Regeneration of the Patellar Tendon After Harvesting Its Central Third With Platelet-rich Plasma. Prospective and Randomized Study.

The central third of the patellar tendon is used as a donor site for anterior cruciate ligament (ACL) reconstruction. After months or years the harvest site partially regenerates. The regeneration process is accomplished by biological mechanisms,including cells and proteins known as growth factors. The platelets are natural reservoirs of growth factors, and a platelet concentrate known as Platelet-Rich Plasma (PRP) has a three to five fold increase in growth factors. The hypothesis of the study is that the PRP can improve the regeneration of the patellar tendon.

The platelets are obtained from the patient's blood through a filtration system called apheresis, with the use of 250 milliliters of blood, with a sterile system. All the others components of blood (red cells, plasma, white cells) returns to the patient. The PRP is then applied in the harvest site on the patellar tendon, at the end of ACL reconstruction.

The patients are randomized in two groups, one with the use of PRP and the other group without PRP. This information for the patients will be granted just at the end of the research. After the surgery the rehabilitation protocol is the same for both groups. An isokinetic testing is done before the surgery and after six months. Questionnaires about the knee function are asked before the surgery and after six months. A magnetic resonance imaging is performed after six months to evaluate the tendon regeneration.