Los Angeles Lakers guard Kobe Bryant underwent an experimental but increasingly popular procedure last month in Germany in an attempt to help heal his oft-injured right knee, a source confirmed to ESPNLosAngeles.com Thursday night.

The procedure, called platelet-rich plasma therapy, consists of centrifuging the patient's blood to isolate platelets and growth factors. The mix is then injected into the injured area to accelerate healing. The concentrated growth factors have been shown to speed tissue growth and healing in surgically created lesions in lab animals.

Golfer Tiger Woods, New York Giants defensive tackle Chris Canty and Philadelphia Phillies pitcher Cliff Lee also reportedly have undergone the treatment.

However, a number of recent studies disputes the effectiveness of the treatment. The New York Times cited a study by Dr. Leon Creaney in the British Journal of Sports Medicine in which patients treated with injections of whole blood for tennis elbow had better outcomes than those treated with PRP therapy after six months.

Another study conducted by doctors in the Netherlands that was printed in the British Journal of Sports Medicine and cited by the Times examined patients treated for Achilles tendinitis with PRP therapy versus a placebo of saline solution. There was no statistical difference in healing between the two groups after six months.

It makes sense, however, that Bryant would try the therapy. He already had surgery in July 2010 to remove bone fragments from the knee, the third procedure on the joint. In January, he said his knee was "almost bone-on-bone."

Because the minimally invasive surgery has a short recovery time and does not restrict movement, there is little downside to seeing if it improves healing in the knee.

The Lakers' leading scorer saw his minutes and productivity decline in 2010-11. He was barely able to practice all season as a result of the knee injury. Bryant has said much of this summer would be dedicated to allowing his body to recover.

The Los Angeles Times first reported that Bryant underwent the procedure. Bryant was not available for comment, and it is not clear why the treatment was done in Germany.