I would not recommend using stem cells at this time for the injury you are describing. There are many issues to consider with this question. I would recommend that you speak to your primary care doctor
for more information and potential treatment options. If needed, an orthopedic surgeon
can be consulted to help surgically repair the knee, however starting with your primary doctor would be advisable.
The first question to answer is what the knee problem is. That is, what is your cause of knee pain. Your doctor can help investigate this. Different causes of knee pain (if it is the bone, joint, muscle or nerve) are all treated differently and knowing the exact cause is important. Your doctor may choose to do an x-ray or MRI of the knee for more information.
Once the diagnosis is known, there are many possible treatments. Medicines can often be helpful. Physical therapy, to strengthen the area can also work. Sometimes surgery
Stem cell research is a developing science -- but currently has no proven benefit or indication. It should not be used at this time as we do not know if it is effective or safe. Try a more standard approach first.
I would recommend that you see your doctor. Good luck!