Bone stress injury continuum

 In Running

Bone Stress Injury

Bone stress injuries result from an imbalance between the formation and removal of load induced damage to bone. Bones deform in response to loading, with the amount of deformation (bone strain) dependant on the magnitude of the load applied and the ability of bone to resist deformation. Exercise can create microscopic damage (microdamage), with the threshold for microdamage formation dependant on; number of bone loading/strain cycles, load/strain size (magnitude), and the bone strain rate (speed at which load/strain is applied).

Microdamage serves as a stimulus for targeted remodelling; removal of damaged bone followed by deposit of new bone. This allowed the bone to adapt to changing demands over time; with >loads being tolerated before microdamage occurs. (Brukner & Khan, Clinical Sports Medicine 5th edition).

Pathology Continuum

Normal Remodelling: [Bone resorption = bone formation] (damaged bone removed approx. as fast as it occurs. Changes in loading well tolerated)
Accelerated Remodelling: [Bone resorption > bone formation] (If insufficient time is allowed between bone loading cycles, adaptation does not occur quickly enough, bone damage forms.)
Stress Reaction Grade 1/2/3 – Sliding scales along line [Bone resorption = bone formation] (damaged bone removed approx. as fast as it occurs. Changes in loading well tolerated)
Stress Reaction Grade 2
Stress Reaction Grade 3
Stress Fracture Grade 4: Discernible fracture line on imaging
Fracture + Complete (at end of continuum)

High Risk Bone Stress Injuries

Occur on tension side of bone bending axis:
  • Femoral neck
  • Anterior cortex of tibia
  • Medial Malleolus
  • Talus (lateral process)
  • Navicular
  • 5th Metatarsal (proximal diaphysis)
  • 2nd Metatarsal (base)
  • Big Toe (sesamoids)

Low Risk Bone Stress Injuries

Occur on compression side of bones bending axis:
  • Posteromedial tibia (shin)
  • Fibia/lateral malleolus
  • Femoral shaft
  • Pelvis
  • Calcaneus
  • Diaphysis of 2nd to 4th metatarsals
  • Big Toe (sesamoids)

Bone Stress Injury

 

 

Brad Beer (APAM)
APA Titled Sports & Exercise Physiotherapist (APAM)
B.Physio/ B. Ex. Sc
Author ‘You CAN Run Pain Free!
Founder POGO Physio
Host The Physical Performance Show

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