A stress fracture occurs when the bone breaks in a specific point because of repetitive pressure.
Imagine a cylindrical piece of hard plastic that breaks down after repetitive movement was applied to a specific point of that piece. The same thing will happen to bones when a force (pressure from the weight) is applied repeatedly to it. It comes from mechanical engineering: When an applied force to a material exceeds its resistance, there is material fatigue happening, and a breaking point occurs.
A stress fracture is very different from a traumatic fracture where the object or the movement causing the trauma is obvious. Stress fractures in the foot take weeks to develop, and they are not “as angry” as a traumatic fracture. You might have a stress fracture without minimal swelling or without any redness at all, especially at the early stages. Stress fractures are always painful unless you have neuropathy.
Unlike traumatic fractures, stress fractures might not be seen straight away on an x-ray. They can be detected on an ultrasound or using other imaging modalities like scintigraphy.
- Poor bone density or osteoporosis.
- A non progressive increase in weight bearing activities.
- Inadequate shoes that do not provide your foot the shock absorption it needs.
- Type of flooring you work/train on.
- Structure of the foot: The foot has naturally weak points in its bones depending on its architecture:
- Length of the metatarsal bones: This usually needs a weight bearing x-rays to be visualised. Genetics determine the metatarsal bone length, and if it is too long, then that bone is having a lot of pressure and can be subject to fractures.
- When the first metatarsal bone is low, or what we call a plantarflexed first ray, it naturally puts a lot of pressure under the 1st metatarsal head and the sesamoid bones
- If one of the metatarso-phalangeal joints is not working properly (osteo-arthritis or hammer toe or a bunion), the load will automatically be transferred to the next joint, and here we are with too much pressure on one specific bone.
How does it happen?
If you go back to the factors that may cause a stress fracture, multiple scenarios can occur:
– Someone who decides to go back to training without proper preparation (drastic increase in the load). We advise you to seek help from an exercise physiologist if you want to get back to sports after a period of sedentarity.
– Someone who decides to go back to training without proper shoes. We advise you to seek help from a podiatrist to evaluate your shoes and your foot type, to recommend the proper shoes for the exercises you do.
– Someone who is at risk of osteoporosis, and does not address the issue. We recommend you speak to your GP about this subject.
– Someone who did not follow a rehabilitation program by a physiotherapist after he was put in a moon boot.
– Working or training on hard floors with old shoes or with shoes without shock absorption
– Key factors to prevent stress fractures are: know your foot type, that will allow you to understand where the pressure points are naturally.
– Choose the right shoes for your foot type, the ground and the sports you do.
– Always do physiotherapy after you have been immobilised, always!
– Keep an eye on your calcium and vitamin D intake, please discuss this matter with your GP, especially if you are at risk of low bone density or osteoporosis.