Wolff's Law - Definition in Physical Therapy

This is How Your Bones Heal

Photo of physical therapist assessing ankle mobility.
Wolff's law can help your PT prescribe the right treatment after a fracture. Jeannot Olivet/Getty Images


Wolff’s Law states that bone grows and remodels in response to the forces that are placed upon it. After injury to bone, placing specific stress in specific directions to the bone can help it remodel and become normal healthy bone again. Your physical therapist should understand Wolff's law to help guide your rehabilitation after a fracture or broken bone.

How Does Wolff's Law Apply to Physical Therapy

Wolff’s Law applies to physical therapy in the treatment of osteoporosis and after a fracture.

If you have osteoporosis, your bones may be brittle and weak. This can lead to pathologic fracture, most commonly in the spine or hip. Weight-bearing and strength exercises are usually recommended as a non-medicinal treatment for osteoporosis.

If you have suffered a fracture, bone healing occurs while you have been immobilized with a cast or splint. After immobilization, gentle range of motion and stress can help improve the overall strength of your bone. This can help ensure that your bone is able to tolerate the loads and stresses that you may encounter during normal functional activities.

Safely Apply Stress to Your Bones

In physical therapy, the single best way to increase stress through your bones is with exercise. But after a fracture, your bones may not be able to tolerate vigorous exercise; too much stress during the healing process can actually re-injure your broken bone. That is why you typically wear a cast or brace after a fracture.

You must protect your fractured bone as it heals.

But what if you have been immobilized in a cast or sling after a fracture? How can you safely start applying the right stress to your injured bone to promote optimal healing? That's where the skilled services of your physical therapist come in.

Your PT can help guide you by prescribing the right exercises for you to do that will add a gradual and progressive stress to your injured bone.

For example, after an ankle fracture, your doctor may order that you remain non-weight bearing for a few weeks immediately after the injury. During this time, there may be some benefit of early mobilization for your ankle. Your physical therapist can prescribe safe exercises that you can do that will place gentle stress through your bone while helping you maintain mobility.

Once some healing has taken place after your fracture, your PT can help progress that amount of stress through your healing bone. He or she can prescribe partial weight bearing exercises and help you progress them to full weight bearing exercises. By controlling this progression, your PT can ensure that you safely return to optimal function quickly and safely.

Although your physical therapist may not talk with you about Wolff's Law, the basic tenets of the law help guide your rehab. 

Your physical therapist can help you with strategies to start applying stress to your bone after injury and fracture or if you have osteoporosis. This can ensure that proper healing takes place and that you return to normal function quickly and safely.

A Word from Verywell

A broken bone can be a painful and scary experience. It may leave you feeling like basic functional tasks are difficult.

Your physical therapist is an expert in helping you regain mobility after a fracture. One important rule to follow during your rehab is Wolff's Law: bones grow and remodel in response to the stress you put upon them. A well-rounded PT and rehab program can ensure you get back to your normal lifestyle quickly and safely.

Pronunciation: (woolfs law)

Common Misspellings: Wolf's Law

Source: Teichtahl, AJ, etal. Wolff’s law in action: a mechanism for early knee osteoarthritis. Arthritis Research & Therapy. 2015; 17:207.