Stress Fractures in the Foot

 

Introduction

Stress fractures are the result of microscopic injuries following repeated submaximal trauma. They account for about 10-30 % of all sports injuries and, of these, about 32 % are in the foot with 80-90 % in the second and third metatarsals. The fifth metatarsal, followed by the navicular, calcaneum, sesamoids and talus are the other common stress fracture sites in athletes.

 

Risk factors

  • Repetitive stressful activities like running, jumping, marching, acrobatics or dancing
  • A specific "female athlete triad" (with risk up to 50%) includes:
    • amenorrhea
    • low bone mineral density
    • dietary restraint
  • Clinicians should have a low threshold for further investigations
  • Delay in diagnosis may contribute to non-unions

Stress fractures in the neuropathic foot may lead to sequential fractures of the metatarsal head / neck due to lack of proprioception; non-weight-bearing in a cast is key to manage these fractures.

 

Second (and third) metatarsal

  • 2nd and 3rd rays are stiffer therefore sustain ~90% of metatarsal stress fractures
  • 75% at head / neck junction; usually heal well
  • Proximal fractures seen in ballet dancers or those with TNJ fusions; more prone to non-union

Diagnosis

  • Often difficult to see on initial X rays but apparent later
  • Consider ultrasound or MRI (expensive) if likely to affect management

 

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Treatment

  • Non-operative management: shoe/boot/cast will suffice for the majority
  • Operative management: consider for proximal fractures or painful non-union (delayed presentation)

 

Fifth metatarsal

  • Symptoms / signs:
    • Chronic lateral foot pain
    • Tenderness over the base of the 5th MT exacerbated by inversion
  • Risk factors:
    • Cavo-varus foot and a protruding 5th metatarsal head

Diagnosis

Oblique x-ray / MRI

Torg classification:

  1. fresh fracture
  2. delayed non-union with widening of the fracture line and periosteal reaction and/or sclerosis
  3. established non-union with complete sclerosis of the medullary canal

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Treatment

Non-operative management

  • Mainstay of treatment
  • Check and treat Vitamin D levels

Operative management

  • Indications:
    • Torg II / III
    • Fracture gap >2mm
    • Athletes needing early return to sport
  • Open reduction:
    • intramedullary fixation with a 4.5-6.5mm size screw depending on the canal size
    • tension band wiring is a suitable alternative
    • bone grafting may be helpful
  • Appreciate need for cavo-varus correction; this alone may be curative
  • Check and treat Vitamin D levels
  • Electro-shock wave therapy has shown some positive results

 

Navicular

  • 2nd most common site in the foot
  • Presents with activity-related dorsal pain which improves with rest
  • Clinician awareness is key to diagnosis

Diagnosis

  • Often missed on X rays
  • CT scans or MRI usually required and diagnostic

Treatment

  • 96% healing at 5 weeks with strict non-weight-bearing cast immobilisation (Torg)
  • Partial weight-bearing may lead to displacement and non-union
  • Failure of conservative management may warrant ORIF +/- bone graft
  • Operative intervention has not shown earlier return to sports

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MCQs

Which of these is not an indication for operative intervention for a stress fracture of the base of 5th metatarsal:

  1. Torg type II or III
  2. Gap more than 2 mm
  3. Protruding 5th metatarsal head
  4. Athletes wanting to go back to sports early

Ballet dancers are predisposed to which particular stress fracture:

  1. Base of 5th metatarsal
  2. Navicular
  3. Distal 2nd metatarsal
  4. Proximal 2nd metatarsal

 

References

Welck MJ, Hayes T, Pastides P, Khan W, Rudge B. Stress fractures of the foot and ankle. Injury. 2017 Aug;48(8):1722-1726. doi: 10.1016/j.injury.2015.06.015. Epub 2015 Sep 15. PMID: 26412591

Lee KT, Park YU, Jegal H, Kim KC, Young KW, Kim JS. Factors associated with recurrent fifth metatarsal stress fracture. Foot Ankle Int. 2013 Dec;34(12):1645-53. doi: 10.1177/1071100713507903. Epub 2013 Nov 11. PMID: 24216284

Torg JS. Fractures of the base of the fifth metatarsal distal to the tuberosity. Orthopedics. 1990 Jul;13(7):731-7. PMID: 2197611

Tenforde AS, Sayres LC, Sainani KL, Fredericson M. Evaluating the relationship of calcium and vitamin D in the prevention of stress fracture injuries in the young athlete: a review of the literature. PM R. 2010 Oct;2(10):945-9. doi: 10.1016/j.pmrj.2010.05.006. PMID: 20970764