Advice from a Certified Hand Therapist: How Do Broken Bones Heal?

Have you ever wondered how a broken bone heals? Broken bones, also called fractures, can heal two different ways.  The two types of bone healing are primary and secondary bone healing.  Secondary bone healing is more common than primary bone healing.

Secondary bone healing occurs when there is slight, controlled motion between the two ends of broken bone during the healing time.   For example, slight motion occurs when the broken bone is set in a cast.  Once the broken bone has been aligned back to its normal position and is placed in a cast, proper healing can begin.

In addition, secondary bone healing progresses through different stages.  The first stage occurs immediately after the fracture.  In this stage, there is swelling and bleeding around the broken bone.  The bleeding then becomes a mass around the break.  This mass is first known as a soft callus and eventually becomes a hard callus.  Once the soft callus becomes hard, the bone is stable.  After a cast is removed, the hard callus is gradually remodeled to normal bone.  This can take up to several years.

Primary bone healing occurs when there is absolutely no movement between the two ends of a broken bone.  The goal of surgery is often to stabilize the bone so that primary healing may occur.  Doctors may use rods, pins, plates, or screws to hold the broken bone together.  This hardware presses the ends of the broken bone together tightly and prevents any movement.  When there is no motion, new bone begins to form immediately across the two ends of broken bone.  In this case, there is no callus that forms around the break.  At first, the hardware holds the break in a very stable position and then new bone grows across the site resulting in a once again normal bone.

Every broken bone is unique.  The decision to cast and allow secondary bone healing to happen or to fix with surgery and allow primary bone healing to happen is made by your doctor.  The ability to realign the pieces of bone and have them stay in a good position for healing will be considered.  Your doctor will also consider the typical activities you are involved in and your health.  With all of these things in mind, your doctor will make a decision that is best for your break and for you so that healing can begin.

Some bones heal quickly and others more slowly.  The speed at which a bone heals depends on the size of the bone, the severity of the break, and the amount of nutrients and blood supply around the bone.  Other things that affect the body’s ability to heal a broken bone are age, general health, and nutrition.  Children tend to heal more quickly than adults do because of the strong tissue around the bone that provides good nutrients for healing.  As people get older, their tissue gradually thins and healing can take longer.  When health issues are present, such as infection or disease, this can also slow the healing process.  A healthy, well-balanced diet will help bone to heal.

X-rays are used to decide if a bone is healed enough to allow use of the injured arm or hand for daily activities.   Once the bone is healed enough for exercise and use, your doctor may send you to a hand therapist to guide you through specific exercises.  With your therapist you will work to gain back your motion, strength, and function.


Courtney Middleton, OTD, OTR/L, CHT, CLT is a certified hand therapist and a member of the American Society of Hand Therapists (ASHT).