PRP is platelet rich plasma. The doctor takes blood and spins it to concentrate platelets and the injects it back into the joint(s). It tends to work best when tightening of soft tissues is needed, I have been told. Imaging is required first for that reason- to make sure it is an appropriate treatment with likelihood of working. You pay out of pocket ($1,000+) because insurance considers it experimental even though it is recommended and practiced by mainstream and top hospitals and doctors.

Has your wife seen doctors? PT? Had imaging?