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Basics ⬇

Author: Nicholas M.Cardinale, MD

A stress fracture (SF) is damage to bone caused by repetitive loading that exceeds healing capacity. SF injury can range from a mild periosteal reaction to a displaced fracture. SFs are grouped as low or high risk. Low-risk stress fractures (LRSFs) occur in the pelvis, femoral shaft (FSSF), posteromedial tibia, fibula, metatarsal shafts, cuboid, calcaneus, and cuneiform. These can be treated nonoperatively. High-risk stress fractures (HRSFs) involve the femoral neck (FNSF), anterior tibial shaft (ATSF), patella, medial malleolus, 2nd metatarsal base, proximal 5th metatarsal, sesamoids, tarsal navicular, and talus. HRSFs have a greater risk of complications. Early advanced imaging and specialty referral is recommended; operative treatment is indicated in some cases. SFs occur in the pelvis and lower extremities in military recruits, endurance athletes, dancers, soccer, and basketball players. SFs may also occur in the spine and upper extremities in certain sports (e.g., football, gymnastics).

Epidemiology

Incidence

  • Highest in female military recruits 21% (1)
  • Incidence varies with activity/sport.

Prevalence

  • >10% of all sports injuries (1,2)
  • 90% involve the lower extremity (3).
  • Tibia, tarsals, and metatarsals are the most common sites (4).

Etiology and Pathophysiology

  • Repetitive load plus inadequate rest
  • Bone resorption is faster than bone formation.
  • Microfractures lead to cortical break.
  • Anatomical sites of HRSFs have reduced vascularity and bear high tensile load.

Genetics

Genes that regulate bone remodeling have shown an association with SFs in recent studies. More research is needed to establish a clear genetic link.

Risk-Factors

  • Female gender
  • Female body mass index (BMI) <19
  • Late menarche ≥15 yr
  • Prior SF
  • Extreme pes cavus or planus
  • >5 degrees knee valgus/external rotation (ER)
  • Inadequate caloric intake
  • Excessive caffeine, alcohol, or tobacco use
  • Amenorrhea/oligomenorrhea
  • Osteopenia
  • Chronic corticosteroid use
  • Rapid increase in training volume
  • Recreational runners >25 miles per week
  • Poor footwear
  • Running on hard surfaces
  • Low 25-hydroxyvitamin D
  • Low testosterone (males)

General Prevention

  • Adequate calories and nutrition
  • 1,500 to 2,000 mg calcium and 800 IU vitamin D per day
  • Screen for female athlete triad.
  • Padded insoles and orthotics (military recruits)
  • Replace footwear after 6 mo or 300 miles.
  • Limit training increase to 10% per week (intensity, duration, frequency).

Commonly Associated Conditions

  • Female athlete triad
  • Chronic corticosteroid use
  • Osteopenia/osteoporosis
  • Amenorrhea/oligomenorrhea

Diagnosis ⬆ ⬇

History

  • Insidious local pain from repetitive activity
  • Worse with continued activity
  • Pain at rest (e.g., night pain)
  • Assess risk factors and training history (miles per week, intensity, frequency).
  • Assess for prior history of SF.
  • Nutrition history (dairy intolerance), reduced calorie intake, weight loss
  • Menstrual irregularity or amenorrhea
  • Corticosteroid use
  • Osteopenia/osteoporosis

Physical Exam

  • Direct bony tenderness ± edema
  • Palpate for callus or bony step off.
  • Limp/pain on weight-bearing
  • Pain with axial compression
  • Tender “N” spot (dorsal central third of the navicular bone between the anterior tibial and hallucis longus tendons) suggestive of SF
  • Calcaneal squeeze test: simultaneous pressure on the medial and lateral aspects of calcaneus, pain suggestive of SF
  • Fulcrum test: pain at the site with bending the long bone over a table edge or examiner’s leg or forearm; useful for tibial and FSSF
  • Log roll test: Passive internal rotation (IR)/ER of the thigh elicits groin pain in an FNSF.
  • Patellar-pubic percussion test: Place stethoscope on the ipsilateral pubic tubercle and percuss the ipsilateral patella or use a tuning fork; the sound is reduced on the side in which an FNSF is present.
  • Flamingo test: Patient stands on the affected side. A positive test is indicated by pain in the location of the SF; useful for FNSF, FSSF, lower leg, and sacral SF
  • Tuning fork test: pain when applying a 128-Hz tuning fork over the site of suspected SF; useful for tibia and fibula SFs
  • Assess lower extremity alignment and foot type that would predispose to SF.

