 600-1,000 international units daily for children and adolescents and 1,500-2,000 international units daily for adults. After three months of supplementation, vitamin D levels will stabilize and 25-hydroxy vitamin D levels can be checked. If still low, increased supplement dose can be recommended.
What can you do for a patient who presents with bone health issues, such as stress fracture or repeated fractures? For children with two or more long bone fractures by age 10 or three or more fractures by age 19, it would be appropriate to order a dual-energy X-ray absorptiometry (DEXA) scan that is done at a facility with pediatric reference data, using the Z-scores instead of the T-scores. Referral to a metabolic bone center would be appropriate as well. Checking basic lab work to include 25-hydroxy vitamin D levels, metabolic panel, complete blood count (CBC), ferritin, thyroid function and celiac panel can also be helpful in revealing underlying issues that could contribute to poor bone health. Other recommendations include counseling the athlete on nutrition and proper dosing of exercise. This can be an opportunity to use the stress fracture as a sentinel event that warrants educating the athletes on optimizing bone health.
For perimenopausal women and Masters athletes, fracture risk increases with aging as it does in the general population. A DEXA Scan is recommended for women over 65 and men over 70 years old, and in perimenopausal women and men ages 50-70 with a risk factor such as a previous fracture, family history, prednisone use greater than three months or chronic disease. A T-score of -2.5 or worse indicates osteoporosis and warrants referral to a metabolic bone practitioner.
Medication is often warranted in patients and athletes with osteoporosis, defined as a “progressive systematic skeletal disease characterized by low bone mass and micro architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture.” 5 There are a host of effective medicines that have a long and proven track record. These include anti-resorptive medications like bisphosphonates, RANKL inhibitors, selective estrogen receptor modulators (SERMS) and, in some cases, hormone replacement. Additionally, several anabolic medicines are now available including parathyroid analogues like teriparatide and abaloparatide as well as the latest romozosumab, which is a sclerostin inhibitor. Limited evidence for faster fracture healing has been shown in the setting of teriparatide and abaloparatide, and some sports doctors have used these medications off-label for that reason. However, these medications generally would not be covered by insurance unless the patient has a severe osteoporosis diagnosis that is well documented.
Bottom line: Sports doctors can be at the crux of promoting good bone health in athletes of all ages. Keep bone health in mind for Osteoporosis Month and all year round!
- Sale, C., Elliott-Sale, K.J. “Nutrition and Athlete Bone Health.” Sports Medicine. 2019;49(Suppl 2):139-151. doi:10.1007/S40279-019-01161-2.
- McInnis, K.C., Ramey, L.N. “High-Risk Stress Fractures: Diagnosis and Management.” PM&R. 2016;8(Suppl 3):S113-S124. doi:10.1016/J.PMRJ.2015.09.019.
- Serrano, M.A., Cañada, J., Moreno, J.C., Gurrea, G. “Solar Ultraviolet Doses and Vitamin D in a Northern Mid-Latitude.” Science of the Total Environment. 2017;574:744-750. doi:10.1016/J.SCITOTENV.2016.09.102.
- de la Puente Yagüe, M., Yurrita, L.C., Ciudad Cabañas, M.J., Cuadrado Cenzual, M.A. “Role of Vitamin D in Athletes and Their Performance: Current Concepts and New Trends.” Nutrients. 2020;12(2). doi:10.3390/NU12020579.
- World Health Organization. “Assessment of Fracture Risk and Its Application to Screening for Postmenopausal Osteoporosis.” Technical Report Series. 843. Published online 1994.