Stress fractures

A stress fracture is a fracture of structurally normal bone due to the coalescence of microfractures caused by repetitive activity. Risk factors include female sex, calcium deficiency, and highly repetitive activity. Clinical manifestations include pain that worsens with activity and improves with rest and tenderness over the affected bone. High-risk stress fractures are stress fractures in locations (e.g., lateral femoral neck, anterior tibia, 5^th metatarsal) that are prone to complications (e.g., fracture progression, nonunion). Stress fractures may be managed based on a clinical diagnosis, but x-rays are typically obtained for confirmation. Because x-rays are often normal, an MRI is indicated if there is a concern for a high-risk stress fracture. Treatment is mainly conservative and focuses on cessation of the inciting activity, but high-risk stress fractures are managed as acute fractures, with immobilization, avoidance of weight-bearing activities, and referral to orthopedics. Calcaneal stress fractures are a low-risk type of stress fracture. They are most commonly caused by repetitive microstress and/or prolonged loadbearing on the heel (e.g., jumping, marching) and can usually be managed conservatively.

Mechanism

Normal bone develops a fracture as a result of bone remodeling due to repetitive microtrauma. ^[1][2]

Risk factors ^[2][3]

• Repetitive high-intensity physical activity
• Improper technique during physical activity
• Ill-fitting footwear
• Poor nutrition and/or low calorie intake (e.g., in anorexia nervosa)
• Low bone density (e.g., bisphosphonates use)
• Calcium and/or vitamin D deficiency
• Female sex ^[4]
• Previous stress fracture ^[5]

The female athlete triad syndrome is associated with an increased risk of stress fractures. ^[5]

Stress fractures are classified according to the risk of healing complications. ^[2][3][5]

Low-risk stress fractures

• Fibula and lateral malleolus
• 2^nd–4^th metatarsal shaft
• Medial femoral neck
• Calcaneal stress fractures
• Cuneiform, cuboid

High-risk stress fractures

• Anterior tibia and medial malleolus
• 5th metatarsal shaft
• Superolateral femoral neck
• Patella
• Talus, tarsal navicular

• Location ^[6]
  • Lower extremities (most common): tibia, tarsal navicular, metatarsals (March fracture), femur, fibula, pelvis
  • Upper extremities (least common): humerus, scapula, ribs
• Symptoms ^[2][3]
  • Pain that worsens with activity and resolves with rest
    • Typically begins several weeks after an increase in exercise intensity
    • Usually well localized
  • Fractures may be asymptomatic (incidental finding). ^[7]
• Signs ^[3][5]
  • Focal bone tenderness, erythema, and/or soft tissue swelling
  • Provocation test reproduces pain
    • Rotation of the hip exacerbates pain from a proximal femur stress fracture.
    • Hop test exacerbates pain from a lower extremity stress fracture.

A preliminary clinical diagnosis guides early management, but imaging of the affected region is indicated for confirmation. ^[5][8]

• X-ray: recommended initial imaging study ^[1]
  • May show radiographic signs of a fracture
  • Often normal in the first 2–3 weeks of disease onset ^[3][8]
  • If the initial radiograph is negative:
    • Suspected low-risk stress fractures: Repeat in 10–14 days.
    • Suspected stress fractures of the pelvis or hips: Obtain early MRI.
    • Other suspected high-risk stress fractures: Consider MRI.
• MRI: : recommended study for early definitive diagnosis ^[1]
  • High sensitivity and specificity
  • Findings include fracture lines, damage to surrounding tissue, and edema
• Other imaging modalities
  • Bone scan
  • CT
  • Ultrasound

Stress fractures may be difficult to see on plain films and should be treated empirically based on the clinical diagnosis. ^[8]

• Soft tissue injury ^[9]
• Tendinopathy ^[3]
• Entrapment neuropathy
• Pathologic fracture
• Peripheral arterial disease ^[10]
• Exertional compartment syndrome ^[5]

The differential diagnoses listed here are not exhaustive.

Initial therapy of stress fractures is typically conservative. Surgical management is reserved for refractory cases and fractures in high-risk locations (e.g. anterior tibia, proximal 5th metatarsal, patella, talus, superolateral femoral neck), which are prone to fracture progression, delayed union, or nonunion.

Low-risk stress fractures ^[6][8]

• Cease inciting activity for 4–6 weeks.
• Continue weight-bearing as tolerated.
• Consider splinting or a short walking boot in case of severe symptoms.
• Pain control (e.g., acetaminophen, ice packs) ^[2]
• Risk factor modification (e.g., improved nutrition, calcium and vitamin D supplementation)
• Screen female patients for female athlete triad. ^[5]

Up to one-third of low-risk stress fractures do not heal with conservative management. Refer patients with refractory fractures to orthopedic surgery. ^[2]

High-risk stress fractures ^[5][8]

• Manage like an acute fracture: See “General principles of fracture management.”
  • Immobilize the affected extremity (e.g., cast, splint).
  • Advise avoidance of weight-bearing activities.
  • Risk factor modification (e.g., improved nutrition, calcium and vitamin D supplementation)
• Refer to orthopedic surgery.

High-risk stress fractures should be managed like acute fractures. ^[5]

• Progression to complete fracture ^[3][5]
• Avascular necrosis
• Delayed healing
• Nonunion

We list the most important complications. The selection is not exhaustive.

Calcaneal stress fractures are most commonly found in individuals who run, jump, and/or march for extended periods of time (e.g., athletes, dancers, soldiers). For acute fractures of the calcaneus, see “Calcaneal fractures.” ^[11]

Etiology ^[11]

• Repetitive microstress to the calcaneus (e.g., weight overload, increase in physical activity)
• Inadequate footwear and activity on hard surfaces increase risk.
• See also “Etiology of stress fractures.”

Clinical features ^[11]

• Heel pain on activity (e.g., weight-bearing activities, walking on hard surfaces)
• Point tenderness on palpation of the posterior calcaneus
• Swelling, warmth, and/or ecchymosis of the heel (uncommon)
• Positive calcaneal squeeze test: pain elicited by mediolateral compression of the heel between thumb and index finger

Diagnostics

• X-ray: foot series with Harris axial view ^[6]
  • Fractures may not be visible until 2–3 weeks after onset of clinical features.
  • Findings: focal sclerosis in posterior calcaneus (most common) ^[11]
• MRI
  • Indicated if clinical features and x-rays are equivocal
  • Findings: sclerosis, soft tissue changes
• See also “Diagnostics for stress fractures.”

Differential diagnosis of chronic heel pain

• Calcaneal stress fracture
• Plantar fasciitis
• Achilles tendinopathy
• Heel pad syndrome
• Tarsal tunnel syndrome
• Calcaneal spur (heel spur)

Treatment ^[11][12]

Calcaneal stress fractures are considered low-risk and can usually be managed conservatively.

• Activity modification with reduced weight bearing
• Heel pad inserts
• Consider a walking boot and/or shock-absorbing orthotic.
• Routine orthopedic follow up
• See also “Treatment of stress fractures.”

Calcaneal stress fractures are often misdiagnosed as soft tissue injuries and undertreated. [#27519