Our bones make slight changes to their architecture every day. This process is called remodelling and it occurs in response to the pressures and forces we put on our bones. These include the force of gravity, tensile force from our muscles pulling on their bony attachments and ground reaction forces: the impact that occurs up our legs every time we take a step.
When the bone is not strong enough to absorb the amount of force put through it a stress reaction occurs. This is the first sign of a problem in bone structure. It can be easily reversed by decreasing how much load that specific bone has to endure until such time as the body can lay down new architecture to make it sufficiently strong. There is a lag of around seven to 14 days from the time the body detects the need to lay down new bone and the actual change in bone strength. Therefore too much stress through a bone may be due to increasing the frequency of stress, not just the total amount of stress.
Bone stress reactions are common in the leg and foot bones of runners, ribs in rowers, and lower back in cricketers. If they are not managed appropriately they may lead to a stress fracture. Stress fractures occur when the repetitive stress put through the bone is enough to cause damage to the outside covering of the bone. Stress fractures usually require a period of unloading (time wearing a boot, no sport) for the bone to heal followed by a progressive strengthening program to disperse the forces more evenly.
Stress reactions of some certain bones are considered high risk. That is because they take longer to heal and can have deleterious effects if left untreated. They include the navicular bone of the foot, the tibia (shin bone) and the fifth metatarsal. These often require prolonged immobilisation and can lead to further complications so early diagnosis is crucial.
Bone stress reactions and stress fractures are more common in the physically active population and often occur after a sudden change in training. They are slightly more common in females. Bone stress injuries are very tender to touch and worsen very quickly with weight bearing. When running it will usually make the person stop within a few steps and is not something you can “run through”. If you suspect you have a bone stress injury book in with one of our physiotherapists for an accurate diagnosis and a thorough assessment of factors that may be contributing to bone overload. We will then create a management plan to get you back to your desired activity in the shortest time possible.
Written by Stephanie Young