Bone stress injuries (BSI) are typically overuse injuries associated with repetitive loading of bone by vigorous weight-bearing activity (such as running/ jogging/ marching) and inadequate recovery.

Dr Rick Seah, Consultant in Sport & Exercise Medicine continues his report on an introduction to bone stress injuries and looks at stress fractures and the risk of non-union:

Risk stratification:

In terms of stratifying risk, it can be useful to divide stress fractures into those at low risk and high risk of developing non-union.

A. Stress fractures at low risk of non-union

  • Femoral neck fractures of the inferior (medial) cortex.
  • Tibial shaft fractures of the posteromedial cortex.
  • Fractures of the distal 2nd to 5th metatarsals.
  • Calcaneal fractures.
  • Fibula fractures.
  • Fractures of the pubic ramus.
  • Cuboid fractures.Cuneiform fracture

B. Stress fractures at high risk of non-union:

  • Femoral neck fractures of the superior cortex.
  • Anterior cortex tibial shaft fractures.
  • Fractures of the 5th metatarsal at the diaphyseal-metaphyseal junction.
  • Navicular fractures.
  • Proximal fractures of the 2nd metatarsal.
  • Talus fractures.
  • Medial malleolus fractures.
  • Sesamoid fractures.

Factors thought to play a role in determining whether a stress fracture is at low or high risk of non-union include the forces exerted across the fracture site (consider compression versus tension) and blood supply (consider good versus poor).

Example of a high-risk stress fracture:

Anterior cortex midshaft tibial stress fractures

These are commoner in jumping athletes, such as dancers. They can be difficult to treat conservatively as they often proceed to delayed union or non-union.

On a lateral X-ray view, it shows up as a ‘dreaded black line(DBL). Further investigation with an MRI or CT scan is helpful.

Initial treatment may be conservative, with a trial of prolonged immobilisation of 3-6 months. This may include electrotherapy modalities such as low-intensity pulse ultrasound (LIPUS) to encourage fracture healing, although recent evidence suggests this may be less beneficial than hoped.

An estimated 60% or more of the patient cohort will subsequently require surgical intervention. Surgical options include excision of the lesion with bone grafting and insertion of an intramedullary rod into the tibia.

Postoperative physiotherapy rehabilitation is indicated, with recovery often taking many months. In high-level athletes, this has the potential to be a career-ending injury. Early detection and accurate diagnosis is therefore vital in preventing the injury from propagating.

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