A study was done from Italy demonstrating clinical improvement in 16/20 male athletes who received a series of 3 prp injctions at 15 day intervals. They were followed up at 6 months. Interestingly 3 out of the 4 patients who failed to improve did not comply with the stretching & strengthening protocol following the injections.
Patellar tendinosis is a challenging condition because of poor blood supply, oxygen, & a lack of nutrition. Over half of athletes are forced to retire, & many continue to have pain after their retirement.
This speaks to the importance of post injection rehabilitation. I learned this firsthand after I tore my own Medial collateral Ligament in my knee after a surfing lesson.
I received a PRP injection and the rehab clearly accelerated the recovery process.