Sports Medicine Research: In the Lab & In the Field: Exercise May Promote Bone Healing (Sports Med Res)


Sunday, February 6, 2011

Exercise May Promote Bone Healing

Exercise Enhances Angiogenesis During Bone Defect Healing in Mice

Holstein JH, Becker SC, Fiedler M, Scheuer C, Garcia P, Histing T, Klein M, Pohlemann T, Menger MD. J Orthop Res. 2011 Jan 21. doi: 10.1002/jor.21352. [Epub ahead of print]

Many clinicians have adopted the concept that while a patient has a musculoskeletal injury it is important to exercise the rest of the body to avoid detraining. We’ve also seen research suggesting that strengthening a limb can prevent muscle atrophy on the other limb. The authors in this animal study provide further support to the notion that patients should exercise the rest of their body when they experience a fracture. They evaluated adult mice to determine whether physical exercise affects the formation of new blood vessels during bone repair. The researchers divided the mice into two groups: a group with a running wheel and one without (they also recorded how much the animals ran). A circular bone defect was made in a cranial bone (so it is not the same mechanism as a typical fracture and it is a flat bone rather than a long bone like the radius). The group that exercised had faster bone healing and larger blood vessel diameters than the control animals. The authors suggest that this supports the idea that physical activity, in the absence of mechanical loading, promotes bone healing and new blood vessel formation in the injured bone.

There are some obvious limitations to applying this study to humans that suffer long bone fractures: 1) mice were studied for only a few days, 2) the bone trauma is not like traditional fractures, and 3) flat bones were injured rather than long bones. The authors suggest, however, that this data may be applicable to long bone healing. More research is needed to verify these claims but this is further evidence that we should encourage our patients to participate in safe physical activity while injured; just because one limb or joint is injured doesn’t mean the rest of the body has to sit idle. Properly supervised exercises may help minimize detraining, promote positive psychosocial benefits, and promote fracture healing.

Written by: Jeffrey Driban
Reviewed by: Stephen Thomas


Stephen J. Thomas, PhD, ATC said...

Basically this model produced an intramembraous ossification process because it was a stable fx. How do you think this will transition into an endochondral ossification when it is more of an unstable fx?

Jeffrey B. Driban, PhD, ATC, CSCS said...

Steve, interesting question. You are right that this model was based on intramembranous ossification. Typical long bones heal with both intramembranous and endochondral ossifications. The authors believe that their data can be applied to long bone healing but you raise some other interesting concerns:

1. The fracture in this study was very stable unlike many of the fractures we see in long bone fractures. We may want the patient to be physically active early on but we do NOT want the fracture site moving or being unstable (this can cause various healing issues). Example: A safe activity for a person with a distal radius fracture may be the stationary bike (we benefit from the physical activity without applying stress to the healing bone). In the end, this decision requires a team approach to evaluate the fracture stability, stage of healing, and optimal selection of exercises.

2. The other thing to keep in mind is that this study looked at the early phases of bone healing. Therefore, we can't say for sure that this study's findings will apply later in the healing process when we often start being more proactive with our patients' exercises.

If we did not already have plenty of reasons to encourage our patients to be physically active while injured this study would not be enough to influence our clinical decisions (more research would be needed). However, we have a lot of research literature that discusses the benefits of physical activity while injured. This study provides further support for our decisions. But you raise the excellent point that we may want the patient to be physically active but never at the expense of the healing tissue.

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