Marc Silberman, M.D. Stress Fractures

“A high school athlete with shin pain has a stress fracture until proven otherwise”

Definition “A fracture caused not by a direct blow, twist, or fall, but by cyclical loading that exceeds the bones natural repair capacity”

Stress fracture hypothesis “Bone remodeling is a balance between osteoclastic resorption and osteoblastic reconstruction” As loading increases, additional bone resorption occurs Time lag between the two is 2 to 3 weeks

Stress fracture hypothesis When activity is increased, local weakness and microdamage may be caused by increased osteoclastic activity Stress fractures occur when muscle becomes fatigued and unable to absorb added force Impact forces are transferred to bone which causes overload and stress fracture

True or False A stress fracture is a tiny crack in a bone

False

True or false Stress fractures are caused by weak bones

False 1. Abnormal stress on normal bone Not weak bones but weak or fatigued muscles 2. Normal stress on abnormal bone 3. Abnormal stress on abnormal bone

Clinical tests There are no clinical tests to diagnose a stress fracture The diagnosis is made by radiological imaging Schneiders AG et al. The Ability of Clinical Tests to Diagnose Stress Fractures: A Systematic Review and Meta-analysis. J Orthop Sports Phys Ther 2012;42(9):

X-ray “While X-ray can rule in a stress fracture, X-ray can not rule out a stress fracture” X-ray sensitivity of 10 to 50%

X-ray

MRI “MRI can rule out a stress fracture and MRI can grade a stress fracture” Sensitivity 88%, Specificity 100% Gaeta M et al. Radiology May; 235(2):553–561.

Grading GradeX-rayMRI 1NormalPositive STIR 2NormalPositive STIR and T2 3NormalPositive T1 and T2 4Fracture, Periosteal reaction Positive T1 and T2, Fracture line Adapted from Arendt et al. Clin Sports Med (2):

Grade 1

Grade 2 Nattiv et al. Am J Sports Med August ; 41(8): 1930–1941.

Grade 3 Nattiv et al. Am J Sports Med August ; 41(8): 1930–1941.

Grade 4

High Risk vs Low Risk High RiskLow Risk Lateral Femoral NeckMedial Femoral Neck Femoral HeadFemoral shaft PatellaPelvis* Anterior tibia cortexPosterior medial tibia Medial MalleoliFibula TalusCuboid NavicularCuneiform Second metatarsal baseCalcaneus* Fifth metatarsal baseOther metatarsals Sesamoid medial

Return to Play Mean daysMedian daysQ25 daysQ75 days LowRiskLowGrade LowRiskHighGrade HighRiskLowGrade HighRiskHighGrade Dobrindt et al. BMC Musculoskeletal Disorders 2012, 13:139. Prolong healing time at high risk fracture sites and at low risk sites with high grade lesion. Take home message: Need a fast and reliable diagnosis.

NCAA Time to return to sport Nattiv et al. Am J Sports Med August ; 41(8): 1930–1941.

NCAA Time to return to sport Nattiv et al. Am J Sports Med August ; 41(8): 1930–1941. Femoral neck, sacrum, pelvis

Prevention

“ The causes of injuries are multifactorial, you can’t blame one thing”

Calcium “There is more to bone health than calcium” The scientific literature is conflicting regarding calcium supplementation on stress fracture prevention and overall bone mineral density Calcium supplementation may cause an increase in cardiovascular events

“ Running injuries are caused by running”

Training Error Too much too soon Not enough recovery Takes less than 2 weeks for a fracture to occur

Nutrition “It’s not about calcium, it’s about food, or rather the lack of” “Edible food like substances” - Michael Pollan

Medications “More children are taking medications than in any other time in the history of mankind” Bad To The Bone NSAIDs SSRIs and Tricyclics increase fracture risk by two-fold IIsotretinoin, Retinoids, and Vitamin A Progesterone, Progesterone-Estrogen Proton pump inhibitors Hidden medications in our food and water (flouride)

Sleep How stress fracture incidence was lowered in the Israeli army: a 25 year struggle Imposing a sleep regimen of at least 6 hours and reducing cumulative marching lowered the incidence by 62% (30.8 % to 11.6% annually) Shoe modifications, orthotics, and Risedronate had no effect Med Sci Sports Exerc Nov; 40(11 Suppl):S623-9

Female Athlete Triad Risk of stress fractures in athletes with menstrual disturbance is 2 to 4 times that of eumenorrheic athletes Disordered eating, amenorrhea, and osteoporosis Functional Hypothalamic Amenorrhea from insufficient energy intake Decreased leptin levels, decreased gonadotropins, hypoestrogenic state lead to reduced calcium absorption, increased bone resorption, suppressed bone formation

Vitamin D Appears more important than calcium Vitamin D level < 40 mg/mL is associated with stress fracture Supplementation of up to 50,000 IU weekly has been suggested Miller JR et al. The Journal of Foot and Ankle Surgery 55 (2016) 117 – 120. Inklebarger J et al. J R Amry Med Coprs 104;160:61-63.

Where do we go from here? "What we must do is change the physical habits of millions of Americans and that is far more difficult than changing their tastes, their fashions or even their politics." President Kennedy, December 5, 1961

Marc Silberman, M.D. Thank you