Stress Fracture

Aka: Stress Fracture

1. Epidemiology: Relative Risks
   1. Women > Men
      1. Relative Risk = 3.5
   2. White males > Black males
      1. Relative Risk = 4.7
   3. White females > Black females
      1. Relative Risk = 8.5
2. Mechanisms of Injury
   1. Weight bearing
   2. Muscle forces
      1. Muscle Strength increases faster than bone strength
   3. Muscle Fatigue
3. Risk factors
   1. Repetitive activity
      1. Military recruits
      2. Sports (e.g. distance Running, track and field sport)
         1. Running (>25 miles per week)
         2. Track and Field
         3. Basketball
         4. Soccer
         5. Dance
   2. Increases in intensity, frequency, and loading
      1. Too fast
      2. Too far
      3. Too soon
   3. Biomechanical forces
      1. Over pronators or Supinators
      2. Hallux Valgus
      3. Genu Varum or genu valgus
      4. Leg Length Discrepancy
      5. External hip rotation
      6. Changes in foot gear or training surface
      7. Muscle Fatigue
   4. Systemic Diseases that weaken bone
      1. Rheumatoid Arthritis
      2. Systemic Lupus Erythematosus
      3. Osteoarthritis
      4. Pyrophosphate Arthropathy
      5. Renal Disease
      6. Osteoporosis (Female Athlete Triad)
      7. Joint Replacement
      8. Nutritional deficiency (e.g. dieting)
         1. Vitamin D Deficiency
   5. Other Associated risk factors
      1. Tobacco abuse
      2. Alcohol >10 drinks per week
      3. Female Athlete Triad
4. Pathophysiology: Common Stress Fracture Sites
   1. Tibia Stress Fracture (23% of Stress Fractures)
   2. Metatarsal Stress Fracture (16% of Stress Fractures)
   3. Fibula Stress Fracture (15% of Stress Fractures)
   4. Tarsal Navicular Stress Fracture
   5. Calcaneal Stress Fracture
   6. Medial Malleolus Stress Fracture
   7. Femoral Neck Stress Fracture (6%)
   8. Femoral Shaft Stress Fracture
   9. Pubic Ramus Stress Fracture
   10. Pelvic Stress Fracture (1-2%)
       1. Seen almost exclusively in women
   11. Lumbar Stress Fracture
   12. Coracoid process Stress Fracture
   13. Humerus Stress Fracture
   14. Olecranon Stress Fracture
5. Symptoms
   1. Deep ache following rapid training change
   2. Pain progression
      1. Start: Pain after activity
      2. Next: Pain with activity
      3. Next: Pain with walking (at presentation in 81% of patients)
      4. Last: Pain at rest
   3. Night pain rarely occurs
      1. Consider another diagnosis
6. Signs
   1. Fracture site intense localized pain
      1. Tenderness to palpation (present in most cases)
      2. Edema at Fracture site may be present
      3. Compression induces pain
      4. Percussion of bone distant from symptomatic site
      5. Vibrating tuning fork (128 Hz) at suspected site
         1. Mediocre Test Sensitivity and Specificity
         2. Lesho (1997) Mil Med 162(12): 802-3 [PubMed]
   2. Specific Tests for leg or pelvis Stress Fracture
      1. Fulcrum Test
      2. Hop Test
         1. Poor Specificity (common finding in Shin Splints)
         2. Batt (1998) Med Sci Sports Exerc 30(11): 1564-71 [PubMed]
7. Differential Diagnosis
   1. Primary benign Bone Neoplasm
      1. Osteoid Osteoma
      2. Osteoblastoma
      3. Eosinophilic Granuloma
   2. Infections
      1. Chronic or Subacute Osteomyelitis
   3. Chronic Musculoskeletal Soft Tissue Injury
      1. Tendonitis
      2. Muscle Strain
      3. Chronic Compartment Syndrome
   4. Metastatic Neoplasm to bone
      1. Breast Cancer
      2. Prostate Cancer
   5. Primary Malignant Bone Neoplasms
      1. Osteosarcoma
      2. Ewing Sarcoma
   6. Nerve Compression Syndromes
      1. Tarsal Tunnel Syndrome
      2. Carpal Tunnel Syndrome
      3. Ulnar Tunnel Syndrome
   7. Herniated Intervertebral Disc
   8. Osteoarthritis
   9. Hypertrophic Pulmonary Osteoarthropathy
8. Imaging
   1. Overall imaging approach (preferred)
      1. Step 1: XRay negative and Stress Fracture suspicion persists
      2. Step 2: Repeat XRay in 2-3 weeks is negative and Stress Fracture suspicion persists
      3. Step 3: Obtain MRI (preferred) or bone scan
   2. Imaging modalities
      1. Stress Fracture XRay
      2. Stress Fracture Bone Scan
      3. Stress Fracture CT
      4. Stress Fracture MRI
      5. Ultrasound is being investigated for specific Stress Fracture sites (e.g. Metatarsal Stress Fracture)
         1. Banal (2009) J Rheumatol 36(8): 1715-9 [PubMed]
9. Management
   1. Rest for 4-7 weeks (may require up to 3 months)
      1. Activity should be pain-free only
      2. Non-weight bearing until pain free while walking
         1. Tibia Stress Fracture
         2. Femoral Stress Fracture
   2. Analgesia
      1. Acetaminophen is preferred over NSAIDS
         1. NSAIDS may delay healing
   3. Immobilization
      1. Short-leg Casting or CAM-Walker Indications
         1. Non-compliance
         2. High-risk for non-union
            1. Navicular Stress Fracture
            2. Metatarsal Stress Fracture
      2. Pneumatic brace (Air cast)
         1. Support results in quicker recovery and less pain
         2. Indicated in tibial and fibular Stress Fractures
   4. Active rest (cross training)
      1. Consider formal rehabilitation program with physical therapy for strength and Stretching
      2. Goals
         1. Cardiovascular conditioning
         2. Flexibility
         3. Proprioception
         4. Strength
      3. Activities
         1. Swimming
         2. Pool Running with float vest
         3. Biking
         4. Stair climbing machines (later stages)
   5. Surgery
      1. Indications
         1. High Risk Fractures for non-union
         2. Non-healing Fractures
      2. Specific high risk sites
         1. Tarsal Navicular Stress Fracture
         2. Proximal anterior Tibia Stress Fracture
         3. Base of fifth Metatarsal Stress Fracture
         4. Femoral Neck Stress Fracture
   6. Experimental: Electromagnetic field devices
      1. Questionable efficacy
      2. High cost
10. Prevention
    1. Do not increase Exercise intensity >10% per week
    2. Stretch and warm-up before Exercise
    3. Choose level Running surfaces
    4. Shoes should be light weight and in good condition
    5. Consider Orthotics for biomechanical factor correction
    6. Shock-absorbing insoles may be beneficial
    7. Osteoporosis Prevention (unclear efficacy)
       1. Consider calcium supplement 1000 mg orally daily
       2. Consider Vitamin D 800 IU orally daily
11. Reference
    1. Simmons (1997) AAFP Sports Med Review
    2. Buckwalter (1997) Am Fam Physician, 56(1):175-182 [PubMed]
    3. Patel (2011) Am Fam Physician 83(1): 39-46 [PubMed]
    4. Sanderlin (2003) Am Fam Physician 68:1527-32 [PubMed]