Joost Peerbooms

45 PRP after total knee arthroplasty the fact that bovine thrombin has been associated years ago with the development of antibodies to thrombin and factor V, which had led to recurrent bleeding in patients who were exposed. 27 Alternatively, the platelets can be activated by autologous thrombin, produced with commercially available thrombin kits. 7, 8 Tsay et al. 23 showed the use of a synthetic peptide that mimics thrombin known as peptide-6 SFLLRN (TRAP). Using the GPS system, the patient’s own platelets (which travel through the bloodstream) can be collected into a highly concentrated formula. We found a slight difference in the haemoglobin drop: 0.16 mmol/L. This is 10 % of the total drop. The mean haemoglobin before operation was 8.6 mmol/L. After operation the haemoglobin in the PG dropped to 7.1 mmol/L and in the control group the haemoglobin dropped to 7.0 mmol/L. This finding is in contrast to an earlier report and might be explained by differences in the technique and methodology. For example, Everts et al. 6 used a PG and fibrin sealant technique, a preparation that differs from our technique. Moreover, their trial included more patients, and the haemoglobin values were scored not only on the first postoperative day (as we did) but also on days 2 to 4 post-surgery and again on the day of hospital discharge. Everts et al. 6 only scored function during the first 5 days and on the day of discharge, whereas we scored function on the first 4 days, and at 2-, 6- and 12-weeks post-surgery. Beneficial effects of concentrated growth factors are said to decrease wound leakage by 25%, minimizing the need for postoperative blood transfusion, decreasing the risk of postoperative infections, and promoting faster functional rehabilitation with less pain. 11, 12 Most reports on PG have discussed its use for healing chronic wounds. 5, 14, 15, 21, 22 To our knowledge, no blinded randomized study has previously been performed. The type of wound dressing is also important. It has been shown that with the use of occlusive dressings both re-epithelialisation and subsequent collagen synthesis are 2-6 times faster than they are in wounds exposed to air. On a cellular level, dressings assist wound healing by creating a hypoxic wound environment wherein fibroblasts proliferate, and angiogenesis occurs more rapidly. 10 The proper timing of dressing removal remains a controversial topic. Studies on clean, and clean contaminated, wounds showed no difference in infections rates according to whether the dressing was removed on the first postoperative day or at the time of suture removal. 4, 20 In our patients, all wounds were dressed with sealed bandages directly after surgery and undressed the second day post-surgery; no beneficial effect of PG was seen. The use of PG has shown good results in difficult to heal wounds and in wounds compared to normal wound treatment. 13, 17, 19 But exogenous applied platelets have no haemostatic effect. Exogenous applied platelets have no haemostatic effect. They have a poor tensile strength to accomplish wound sealing. Altmeppen et al. 3 have shown that an autologous platelet-enriched plasma cannot be used as a glue in the common sense to seal stitches 3