Tarsal Navicular Stress Fracture

Aka: Tarsal Navicular Stress Fracture

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II. Epidemiology

  1. Accounts for 14-35% of Stress Fractures
  2. Track athletes account for 59% of these injuries

III. Mechanism of injury

  1. Central one third of navicular is avascular
  2. Chronic Trauma from repetitive foot strike

IV. Risk factors

  1. No Statistically Significant risk factors identified
  2. Most common in track and field athletes
  3. Also seen in Australian football and basketball

V. Symptoms

  1. Cramping pain or ache at the dorsal midfoot
    1. Radiates along medial arch
    2. Usually unilateral
  2. Provocative activities
    1. Running
    2. Jumping
  3. Palliative
    1. Altered gait with less pressure on forefoot
    2. Relieved with rest
  4. Timing
    1. Onset occurs with provocative activities above
    2. Duration of pain increases as injury progresses

VI. Signs

  1. Pain localized to 'N' Spot
    1. Small area approximately the size of a nickel
    2. Find talonavicular joint (Evert and invert the foot)
      1. Navicular bone is just distal and medial to joint
    3. Test Sensitivity: 81% tenderness in Stress Fracture
  2. Provocative maneuvers
    1. Hopping
    2. Toe hopping
    3. Standing on tip-toes

VII. Radiology

  1. Foot XRay (Recommended as Initial study)
    1. Test Sensitivity for navicular Stress Fracture: 33%
    2. Fractures appearance may also be delayed 3 weeks
  2. Triple Phase Bone scan (Recommended as second study)
    1. Test Sensitivity: 100%
    2. Poor Specificity (e.g. bone stress reaction)
      1. Confirm positive result with other imaging below
    3. Delayed-phase images normalize 2 years after union
  3. CT Foot (Use to confirm bone scan results)
    1. 1.5 mm slices Through plane of talonavicular joint
    2. Allows for classifying Fracture as below
  4. MRI Foot
    1. Test Sensitivity: 100% for Stress Fracture
    2. Highly specific and good anatomic resolution
    3. Offers similar information as bone scan with CT
      1. Bone scan and CT foot are preferred due to cost

VIII. Classification (Based on CT above)

  1. Type I: Dorsal cortical break
  2. Type II: Fracture propagates into navicular body
  3. Type III: Fracture propagates into other cortex
    1. Requires longest healing time
    2. May require internal fixation

IX. Management: Protocol

  1. Non-weight bearing short-leg cast for 6 weeks
  2. Check navicular tenderness on cast removal
    1. Navicular tenderness at cast removal
      1. Recast for two weeks and re-examine
    2. Non-tender at cast removal and at every 2 week checks
      1. Functional rehabilitation for 6 weeks (See below)
      2. Full activity resumes 6 weeks after cast removal
  3. Repeat imaging not indicated
    1. Repeat XRay, bone scan or CT are not usually helpful
  4. Surgery indications (Intramedullary nailing)
    1. Displaced or fragmented Tarsal Navicular Fracture
    2. Failed conservative therapy
      1. Delayed union or nonunion
    3. Type III Fracture (relative indication)
    4. High level athlete for faster return to play

X. Management: Functional Rehabilitation

  1. Stop program and reassess if any 'N' Spot tenderness
  2. Week 1-2: Activities of Daily Living, Swimming
    1. Gradual weight bearing in semirigid shoe
  3. Week 3-4: Jog on grass for 5 minutes on alternate days
  4. Week 5-6: Run at half speed on alternate days
  5. Week 6: Gradually return to full activity

XI. Course

  1. Delayed diagnosis is very common
  2. Average time to return to sport
    1. Non-weight bearing cast: 3-4 month
    2. Surgical intervention: 5-6 months

XII. References

  1. Coris (2003) Am Fam Physician 67(1):85-90 [PubMed]
  2. Khan (1994) Sports Med 17:65-76 [PubMed]
  3. Ostlie (2001) J Am Board Fam Pract 14(5):381-5 [PubMed]

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