Wolff’s Law was developed by a brilliant German anatomist and surgeon, Julius Wolff (1836–1902). It states that bone in a healthy person or animal will adapt to the loads under which it is placed. If loading on a bone increases, the bone will remodel itself over time to become stronger to resist that type of loading. The inverse is true as well: if the loading on a bone decreases, the bone will become less dense and weaker due to the lack of the stimulus required for continued remodelling.
Wolff’s law is critical for all physiotherapists to understand, as we need to carefully introduce our patient’s bones (and whole body) to new stress as we provide rehabilitation and recovery from injury. Muay Thai Kick-Boxers quickly learn this principal and savvy fighters often use repeated hits with a block of wood on the tibia (shin-bone) to ensure it becomes harder so it can be used as a powerful weapon and also more resistant to fracture.
It is principals such as Wolff’s Law that make us physios love our job so much – working with the amazing adaptability of the human body – whatever you throw at it, just give it some time and it will handle it! Too often a patient does not give bones adequate recovery from the stress and injury occurs. People sign up for a race or event and train too frequently or too long and do not allow adequate recovery and the bones (and soft tissues) will become painful. This is why beginner runners are the most susceptible to ‘shin splints’, and experienced runners who increase their training quickly are more likely to get stress fractures.
Wolff’s Law also shows that the ‘running is bad for the knees’ mantra is misguided; the bones will adapt to the load of running and become denser, and therefore running will actually help prevent arthritis, rather than promote it. Cyclists are also beginning to understand the importance of Wolff’s Law as many professionals who avoid weight bearing are showing signs of early onset osteopenia and suffering fractures from small falls, so many are incorporating running or walking into their bike training regime.
So, to prevent all types of fractures and osteoarthritis, introduce new stressors to your body in planned, incremented doses, move on your feet and lift some weights. Thanks Dr. Wolff!