Platelet-rich plasma therapy improved both the pain scores and elbow tenderness for almost three-quarters of patients suffering from tennis elbow during a 6-month randomized, double-blind controlled trial.
This study is the third to show a treatment response with no significant complications in patients with lateral epicondylar tendinopathy, commonly known as tennis elbow, from platelet-rich plasma (PRP) injections.
Dr. Allan Mishra, of Stanford (Calif.) University Medical Center,* and his coinvestigators from eight other institutions presented their findings from the trial at the annual meeting of the American Academy of Orthopaedic Surgeons in Chicago.
The 230 study participants had symptoms for at least 3 months and reported tenderness at the lateral epicondyle and pain scored at a minimum of 50 out of 100 on a visual analog scale during a resisted wrist extension. All participants failed to respond to conventional therapy, including a combination of physical therapy, nonsteroidal anti-inflammatory medications, and/or steroid injections, the investigators reported.
Dr. Mishra and his colleagues used a Biomet GPS centrifuge and canister system to prepare a formulation of 2-3 mL of PRP for 116 patients who received the intervention. The PRP contained concentrated platelets and concentrated white blood cells at a concentration five to six times greater than in plasma at baseline.
Both the patients who received PRP and the 114 active controls were given a local anesthesia block of 0.25% bupivacaine with epinephrine before investigators needled the origin of their extensor tendons, delivering the PRP only to the intervention group.
At 12 weeks’ follow-up, patients receiving the PRP injections reported 55.1% improvement in their pain scores, compared with their baseline pain before the procedure, whereas controls reported 47.4% improvement in pain compared with baseline. The findings were not statistically significant (P = .094). The 12-week secondary outcome measurement was statistically significant, with 37.4% of the intervention group reporting significant elbow tenderness, compared with 48.4% of controls reporting significant tenderness (P = .036).
At 24 weeks, the difference in pain scores between the two groups was statistically significant: PRP patients reported 71.5% improvement, whereas controls reported 56.1% improvement (P = .027). Similarly, significant elbow tenderness remained in 29.1% of PRP patients and 54% of the controls (P less than .001).
The two previous trials, one led by Dr. Mishra with a mean 25.6-month follow-up, and another 2-year study, used the same methodology and PRP system as this one and showed similar improvements, said Dr. Mishra. "Together these studies have treated 350 patients in a prospective, controlled fashion with all of the studies showing superiority when patients are treated with PRP," he said.
However, PRP treatment should not be used as a first-line therapy, he said. "Most patients will respond to conservative treatment such as exercise and rest," Dr. Mishra said. "PRP should, however, be used instead of cortisone for patients who have failed initial treatment."
The investigators noted that there are several potential mechanisms by which the PRP helps improve the pain in tennis elbow. Preclinical studies have shown that PRP can improve cell proliferation and others have shown it improves local blood flow, Dr. Mishra said. "Finally, it may be possible that PRP modifies neurogenic pain receptors and thereby improves clinical outcomes," he said. "More research is clearly needed in this area."
As with the other two studies, no significant complications were reported among the participants in this study, the investigators found. "Importantly, these studies were conducted over the course of a decade with an excellent safety profile for PRP," Dr. Mishra said. "Clinicians and patients can now be confident when using this specific form of PRP to treat chronic tennis elbow."
The study was funded by Biomet Biologics. All authors have received funding from a range of industry sources, including Biomet.
* Correction, 3/28/13: Dr. Mishra's affiliation has been corrected and not all of the investigators were from the same institution.