Differential Diagnosis

  • Muscle strain/tendinopathy
  • Fasciitis/periostitis
  • Exertional compartment syndrome
  • Nerve/artery entrapment
  • Bone tumor
  • FNSF may mimic adductor or hip flexor strain.
  • ATSF can be confused with shin splints.
  • Medial tibial SF can mimic anserine bursitis.

Diagnostic Tests & Interpretation

Initial Tests (lab, imaging)

  • X-rays:
    • Initial test, low cost and available. Sensitivity is only 10–56% (4,5).
    • Repeat x-ray (2 to 3 wk) is 30–70% sensitive; lucency or callus formation visible
  • Bone scan:
    • 74–100% sensitive but less specific and can be falsely positive with infection or tumor (4)
    • Time-consuming (3 to 4 hr) and radiation exposure (5)
  • Computed tomography (CT) scan:
    • Less sensitive than bone scan or magnetic resonance imaging (MRI) and involves significant radiation
    • Bone scan combined with single photon emission CT may be more accurate than MRI for pars interarticularis SF (4).
  • Diagnostic ultrasound:
    • May be useful for superficial structures like metatarsals with a sensitivity of 83% and specificity of 75% in small studies (4)
  • MRI:
    • The gold standard with a sensitivity of 86–100% and specificity of 100% (1). Is preferred over bone scan (4,5). T1 images show a fracture line; T2 and Short tau inversion recovery images show marrow edema.
    • Excludes other diagnoses and can grade severity which can aid in prognosis (3)
  • Obtain labs based on clinical suspicion of nutritional, endocrine, and metabolic factors.
  • 25-OH vitamin D3, complete blood count (CBC), chem 7, calcium, thyroid-stimulating hormone (TSH), albumin, prealbumin, phosphate, and parathyroid hormone
  • Females with menstrual dysfunction: follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, testosterone, human chorionic gonadotropin (HCG)
  • Dexamethasone suppression test if excess cortisol suspected

Follow-Up Tests & Special Considerations

  • X-rays are useful in follow-up to demonstrate callus formation and union.
  • CT provides greater detail to assess healing.
  • Bone scan remains positive for over a year and is not useful for follow-up.
  • MRI may show positive findings after the patient is asymptomatic.

Diagnostic Procedures/Other

A bone biopsy may sometimes be obtained to differentiate tumor from SF.

Treatment ⬆ ⬇

General Measures

  • Stop the offending activity.
  • Use a cast, pneumatic boot, rigid sole shoe, or crutches to ensure pain-free relative rest.
  • A compression boot for tibial SFs leads to earlier return to play (4)[A].
  • Allow progressive weight-bearing based on symptomatic improvement.

Medication

  • Acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) for pain
  • Use NSAIDs cautiously due to potential inhibition of bone healing.
  • Bisphosphonates are controversial for treatment and not recommended for prevention (1,4)[B].

Issues for Referral

  • Urgent orthopedic/sports medicine consultation for HRSFs
  • Early advanced imaging of HRSFs is needed to avoid complications and provide timely surgery if needed.

Additional Therapies

  • Electromagnetic or ultrasonic bone stimulation may be considered for recalcitrant cases, but evidence is lacking for efficacy (4)[B].
  • Extracorporeal shock wave therapy (ESWT) has shown benefit in small studies (randomized controlled trial [RCT] and case series) (6)[B].
  • Gait training may help runners reduce impact which may help prevent SFs.

