medpageTODAY.com—February 18, 2011
Platelet-rich plasma (PRP), whether injected or incorporated into fibrin matrix implants, did not promote recovery from tendon injuries, according to several studies presented here.
In two randomized trials of platelet-rich fibrin matrix (PRFM) implants to augment arthroscopic repair of rotator cuff tears, no benefit from the treatment could be discerned in clinical or imaging-based evaluations.
Scott Rodeo, MD, of Hospital for Special Surgery in New York City, who was lead investigator in one of the rotator cuff studies, said during a media briefing that the balance of evidence was tilting against PRP-based treatments for such injuries.
PRP is an autologous product in which a patients' blood is centrifuged to isolate platelets, which are then returned to the plasma for reinfusion. Alternatively, the platelets can be impregnated into a fibrin matrix -- essentially a blood clot minus the red cells, also autologous -- which is more solid and therefore amenable to fixation at an injury site.
Rodeo did point out, however, that the studies conducted to date all had substantial limitations, and therefore the possibility of benefit for some patients can't be ruled out.
"I think there's something there," he said. "There's enough data out there to suggest that it has, and can have, a positive role in degenerative tendon and maybe even in cartilage. The problem now is that there's such variability in the types of preparations of PRP that are out there."
As Rodeo explained, platelets are far more than blood coagulation agents. "There are 1,100 proteins in platelets," he said.
These include growth factors that promote cell proliferation as well as chemotactic factors for recruiting progenitor cells that can form the basis for new tissue.
Some earlier studies had found that PRP or PRFM implants increased healing rates in patients. But the studies reported here did not support those findings.
Rodeo's colleague Demetris Delos, MD, also of Hospital for Special Surgery, presented results of a 67-patient randomized trial of PRFM in patients with rotator cuff tears.
Patients were assigned to receive a PRFM implant or not during arthroscopic repair of their injuries. Evaluations were performed periodically for one year, including clinical exams for such factors as muscle strength and tendon stability, along with ultrasonography to visualize the injury site and assess vascularity.
There were no significant differences between the study groups in any outcome measure, Delos reported.
The primary endpoint, ultrasound-confirmed repair integrity, was met by 67% of patients receiving the PRFM versus 81% of the control group (P=0.198).
Subgroup analysis indicated that other factors such as tear size, type of repair, or preoperative platelet counts did not affect outcomes.
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