Platelet-rich plasma (PRP) has been used clinically for its potentially enhanced soft-tissue healing properties. These healing properties, which stem from its derivation from autologous blood, have been attributed to the increased concentrations of growth factors and secretory proteins. PRP thereby hopefully enhances the recruitment, proliferation, and differentiation of cells involved in tissue regeneration1,2.
The majority of orthopaedic applications for PRP can be classified into four groups: chronic tendinopathies, acute ligamentous injuries, muscle injuries, and intraoperative augmentation2. As noted by Hall et al.1, several PRP preparation systems are commercially available. The volume of autologous blood, centrifugation rate and time, delivery method, activating agent, leukocyte concentration, final PRP volume, and final platelet and growth factor concentrations vary among these systems. Hematologic variations between patients (e.g., leukocyte count and platelet count) may also affect the final PRP preparation. Debate continues regarding the optimal quantity of platelets and growth factors required for muscle and tendon-healing1.
In this study, the authors evaluated their results of single-row arthroscopic repair of large posterosuperior rotator cuff tears in eighty consecutive patients. Group-I patients had a platelet-leukocyte membrane placed under the repaired rotator cuff, whereas group-II patients did not. Constant scores and magnetic resonance imaging (MRI) were used to evaluate the patients at a mean follow-up of thirteen months. Retears of the repaired rotator cuff were observed only in group-II patients. A thin but intact tendon was observed more frequently in this group as well. The authors concluded that the use of the membrane was associated with significantly better rotator cuff repair integrity (p = 0.04). However, only three of thirty-seven group-II patients were noted to have a retear of the rotator cuff repair compared with no retears in thirty-nine group-I patients.
The authors are to be commended on their attempt to determine, by means of a well-designed randomized controlled trial, whether PRP has a role in augmenting rotator cuff repairs. As the authors conclude, the use of platelet-leukocyte membrane led to a slight improvement in the repair of large tears involving the supraspinatus tendon, although this improvement was not associated with a better functional outcome.
The authors do discuss some of the limitations of their study, including a short follow-up of thirteen months and a significant (p = 0.02) difference in age between the two groups (sixty years in group I compared with sixty-three years in group II). In contrast to previous studies reporting high rotator cuff retear rates, the authors believe that the relative scarcity of recurrent tears in both groups could be attributed to the short duration of follow-up and the fact that their study did not enroll patients with massive tears.
Castricini et al.3 reported the results of a randomized controlled trial of eighty patients with arthroscopic double-row repair of small and medium-size rotator cuff tears. A platelet-rich fibrin matrix (PRFM) was also placed under the supraspinatus tendon at the time of rotator cuff repair. At sixteen months postoperatively, the authors found no significant difference in total Constant scores or MRI-based tendon scores between rotator cuff repairs treated with and without augmentation with autologous PRFM. Their study did not support the use of autologous PRFM to improve tendon-healing of small to medium-size rotator cuff tears.
Randelli et al.4 reported an uncontrolled pilot study of fourteen patients with arthroscopically repaired rotator cuff tears. PRP was injected with thrombin into the rotator cuff footprint after the rotator cuff repair had been performed. They found that all patients had significant improvements from the preoperative to the postoperative VAS (visual analog scale) pain, Constant, and UCLA (University of California Los Angeles) shoulder scores at a mean of two years of follow-up.
Several factors still need to be elucidated, including the appropriate timing of PRP injections; optimal activation of PRP; optimal growth factor, platelet, and leukocyte concentrations; evaluation of a possible acute inflammatory response following use of PRP injection; and concerns regarding the use of PRP injection in athletes subject to anti-doping regulations1,2.
In view of the contrasting findings reported in these limited studies of PRP use, further clinical trials will be needed to justify the increases in cost and surgical time associated with this technology.