Surgery/Other Procedures

  • FNSF tension side (superolateral femoral neck) requires emergent surgical fixation.
  • Compression side involving <50% of the width of the inferomedial neck can be treated with prolonged weight-bearing rest (average of 12 wk to return to sport) (1,2,3).
  • ATSF has a high rate of nonunion, and surgery is recommended if 3 to 6 mo of conservative treatment has failed.
  • Navicular SFs are often treated surgically in elite athletes, but outcomes are comparable with nonoperative treatment (2)[B].
  • Proximal 5th metatarsal SFs involving zones 2 or 3 (distal to the tuberosity) benefit from surgical fixation with reduced complications and earlier return to sport (2)[A].

Ongoing Care ⬆ ⬇

Follow-up Recommendations

  • Athletes are typically followed every 2 to 4 wk to assess for symptomatic improvement and allow a gradual increase in weight-bearing. A progressive jogging protocol can be used for return to sport.
  • Follow-up imaging is used in HRSFs and complicated cases. Athletes with LRSFs may be followed on the basis of clinical signs and symptoms without repeat imaging.

Diet

  • Adequate calories, protein, and carbohydrates for age; body type and sport
  • Daily calcium 2,000 mg and vitamin D 800 IU
  • 50,000 IU vitamin D weekly ×12 if deficient

Patient Education

  • Athletes should understand their individual intrinsic and extrinsic risk factors and modify when possible. Individualize training to reduce injury and optimize performance.
  • Do not ignore pain symptoms and resist overtraining.

Prognosis

  • Excellent for most if treated early with adequate weight-bearing rest
  • Poor for ATSF with evidence of cortical disruption (dreaded black line)
  • Completed FNSF can be associated with long-term morbidity and disability.

Complications

Complete fracture, delayed union, nonunion, avascular necrosis

Additional Reading ⬆ ⬇

  • Reiman MP, Mather RC III, Cook CE. Physical examination tests for hip dysfunction and injury. Br J Sports Med. 2015;49(6):357–361.
  • Varley I, Greeves JP. Functional polymorphisms in the P2X7 receptor gene are associated with stress fracture injury. Purinergic Signal. 2016;12(1):103–113.
  • Zhao L, Chang Q, Huang T, et al. Prospective cohort study of the risk factors for stress fractures in Chinese male infantry recruits. J Int Med Res. 2016;44(4):787–795.

References ⬆ ⬇

  1. DeFroda SF, Cameron KL, Posner M, et al. Bone stress injuries in the military: diagnosis, management, and prevention. Am J Orthop (Belle Mead NJ). 2017;46(4):176–183.
  2. McInnis KC, Ramey LN. High-risk stress fractures: diagnosis and management. PM R. 2016;8(Suppl 3):S113–S124.
  3. Robertson GA, Wood AM. Lower limb stress fractures in sport: optimising their management and outcome. World J Orthop. 2017;8(3):242–255.
  4. Patel DS, Roth M, Kapil N. Stress fractures: diagnosis, treatment, and prevention. Am Fam Physician. 2011;83(1):39–46.
  5. Nye NS, Covey CJ, Sheldon L, et al. Improving diagnostic accuracy and efficiency of suspected bone stress injuries. Sports Health. 2016;8(3):278–283.
  6. Leal C, D’Agostino C, Gomez Garcia S, et al. Current concepts of shockwave therapy in stress fractures. Int J Surg. 2015;24(Pt B):195–200.

Clinical Pearls ⬆

  • Diagnosis is based on high index of suspicion, risk factors, and clinical findings. Negative x-rays do not exclude SFs.
  • Obtain urgent advanced imaging in patients with antalgic gait and clinical findings consistent with a HRSF. Use of an algorithm may aid the diagnostic approach.
  • MRI is the advanced imaging study of choice.
  • HRSFs warrant orthopedic or sports medicine specialty evaluation.
  • High-demand athletes may benefit from early surgery to ensure a more rapid return to play.