What would be the best method to advance a persons natural healing to heal sports injuries using ki?

My research has lead me to Rei Ki, a japanese art of healing using external ki from a persons surrounding environment, but nowhere did I find any information on healing a specific injury. Rei Ki was always used for general well being.
I also discovered a method of internal ki healing which was to use the mind to channel/focus your concentration on a particular point on your body and to guide your energy there through meditation to create a desired Effect, (where as in Rei Ki, one is not suppose to visualise a desired effect but hope the energy gained will help)
Is it appropriate to use Rei Ki to heal a particular injury, i.e. a broken arm, and how does it exactly work?
OR
Is it more apropriate to use internal Ki in this situation?
And can you hurt yourself with Rei Ki if you dont fully understand the concepts?