14 Jun Rest or not Rest – Bone Healing after a Fracture
Written By Megan Hunter
Who hasn’t broken a bone in their body? Traumatic fracture healing might be the most familiar healing process that we will cover in this blog series. Even though you know rest is best for most acute fractures from the cast you may have been stuck in, what happens in the bone during that time and it is magically healed when it comes out of the cast? When an acute fracture occurs the first step is haematoma formation – bleeding caused by the disruption of blood vessels at the fracture site followed by blood clotting forming a “temporary frame” for healing. This also acts as a signal for out inflammatory cell clean up and regeneration crews to come on in.
From day 5 onwards bone cells are recruited to the area and a fibrocartilage network (think scaffolding fibres) is produced to form a temporary structural support – known as a fibrocartilaginous callus or, in colloquial terms, a soft callus. This soft callus can be thought of as the equivalent stage to scar tissue formation in soft tissue injuries. From day 11-28 this soft callus undertakes a process called ossification where the soft callus becomes a hard callus through calcification. However, this hard callus is still “immature bone” and needs to be remodelled into the specific type of bone needed for the area. Remodelling occurs with the stimulation of bone cells called osteocytes, osteoclasts and osteoblasts which balance to “break down” and “build” the bone into the specific structure that is needed. These cells are notoriously known for being stimulated by movement, stress and load.
If we think about the bones in our body, all of them have a different location with a different function and incur a different amount of load. Our body knows how strong a bone needs to be or what structure is needed by the stress and load we put through the body on a day-to-day basis. Therefore, in the remodelling phase – how is our body supposed to know what it is to build if we don’t stress and load it?
So, yes, we all know that rest is best for acute fractures and the amount of time for rest will again depend on the location of the fracture and the general health/ability for the bone to heal within the discussed timeframes. BUT when the cast is removed our bone is not fully healed – it is most of the time in the remodelling phase and needs return to being loaded to complete healing.
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