Stress Fracture.Care & specialists in New Zealand

• •Bone pain during activity that diminishes early in a session and returns after
• •Recent training volume or intensity increase of more than 10% per week, change in surface, footwear, or technique
• •Persistent localized bony tenderness on palpation outside the soft tissues
• •Female athlete with menstrual irregularity, low body weight, or restrictive eating patterns
• •Recurrent stress reactions or fractures at any site — investigate energy availability, bone density, and vitamin D

Diagnosis combines a focused history, examination, and confirmatory imaging. The history details onset (insidious activity-related pain), recent training changes (volume, intensity, surface, footwear), nutritional and menstrual history, prior injury, and bone-relevant medications. Examination locates point tenderness over specific bony landmarks (medial tibial border, dorsum of midfoot, navicular tubercle, sacrum, pars interarticularis), checks for swelling and warmth, and applies provocation tests: single-leg hop test for tibia and metatarsals, fulcrum test for femoral shaft, single-leg extension test (Stork test) for pars interarticularis, and FABER/FADIR for femoral neck and pelvis. Imaging strategy depends on suspicion and site. Plain radiographs are 15-35% sensitive for stress fractures within the first 2 weeks but rise to 50-70% sensitivity at 4-6 weeks; they detect cortical thickening, periosteal reaction, and visible fracture lines. MRI is the gold standard for early detection with 95-100% sensitivity within days of symptom onset, distinguishes bone stress injury from soft-tissue mimics, and grades severity using the Fredericson (tibia) or Arendt (foot) systems. CT is useful for navicular and pars stress fractures where MRI is equivocal. Bone scintigraphy with technetium-99m MDP has near-100% sensitivity but limited specificity and has largely been replaced by MRI. DXA bone density measurement is recommended in any athlete with recurrent stress fracture, RED-S features, or trabecular-rich site fracture (sacrum, pelvis, femoral neck). Laboratory workup in recurrent or atypical cases includes vitamin D, calcium, phosphorus, thyroid function, parathyroid hormone, urine pregnancy test, menstrual history, and energy availability assessment. Risk stratification (high-risk vs low-risk site) determines treatment urgency and modality.

• ✓Relative rest with protected weight-bearing
• ✓Walking boot (CAM walker) or stiff-soled postoperative shoe
• ✓Non-weight-bearing on crutches
• ✓Calcium 1,000 mg/day and vitamin D 1,000-2,000 IU/day supplementation

Rapid increase in training volume, intensity, or frequency

Adding more than 10% weekly mileage, abrupt transition from offseason to high volume, or stacking heavy training days produces mechanical loading that outpaces bone remodeling. Up to 70% of stress fractures in runners follow recent training change.

Female Athlete Triad / Relative Energy Deficiency in Sport (RED-S)

Low energy availability (insufficient dietary intake for training expenditure) causes menstrual dysfunction and low bone mineral density. Affected female athletes have 2-4× higher stress fracture incidence. RED-S extends to men and includes broader physiologic effects (IOC 2014/2018).

Biomechanical malalignment

Cavus foot, pes planus, leg-length discrepancy >5 mm, excessive forefoot supination/pronation, and weak hip abductors raise specific-site stress fracture risk. Tibial varum increases anterior tibial cortex tension-side loading.

Footwear, surface, and equipment factors

Worn-out running shoes (over 600-800 km), sudden transition to minimalist shoes, change from track to road or vice versa, and rigid playing surfaces (artificial turf, concrete) raise mechanical load delivered to bone.

Low bone mineral density

Z-score below -1.0 in young athletes or T-score below -1.0 in adults raises stress fracture risk 2-3 fold. Vitamin D deficiency (25-OH vitamin D below 32 ng/mL) is independently associated with risk in military recruits (Lappe randomized trial 2008).

Medications affecting bone metabolism

Long-term corticosteroids, depot medroxyprogesterone acetate (DMPA), aromatase inhibitors, proton pump inhibitors, and selective serotonin reuptake inhibitors are associated with reduced bone density and elevated stress fracture risk.

Female sexnon-modifiable

Female athletes have 1.5-3.5× higher stress fracture incidence than matched males, partly due to higher prevalence of menstrual dysfunction, lower body weight, and lower bone mineral density.

Sudden training increase or transitionmodifiable

Weekly volume increases above 10%, sudden surface change, or abrupt minimalist shoe transition account for 50-70% of stress fractures in distance runners. Gradual progression with 1 rest day per week reduces risk substantially.

Low energy availability and menstrual dysfunctionmodifiable

Energy availability below 30 kcal/kg lean body mass per day suppresses estrogen, raises cortisol, and reduces bone formation. Amenorrheic athletes have 2-4× higher stress fracture risk. Recovery of normal menses correlates with normalization of bone turnover.

Vitamin D deficiency (25-OH vitamin D below 32 ng/mL)modifiable

Lappe et al. 2008 randomized trial: calcium plus 800 IU vitamin D daily reduced stress fracture incidence by 27% in female navy recruits versus placebo. Supplementation to maintain serum 25-OH vitamin D ≥40 ng/mL is recommended in at-risk athletes.

Prior stress fracturenon-modifiable

Personal history of any stress fracture raises lifetime risk of subsequent fracture 5-10 fold, often at a different site. Recurrent fractures should trigger comprehensive bone health and energy availability workup.

Restrictive eating pattern, anorexia nervosa, or low BMImodifiable

• •Adequate energy intake calibrated to training expenditure — aim for energy availability above 30-45 kcal/kg lean body mass per day
• •Calcium 1,000-1,200 mg daily from dairy, fortified plant milks, leafy greens, and sardines
• •Vitamin D 1,000-2,000 IU daily targeting serum 25-OH vitamin D ≥32-40 ng/mL
• •Adequate protein (1.4-2.0 g/kg/day) and carbohydrate distribution to support training and bone formation

• •Severe energy restriction or weight cutting during periods of high training load
• •Excessive caffeine intake (above 400 mg/day), which modestly reduces calcium retention
• •High-dose vitamin A (above 10,000 IU/day) and excess phosphate from carbonated cola beverages
• •Heavy alcohol intake, which impairs bone formation and slows healing